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Sample records for optical alignment techniques

  1. Innovative optical alignment technique for CMP wafers

    NASA Astrophysics Data System (ADS)

    Sugaya, Ayako; Kanaya, Yuho; Nakajima, Shinichi; Nagayama, Tadashi; Shiraishi, Naomasa

    2002-07-01

    Detecting position of the wafers such as after CMP process is critical theme of current and forthcoming IC manufacturing. The alignment system must be with high accuracy for any process. To satisfy such requirements, we have studied and analyzed factors that have made alignment difficult. From the result of the studies, we have developed new optical alignment techniques which improve the accuracy of FIA (alignment sensor of Nikon's NSR series) and examined them. The approaches are optimizing the focus position, developing an advanced algorithm for position detection, and selecting a suitable mark design. For experiment, we have developed the special wafers that make it possible to evaluate the influence of CMP processes. The experimental results show that the overlay errors decrease dramatically with the new alignment techniques. FIA with these new techniques will be much accurate and suitable alignment sensor for CMP and other processes of future generation ULSI production.

  2. Passive alignment and soldering technique for optical components

    NASA Astrophysics Data System (ADS)

    Faidel, Heinrich; Gronloh, Bastian; Winzen, Matthias; Liermann, Erik; Esser, Dominik; Morasch, Valentin; Luttmann, Jörg; Leers, Michael; Hoffmann, Dieter

    2012-03-01

    The passive-alignment-packaging technique presented in this work provides a method for mounting tolerance-insensitive optical components e.g. non-linear crystals by means of mechanical stops. The requested tolerances for the angle deviation are +/-100 μrad and for the position tolerance +/-100 μm. Only the angle tolerances were investigated, because they are more critical. The measurements were carried out with an autocollimator. Fused silica components were used for test series. A solder investigation was carried out. Different types of solder were tested. Due to good solderability on air and low induced stress in optical components, Sn based solders were indicated as the most suitable solders. In addition several concepts of reflow soldering configuration were realized. In the first iteration a system with only the alignment of the yaw angle was implemented. The deviation for all materials after the thermal and mechanical cycling was within the tolerances. The solderability of BBO and LBO crystals was investigated and concepts for mounting were developed.

  3. 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.

  4. In situ focus characterization by ablation technique to enable optics alignment at an XUV FEL source

    SciTech Connect

    Gerasimova, N.; Dziarzhytski, S.; Weigelt, H.; Chalupsky, J.; Hajkova, V.; Vysin, L.; Juha, L.

    2013-06-15

    In situ focus characterization is demonstrated by working at an extreme ultraviolet (XUV) free-electron laser source using ablation technique. Design of the instrument reported here allows reaching a few micrometres resolution along with keeping the ultrahigh vacuum conditions and ensures high-contrast visibility of ablative imprints on optically transparent samples, e.g., PMMA. This enables on-line monitoring of the beam profile changes and thus makes possible in situ alignment of the XUV focusing optics. A good agreement between focal characterizations retrieved from in situ inspection of ablative imprints contours and from well-established accurate ex situ analysis with Nomarski microscope has been observed for a typical micro-focus experiment.

  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. Optics Alignment Panel

    NASA Technical Reports Server (NTRS)

    Schroeder, Daniel J.

    1992-01-01

    The Optics Alignment Panel (OAP) was commissioned by the HST Science Working Group to determine the optimum alignment of the OTA optics. The goal was to find the position of the secondary mirror (SM) for which there is no coma or astigmatism in the camera images due to misaligned optics, either tilt or decenter. The despace position was reviewed of the SM and the optimum focus was sought. The results of these efforts are as follows: (1) the best estimate of the aligned position of the SM in the notation of HDOS is (DZ,DY,TZ,TY) = (+248 microns, +8 microns, +53 arcsec, -79 arcsec), and (2) the best focus, defined to be that despace which maximizes the fractional energy at 486 nm in a 0.1 arcsec radius of a stellar image, is 12.2 mm beyond paraxial focus. The data leading to these conclusions, and the estimated uncertainties in the final results, are presented.

  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. Fast DNA sequence alignment using optical computing

    SciTech Connect

    Yee, M.L.; Craft, D.C.

    1996-11-01

    Alignment of DNA sequences is a necessary step prior to comparison of sequence data. High-speed alignment is needed due to the large size of DNA databases. Correlation, a standard pattern recognition technique, can be used to perform alignment. Correlation can be performed rapidly using optical techniques. Thus, optical correlation offers the potential for high-speed processing of DNA sequence data. This report describes research efforts to apply one-dimensional acousto-optical correlation methods to the problem of DNA sequence alignment. Experimental results are presented.

  10. 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.

  11. 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.

  12. Systematic Image Based Optical Alignment and Tensegrity

    NASA Technical Reports Server (NTRS)

    Zeiders, Glenn W.; Montgomery, Edward E, IV (Technical Monitor)

    2001-01-01

    This presentation will review the objectives and current status of two Small Business Innovative Research being performed by the Sirius Group, under the direction of MSFC. They all relate to the development of advanced optical systems technologies for automated segmented mirror alignment techniques and fundamental design methodologies for ultralight structures. These are important to future astronomical missions in space.

  13. Optical alignments of the Cosmic Background Explorer (COBE) observatory

    NASA Technical Reports Server (NTRS)

    Sampler, Henry P.

    1990-01-01

    The angular alignments and stabilities of multiple components in a single coordinate system were determined using various alignment tooling techniques. These techniques use autocollimation measurements with a first order theodolite and transformation of coordinates to determine the relative alignment between various components with respect to a common set of COBE spacecraft coordinate axes. Optical-mechanical alignment techniques were also used to integrate the flight COBE observatory attitude control system module that consists of gyros, reaction wheels, and a momentum wheel. Particular attention is given to the techniques for alignments and stabilities of the earth scanners, sun sensors, far IR absolute spectrophotometer, Diffuse Infrared Background Experiment, and differential microwave radiometer antenna horn boresights.

  14. 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.

  15. 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.

  16. Self-Illuminating Optical Alignment Target

    NASA Technical Reports Server (NTRS)

    Ashcraft, Carl D.; Trenn, David A.

    1996-01-01

    Optoelectronic instrument designed for use as self-illuminating optical alignment target. Called "fiber-optic remote target" (FORT), instrument facilitates and accelerates optical alignment by providing small, bright reference spot of light easily visible, without having to supply illumination from external source, without concern for shadowing, and without need for antiglare adjustments.

  17. 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 methodology showing how it is possible to reduce complex alignment directions into a simplified set of instructions for layman service engineers.

  18. 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.

  19. Optical alignment Proceedings of the Seminar, San Diego, CA, July 29-31, 1980

    SciTech Connect

    Shagam, R.N.; Sweatt, W.C.

    1980-01-01

    Topics discussed include alignment methods and techniques, alignment instrumentation, astronomical and spacecraft instrumentation alignment, and laser system alignment. Papers are presented on the interferometric alignment of multielement optical systems and on electronic autocollimators, the centration of a linear cone to the optical axis of a reflaxicon, and the evolution of Shiva laser alignment systems. Attention is also given to the alignment of off-axis aspheric surfaces, the boresighting of airborne laser designator systems, an alignment design for a cryogenic telescope, and an alignment and focusing device for a multibeam laser system.

  20. Accurate laboratory boresight alignment of transmitter/receiver optical axes

    NASA Astrophysics Data System (ADS)

    Martinek, Stephen J.

    1986-01-01

    An apparatus and procedure for the boresight alignment of the transmitter and receiver optical axes of a laser radar system are described. This accurate technique is applicable to both shared and dual aperture systems. A laser autostigmatic cube interferometer (LACI) is utilized to align a paraboloid in autocollimation. The LACI pinhole located at the paraboloid center of curvature becomes the far field receiver track and transmit reference point when illuminated by the transmit beam via a fiber optic pick-off/delay line. Boresight alignment accuracy better than 20 microrad is achievable.

  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. Magnetic and optical properties of Mn-doped ZnO vertically aligned nanorods synthesized by hydrothermal technique

    NASA Astrophysics Data System (ADS)

    Panda, J.; Sasmal, I.; Nath, T. K.

    2016-03-01

    In this paper we have reported the synthesis of high quality vertically aligned undoped and Mn-doped ZnO single crystalline nanorods arrays on Si (100) substrates using two steps process, namely, initial slow seed layer formation followed by solution growth employing wet chemical hydrothermal method. The shapes of the as grown single crystalline nanorods are hexagonal. The diameter and length of the as grown undoped ZnO nanorods varies in the range of 80-150 nm and 1.0 - 1.4 μm, respectively. Along with the lattice parameters of the hexagonal crystal structure, the diameter and length of Mn doped ZnO nanorods are found to increase slightly as compared to the undoped ZnO nanorods. The X-ray photoelectron spectroscopy confirms the presence of Mn atoms in Mn2+ state in the single crystalline ZnO nanorods. The recorded photoluminescence spectrum contains two emissions peaks having UV exciton emissions along with a green-yellow emission. The green-yellow emissions provide the evidence of singly ionized oxygen vacancies. The magnetic field dependent magnetization measurements [M (H)] and zero field cooled (ZFC) and field cooled (FC) magnetization [M(T)] measurements have been carried out at different isothermal conditions in the temperature range of 5-300 K. The Mn doped ZnO nanorods clearly show room temperature ferromagnetic ordering near room temperature down to 5 K. The observed magnetization may be attributed to the long range ferromagnetic interaction between bound magnetic polarons led by singly charged oxygen vacancies.

  3. State estimation in optical system alignment using monochromatic beam imaging

    NASA Astrophysics Data System (ADS)

    Fang, Joyce; Savransky, Dmitry

    2015-09-01

    Automated alignment of optical systems saves the time and energy needed for manual alignment and is required in cases where manual intervention is impossible. This research discusses the state estimation of the misalignment of a reimaging system using a focal plane sensor. We control two moving lenses to achieve high precision alignments by feeding back state estimates calculated from images from a CCD camera. We perform a Principal Component Analysis (PCA) on a simulated data set. The monochromatic images are decoupled into Karhunen- Love (KL) modes, which are used as the measurement in state estimation. An Extended Kalman filter (EKF) is used to estimate the misalignment of the optical components, and we describe a closed-loop control system with monochromatic beam to demonstrate the performance of the state estimation process. The state and measurement residuals converge with the Kalman observer. The automated alignment technique can be extended to reconfigurable systems with multiple lenses and other optical components.

  4. Projection moire alignment technique for mix and match lithographic system

    NASA Astrophysics Data System (ADS)

    Sugimoto, Dai; Kimura, Seiichiro; Eishima, Masami; Nomura, Tsutomu; Uchida, Yoshiyuki; Hattori, Shuzo

    1990-05-01

    Projection moire alignment is a highly useful technique for mix and match lithographic system. The same alignment marks are used for both photo and X-ray photolithography and high sensitivity is obtained using simple alignment optics. This paper deals with a projection moire alignment system which applies to a g-line or i-line stepper that is part of a mix and match lithographic system. A He-Ne laser is used as the light for alignment. By using two pairs of gratings which are 1/2 grating pitch out of phase with each other, we obtain two moire signals which are also 1/2 grating pitch out of phase. Using difference of these two moire signals, high sensitivity is obtained. In order to achieve high overlay accuracy in automatic alignment, it is important to consider the shape of the alignment marks. Asymmetrical resist coverage caused by spin coating causes an offset error and in case of aluminum coated wafers, a rough surface causes a random error. Some defects in the gratings caused during etching process also produce error. For the purpose of analyzing some effects of alignment marks on projection moire alignment, we calculated alignment error using Fresnel diffraction integral. We obtained the following results. An aberration method using reflected light from wafer marks is useful for rough surfaces. Defects in a grating are eliminated by average effects. And we calculated an alignment error caused by wafer tilt. By tilting 5 second to 10 second, output waves become asymmetry and contrast is reduced. Tilt of 5 sec. makes an alignment error of about 0.03 tm.

  5. HETDEX: Optical Alignment Of The Virus Spectrographs

    NASA Astrophysics Data System (ADS)

    Martin, Emily; Marshall, J.; Rheault, J.; DePoy, D.; Prochaska, T.; Allen, R.; Hill, G.; HETDEX Collaboration

    2012-01-01

    We present an optical alignment procedure for the Visible Integral-Field Replicable Unit Spectrograph (VIRUS) collimator. Texas A&M is helping to build the VIRUS spectrographs, designed in collaboration with The University of Texas at Austin. The Hobby Eberly Telescope Dark Energy Experiment (HETDEX) will use as many as 192 units of this instrument to search for answers regarding Dark Energy. Texas A&M is currently assembling the collimators for VIRUS and designing alignment fixtures to aid in the assembly. We used ZEMAX models of VIRUS optics made by UT engineers to analyze various alignment methods we have considered. Our current plan uses two steps to properly align the collimator within the tolerance of 0.1-degrees. This will permit interchangeability among the various VIRUS parts.

  6. Smart and precise alignment of optical systems

    NASA Astrophysics Data System (ADS)

    Langehanenberg, Patrik; Heinisch, Josef; Stickler, Daniel

    2013-09-01

    For the assembly of any kind of optical systems the precise centration of every single element is of particular importance. Classically the precise alignment of optical components is based on the precise centering of all components to an external axis (usually a high-precision rotary spindle axis). Main drawback of this timeconsuming process is that it is significantly sensitive to misalignments of the reference (e.g. the housing) axis. In order to facilitate process in this contribution we present a novel alignment strategy for the TRIOPTICS OptiCentric® instrument family that directly aligns two elements with respect to each other by measuring the first element's axis and using this axis as alignment reference without the detour of considering an external reference. According to the optical design any axis in the system can be chosen as target axis. In case of the alignment to a barrel this axis is measured by using a distance sensor (e.g., the classically used dial indicator). Instead of fine alignment the obtained data is used for the calculation of its orientation within the setup. Alternatively, the axis of an optical element (single lens or group of lenses) whose orientation is measured with the standard OptiCentric MultiLens concept can be used as a reference. In the instrument's software the decentering of the adjusting element to the calculated axis is displayed in realtime and indicated by a target mark that can be used for the manual alignment. In addition, the obtained information can also be applied for active and fully automated alignment of lens assemblies with the help of motorized actuators.

  7. High precision geometrical characterization and alignment of miniaturized optics

    NASA Astrophysics Data System (ADS)

    Langehanenberg, Patrik; Heinisch, Josef; Dumitrescu, Eugen

    2012-03-01

    Miniaturized optical systems like endoscopy or cell phone lenses systems comprise several optical elements like lenses, doublets and plane optics. To receive a good imaging quality the distances and angles between the different optical elements have to be as accurate as possible. In the first step we will describe how the distances and angles between different elements can be monitored and finally we will describe a technique to actively align small optics (diameter approx. 1mm and smaller) with respect to each other. For the measurement electronic autocollimators combined with white-light-interferometers are used. The electronic autocollimator reveals the exact centration errors between optical elements and the low coherence interferometer reveals the distances between surfaces. The accuracy of the centration error measurement is in the range of 0.1μm and the accuracy of the distance measurement is 1μm. Both methods can be applied to assembled multi-element optics. That means geometrical positions of all single surfaces of the final optical system can be analysed without loss of information. Both measurement techniques complement one another. Once the exact x,y,z - Position of each optical surface and element is known computer controlled actuators will be used to improve the alignment of the optics. For this purpose we use piezo-electric-actuators. This method had been applied to cement e.g. doublets for endoscope optics. In this case the optical axis of one lens has been aligned with respect to the optical axis of a second reference lens. Traditional techniques usually rely on an uncertain mechanical reference.

  8. Optical alignment of the Global Precipitation Measurements (GPM) star trackers

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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 autocollimation 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.

  9. 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.

  10. 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.

  11. Corrective optics space telescope axial replacement alignment system

    NASA Astrophysics Data System (ADS)

    Slusher, Robert B.; Satter, Michael J.; Kaplan, Michael L.; Martella, Mark A.; Freymiller, Ed D.; Buzzetta, Victor

    1993-10-01

    To facilitate the accurate placement and alignment of the corrective optics space telescope axial replacement (COSTAR) structure, mechanisms, and optics, the COSTAR Alignment System (CAS) has been designed and assembled. It consists of a 20-foot optical bench, support structures for holding and aligning the COSTAR instrument at various stages of assembly, a focal plane target fixture (FPTF) providing an accurate reference to the as-built Hubble Space Telescope (HST) focal plane, two alignment translation stages with interchangeable alignment telescopes and alignment lasers, and a Zygo Mark IV interferometer with a reference sphere custom designed to allow accurate double-pass operation of the COSTAR correction optics. The system is used to align the fixed optical bench (FOB), the track, the deployable optical bench (DOB), the mechanisms, and the optics to ensure that the correction mirrors are all located in the required positions and orientations on-orbit after deployment. In this paper, the layout of the CAS is presented and the various alignment operations are listed along with the relevant alignment requirements. In addition, calibration of the necessary support structure elements and alignment aids is described, including the two-axis translation stages, the latch positions, the FPTF, and the COSTAR-mounted alignment cubes.

  12. 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.

  13. Alignment of vacuum feed stations on the Navy Prototype Optical Interferometer

    NASA Astrophysics Data System (ADS)

    Clark, James H., III; Murphy, James; Ha, Long; Walton, Joshua P.; Howard, James; Armstrong, J. T.; Gilbreath, G. C.; Hindsley, Robert B.; Pauls, Thomas A.

    2004-10-01

    At the Navy Prototype Optical Interferometer (NPOI) we have developed a two-stage method for preparation and installation of the optical feed relay stations (elevators). This method reduces contamination, increases consistency, and allows greater management in testing and upgrades. In stage one, we prepare a pre-alignment facility in a laboratory. Using this facility we accurately position the feed stations, internal optics and detector optics relative to the NPOI array line-of-sight. The feed station is cleaned, assembled, internally aligned, tested and placed in its vacuum canister. It is stored under vacuum until transported to the array. In stage two, we align the station on the array by global five-axis adjustments of the vacuum canister. No further independent internal alignments are necessary. The canister is continuously under vacuum during global alignments. We describe the methodology and techniques for installing the optical feed stations.

  14. JWST-MIRI spectrometer main optics alignment and tolerancing philosophy

    NASA Astrophysics Data System (ADS)

    Kroes, Gabby; Meijers, Michael; Oudenhuysen, Ad; Pel, Jan Willem

    2007-09-01

    MIRI ('Mid Infrared Instrument') is the combined imager and integral field spectrometer for the 5-29 micron wavelength range under development for the JWST. The Spectrometer Main Optics (SMO) system has been designed on the basis of a 'no adjustments' philosophy. This means that the optical alignment precision depends strongly on the design, tolerance analysis and detailed knowledge of the manufacturing process. Because in principle no corrections are possible after assembly, continuous tracking of the alignment performance during the design and manufacturing phases is important. This is done by controlling the "alignment budget" which allows a detailed comparison of the required and achieved alignment from component to system level. This paper will describe the development of the SMO alignment budget, and how it is used to bring the alignment performance under control. In addition, we will discuss the results of the actual alignment measurements on the SMO hardware and the feedback of these results into the alignment budget.

  15. Precise alignment through thick wafers using an optical copying techniquev.

    PubMed

    Jahns, J; Däschner, W

    1992-03-15

    Submicrometer alignment of two mask patterns on the top and the bottom surface of a thick glass substrate is possible by using optical copying. The optical copying step transfers an alignment pattern from one surface to the other by shadow casting or Fresnel propagation. In a demonstration experiment, the alignment between the two surfaces of a 3-mm-thick quartz glass substrate was achieved with a precision of 0.5-0.7 microm. PMID:19784337

  16. 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

  17. 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

  18. 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.

  19. Dry contact transfer printing of aligned carbon nanotube patterns and characterization of their optical properties for diameter distribution and alignment.

    PubMed

    Pint, Cary L; Xu, Ya-Qiong; Moghazy, Sharief; Cherukuri, Tonya; Alvarez, Noe T; Haroz, Erik H; Mahzooni, Salma; Doorn, Stephen K; Kono, Junichiro; Pasquali, Matteo; Hauge, Robert H

    2010-02-23

    A scalable and facile approach is demonstrated where as-grown patterns of well-aligned structures composed of single-walled carbon nanotubes (SWNT) synthesized via water-assisted chemical vapor deposition (CVD) can be transferred, or printed, to any host surface in a single dry, room-temperature step using the growth substrate as a stamp. We demonstrate compatibility of this process with multiple transfers for large-scale device and specifically tailored pattern fabrication. Utilizing this transfer approach, anisotropic optical properties of the SWNT films are probed via polarized absorption, Raman, and photoluminescence spectroscopies. Using a simple model to describe optical transitions in the large SWNT species present in the aligned samples, polarized absorption data are demonstrated as an effective tool for accurate assignment of the diameter distribution from broad absorption features located in the infrared. This can be performed on either well-aligned samples or unaligned doped samples, allowing simple and rapid feedback of the SWNT diameter distribution that can be challenging and time-consuming to obtain in other optical methods. Furthermore, we discuss challenges in accurately characterizing alignment in structures of long versus short carbon nanotubes through optical techniques, where SWNT length makes a difference in the information obtained in such measurements. This work provides new insight to the efficient transfer and optical properties of an emerging class of long, large diameter SWNT species typically produced in the CVD process. PMID:20092353

  20. The optical alignment of the Gemini planet imager adaptive optics bench

    NASA Astrophysics Data System (ADS)

    Pazder, John; Bauman, Brian; Dillon, Daren; Fletcher, Murray; Lacoursière, Jean; Reshetov, Vlad

    2012-09-01

    The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. This paper describes the methods used for optical alignment of the adaptive optics (AO) bench. The optical alignment of the off-axis paraboloid mirrors was done using a pre-alignment method utilizing a HeNe laser and alignment telescopes followed by a fine-tuning using a Shack-Hartmann wavefront sensor and a shear plate. A FARO arm measuring system was used to place the fiducials for the alignment. Using these methods the AO bench was aligned to 13nm RMS of wavefront error.

  1. Precision alignment of integrated optics in surface electrode ion traps for quantum information processing

    NASA Astrophysics Data System (ADS)

    Young, Amber L.; Hunker, Jeffrey D.; Ellis, A. Robert; Samora, Sally; Wendt, Joel R.; Stick, Daniel L.

    2014-03-01

    The integration of optics for efficient light delivery and the collection of fluorescence from trapped ions in surface electrode ion traps is a key component to achieving scalability for quantum information processing. Diffractive optical elements (DOEs) present a promising approach as compared to bulk optics because of their small physical profile and their flexibility in tailoring the optical wavefront. The precise alignment of the optics for coupling fluorescence to and from the ions, however, poses a particular challenge. Excitation and manipulation of the ions requires a high degree of optical access, significantly restricting the area available for mounting components. The ion traps, DOEs, and other components are compact, constraining the manipulation of various elements. For efficient fluorescence collection from the ions the DOE must be have a large numerical aperture (NA), which results in greater sensitivity to misalignment. The ion traps are sensitive devices, a mechanical approach to alignment such as contacting the trap and using precision motors to back-off a set distance not only cannot achieve the desired alignment precision, but risks damage to the ion trap. We have developed a non-contact precision optical alignment technique. We use line foci produced by off-axis linear Fresnel zone plates (FZPs) projected on alignment targets etched in the top metal layer of the ion trap and demonstrate micron-level alignment accuracy.

  2. 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.

  3. Test procedure for calibration, grooming and alignment of the LDUA Optical Alignment Scope

    SciTech Connect

    Potter, J.D.

    1995-12-07

    The Light Duty Utility Arm (LDUA) is a remotely operated manipulator used to enter into underground waste tanks through one of the tank risers. The LDUA must be carefully aligned with the tank riser during the installation process. The Optical Alignment Scope (OAS) is used to determine when optimum alignment has been achieved between the LDUA and the riser. This procedure is used to assure that the instrumentation and equipment comprising the OAS is properly adjusted in order to achieve its intended functions successfully.

  4. Optical assembly and alignment for the National Ignition Facility project

    SciTech Connect

    Hurst, P.A.; Grasz, E.L.; Wong, H.; Schmitt, E.H.; Simmons, M.R.

    1997-12-23

    The National Ignition Facility (NIF) will use about 8,000 large optics to carry a high-power laser through a stadium-size building, and will do so on a very tight schedule and budget. The collocated Optics Assembly Building (OAB) will assemble and align, in a clean-room environment, the NIF`s large optics, which are the biggest optics ever assembled in such an environment. In addition, the OAB must allow for just-in-time processing and clean transfer to the areas where the optics will be used. By using a mixture of off-the-shelf and newly designed equipment and by working with industry, we have developed innovative handling systems to perform the clean assembly and precise alignment required for the full variety of optics, as well as for postassembly inspection. We have also developed a set of loading mechanisms that safely get the clean optics to their places in the main NIF building.

  5. 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

  6. The art of planning for optical systems integration and alignment

    NASA Astrophysics Data System (ADS)

    Sullivan, Joseph F.

    2015-09-01

    This will address Lessons Learned on the approaches that worked or did not work over various programs when integrating and aligning elements into fairly complex optical systems. The appropriate planning can prevent many unnecessary headaches and achieve the desired optical performance while optimizing integration efficiency.

  7. 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 is sketched in Figure 2(b) (the figure also shows the tapping tool and where to tap). At this point the fasteners for the PCB are torqued slightly so the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3 to 4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). A 10- to 30-micron mounting accuracy has been achieved utilizing this method..

  8. TOW optical and infrared test and alignment calibration capability

    NASA Astrophysics Data System (ADS)

    Wolk, Martin; Armstrong, Edward P.; Mann, Edward L.

    1996-08-01

    This paper describes the design of test equipment constructed to enable the Marine Corps Logistics Base the capability to provide the required optical/IR boresight and electronic tests for rebuild and TOSH (TOW optical sight hardening) modification for the TOW (tube launched, optically tracked, wire guided) guided missile launcher optical/infrared sight. Optical modification and calibration are performed to improve system accuracy and reliability against failure, especially in a battlefield environment. Although principle concern was for the day sight, provision for the thermal night sight was also included. This design includes a large diameter optical beam, provision for thermal targets and night sight boresight alignment capability with the day sight. Primarily, a specially constructed collimator test set is discussed, implemented as the TOW 150 test and alignment station. In addition, a precision TOSH prism test system is briefly described, which is used to facilitate internal optical component boresight alignment utilizing a HeNe laser, alignment telescope and video camera. Radiometric theory is applied to the collimator geometry, which includes the modulation factor, Planck radiation function and appropriate bandpass integrated to yield effective rms irradiance values for calibration of the day sight.

  9. Implant alignment in total elbow arthroplasty: conventional vs. navigated techniques

    NASA Astrophysics Data System (ADS)

    McDonald, Colin P.; Johnson, James A.; King, Graham J. W.; Peters, Terry M.

    2009-02-01

    Incorrect selection of the native flexion-extension axis during implant alignment in elbow replacement surgery is likely a significant contributor to failure of the prosthesis. Computer and image-assisted surgery is emerging as a useful surgical tool in terms of improving the accuracy of orthopaedic procedures. This study evaluated the accuracy of implant alignment using an image-based navigation technique compared against a conventional non-navigated approach. Implant alignment error was 0.8 +/- 0.3 mm in translation and 1.1 +/- 0.4° in rotation for the navigated alignment, compared with 3.1 +/- 1.3 mm and 5.0 +/- 3.8° for the non-navigated alignment. Five (5) of the 11 non-navigated alignments were malaligned greater than 5° while none of the navigated alignments were placed with an error of greater than 2.0°. It is likely that improved implant positioning will lead to reduced implant loading and wear, resulting in fewer implantrelated complications and revision surgeries.

  10. Breaking through 1D layout limitations and regaining 2D design freedom Part I: 2D layout decomposition and stitching techniques for hybrid optical and self-aligned multiple patterning

    NASA Astrophysics Data System (ADS)

    Liu, Hongyi; Zhou, Jun; Chen, Yijian

    2015-03-01

    To break through 1-D IC layout limitations, we develop computationally efficient 2-D layout decomposition and stitching techniques which combine the optical and self-aligned multiple patterning (SAMP) processes. A polynomial time algorithm is developed to decompose the target layout into two components, each containing one or multiple sets of unidirectional features that can be formed by a SAMP+cut/block process. With no need of connecting vias, the final 2-D features are formed by directly stitching two components together. This novel patterning scheme is considered as a hybrid approach as the SAMP processes offer the capability of density scaling while the stitching process creates 2-D design freedom as well as the multiple-CD/pitch capability. Its technical advantages include significant reduction of via steps and avoiding the interdigitating types of multiple patterning (for density multiplication) to improve the processing yield. The developed decomposition and synthesis algorithms are tested using 2-D layouts from NCSU open cell library. Statistical and computational characteristics of these public layout data are investigated and discussed.

  11. 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.

  12. 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.

  13. VISA UNDULATOR RE-ALIGNMENT USING AN OPTICAL MONITORING SYSTEM.

    SciTech Connect

    TREMAINE,A.; MUROKH,A.; WANG,X.J.

    2001-01-01

    The VISA experiment is designed to reach and study saturation in a high gain 800nm SASE FEL at the Brookhaven Accelerator Test Facility (ATF). To do this, the undulator must be aligned at first to within 20 {micro}m with use of a laser interferometric system. Once aligned, any small movements from the aligned position will greatly detriment the SASE FEL performance thus making continuous monitoring of the undulator position necessary. This is quite a complicated task since the 4m undulator is made up of four 1m sections enclosed in a vacuum chamber. We have developed an in situ optical system to monitor the undulator position with an accuracy better than 10 {micro}m. In addition, we have demonstrated the accuracy of this system by bringing the grossly misaligned VISA undulator ({approximately} 500 {micro}m in some locations) into alignment and attaining very high gain of the SASE FEL.

  14. Alignment and focusing tolerance influences on optical performance

    SciTech Connect

    Cross, E.W.

    1982-01-01

    Alignment errors among components of an optical system may substantially degrade the image quality. Focus errors also affect system performance. The potential for serious degradation of image quality is substantial and requires that the tolerances for these errors receive significant attention early in system design. The image quality and reconnaissance performance of an all-reflecting Cassegrain is compared to an all-refractive optical system under conditions of zero and anticipated real world misalignments.

  15. A new multimode optical fiber splicing technique

    NASA Astrophysics Data System (ADS)

    Ruello, Y.; Malavieille, F. L.

    1986-11-01

    For the French local cable network, it is necessary to perform a great number of multimode optical fiber splices. We present a low cost splicing technique which has been industrialized to satisfy the requirements of the videocommunication networks. In this splice, fibers are aligned in an elastomeric groove and then, bonded to a glass plate. Training time is very short and field installation is easy. It is a good quality, reliable splice and more than 100,000 splices has been already realized in the field. In this paper we present this splicing technique and the performances of the splice.

  16. 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.

  17. 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 calibration is a function of the interferometer error and the aspheric departure of the desired test surface. This calibration is most effective at reducing coma and trefoil from figure error or misalignments of the interferometer components. The enhanced calibration can reduce overall measurement uncertainty or allow the budgeted error contribution from another source to be increased. A single set of sphere measurements can be used to calculate calibration maps for closely related aspheres, including segmented primary mirrors for telescopes. A parametric model is developed and compared to the simulated calibration of a case study interferometer.

  18. 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.

  19. Optomechanical tolerancing and lens alignment using elastomeric lens mount to efficiently meet optical requirements

    NASA Astrophysics Data System (ADS)

    Lamontagne, Frédéric; Doucet, Michel; Savard, Maxime; Wang, Min

    2013-09-01

    Lens positioning accuracy and manufacturing cost are two main concerns for optomechanical engineers looking for solutions to reduce costs while meeting stringent optical and environmental requirements. Minimizing optical component positioning errors generally translates into significant cost increases. To maximize the precision-to-cost ratio, there are significant advantages in having both an accurate optomechanical tolerance calculation method and an effective technique to mount and align lenses. This paper presents a tool that has been developed at INO to easily perform complex optomechanical statistical tolerancing using Monte Carlo simulation to reduce manufacturing and alignment costs. This tolerancing method provides a more realistic prediction of optical component errors compared to the classical worst case and root sum square calculations. In addition, precision alignment using elastomeric lens mounting is presented. Thermal stability and often overlooked factors for effective alignments are discussed. Results of tests performed on real optical assemblies are presented for tolerancing, thermal stability and alignment performance. The use of these methods can considerably reduce cost while efficiently ensuring compliance with requirements.

  20. 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 through the relay lenses and the beam compressor/expander, then split so that half goes to a detector and half to the interferometer. The output of the detector is used as a feedback control signal for the six-axis stage to effect alignment.

  1. 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.

  2. Improved assessment of lower extremity alignment using new roentgenographic techniques

    SciTech Connect

    Petersen, T.D.; Rohr, W. Jr.

    1987-06-01

    Accurate assessment of total hip and knee alignment requires a single-exposure weight-bearing roentgenogram of the involved limb. The problem with single-exposure technique is that a good exposure of the hip overexposes the lower leg. This problem is solved by using leaded acrylic wedges, which, when placed in front of the X-ray tube (collimator), block excessive radiation to the lower limb and create an evenly exposed film of the entire lower extremity. The development of these collimator wedge filters and the advent of newer fast-speed film and screens have reduced the amount of radiation absorbed by the patient by eight times or more. Guided by a chart to interchange and choose between film/screen combinations, the method and technique provides the surgeon with an exact alignment of the limb and joints for all kinds of operations.

  3. 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.

  4. 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.

  5. 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

  6. Inverting Image Data For Optical Testing And Alignment

    NASA Technical Reports Server (NTRS)

    Shao, Michael; Redding, David; Yu, Jeffrey W.; Dumont, Philip J.

    1993-01-01

    Data from images produced by slightly incorrectly figured concave primary mirror in telescope processed into estimate of spherical aberration of mirror, by use of algorithm finding nonlinear least-squares best fit between actual images and synthetic images produced by multiparameter mathematical model of telescope optical system. Estimated spherical aberration, in turn, converted into estimate of deviation of reflector surface from nominal precise shape. Algorithm devised as part of effort to determine error in surface figure of primary mirror of Hubble space telescope, so corrective lens designed. Modified versions of algorithm also used to find optical errors in other components of telescope or of other optical systems, for purposes of testing, alignment, and/or correction.

  7. Molecular alignment relaxation in polymer optical fibers for sensing applications

    NASA Astrophysics Data System (ADS)

    Stajanca, Pavol; Cetinkaya, Onur; Schukar, Marcus; Mergo, Pawel; Webb, David J.; Krebber, Katerina

    2016-03-01

    A systematic study of annealing behavior of drawn PMMA fibers was performed. Annealing dynamics were investigated under different environmental conditions by fiber longitudinal shrinkage monitoring. The shrinkage process was found to follow a stretched exponential decay function revealing the heterogeneous nature of the underlying molecular dynamics. The complex dependence of the fiber shrinkage on initial degree of molecular alignment in the fiber, annealing time and temperature was investigated and interpreted. Moreover, humidity was shown to have a profound effect on the annealing process, which was not recognized previously. Annealing was also shown to have considerable effect on the fiber mechanical properties associated with the relaxation of molecular alignment in the fiber. The consequences of fiber annealing for the climatic stability of certain polymer optical fiber-based sensors are discussed, emphasizing the importance of fiber controlled pre-annealing with respect to the foreseeable operating conditions.

  8. 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).

  9. 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.

  10. Optical Properties of Aligned Carbon Nanotube Mats for Photonic Applications

    NASA Astrophysics Data System (ADS)

    Zhao, G. L.; Bagayoko, D.; Yang, L.

    2006-03-01

    We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0) and (8, 4) mats for photonic device applications. We employed the ab-initio density functional calculations in the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions of photon energy. The calculated dielectric functions of the aligned carbon nanotube mats show a strong anisotropy when the electric field of light is parallel or perpendicular to the tube axes. Especially, there are strong peaks in the imaginary part of the dielectric function near the absorption edges, when the electric field of light is parallel to the carbon nanotube axes. The unusual optical properties of the semiconducting carbon nanotube mats present a new opportunity for applications in new electro-optical devices in the infrared energy region. Acknowledgments: this work was funded in part by NSF (Award No. 0508245), NASA (Award No. NCC 2-1344), and ONR (Grant No: N00014-05-1-0009).

  11. Registration fiducials for automated alignment with optical processing.

    PubMed

    Glaser, I; Katzir, Y

    1982-10-15

    Since automated assembly, as well as automated inspection and sorting, usually require prealigned work-pieces, the availability of rapid and simple automatic alignment is a prerequisite to widespread acceptance of such systems. Coherent optical correlators potentially offer the necessary speed, but they have required mechanically coupled image rotation prisms and spatial light modulators and are, therefore, quite complicated and cumbersome. We describe here an alternative approach in which circularly symmetric fiducials are incorporated into the object itself and detected with an incoherent optical correlator. With incoherent correlators there is no need for spatial light modulators; also, the fiducials are so chosen that the correlation is not rotation sensitive. Since several (typically three) identical fiducials are used, their location can provide sufficient information on the object orientation. The approach was tested in the laboratory, and some experimental examples are included. PMID:20396300

  12. CWDM based HDMI interconnect incorporating passively aligned POF linked optical subassembly modules

    NASA Astrophysics Data System (ADS)

    Lee, Hak-Soon; Lee, Sang-Shin; Son, Yung-Sung

    2011-08-01

    A four-channel transmitter OSA (TOSA) and a receiver optical sub-assembly (ROSA) module were presented. They take advantage of a coarse WDM (CWDM) scheme, employing two types of VCSELs at 780 and 850 nm, where no wavelength filters are involved in the TOSA. The ROSA and TOSA were constructed through a fully passive alignment process using components produced by virtue of a cost effective plastic injection molding technique. In order to build a high quality optical HDMI interconnect, four channel optical links between these modules ware established via two graded-index plastic optical fibers (GI-POFs). The HDMI interconnect was thoroughly evaluated in terms of the alignment tolerance, the light beam propagation, and the data transmission capability. For the ROSA, the measured tolerance, as affected by the photodiode alignment, was ~45 μm and over 200 μm for the transverse and longitudinal directions, respectively. For the TOSA, the tolerance, which is mostly dependent upon the VCSEL alignment, was ~20 μm and more than 200 μm for the transverse and longitudinal directions, respectively. The beam profiles for the TOSA and ROSA were monitored to confirm their feasibility from the optical coupling perspective. A digital signal at 2.5 Gb/s was efficiently transmitted through the HDMI interconnect with a bit error ratio of below 10-16. A 1080p HDMI signal from a Blu-ray player was delivered through the interconnect to an LCD monitor and successfully displayed a high quality video.

  13. Panoramic alignment system for optical wireless communication systems

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Free space optical communication may provide a viable adjunct to radio frequency (RF) technology for mobile communications, especially in "RF-denied" settings in which RF-based communication may be prohibited or impractical. These settings may include military tactical environments or settings which suffer from RF jamming or interference. Unlike many RF communication systems, point-to-point optical communications between mobile nodes typically require establishing and maintaining alignment, which requires each node to have awareness of the locations of neighboring nodes. We propose a method to create this situational awareness between nodes using purely optical means. This method uses a camera that is focused on a hyperboloidal mirror, thus providing a 360-degree view of the surrounding environment. The camera and mirror are used to detect light emitted from the beacon transmitters from neighboring nodes, with the location of the beacon image in the sensor plane of the camera yielding elevation and azimuth information of the beacon. The beacon transmitter itself is modulated, allowing it to be distinguished from the environment. In discussing our experimental realization of this system, we assess its performance.

  14. 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.

  15. Optical alignment of liquid crystal displays and devices via polarized light

    SciTech Connect

    Gibbons, W.M.; Shannon, P.J.; Sun, Shao-Tang

    1995-12-31

    The optical alignment of liquid crystals provides spatial and angular control of the local liquid crystals provides spatial and angular control of the local liquid crystal director. This is achieved by properly designing photosensitive polymer alignment layers. These photosensitive alignment polymers are illuminated with polarized light which alters the bulk and surface properties of the polymer. The liquid crystal molecules adjacent to the alignment polymer interact with the altered polymer and align accordingly. The long range interaction of the liquid crystal molecules transfers the aligned state at the interface to the bulk of the liquid crystal layer. Since the alignment polymer itself is altered, the liquid crystal remains aligned after the illumination is terminated. With the proper design of the alignment material, the process is reversible allowing for the potential of real-time write/re-write control of the local liquid crystal director. In this presentation, we will discuss the use of optical alignment as a non-contact method to align liquid crystal displays. Issues such as the pre-tilt angle and the dielectric properties of the optically controlled alignment polymer will be addressed. Other liquid crystal applications can be realized by combining the high spatial and angular resolution of this process with the birefringent and electro-optical properties of liquid crystals. Novel liquid crystal binary phase and holographic devices, and erasable optical data storage media based on liquid crystals, are possible when reversible optically controlled alignment polymers are used. If time permits, we will review the use of the optical alignment technology for these applications.

  16. 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.

  17. 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 almost no adjustment.

  18. 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.

  19. Ribbon plastic optical fiber linked optical transmitter and receiver modules featuring a high alignment tolerance.

    PubMed

    Lee, Hak-Soon; Park, Jun-Young; Cha, Sang-Mo; Lee, Sang-Shin; Hwang, Gyo-Sun; Son, Yung-Sung

    2011-02-28

    Ribbon plastic optical fiber (POF) linked four-channel optical transmitter (Tx) and receiver (Rx) modules have been proposed and realized featuring an excellent alignment tolerance. The two modules share a common configuration involving an optical sub-assembly (OSA) with vertical cavity surface emitting lasers (VCSELs)/photodetectors (PDs), and their driver ICs, which are integrated onto a single printed circuit board (PCB) substrate. The OSA includes an alignment structure, a beam router and a fiber guide, which were produced by using plastic injection molding. We have accomplished a fully passive alignment between the VCSELs/PDs and the ribbon POF by taking advantage of the alignment structure that serves as a reference during the alignment of the constituent parts of the OSA. The electrical link, which largely determines the operation speed, has been remarkably shortened, due to a direct wire-bonding between the VCSELs/PDs and the driver circuits. The light sources and the detectors can be individually positioned, thereby overcoming the pitch limitations of the ribbon POF, which is made up of perfluorinated graded-index (GI) POF with a 62.5 μm core diameter. The overall alignment tolerance was first assessed by observing the optical coupling efficiency in terms of VCSEL/PD misalignment. The horizontal and vertical 3-dB alignment tolerances were about 20 μm and 150 μm for the Tx and 50 μm and over 200 μm for the Rx, respectively. The VCSEL-to-POF coupling loss for the Tx and the POF-to-PD loss for the Rx were 3.25 dB and 1.35 dB at a wavelength of 850 nm, respectively. Subsequently, a high-speed signal at 3.2 Gb/s was satisfactorily delivered via the Tx and Rx modules over a temperature range of -30 to 70°C with no significant errors; the channel crosstalk was below -30 dB. Finally, the performance of the prepared modules was verified by transmitting a 1080p HDMI video supplied by a Bluelay player to an LCD TV. PMID:21369260

  20. A Novel Injection-Molded Precision Plastic Platform for the Passive Alignment of a Polymer Waveguide Film and Optical Fibers

    NASA Astrophysics Data System (ADS)

    Tamura, Yasuaki; Hikita, Makoto; Shuto, Yoshito; Amano, Michiyuki; Tomaru, Satoru; Sato, Hirotsugu; Imamura, Saburo; Tohno, Shun-ichi

    1998-06-01

    A newly-designed plastic alignment platform formed by a precise injection molding technique is proposed for connecting a polymer waveguide film to optical fibers. This platform consists of a pair of parallel arrayed V-grooves separated by a flat cavity for the polymer waveguide film. The core positions of the film are strictly determined by using polymer processing techniques including microlithography. A precisely aligned connection is then realized simply by placing the polymer waveguide in the mount cavity of the component. This provides an average connection loss of 0.2 dB/port.

  1. Minimal-effort planning of active alignment processes for beam-shaping optics

    NASA Astrophysics Data System (ADS)

    Haag, Sebastian; Schranner, Matthias; Mller, Tobias; Zontar, Daniel; Schlette, Christian; Losch, Daniel; Brecher, Christian; Romann, Jrgen

    2015-03-01

    In science and industry, the alignment of beam-shaping optics is usually a manual procedure. Many industrial applications utilizing beam-shaping optical systems require more scalable production solutions and therefore effort has been invested in research regarding the automation of optics assembly. In previous works, the authors and other researchers have proven the feasibility of automated alignment of beam-shaping optics such as collimation lenses or homogenization optics. Nevertheless, the planning efforts as well as additional knowledge from the fields of automation and control required for such alignment processes are immense. This paper presents a novel approach of planning active alignment processes of beam-shaping optics with the focus of minimizing the planning efforts for active alignment. The approach utilizes optical simulation and the genetic programming paradigm from computer science for automatically extracting features from a simulated data basis with a high correlation coefficient regarding the individual degrees of freedom of alignment. The strategy is capable of finding active alignment strategies that can be executed by an automated assembly system. The paper presents a tool making the algorithm available to end-users and it discusses the results of planning the active alignment of the well-known assembly of a fast-axis collimator. The paper concludes with an outlook on the transferability to other use cases such as application specific intensity distributions which will benefit from reduced planning efforts.

  2. 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.

  3. Holographic weapons sight as a crew optical alignment sight

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  4. 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 four AO systems for the interferometric mode of the VLT). ESO PR Photo 19b/07 ESO PR Photo 19b/07 The Globular Cluster Omega Centauri (MAD/VLT) Present AO systems can only correct the effect of atmospheric turbulence in a relative small region of the sky - typically 15 arcseconds, the correction degrading very quickly when moving away from the central axis. Engineers have therefore developed new techniques to overcome this limitation, one of which is multi-conjugate adaptive optics (MCAO). At the end of 2003, ESO, together with partners in Italy and Portugal, started the development of a MCAO Demonstrator, named MAD. "The aim of MAD is to prove the feasibility and performances of new adaptive optics techniques, such as MCAO, meant to work on large fields of view and to serve as a very powerful test tool in understanding some of the critical issues that will determine the development of future instruments, for both the VLT and the Extremely Large Telescopes," said Norbert Hubin, head of the AO group at ESO. MAD is an advanced generation adaptive optics system, capable of compensating for the atmospheric turbulence disturbance on a large field of view (FoV) on the sky. It can successfully correct a 1-2 arcmin FoV, much larger than the ~15 arcsec typically provided by the existing adaptive optics facilities. MAD was fully developed and extensively characterized by ESO using a dedicated turbulence generator (MAPS, Multi Atmospheric Phase screens and Stars) able to reproduce in the laboratory the temporal evolution and the vertical structure of the turbulence observed at the Observatory. ESO PR Photo 19c/07 ESO PR Photo 19c/07 The MCAO Concept MAD was then disassembled and shipped to Paranal for re-integration at the Nasmyth Visitor focus of UT3. The integration took about 1 month, after which the system was ready for daylight testing and further characterization. "On the night of 25 March, we could successfully close the first MCAO loop on the open cluster NGC 3293," said Enrico Marchetti, the MAD Project Manager. "The system behaviour was very stable and the acquisition and closed loop operations were fast and smooth." ESO PR Photo 19d/07 ESO PR Photo 19d/07 AO Strehl Maps After routine checks on the closed loop stability and preliminary scans of the system parameters, the telescope was pointed to Omega Centauri, a very crowded area in the sky, and an optimal test case for extracting accurate measurements on AO correction performance with good spatial resolution on the FoV. Three 11 magnitude stars within a circle of ~1.5 arcmin diameter were selected as the baseline for wavefront sensing and the MCAO loop was closed successfully. Omega Centauri will be observed for several nights more, in order to test the AO correction in different seeing conditions. "This is a tremendous achievement that opens new perspectives in the era of extremely large telescopes," said Catherine Cesarsky, ESO's Director General. " "I am very proud of the ESO staff and wish to congratulate all involved for their prowess," she added. The MAD images perfectly show the validity of the concept. The image quality was almost uniform over the whole field of view and beautifully corrected for some of the atmospheric turbulence. More Information The Multi-Conjugate Adaptive Optics (MCAO) Demonstrator MAD was built by ESO in collaboration with the Astronomical Observatories of Arcetri and Padova (Italy) and the Faculdade de Ciencias da Universidade de Lisboa (Portugal), as a pathfinder for 2nd generation VLT instrumentation and the European Extremely Large Telescope project. The MCAO technique is based on probing the atmospheric turbulence on a large volume of atmosphere by means of several wavefront sensors (WFS), which point at different locations in the observed field of view, and by means of several deformable mirrors - optically conjugated at different altitudes on the atmosphere above the telescope - which correct for the atmospheric disturbance. The signals provided by the wavefront sensors are reconstructed to generate accurate information on the vertical structure of the atmospheric turbulence and then recombined in an optimal way to accomplish the best correction with the deformable mirrors located in the AO system. Since the wavefront sensors look at different directions in the field of view, the resulting correction is then optimized and homogeneously maximized across it. MAD makes use of two deformable mirrors, optically conjugated at 0 and 8.5 kilometres above the telescope.

  5. 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.

  6. High-precision optical systems with inexpensive hardware: a unified alignment and structural design approach

    NASA Astrophysics Data System (ADS)

    Winrow, Edward G.; Chavez, Victor H.

    2011-09-01

    High-precision opto-mechanical structures have historically been plagued by high costs for both hardware and the associated alignment and assembly process. This problem is especially true for space applications where only a few production units are produced. A methodology for optical alignment and optical structure design is presented which shifts the mechanism of maintaining precision from tightly toleranced, machined flight hardware to reusable, modular tooling. Using the proposed methodology, optical alignment error sources are reduced by the direct alignment of optics through their surface retroreflections (pips) as seen through a theodolite. Optical alignment adjustments are actualized through motorized, sub-micron precision actuators in 5 degrees of freedom. Optical structure hardware costs are reduced through the use of simple shapes (tubes, plates) and repeated components. This approach produces significantly cheaper hardware and more efficient assembly without sacrificing alignment precision or optical structure stability. The design, alignment plan and assembly of a 4" aperture, carbon fiber composite, Schmidt-Cassegrain concept telescope is presented.

  7. 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

  8. Optical proximity effect of a next-generation superresolution technique

    NASA Astrophysics Data System (ADS)

    Kamon, Kazuya

    1997-07-01

    A new super resolution technique with wide applicability and high resolution enhancement has been developed. Various optical properties of the new optics have been analyzed by some optical simulations. Using a spontaneously optimized source shape for the mask pattern itself leads to better applicability with the new optics. From experimental verification, the DOF of the new optics is 1.5 times wider than the modified illumination. An alignment accuracy of 0.1 micrometers (on mask) is acceptable between the first and second mask. According to simulation results, the optical proximity effect is reduced by the new optics. These features offer significant merits to photolithography technology. Therefore, we estimate the optical proximity effect by optical image measurements and simulations. From the simulation result, we can use the third source aperture to control the optical proximity effects. For conventional illumination, a 0.35 micrometers L/S image is formed by two beam interference. For the new optics, the same pattern is imaged by four beam interference because the UV light is diffracted twice by the mask pattern. While the optical proximity correction system was being developed, it was confirmed that the pattern size fluctuation is sufficiently smaller for four or more beam interference. The experimental results of an x-z image profile for 0.35 micrometers , 0.4 micrometers or 0.5 micrometers line and any space are consistent with simulation results.

  9. 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. PMID:27026022

  10. 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.

  11. Substrate patterning for liquid crystal alignment by optical interference

    SciTech Connect

    Lu Xuemin; Lee, Fuk Kay; Sheng, Ping; Kwok, H.S.; Chigrinov, V.; Tsui, Ophelia K.C.

    2006-06-12

    Inhomogeneous liquid crystal (LC) alignment surfaces comprising a succession of microdomains favoring different LC alignment directions have been demonstrated for a number of optoelectronic applications. However, the prevalent method used to fabricate these surfaces is time consuming and produce functional areas that are too small for practical use. Here, we demonstrate a simple method based on photopatterning of an azodye layer with an interference pattern produced by intercepting two coherent UV beams. This method can produce alignment patterns within seconds with a practical size of {approx}(0.5 cm){sup 2}.

  12. 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.

  13. 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.

  14. A No-Buff Technique to Produce Surfaces That Induce Alignment in Liquid Crystals

    NASA Astrophysics Data System (ADS)

    Harrison, Daniel; Fisch, Michael R.; Petschek, Rolfe G.; Li, J.-F.; Harris, Frank; Korns, Heather

    2002-04-01

    Alignment layers for liquid crystal cells were prepared by directional deposition of high molecular weight rigid-rod ionomers on glass and indium-tin-oxide substrates. Several deposition techniques were developed and tested. Material type, concentration, temperature, and application technique were systematically varied and the resultant alignment of the liquid crystals studied. Three different methods of applying the alignment layer were investigated: directional spray deposition, brushing, and directional deposition using a squeegee (doctor bar). The application temperature ranged from 30 to 80°C. The best results were obtained using a squeegee to perform directional deposition at temperature of less than 60°C. The alignment layers obtained in this way are robust, exhibit excellent alignment, and have pretilt angles of a few degrees.

  15. Adiabatic Field-Free Alignment of Asymmetric Top Molecules with an Optical Centrifuge

    NASA Astrophysics Data System (ADS)

    Korobenko, A.; Milner, V.

    2016-05-01

    We use an optical centrifuge to align asymmetric top SO2 molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines the sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment that persists after the molecules are released from the centrifuge. The periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 deg, permanent field-free alignment offers new ways of controlling molecules with laser light.

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

    PubMed

    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

  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. Analysis of the influence of manufacturing and alignment related errors on an optical tweezer system

    NASA Astrophysics Data System (ADS)

    Kampmann, R.; Sinzinger, S.

    2014-12-01

    In this work we present the design process as well as experimental results of an optical system for trapping particles in air. For positioning applications of micro-sized objects onto a glass wafer we developed a highly efficient optical tweezer. The focus of this paper is the iterative design process where we combine classical optics design software with a ray optics based force simulation tool. Thus we can find the best compromise which matches the optical systems restrictions with stable trapping conditions. Furthermore we analyze the influence of manufacturing related tolerances and errors in the alignment process of the optical elements on the optical forces. We present the design procedure for the necessary optical elements as well as experimental results for the aligned system.

  19. Field-free long-lived alignment of molecules with a two-dimensional optical centrifuge

    NASA Astrophysics Data System (ADS)

    Milner, A. A.; Korobenko, A.; Milner, V.

    2016-05-01

    We introduce an optical tool—a "two-dimensional optical centrifuge"—capable of aligning molecules in extreme rotational states. The alignment is studied in oxygen under ambient conditions, and in a cold jet of nitrogen. Unlike the conventional centrifuge, which confines the molecules in the plane of their rotation, its two-dimensional version aligns the molecules along a well-defined axis, similar to the effect of a single linearly polarized laser pulse, but at a much higher level of rotational excitation. We observe long lifetimes of the created alignment due to the increased robustness of ultrahigh rotational states with respect to collisions. The adiabatic nature of the centrifuge excitation provides a means of generating stationary aligned states.

  20. 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.

  1. Localized surface plasmon resonance anisotropy in template aligned silver nanoparticles: A case of biaxial metal optics

    NASA Astrophysics Data System (ADS)

    Ranjan, Mukesh; Bhatnagar, Mukul; Mukherjee, Subroto

    2015-03-01

    Generalized ellipsometry is used to extract the dielectric functions of self-aligned silver nanoparticles on silicon ripple patterns which account for the anisotropic Localized Surface Plasmon Resonance shown by such nanostructures. The biaxial nature of dielectric functions shows its presence through the modified in-plane plasmonic behaviour as compared to the case of random nanoparticles. The nature of in-plane optical coupling and out of plane metallic behavior is further investigated by tuning the interparticle gap along the ripple direction and also varying the ripple periodicity. Thus, we propose that generalized ellipsometry may be used as an effective process monitoring technique to develop anisotropic plasmonic substrates with potential applications in photovoltaic systems as a plasmonic back reflector.

  2. 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.

  3. Microfabricated clamps for high-precision passive alignment and packaging of optical fibres in optoelectronics devices

    NASA Astrophysics Data System (ADS)

    Dai, Xuhan; Zhao, Xiaolin; Ding, Guifu; Wang, Hong; Cai, Bingchu

    2005-11-01

    A novel micro-mechanical structure has been put forwarded. It is designed for high precision passive alignment and packaging of optical fibres in optoelectronics devices. The electroplated nickel micro clamp has been fabricated above the silicon V grooves. The clamps, work together with the V groove, fix the optical fibers with high precision for optical alignment when the fibers are inserted into the grooves. The fabrication of the micro clamp involves only one more photolithography and electroplating process. two single mode optical fibers have been fixed into the silicon V-groove by the nickel clamp; the measured insertion loss is lower than 0.1dB. The proposed nickel micro clamp is proved to be a low cost, high performance approach that could be widely applied in passive alignment and packaging of fiber in opto-electronics devices.

  4. Aligned Nanofibers from Polypyrrole/Graphene as Electrodes for Regeneration of Optic Nerve via Electrical Stimulation.

    PubMed

    Yan, Lu; Zhao, Bingxin; Liu, Xiaohong; Li, Xuan; Zeng, Chao; Shi, Haiyan; Xu, Xiaoxue; Lin, Tong; Dai, Liming; Liu, Yong

    2016-03-23

    The damage of optic nerve will cause permanent visual field loss and irreversible ocular diseases, such as glaucoma. The damage of optic nerve is mainly derived from the atrophy, apoptosis or death of retinal ganglion cells (RGCs). Though some progress has been achieved on electronic retinal implants that can electrically stimulate undamaged parts of RGCs or retina to transfer signals, stimulated self-repair/regeneration of RGCs has not been realized yet. The key challenge for development of electrically stimulated regeneration of RGCs is the selection of stimulation electrodes with a sufficient safe charge injection limit (Qinj, i.e., electrochemical capacitance). Most traditional electrodes tend to have low Qinj values. Herein, we synthesized polypyrrole functionalized graphene (PPy-G) via a facile but efficient polymerization-enhanced ball milling method for the first time. This technique could not only efficiently introduce electron-acceptor nitrogen to enhance capacitance, but also remain a conductive platform-the π-π conjugated carbon plane for charge transportation. PPy-G based aligned nanofibers were subsequently fabricated for guided growth and electrical stimulation (ES) of RGCs. Significantly enhanced viability, neurite outgrowth and antiaging ability of RGCs were observed after ES, suggesting possibilities for regeneration of optic nerve via ES on the suitable nanoelectrodes. PMID:26926578

  5. Ultra-high-precision alignment technology for lens manufacturing used for high-end optics

    NASA Astrophysics Data System (ADS)

    Schiffner, Sebastian; Sure, Thomas

    2013-09-01

    This article describes the progress in the area of modern centration technology by using digital image processing. This work is motivated by the continuously increasing demand for high-end optics. During the last years the surface lens quality has been continuously improved. Today the image quality is more determined by the manufacturing tolerances for the mechanical interface which is responsible for decenter and tilt of the lenses respectively the subgroups. Some of the aberrations are directly linked to the decenter of the lenses, Coma for example. Hence it is necessary to realize the subgroups with tolerances below lpm. To determine the decenter of a lens an auto collimation telescope is used to image the reflex of the lens surfaces onto a detector, commonly a half covert photodiode. Rotating the lens generates a sinusoidal signal, which is evaluated by a lock-in amplifier to drive two actuators to adjust the alignment chuck. Typical internal reflections caused by stray light for example disturb the current procedure in such a way that it is impossible to get a stable alignment process. Digital image processing allows us to fix these problems with image recognition. We will demonstrate how a modified auto collimation telescope in combination with the developed software algorithms made the manufacturing process more accurate, faster and useable for a broad spectrum of lenses. It has been proofed by some thousand diverse lenses that with these new technique subgroups can be centered within 0.25μm.

  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. Techniques used in the alignment of TJNAF's accelerators and experimental halls

    SciTech Connect

    C.J. Curtis; J.C. Dahlberg; W.A. Oren; K.J. Tremblay

    1997-10-13

    With the successful completion of the main accelerator in 1994 the alignment emphasis at the Thomas Jefferson National Accelerator Facility (formerly CEBAF) switched to the continuing installation and upgrades in the three experimental halls. This presentation examines the techniques used in completing the CEBAF machine and also gives an update on the alignment of the new accelerator, a 1 kW free-electron laser, currently being built at the facility.

  8. TKA Sagittal Alignment with Navigation Systems and Conventional Techniques Vary Only a Few Degrees

    PubMed Central

    Kobayashi, Akio; Iwaki, Hiroyoshi; Ohashi, Hirotsugu; Takaoka, Kunio

    2008-01-01

    Navigation systems have been developed to achieve more reliable prosthetic alignment in TKAs. However, the component alignment in the sagittal plane is reportedly less reliable than in the coronal plane even with navigation systems. We measured and compared sagittal prosthetic alignments for TKAs with the conventional technique and three navigation approaches to establish reference frames, using radiographs of the entire lower extremity while standing. The sagittal alignments simulated on the radiographs with the conventional technique and navigation systems differed by a mean of 2° to 4°. Use of navigation systems resulted in a mean of 1° to 4° hyperextension between the femoral and tibial components and use of the conventional technique resulted in a mean of 1° flexion. Use of different reference points on the distal femoral condyle for the navigation systems resulted in differences of as much as 3° alignment in the sagittal plane. Although optimal prosthetic alignment for TKA in the sagittal plane is unknown, surgeons and technicians using navigation systems should be aware of this difference in the sagittal plane and the risk of hyperextension between the femoral and tibial components, which might be associated with osteolysis and anterior post-cam impingement. PMID:18712579

  9. Optical tweezers technique and its applications

    NASA Astrophysics Data System (ADS)

    Guo, HongLian; Li, ZhiYuan

    2013-12-01

    Since their advent in the 1980s, optical tweezers have attracted more and more attention due to their unique non-contact and non-invasion characteristics and their wide applications in physics, biology, chemistry, medical science and nanoscience. In this paper, we introduce the basic principle, the history and typical applications of optical tweezers and review our recent experimental works on the development and application of optical tweezers technique. We will discuss in detail several technological issues, including high precision displacement and force measurement in single-trap and dual-trap optical tweezers, multi-trap optical tweezers with each trap independently and freely controlled by means of space light modulator, and incorporation of cylindrical vector optical beams to build diversified optical tweezers beyond the conventional Gaussian-beam optical tweezers. We will address the application of these optical tweezers techniques to study biophysical problems such as mechanical deformation of cell membrane and binding energy between plant microtubule and microtubule associated proteins. Finally we present application of the optical tweezers technique for trapping, transporting, and patterning of metallic nanoparticles, which can be harnessed to manipulate surface plasmon resonance properties of these nanoparticles.

  10. 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.

  11. [The alignment of the optical system for 216 coude focus echelle spectrometer].

    PubMed

    Zhu, Y; Pan, J

    1997-04-01

    This paper gives a brief introduction about the structure of the echelle spectrometer which was installed at coude focus of the chinese 2. 16 meter astronomical telescope. According to the design requirment of this echelle spectrometer, the main points and steps of alignment of optical system are analysed. Authors work out a practical alignment scheme in which the fewest auxiliary tools are used. PMID:15810402

  12. 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.

  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. 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.

  15. 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.

  16. Error Management Techniques For Optical Disk Systems

    NASA Astrophysics Data System (ADS)

    Corsover, S. L.; Thomas, C. H.

    1982-04-01

    RCA Corporation has been actively developing optical disc media, techniques and systems which can store 1011 bits per disc at bit error rates of 10-9 and user data rates of 100 Mb/s. In parallel with efforts to improve the media and hardware, new techniques have been developed to manage the statistically inevitable errors which will occur in the recording, storage and playback process. These techniques, which include EDAC codes, data blocking formats and data verification schemes, have been implemented in operating hardware at RCA. Error sources in Optical Disc systems are outlined and media and hardware error management techniques are described.

  17. Object recognition using an efficient technique for aligning quadric surfaces

    NASA Astrophysics Data System (ADS)

    Alvertos, Nicolas; D'Cunha, Ivan

    1992-11-01

    Pose and orientation of an object are central issues in 3-D recognition problems. Most of today's available techniques require considerable pre-processing, such as detecting edges or joints, fitting curves or surfaces to segment images, and trying to extract higher order features from the input images. In this paper we present a method based on analytical geometry, whereby all the rotation parameters of any quadric surface are determined and subsequently eliminated. This procedure is iterative in nature and has been found to converge to the desired results in as few as three iterations. The approach enables us to position the quadric surface in a desired coordinate system, then, utilize the presented shape information to explicitly represent and recognize the 3-D surface. Experiments were conducted with simulated data for objects such as hyperboloid of one and two sheets, elliptic and hyperbolic paraboloid, elliptic and hyperbolic cylinders, ellipsoids, and quadric cones. Real data of quadric cones and cylinders were also utilized. Both of these sets yielded excellent results.

  18. 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.

  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. Electrical dependencies of optical modulation capabilities in digitally addressed parallel aligned liquid crystal on silicon devices

    NASA Astrophysics Data System (ADS)

    Martínez, Francisco Javier; Márquez, Andrés; Gallego, Sergi; Ortuño, Manuel; Francés, Jorge; Beléndez, Augusto; Pascual, Inmaculada

    2014-06-01

    Parallel aligned liquid crystal on silicon (PA-LCoS) displays have found wide acceptance in applications requiring phase-only modulation. Among LCoS devices, and PA-LCoS as a specific case, digital addressing has become a very common technology. In principle, modern digital technology provides some benefits with respect to analog addressing such as reduced interpixel cross-talk, lower power consumption and supply voltage, gray level scale repeatability, high programmability, and noise robustness. However, there are also some degradating issues, such as flicker, which may be enhanced. We analyze the characteristics of the digital pulse width modulated voltage signals in relation to their effect on the optical modulation capabilities of LCoS displays. We apply calibration techniques developed in our laboratory, basically the classical linear polarimeter extended to take into account the existence of flicker. Various digital sequence formats are discussed, focusing the analysis on the variations in the magnitude of the applied voltages across the LC layer. From this analysis, we obtain how to amplify the retardance dynamic range and how to enhance linearity in the device without enhancing flicker and without diminishing the number of available quantization levels. Electrical configurations intended for phase-only and intensity modulation regimes, useful in diffractive optics, are given.

  2. Automated self-alignment procedure for optical correlators

    NASA Astrophysics Data System (ADS)

    Montes-Usategui, Mario; Monroe, Stanley E.; Juday, Richard D.

    1997-06-01

    We propose a general and fully automated procedure that enables the self-correction of the errors and performance losses produced by the misalignment of the components of an optical correlator. This method is simple, is carried out entirely by software, and has minimal operating constraints. There are no moving parts and no extra hardware is required.

  3. Mechanical and magnetic alignment techniques for the RADLAC-II linear accelerator

    SciTech Connect

    Armistead, D.J.; Bolton, D.L.; Mazarakis, M.G.; Peredo, R.

    1987-01-01

    The RADLAC-II beam line, which includes nine accelerating cavities, 25 solenoidal magnets, and a nine-cryopump vacuum system, is suspended from the top of a water tank by 60, 0.5 cm-diameter, stainless steel rods. There are seven swiveling joints providing beam line flexibility (similar to that of a spinal cord). We have developed a technique to mechanically align the approx.12-meter-long accelerator vacuum pipe to within a fraction of a millimeter. A high accuracy microprocessor-equipped theodolite is being used with a television camera, monitor, and hard copier for observation ease, comparison, and documentation. Three illuminated lucite targets with cross hairs are utilized to align the beam line which comprises vacuum pipes of three different I.D.s. For the in-situ magnetic alignment of the solenoids, a new technique is currently being developed and will be presented.

  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. PMID:24500519

  5. 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.

  6. 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.

  7. A new optical axle measuring instrument for wheel alignment in assembly-line production

    SciTech Connect

    Bruhn, H.; Felske, A.

    1985-01-01

    The newly developed optical measuring system allows adjustment of front and rear wheel angularities - toe, camber, caster - in assembly-line production. There is no need to align the car, since the measuring base for the angle alignment is formed by the car itself. Defined spring compression values and direct caster angle determination lead to higher accuracy. Adjustment is carried out directly on the assembly line. Measuring pits are not required. The working time for each car and the working area required, which are important cost factors, are markedly lower than with conventional instruments. The axle measuring system was developed for the VW Vanagon, but can also be used for passenger car chassis. The measuring principle, the optical and mechanical design of the device, and a statistical analysis of over 100 cars aligned by means of this system are described in comparison with conventional measuring instruments.

  8. Surveying and optical tooling technologies combined to align a skewed beamline at the LAMPF accelerator

    SciTech Connect

    Bauke, W.; Clark, D.A.; Trujillo, P.B.

    1985-01-01

    Optical Tooling evolved from traditional surveying, and both technologies are sometimes used interchangeably in large industrial installations, since the instruments and their specialized adapters and supports complement each other well. A unique marriage of both technologies was accomplished in a novel application at LAMPF, the Los Alamos Meson Physics Facility. LAMPF consists of a linear accelerator with multiple target systems, one of which had to be altered to accommodate a new beamline for a neutrino experiment. The new line was to be installed into a crowded beam tunnel and had to be skewed and tilted in compound angles to avoid existing equipment. In this paper we describe how Optical Tooling was used in conjunction with simple alignment and reference fixtures to set fiducials on the magnets and other mechanical components of the beamline, and how theodolites and sight levels were then adapted to align these components along the calculated skew planes. Design tolerances are compared with measured alignment results.

  9. Tests and results of active alignment fiber optic connectors for space usage

    NASA Astrophysics Data System (ADS)

    McMurray, Lisa J.

    1996-10-01

    There exist commercially available fiber optic connectors which are capable of extremely low insertion losses per mated pair due to the utilization of a unique process of optical centering and crimping during termination. We have identified both single-fiber and multi-fiber connectors which utilize this process and have acquired a fabrication line which is capable of performing the active alignment termination process. This paper discusses tests and results required for space usage.

  10. Novel optical password security technique based on optical fractal synthesizer

    NASA Astrophysics Data System (ADS)

    Wu, Kenan; Hu, Jiasheng; Wu, Xu

    2009-06-01

    A novel optical security technique for safeguarding user passwords based on an optical fractal synthesizer is proposed. A validating experiment has been carried out. In the proposed technique, a user password is protected by being converted to a fractal image. When a user sets up a new password, the password is transformed into a fractal pattern, and the fractal pattern is stored in authority. If the user is online-validated, his or her password is converted to a fractal pattern again to compare with the previous stored fractal pattern. The converting process is called the fractal encoding procedure, which consists of two steps. First, the password is nonlinearly transformed to get the parameters for the optical fractal synthesizer. Then the optical fractal synthesizer is operated to generate the output fractal image. The experimental result proves the validity of our method. The proposed technique bridges the gap between digital security systems and optical security systems and has many advantages, such as high security level, convenience, flexibility, hyper extensibility, etc. This provides an interesting optical security technique for the protection of digital passwords.

  11. Optical fiber termination and splicing techniques

    SciTech Connect

    George, M.; Miller, M.M.

    1984-06-01

    This report details various techniques that have been developed during the course of optical fiber experimentation and installations. During the development phases, attempts have been made to devise the quickest and least tedious methods in each area of optical fiber work. These procedures include the termination and splicing of various cable types. Also included are appendices containing information on tools, connectors, jumpers, and splicing equipment.

  12. 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.

  13. Enzyme-etching technique to fabricate micropatterns of aligned collagen fibrils

    PubMed Central

    Liu, Honghai; Chen, Ruikai; Yang, Huaxiao; Qin, Wan; Borg, Thomas K.; Dean, Delphine; Xu, Meifeng; Gao, Bruce Z.

    2014-01-01

    A technique to tailor-make pre-coated, pre-aligned bovine collagen fibrils, derived from neonatal cardiomyocytes, on the surface of a glass slide into a designated pattern is reported. The unwanted collagen-coated area was erased by a collagenase solution and the tailored area was retained by attaching a microfabricated polydimethylsiloxane stamp directly to the collagen-coated surface. Using this technique, collagen patterns with designated orientations and with clear pattern boundaries and defined shapes were fabricated. PMID:24562408

  14. Microstructural and optical properties of nanocrystalline ZnO deposited onto vertically aligned carbon nanotubes by physical vapor deposition

    SciTech Connect

    Borkar, Tushar; Chang, Won Seok; Hwang, Jun Yeon; Shepherd, Nigel D.; Banerjee, Rajarshi

    2012-10-15

    Nanocrystalline ZnO films with thicknesses of 5 nm, 10 nm, 20 nm, and 50 nm were deposited via magnetron sputtering onto the surface of vertically aligned multi-walled carbon nanotubes (MWCNTs). The ZnO/CNTs heterostructures were characterized by scanning electron microscopy, high resolution transmission electron microscopy, and X-ray diffraction studies. No structural degradation of the CNTs was observed and photoluminescence (PL) measurements of the nanostructured ZnO layers show that the optical properties of these films are typical of ZnO deposited at low temperatures. The results indicate that magnetron sputtering is a viable technique for growing heterostructures and depositing functional layers onto CNTs.

  15. 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.

  16. Optical switch and interconnect techniques based on semiconductor optical amplifiers

    NASA Astrophysics Data System (ADS)

    Liu, Deming; Hu, Xiaojun; Huang, Dexiu

    1999-11-01

    In this paper the new progress in the researching fields of optical switch were reviewed. A compute model for calculating the switch speed, extinction ratio, noise figure, dynamic range as well as the switch gain was presented. The switch time, contrast ratio of SOA gate are calculated and evaluated. The methods to suppress the ASE noise are discussed. A novel and special method to extract optical route signal is presented. The result of the theoretical analysis showed that the optical gain of the SOA should be setup in optimum so as to obtain the best performances of the switch. An optical switch matrix using the polarization-insensitive strained quantum well SOAs and the optical couplers was fabricated and a novel and simplified method for extracting the logical control signal of the optical switch was specially designed, in which the optoelectronic integrated circuit (OEIC) techniques could be used to fabricate a compact, effect, high speed and low-cost optical switch matrix. IT is show that with the rapid improvement of OEIC techniques, the larger scale switch matrix based on SOA gate would be able to get into practice in the near future.

  17. Optimal analysis for segmented mirror capture and alignment in space optics system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaofang; Yu, Xin; Wang, Xia; Zhao, Lei

    2008-07-01

    A great deal segmented mirror errors consisting of piston and tip-tilt exist when space large aperture segmented optics system deploys. These errors will result in the departure of segmented mirrors images from the view. For that, proper scanning function should be adopted to control actuators rotating the segmented mirror, so that the images of segmented mirror can be put into the view and placed in the ideal position. In my paper, the scanning functions such as screw-type, rose-type, and helianthus-type and so on are analyzed and discussed. And the optimal scanning function principle based on capturing images by the fastest velocity is put forward. After capturing, each outer segmented mirror should be brought back into alignment with the central segment. In my paper, the central and outer segments with surface errors have the different figure, a new way to control the alignment accuracy is present, which can decrease the bad effects from mirror surface and position errors effectively. As a sample, a simulation experiment is carried to study the characteristics of different scanning functions and the effects of mirror surface and position errors on alignment accuracy. In simulation experiment, the piston and tip-tilt errors scale and the ideal position of segmented mirror are given, the capture and alignment process is realized by utilizing the improved optics design software ZEMAX, the optimal scanning function and the alignment accuracy is determined.

  18. 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.

  19. Method of light path alignment for femtosecond laser tracker based on double optical wedge

    NASA Astrophysics Data System (ADS)

    Cui, Chengjun; Zhou, Weihu; Lao, Dabao; Zhang, Wenying

    2015-08-01

    There are two light sources in Femtosecond laser tracker, the center wavelengths of which are different. In order to achieve precise distance, light beams from the two sources should be combined. In this paper, key technology of light path alignment for femtosecond laser tracker based on double optical wedge is presented. Precise steering of incident light beam can be realized by changing the angle of the double optical wedge. Method for adjusting the angle and translation of light beam using two pairs of double optical wedge is proposed. Also mathematical model on the basis of vector superposition method is established to correct offset of light beam, which is validated with Zemax.

  20. 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 order to estimate CLASP spatial resolution after its alignment in visible light.

  1. 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.

  2. Study of optical destruction techniques for optical discs

    NASA Astrophysics Data System (ADS)

    Choi, Taeyoung

    The topic of this dissertation is on the investigation of optical techniques for completely destroying data stored in optical discs. Complete and secure destruction of data is important when disposal of an optical disc containing sensitive and possibly classified information is concerned, since some information can be retrieved even from a fragment of a disc. After several candidate techniques and related systems are examined and fundamental system components are identified, an optical data destruction (ODD) system using a focused high power laser beam is devised, and a prototype system is designed and constructed. The ODD system uses a high power laser diode (HPLD) to expose data marks on optical discs and maintains the focused laser beam on a data layer by a focus servo using a diffractive optical element (DOE). The optical characteristics of the beam emitted from an HPLD are thoroughly investigated, and a few methods of modeling an HPLD beam in an optical system are studied. With the understanding of the HPLD beam properties, a limited-divergence raytracing (LDRT) model is developed to predict the propagation behavior of the HPLD beam in an optical system and shows good agreement with the real HPLD beam. This LDRT method is used to model the HPLD beam in the ODD system and simulate the resultant focus error signal with and without fabrication errors. The DOE focus sensor overcomes the problems in conventional focus sensors associated with the use of an intense line beam. The DOE comprising two angled gratings is designed to use only two weak 3rd order beams for focus sensing and fabricated on a chrome-coated glass substrate using a maskless lithography tool. The constructed ODD system is then used to perform destruction tests on various optical discs, which are examined using static and dynamic methods of data observation and retrieval. The observations show that data marks are optical invisible or completely covered with numerous micro-bubbles. These test results demonstrate that secure and complete destruction of data on optical discs is achieved using an ODD system. Successful destruction, however, depends greatly on exposure conditions and the type of optical media.

  3. 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.

  4. Alignment techniques for calibration and installation of a 6-m Toroidal Grating Monochromator

    NASA Astrophysics Data System (ADS)

    Wallace, Daniel J.; Hansen, Roger W. C.; Perkins, F. Keith; Pruett, Charles H.; Welnak, John

    1990-05-01

    The University of Wisconsin Synchrotron Radiation Center Optics Group has recently completed the installation of three 6-m Toroidal Grating Monochromator (TGM) beamlines on the Aladdin ring. Two of these beamlines image bending-magnet radiation and the third images radiation from the 30-period undulator on loan to the Synchrotron Radiation Center from the Stanford Synchrotron Radiation Laboratory and Lawrence Berkeley Laboratory. Each beamline required an accurate alignment strategy. This is due to the long source-to-final-image distance and the five independent critical elements: entrance mirror, entrance slit, grating chamber, exit slit, and exit mirror. The TGM grating chamber houses up to six gratings on a revolving carousel which is scanned with a sine-drive. We will describe grating stability checks and adjustments to linearize the grating scan calibration. We will also outline the basic alignment procedures from the source point, through the grating chamber, to the final focus. The procedure we have used provided sufficiently accurate alignment to realize the high throughput and resolution capabilities of the 6-m TGMs. The methods also allow later checks on critical degrees of freedom of the optical components.

  5. 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.

  6. A one-step technique to prepare aligned arrays of carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Mahanandia, Pitamber; Nanda, Karuna Kar

    2008-04-01

    A simple effective pyrolysis technique has been developed to synthesize aligned arrays of multi-walled carbon nanotubes (MWCNTs) without using any carrier gas in a single-stage furnace at 700?C. This technique eliminates nearly the entire complex and expensive machinery associated with other extensively used methods for preparation of CNTs such as chemical vapour deposition (CVD) and pyrolysis. Carbon source materials such as xylene, cyclohexane, camphor, hexane, toluene, pyridine and benzene have been pyrolyzed separately with the catalyst source material ferrocene to obtain aligned arrays of MWCNTs. The synthesized CNTs have been characterized by scanning electron microscopy (SEM), x-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and Raman spectroscopy. In this technique, the need for the tedious and time-consuming preparation of metal catalysts and continuously fed carbon source material containing carrier gas can be avoided. This method is a single-step process where not many parameters are required to be monitored in order to prepare aligned MWCNTs. For the production of CNTs, the technique has great advantages such as low cost and easy operation.

  7. 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.

  8. Asymmetric dyes align inside carbon nanotubes to yield a large nonlinear optical response.

    PubMed

    Cambr, Sofie; Campo, Jochen; Beirnaert, Charlie; Verlackt, Christof; Cool, Pegie; Wenseleers, Wim

    2015-03-01

    Asymmetric dye molecules have unusual optical and electronic properties. For instance, they show a strong second-order nonlinear optical (NLO) response that has attracted great interest for potential applications in electro-optic modulators for optical telecommunications and in wavelength conversion of lasers. However, the strong Coulombic interaction between the large dipole moments of these molecules favours a pairwise antiparallel alignment that cancels out the NLO response when incorporated into bulk materials. Here, we show that by including an elongated dipolar dye (p,p'-dimethylaminonitrostilbene, DANS, a prototypical asymmetric dye with a strong NLO response) inside single-walled carbon nanotubes (SWCNTs), an ideal head-to-tail alignment in which all electric dipoles point in the same sense is naturally created. We have applied this concept to synthesize solution-processible DANS-filled SWCNTs that show an extremely large total dipole moment and static hyperpolarizability (?0?=?9,800??10(-30)?e.s.u.), resulting from the coherent alignment of arrays of ?70 DANS molecules. PMID:25643253

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. The Pressure Modulator Infrared Radiometer (PMIRR) optical system alignment and performance

    NASA Technical Reports Server (NTRS)

    Chrisp, Michael P.; Macenka, Steven A.

    1991-01-01

    The alignment and performance of the optical system for the Pressure Modulator Infrared Radiometer (PMIRR) are described. This limb and nadir scanning instrument will be used for remote sounding of the Martian atmosphere and will be launched on Mars Observer in 1992. The instrument has nine channels distributed over the wavelength range 0.3 to 50 microns and has two pressure modulator cells for water vapor and carbon dioxide.

  15. 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.

  16. Optical alignment influenced aberrations in laser beam delivery systems and their correction

    NASA Astrophysics Data System (ADS)

    Scaggs, Michael; Haas, Gil

    2015-03-01

    Industrial high power laser systems are often evaluated based upon spatial profile of the beam before they are brought to focus for processing materials. It is therefore often assumed that if the raw beam profile is good that the focus is equally as good. The possibility of having good optics and poor alignment or bad optics and good alignment and therefore not achieve a good focal spot is quite high due to the fact that a raw beam spatial profile does not manifest third order aberrations. In such instances the focal spot will contain aberrations when there are slightly misaligned, poor quality, high power optics in the system such as a beam expander or eye piece and objective of a 3-axis galvo. Likewise, if the beam itself is not on axis, the third order aberrations of astigmatism and coma are likely to appear but again not be seen in the unfocused beams spatial profile. The third order aberrations of astigmatism, coma and spherical aberration can significantly alter both the size and spatial profile at the focus resulting in out of spec performance. The impact of beam and zoom expanders and their alignment in beam delivery systems is investigated by measuring both the far field unfocused and the far field focus beams using an all passive beam waist analyzer system.

  17. Alignment, Assembly and Testing of High Energy X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Ramsey, Brian

    2005-01-01

    We are developing grazing-incidence x-ray imaging optics for a balloon-borne hard x-ray telescope (HERO). The HERO payload, scheduled for launch in May 2005, currently consists of 8 mirror modules each containing 12 mirror shells fabricated using electroform-nickel replication off super-polished cylindrical mandrels. An optical system developed for aligning and assembling the shells in the modules will be described. Sources for systematic errors associated with this process will be discussed and results from on-ground x-ray testing of each module will be presented.

  18. Mounting and Alignment of Full-Shell Replicated X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Gubarev, Mikhail; Arnold, William; Kester, Thomas; Ramsey, Brian; Smithers, Martin

    2007-01-01

    We are developing grazing-incidence x-ray optics for astronomy. The optics are full-cylinder mirror shells fabricated using electroformed-nickel replication off super-polished mandrels. For space-based applications where weight is at a premium, very-thin-walled, light-weight mirrors are required. Such shells have been fabricated at MSFC with greater than 15 arcsec resolution. The challenge, however, is to preserve this resolution during mounting and assembly. We present here a status report on a mounting and alignment system currently under development at Marshall Space Flight Center to meet this challenge.

  19. Alignment, assembly, and testing of high-energy x-ray optics

    NASA Astrophysics Data System (ADS)

    Gubarev, Mikhail; Alexander, Cheryl; Ramsey, Brian

    2005-08-01

    We are developing grazing incidence x-ray imaging optics for a balloon-borne hard x-ray telescope (HERO). The HERO payload, scheduled for launch in May 2006, consists of 8 mirror modules with 12 mirror shells each fabricated using electroform-nickel replication off super polished cylindrical mandrels. An optical system for alignment and assembly of the shells into their modules will be described together with an assessment of the systematic errors associated with this process. Full details of the assembly procedures and results of the on-ground x-ray testing of the HERO modules will be provided.

  20. Tailoring the Optical Dipole Force for Molecules by Field-Induced Alignment

    NASA Astrophysics Data System (ADS)

    Purcell, S. M.; Barker, P. F.

    2009-10-01

    We report on the ability to tailor the optical dipole force for molecules by tuning their effective polarizability with strong field alignment using polarized fields. We have measured a difference of 20% in the dipole force on cold CS2 molecules when changing from linear to near-circular polarization using peak field intensities of 5.7×1011Wcm-2. A variation in the focal length with laser polarization of a molecular-optical lens formed by a single focused laser beam was also measured. This provides a new way of modifying this force for many molecules.

  1. 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.

  2. Fully automated beam-alignment and single stroke guided manual alignment of counter-propagating multi-beam based optical micromanipulation systems

    NASA Astrophysics Data System (ADS)

    Seidelin Dam, Jeppe; Rodrigo, Peter John; Perch-Nielsen, Ivan R.; Glückstad, Jesper

    2007-06-01

    In a previous paper [J. S. Dam et al, Opt. Express 15, 1923 (2007)] we demonstrated computerized “drag-and-drop” optical alignment of a counter-propagating multi-beam based micromanipulation system. By inclusion of image analysis, we report here on the extension of this work to accommodate a completely automated beam-alignment process. Additionally, to maintain a cost-effective and technically less demanding system architecture, we also report on a computer-guided manual alignment procedure. In the manual version, the computer analyzes the initial misalignment and the required compensations for each mirror in the system are calculated. Subsequently, the user is guided in adjusting the mirrors exactly by the requisite amount. This way, all mirrors only need to be moved once. The image analysis utilized in both calibration schemes employs a fitting algorithm to determine the position of beam-center with sub-pixel accuracy, thereby providing “better than human” alignment.

  3. Integration and alignment of adaptive optics systems: 10 years of experience at the VLT

    NASA Astrophysics Data System (ADS)

    Tordo, Sbastien

    2010-07-01

    The number and importance of the adaptive optics instruments has grown in the world through the last two decades. Such systems are becoming key elements for large telescopes, with increasing types and complexity. The Very Large Telescope (VLT) has been equipped with many instruments using adaptive optics such as Shack-Hartmann, curvature or pyramid wavefront sensors. In this framework the European Southern Observatory (ESO) has collected a large expertise in the field of instrument integration and in particular the integration of adaptive optics systems. The purpose of this article is to share this expertise with the community and tell how instruments are being built in our organization. Therefore this article is aimed at persons who have some or little experience in integration and optical alignment.

  4. 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.

  5. Nanometer-scale gaps between metallic electrodes fabricated using a statistical alignment technique

    NASA Astrophysics Data System (ADS)

    Steinmann, P.; Weaver, J. M. R.

    2005-02-01

    We describe a fabrication process for the creation of nanoscale gaps between metallic electrodes based on a statistical alignment method. This technique is appropriate for applications in which a sparse array of gaps, connected to macroscopic electrodes and pads, is required, for example the study of single molecule electrical conduction. This process relies on aligning two separate levels of electron beam lithography defining opposing arrays of metallic wires, so that the gap may be defined between wires of two dissimilar materials, such as nickel and gold. Lithographic definition of gaps small enough to permit tunneling was reliable and had high yield. Fitting an analytical model of tunnel conductance to measured electrical characteristics of a typical gap demonstrates a gap spacing of 1.3±0.7nm. The process is compatible with most conventional electron-beam lithography systems and does not require the use of unusually high resolution or accurate pattern placement.

  6. Analysis of dimensional tolerance for an optical demultiplexer of a highly alignment tolerant 4 25 Gb/s ROSA module.

    PubMed

    Lee, Joon Ki; Huh, Joon Young; Kang, Sae-Kyoung; Jang, Youn-Seon

    2014-02-24

    We have developed a 4 25 Gb/s ROSA (receiver optical sub-assembly) module for 100G Ethernet optical transceiver. This ROSA module has very large alignment tolerance of more than 250 m between the optical DMUX (demultiplexer) and four photodiodes, for the reason it has the advantage of being easily assembled. The large alignment tolerance can be attributed to the dimensional tolerant optical DMUX, which is composed of four thin film filters attached to a parallelogram-shaped optic block. Since it is important to define the fabrication specifications for the dimension of the optic block, we analyze dimensional tolerance for the optic block using three-dimensional simulation. This parallelogram-shaped optical DMUX permits length tolerance of 300 m and angular tolerance of 0.1. The fabricated optical DMUX is estimated to have the angular error of less than 0.09. PMID:24663754

  7. High-resolution dual-trap optical tweezers with differential detection: alignment of instrument components.

    PubMed

    Bustamante, Carlos; Chemla, Yann R; Moffitt, Jeffrey R

    2009-10-01

    Optical traps or "optical tweezers" have become an indispensable tool in understanding fundamental biological processes. Using our design, a dual-trap optical tweezers with differential detection, we can detect length changes to a DNA molecule tethering the trapped beads of 1 bp. By forming two traps from the same laser and maximizing the common optical paths of the two trapping beams, we decouple the instrument from many sources of environmental and instrumental noise that typically limit spatial resolution. The performance of a high-resolution instrument--the formation of strong traps, the minimization of background signals from trap movements, or the mitigation of the axial coupling, for example--can be greatly improved through careful alignment. This procedure, which is described in this article, starts from the laser and advances through the instrument, component by component. Alignment is complicated by the fact that the trapping light is in the near infrared (NIR) spectrum. Standard infrared viewing cards are commonly used to locate the beam, but unfortunately, bleach quickly. As an alternative, we use an IR-viewing charge-coupled device (CCD) camera equipped with a C-mount telephoto lens and display its image on a monitor. By visualizing the scattered light on a pair of irises of identical height separated by >12 in., the beam direction can be set very accurately along a fixed axis. PMID:20147041

  8. 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.

  9. 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. PMID:26876850

  10. 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.

  11. 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.

  12. Optical techniques for measurement of high temperatures

    NASA Astrophysics Data System (ADS)

    Veligdan, J. T.

    1991-10-01

    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; and (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.

  13. 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.

  14. Finding the optical axis of a distant object using an optical alignment system based on a holographic marker

    NASA Astrophysics Data System (ADS)

    Zhuk, D. I.; Denisyuk, I. Yu.; Gutner, I. E.

    2015-07-01

    A way to construct a holographic indicator of the position of the central axis of a distant object based on recording a transmission hologram in a layer of photosensitive material and forming a remote real image before a light source is considered. A light source with a holographically formed marker designed for visual guidance to the object axis; it can be used to simplify aircraft landing on a glide path, preliminary visual alignment of large coaxial details of various machines, etc. Specific features of the scheme of recording a holographic marker and the reconstruction of its image are considered. The possibility of forming a remote holographic image marker, which can be aligned with a simultaneously operating reference laser system for determining the direction to an object and its optical axis, has been demonstrated experimentally.

  15. 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.

  16. 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.

  17. A synchronization technique for optical PPM signals

    NASA Technical Reports Server (NTRS)

    Vilnrotter, V. A.; Rodemich, E. R.; Tan, H. H.

    1986-01-01

    A technique for maintaining synchronization between optical PPM (pulse-position modulation) pulses and a receiver clock by means of a delay-tracking loop is described and analyzed. The tracking loop is driven by a doubly stochastic Poisson process that contains information about the location of the desired slot boundaries. The slot boundaries are subject to slowly varying random delays that are ultimately tracked by the loop. The concept of fractional rms delay error is introduced to quantify the effects of signal and background induced shot noise on the performance of the delay-tracking loop.

  18. 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.

  19. 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)…

  20. 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. PMID:25249192

  1. New short-time alignment technique for 70-meter antenna surface panels

    NASA Technical Reports Server (NTRS)

    Katow, M. S.

    1986-01-01

    With severely limited field modification time for upgrading the 64-m antenna to 70-m diameter, a new shorter time method for aligning the surface panels of the main reflector was needed. For each target on the surface panel, both distance (or range) and elevation angle measurements are made. A new technique for setting the surface panels at zenith look has been devised. This article describes the software required to convert the computed target distortions obtained from the JPL-IDEAS structural analysis computer program (defining the gravity load change from a 45-deg elevation angle to zenith look) into the theodolite reading at zenith look. The technique results in a perfectly shaped reflector at the 45-deg rigging elevation, with acceptable surface error tolerance.

  2. 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 intracavernous pressure (ICP) response in the penis, was achieved with the laser operating in CW mode. CW optical nerve stimulation provides a significantly faster ICP response time using a lower laser power laser than conventional pulsed stimulation. An all-single-mode fiber design was successfully tested in a rat model. The CN reached a threshold temperature of ˜ 42 °C, with response times as short as 3 s, and ICP responses in the rat penis of up to 50 mmHg compared to a baseline of 5--10 mmHg. Chemical etching of the distal single-mode-fiber tip produced a concave shape and transformed the Gaussian to a flat-top spatial beam profile, resulting in simplified alignment of the laser beam with the nerve. This novel, all-single-mode-fiber laser nerve stimulation system introduces several advantages including: (1) a less expensive and more compact ONS configuration; (2) elimination of alignment and cleaning bulk optical components; and (3) improved spatial beam profile for simplified alignment. For the fascia layers over the CN's (240--600 microm), the 1550 nm laser with an optical penetration depth of ˜ 930 microm in water was substituted for the 1455 nm laser. Successful ONS was achieved, for the first time, in fascia layers up to 450 microm thick which is critical for future clinical translation of this method for intra-operative identification and preservation of CN's during prostate cancer surgery. In order to define the upper limit of the therapeutic window for ONS of CN in a rat model, in vivo, identification of the thermal damage threshold for the CN after laser irradiation was investigated by direct comparison of the visible thermal damage data with a theoretical thermal damage calculation utilizing a standard Arrhenius integral model.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26121614

  4. Pinned, optically aligned diagnostic dock for use on the Z facility.

    PubMed

    Gomez, M R; Rochau, G A; Bailey, J E; Dunham, G S; Kernaghan, M D; Gard, P; Robertson, G K; Owen, A C; Argo, J W; Nielsen, D S; Lake, P W

    2012-10-01

    The pinned optically aligned diagnostic dock (PODD) is a multi-configuration diagnostic platform designed to measure x-ray emission on the Z facility. The PODD houses two plasma emission acquisition (PEA) systems, which are aligned with a set of precision machined pins. The PEA systems are modular, allowing a single diagnostic housing to support several different diagnostics. The PEA configurations fielded to date include both time-resolved and time-integrated, 1D spatially resolving, elliptical crystal spectrometers, and time-integrated, 1D spatially resolving, convex crystal spectrometers. Additional proposed configurations include time-resolved, monochromatic mirrored pinhole imagers and arrays of filtered x-ray diodes, diamond photo-conducting diode detectors, and bolometers. The versatility of the PODD system will allow the diagnostic configuration of the Z facility to be changed without significantly adding to the turn-around time of the machine. Additionally, the PODD has been designed to allow instrument setup to be completed entirely off-line, leaving only a refined alignment process to be performed just prior to a shot, which is a significant improvement over the instrument the PODD replaces. Example data collected with the PODD are presented. PMID:23126888

  5. Pinned, optically aligned diagnostic dock for use on the Z facilitya)

    NASA Astrophysics Data System (ADS)

    Gomez, M. R.; Rochau, G. A.; Bailey, J. E.; Dunham, G. S.; Kernaghan, M. D.; Gard, P.; Robertson, G. K.; Owen, A. C.; Argo, J. W.; Nielsen, D. S.; Lake, P. W.

    2012-10-01

    The pinned optically aligned diagnostic dock (PODD) is a multi-configuration diagnostic platform designed to measure x-ray emission on the Z facility. The PODD houses two plasma emission acquisition (PEA) systems, which are aligned with a set of precision machined pins. The PEA systems are modular, allowing a single diagnostic housing to support several different diagnostics. The PEA configurations fielded to date include both time-resolved and time-integrated, 1D spatially resolving, elliptical crystal spectrometers, and time-integrated, 1D spatially resolving, convex crystal spectrometers. Additional proposed configurations include time-resolved, monochromatic mirrored pinhole imagers and arrays of filtered x-ray diodes, diamond photo-conducting diode detectors, and bolometers. The versatility of the PODD system will allow the diagnostic configuration of the Z facility to be changed without significantly adding to the turn-around time of the machine. Additionally, the PODD has been designed to allow instrument setup to be completed entirely off-line, leaving only a refined alignment process to be performed just prior to a shot, which is a significant improvement over the instrument the PODD replaces. Example data collected with the PODD are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    A strategy is presented to enable optical-sectioning microscopy with improved contrast and imaging depth using low-power (0.5 mW) diode laser illumination. While the DAC architecture's intersecting illumination and collection beams significantly improves the spatial-filtering and opticalsectioning performance of confocal microscopy, we propose that modulating the spatial alignment of the dual-axis beams at a frequency f, such the focal volume signal of the microscope is modulated at 2f, further provides nearly an order-of-magnitude improvement in optical-sectioning contrast. Lock-in detection is used to remove the unmodulated background light, thereby enhancing our ability to image deeply within highly scattering tissues.

  7. 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.

  8. Active alignment of vertebrate cone and rod photoreceptor waveguides: might this serve as a useful fiber-optics model?

    NASA Astrophysics Data System (ADS)

    Enoch, Jay M.

    2009-08-01

    Some years ago, the speaker demonstrated that vertebrate retinal photoreceptors are fiber optics elements and waveguides, and he succeeded in defining many of their properties. For a summary of much of this research, please see the reference to Enoch and Tobey listed below (Reference 4). Included are studies of photo-receptor alignments and maintenance of receptor alignments across the retina in normal and abnormal human eyes. With very rare exceptions, rod and cone photoreceptors across the retina align remarkably and precisely with the center-of-the-exit-pupil-of-the-optics-ofthe- eye throughout the lifetime of the individual! And within a modest period of time (a day or a bit more), it proved possible to alter that photoreceptor alignment by physically displacing the pupillary aperture; and with recentration of the eye pupil, these alignments recovered their original state. Here, the author asks, "Might advantage be gained by developing alignment sensitive, photoactivated, waveguide/fiber optic units? That is, might comparable mechanisms be adapted in a useful manner to non-biological fiber-optics applications? Since such characteristic responses have been clearly of great value for biological species; might similar designs serve other important roles?"

  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. Magnetic field alignment of supramolecular perylene/block copolymer complexes for electro-optic thin films

    NASA Astrophysics Data System (ADS)

    Gopinadhan, Manesh; Majewski, Pawel; Shade, Ryan; Dell, Emma; Gupta, Nalini; Campos, Luis; Osuji, Chinedum

    2012-02-01

    The realization of nanostructured electro-optic materials by self-assembly is complicated by the persistence of structural defects which render the system properties isotropic on macroscopic length scales. Here we demonstrate the use of magnetic fields to facilitate large area alignment of a supramolecular system consisting of a poly(styrene-b-acrylic acid) (PS-b-PAA) diblock copolymer host and a semiconducting perylene ligand. Hydrogen bonding between the carboxylic acid groups of PAA and imidazole head group of the perylene species results in hierarchically ordered materials with smectic perylene layers in a matrix of hexagonally packed PS cylinders at appropriate stoichiometries. The smectic layers and the PS domains are strongly aligned by the application of large (> 2T) magnetic fields in a manner reflective of the positive diamagnetic anisotropy and the planar anchoring of perylene units at the PS interface. We use a combination of SAXS studies in-situ with applied magnetic fields, GISAXS and polarized optical transmission measurements to characterize the system. Magnetic fields thus offer a viable route for directing the self-assembly of functional materials based on rigid chromophores and further, that supramolecular approaches can be complementary to such efforts.

  11. Measurement of anchoring coefficient of homeotropically aligned nematic liquid crystal using a polarizing optical microscope in reflective mode

    NASA Astrophysics Data System (ADS)

    Baek, Sang-In; Kim, Sung-Jo; Kim, Jong-Hyun

    2015-09-01

    Although the homeotropic alignment of liquid crystals is widely used in LCD TVs, no easy method exists to measure its anchoring coefficient. In this study, we propose an easy and convenient measurement technique in which a polarizing optical microscope is used in the reflective mode with an objective lens having a low depth of focus. All measurements focus on the reflection of light near the interface between the liquid crystal and alignment layer. The change in the reflected light is measured by applying an electric field. We model the response of the director of the liquid crystal to the electric field and, thus, the change in reflectance. By adjusting the extrapolation length in the calculation, we match the experimental and calculated results and obtain the anchoring coefficient. In our experiment, the extrapolation lengths were 0.31 ± 0.04 μm, 0.32 ± 0.08 μm, and 0.23 ± 0.05 μm for lecithin, AL-64168, and SE-5662, respectively.

  12. FMCW optical ranging technique in turbid waters

    NASA Astrophysics Data System (ADS)

    Illig, David W.; Laux, Alan; Lee, Robert W.; Jemison, William D.; Mullen, Linda J.

    2015-05-01

    The performance of a frequency-modulated continuous-wave (FMCW) hybrid lidar-radar system will be presented in the context of an underwater optical ranging application. In adapting this technique from the radar community, a laser is intensity-modulated with a linear frequency ramp. A custom wideband laser source modulated by a new wideband digital synthesizer board is used to transmit an 800 MHz wide chirp into the underwater channel. The transmitted signal is mixed with a reference copy to obtain a "beat" signal representing the distance to the desired object. The expected form of the return signal is derived for turbid waters, a highly scattering environment, indicating that FMCW can detect both the desired object and the volumetric center of the backscatter "clutter" signal. This result is verified using both laboratory experiments and a realistic simulation model of the underwater optical channel. Ranging performance is explored as a function of both object position and water turbidity. Experimental and simulated results are in good agreement and performance out to ten attenuation lengths is reported, equivalent to 100 meters in open ocean or 5 meters in a turbid harbor condition.

  13. Fiber probes based optical techniques for biomedical diagnosis

    NASA Astrophysics Data System (ADS)

    Arce-Diego, José L.; Fanjul-Vélez, Félix

    2007-06-01

    Although fiber optics have been applied in optical communication and sensor systems for several years in a very successful way, their first application was developed in medicine in the early 20's. Manufacturing and developing of optical fibers for biomedical purposes have required a lot of research efforts in order to achieve a non-invasive, in-vivo, and real-time diagnosis of different diseases in human or animal tissues. In general, optical fiber probes are designed as a function of the optical measurement technique. In this work, a brief description of the main optical techniques for optical characterization of biological tissues is presented. The recent advances in optical fiber probes for biomedical diagnosis in clinical analysis and optical biopsy in relation with the different spectroscopic or tomographic optical techniques are described.

  14. 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 overall phase uniformity.

  15. Optical inspection techniques for security instrumentation

    NASA Astrophysics Data System (ADS)

    van Renesse, Rudolf L.

    1996-03-01

    This paper reviews four optical inspection systems, in which development TNO Institute of Applied Physics was involved: (1) intaglio scanning and recognition, (2) banknote quality inspection, (3) visualization and reading of a finger pattern, and (4) 3DAS authentication. (1) Intaglio is reserved for high security printing. It renders a tactile relief that can be recognized by a laser scanning technique. This technique is applied by various national banks to detect counterfeit banknotes returning from circulation. A new system is proposed that will detect intaglio on arbitrary wrinkled banknotes. (2) A banknote fitness inspection system (BFIS) that inspects banknotes in specularly reflected light is described. As modern banknotes are provided increasingly with reflective security foils, a new system is proposed that inspects banknotes in specular and diffuse reflection, as well as in transmission. (3) An alternative visualization method for visualization of finger patterns is described, employing a reflective elastomer. A CD scanning system reads the finger patterns. (4) A nonwoven structure has two advantageous properties for card authentication: a random structure which renders each few square millimeters of the pattern uniqueness (identification) and a 3D structure which makes it virtually impossible to be counterfeited (authentication). Both properties are inspected by an extremely simple lenseless reader.

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

    PubMed

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

    2014-11-01

    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. PMID:25129745

  17. 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…

  18. 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

  19. Field validation of optical turbulence lidar technique

    NASA Astrophysics Data System (ADS)

    Gimmestad, G. G.; Dawsey, M. W.; Roberts, D. W.; Stewart, J. M.; Wood, J. W.; Eaton, F. D.; Jensen, M. L.; Welch, R. J.

    2005-05-01

    A new type of lidar is under development for measuring profiles of atmospheric optical turbulence. The principle of operation of the lidar is similar to the astronomical seeing instrument known as the Differential Image Motion Monitor, which views natural stars through two or more spatially separated apertures. A series of images is acquired, and the differential motion of the images (which is a measure of the difference in wavefront tilt between the two apertures) is analyzed statistically. The differential image motion variance is then used to find Fried's parameter r0. The lidar operates in a similar manner except that an artificial star is placed at a set of ranges, by focusing the laser beam and range-gating the imager. Sets of images are acquired at each range, and an inversion algorithm is then used to obtain the strength of optical turbulence as a function of range. In order to evaluate the technique in the field and to provide data for inversion algorithm development, a simplified version of the instrument was developed using a CW laser and a hard target carried to various altitudes by a tethered blimp. Truth data were simultaneously acquired with instruments suspended below the blimp. The tests were carried out on a test range at Eglin AFB in November 2004. Some of the resulting data have been analyzed to find the optimum frame rate for ground-based versions of the lidar instrument. Results are consistent with a theory that predicts a maximum rate for statistically independent samples of about 50 per second, for the instrument dimensions and winds speeds of the Eglin tests.

  20. 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

  1. Integrated motion system for self-alignment of micro-optical devices

    NASA Astrophysics Data System (ADS)

    Collard, Dominique; Fukuta, Y.; Akiyama, T.; Chauvel, Dominique; Fujita, Hiroyuki

    1996-08-01

    The purpose of this paper is to investigate an integrated X/Y motion system, compatible with silicon process that will allow the positioning of micro-optical devices. The basic actuator, used for this system is referred as scratch drive actuator (SDA). SDA is able to produce a 1-D displacement, so, by combining several SDA, multi-degree of freedom motion is obtained. First, the SDA dimension dependent yield was analyzed. From this study, SDA with 50 micrometer long and 70 micrometer wide scratching area are appropriate for the integrated alignment system. According to these dimensions, various X/Y stages configurations are designed and fabricated as well as other actuated components such as long springs, integrated snapping devices and also nonrectangular shaped SDA. Two-dimensional motion of a 150 micrometer by 150 micrometer polysilicon stage have been demonstrated, proving the SDA out force is able to overcome friction effects of this kind of device. Active snapping system have been also successfully implemented. Control schemes for the X/Y motion and for the alignment are now under investigation.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

  4. 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. PMID:26726580

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

    PubMed

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

    2015-10-01

    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. PMID:26521008

  6. Optical alignment and testing of the Diffuse IR Background Experiment IR cryogenic telescope

    NASA Technical Reports Server (NTRS)

    Wood, H. John

    1989-01-01

    Diffuse Infrared Background Experiment (DIRBE) optical alignment and testing methods are discussed. Using strobe videography, vibration and performance testing of a 32 hz tuning-fork chopper was carried out. The Cosmic Background explorer satellite provides improved microwave and IR all-sky maps of the cosmic background radiation from a polar orbit. A liquid helium cryostat houses the DIRBE and the Far IR Absolute Spectrophotometer (FIRAS) instruments at a temperature of 2 K. Differential MicRowave Radiometers (DMRs) provide large scale maps of anisotropy of the 3 K background at wavelengths of 3.3, 5.7, and 9.6 mm. The DIRBE telescope is an IR photometric instrument with 10 wavelength bands between 1 and 300 microns, designed to measure radiation from the epoch of galaxy formation. Stringent stray light requirements mean that the DIRBE flight instrument has to be built and tested in a class 100 environment.

  7. 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.

  8. Patella re-alignment in children with a modified Grammont technique

    PubMed Central

    2012-01-01

    Background and purpose In skeletally immature patients, surgical options due to recurrent patella dislocation are limited, because bony procedures bear the risk of growth disturbances. In this retrospective study, we report the long-term functional and radiographic outcome in skeletally immature patients using the modified Grammont surgical technique. Patients Between 1999 and 2004, 65 skeletally immature knees (49 children) were treated with a modified Grammont procedure: an open lateral release and a shift of the patella tendon insertion below the growth plate on the tuberositas tibia, allowing the tendon to medialize. At mean 8 (5.6–11) years after surgery, 58 knees in 43 patients were evaluated by clinical examination, from functional scores (Lysholm, Tegner), and from radiographs of the knees. Results Mean Lysholm score was 82 postoperatively. Tegner score decreased from 6.2 to 5. Eight knees had a single dislocation within 3 months of surgery. 3 knees had repeated late dislocations, all with a high grade of trochlea dysplasia. 6 knees showed mild signs of osteoarthritis. No growth disturbances were observed. Interpretation The modified Grammont technique in skeletally immature patients allows restoration of the distal patella tendon alignment by dynamic positioning. Long-term results showed that there were no growth disturbances and that there was good functional outcome. However, patients with a high grade of trochlea dysplasia tended to re-dislocate. PMID:23039166

  9. 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 robustness according to the FEA model. Finally connector-assemblies are made with the alignment system and we show that an insertion loss down to 0.1 dB is achievable. The prototypes are subsequently used as a sacrificial master for mould fabrication through electroplating with the goal of low-cost replication through hot embossing.

  10. 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.

  11. 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.

  12. 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.

  13. Updates to the optical alignment and test plan for the James Webb Space Telescope integrated science instrument module

    NASA Astrophysics Data System (ADS)

    Ohl, R.

    2009-08-01

    NASA's James Webb Space Telescope (JWST) is a 6.6m diameter, segmented, deployable telescope for cryogenic IR space astronomy (~40K). The JWST Observatory architecture includes the Optical Telescope Element (OTE) and the Integrated Science Instrument Module (ISIM) element that contains four science instruments (SI) including a Guider. The SIs and Guider are mounted to a composite metering structure with outer dimensions of ~2.2x2.2x1.7m. The SI and Guider units are integrated to the ISIM structure and optically tested at NASA Goddard Space Flight Center as an instrument suite using a telescope simulator (Optical telescope element SIMulator; OSIM). OSIM is a high-fidelity, cryogenic JWST telescope simulator that features a ~1.5m diameter powered mirror. The SIs are aligned to the structure's coordinate system under ambient, clean room conditions using optomechanical metrology. OSIM is aligned to the ISIM mechanical coordinate system at the cryogenic operating temperature via internal mechanisms and feedback from alignment sensors in six degrees of freedom. SI performance, including focus, pupil shear, pupil roll, boresight, wavefront error, and image quality, is evaluated at the operating temperature using OSIM. This work updates the assembly and ambient and cryogenic optical alignment, test and verification plan for ISIM.

  14. Micro-optics and lithography simulation are key enabling technologies for shadow printing lithography in mask aligners

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna; Noell, Wilfried

    2015-02-01

    Mask aligners are lithographic tools used to transfer a pattern of microstructures by shadow printing lithography onto a planar wafer. Contact lithography allows us to print large mask fields with sub-micron resolution, but requires frequent mask cleaning. Thus, contact lithography is used for small series of wafer production. Proximity lithography, where the mask is located at a distance of typically 30-100 μm above the wafer, provides a resolution of approximately 3-5 μm, limited by diffraction effects. Proximity lithography in mask aligners is a very cost-efficient method widely used in semiconductor, packaging and MEMS manufacturing industry for high-volume production. Micro-optics plays a key role in improving the performance of shadow printing lithography in mask aligners. Refractive or diffractive micro-optics allows us to efficiently collect the light from the light source and to precisely shape the illumination light (customized illumination). Optical proximity correction and phase shift mask technology allow us to influence the diffraction effects in the aerial image and to enhance resolution and critical dimension. The paper describes the status and future trends of shadow printing lithography in mask aligners and the decisive role of micro-optics as key enabling technology.

  15. 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

  16. Optical Techniques for Low Noise Microwave Frequency Sources

    NASA Technical Reports Server (NTRS)

    Maleki, Lute

    2005-01-01

    Optical techniques and mathematical models are described for low noise microwave frequency sources. The contents include: 1) Why Optical Techniques; 2) Wavemixing: Advantages and Disadvantages; 3) Wavemixing with Feedback: The OEO; 4) Feedback in both loops: COEO; and 5) State of the Art and Future Prospects.

  17. 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.

  18. 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.

  19. CIS-ZnS quantum dots for self-aligned liquid crystal molecules with superior electro-optic properties

    NASA Astrophysics Data System (ADS)

    Lee, Won-Kyu; Hwang, Seung Jun; Cho, Min-Jae; Park, Hong-Gyu; Han, Jin-Woo; Song, Seogjeong; Jang, Jong Hyun; Seo, Dae-Shik

    2012-12-01

    We demonstrate self-aligned and high-performance liquid crystal (LC) systems doped with 1-dimensional (1D) chain-like clusters of CuInS2 (CIS)-ZnS core-shell quantum dots (QDs). By changing the cell fabrication method of the LC-QD composites, we can selectively control the orientation of the LC molecules between the homogeneous and homeotropic states without conventional LC alignment layers. The homeotropic alignment of LCs was achieved by random dropcasting and the homogeneous alignment was performed using a capillary injection of LC-QDs due to the random or linear diffusion of QD clusters into ITO defects. The electrically compensated bend (ECB)- and vertically aligned (VA) mode LC displays (LCDs) containing our LC-QD composite both showed superior electro-optic (EO) properties. A 37.1% reduction in the threshold voltage (Vth) and a 36.6% decrease in the response time were observed for ECB mode LCDs, and a 47.0% reduction in the Vth and a 38.3% decrease in the response time were observed for VA mode LCDs, meaning that the proposed LC-QD composites have a great potential for the production of advanced flexible LCDs.We demonstrate self-aligned and high-performance liquid crystal (LC) systems doped with 1-dimensional (1D) chain-like clusters of CuInS2 (CIS)-ZnS core-shell quantum dots (QDs). By changing the cell fabrication method of the LC-QD composites, we can selectively control the orientation of the LC molecules between the homogeneous and homeotropic states without conventional LC alignment layers. The homeotropic alignment of LCs was achieved by random dropcasting and the homogeneous alignment was performed using a capillary injection of LC-QDs due to the random or linear diffusion of QD clusters into ITO defects. The electrically compensated bend (ECB)- and vertically aligned (VA) mode LC displays (LCDs) containing our LC-QD composite both showed superior electro-optic (EO) properties. A 37.1% reduction in the threshold voltage (Vth) and a 36.6% decrease in the response time were observed for ECB mode LCDs, and a 47.0% reduction in the Vth and a 38.3% decrease in the response time were observed for VA mode LCDs, meaning that the proposed LC-QD composites have a great potential for the production of advanced flexible LCDs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32458j

  20. Optical Second Harmonic Generation in the BaTiO3 phase of magnetically aligned multiferroic nanofibers

    NASA Astrophysics Data System (ADS)

    Gasperi, Katia

    Multiferroic materials enable the exploration of electrical control of magnetic properties and vice versa. Their increasing interest is especially due to their potential applications in the industry of information storage. Thanks to recent progress in nanotechnology, they have also been found to have many other applications such as transducers and sensors, and they already occupy a unique place in the biomedical field. The objective of this project is to study multiferroic nanofibers made of cobalt ferrite CoFe2O 4 (CFO) and barium titanate BaTiO3 (BTO) with a specific focus in the characterization of the ferroelectric phase. We researched the state of knowledge concerning the size effects on phase transition for nanoparticles and polycrystals BTO. The ferroelectric phase transition of BTO occurs when it changes from a tetragonal (anisotropic) crystal structure to a cubic (isotropic) structure. This change suggests that optical second harmonic generation (SHG) is a good measurement technique for monitoring the phase transition of the BTO half of the nanofibers. We designed and prepared a temperature dependent SHG experiment on magnetically aligned fibers in transmission with the possibility to investigate the polarization dependence of the signal. We also prepared interdigital electrodes on glass for the future study of the fibers in an external electric field.

  1. Wavefront sensing techniques for adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Ray, Mina; Sarkar, Samir K.; Chakraborty, Rabindra N.; Basuray, Amitabha

    2001-09-01

    The design and fabrication of a fiber optic pH sensor working on the basis of evanescent wave absorption is presented. A pH sensitive dye is immobilized on the uncladded portion of the optic fiber by sol-gel route. The sensitivity of the device is found to increase when multiple sol-gel coatings are used as the cladding in the sensing region. The sensor response and its dynamic range are reported for two pH indicator dyes, vis. bromocresol purple and bromocresol green.

  2. 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.

  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. 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.

  5. Optical fiber measurement techniques based on complementary correlation codes

    NASA Astrophysics Data System (ADS)

    Fang, Tao; Wen, Ke; Wang, Rong; Xu, Zhi-Yong

    2001-10-01

    Now, single-mode optical fiber has been widely applied in communication systems and the users of optical fiber have migrated to longer transmission wavelengths, which results in the task of optical fiber measurement becoming more difficult. A method measuring optical fiber properties such as fiber loss and attenuation is optical time domain reflectometer (OTDR) measurement. Conventional OTDRs have a limitation: the trade-off between signal-to-noise ratio and response resolution. This paper presents an approach that applies spectrum-spread techniques to remedy this limitation, and improves dynamic range and reduces measurement time without sacrificing response resolution.

  6. 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. PMID:18773033

  7. A Simple Technique for Visualizing Ultrasound Fields Without Schlieren Optics.

    PubMed

    Kudo, Nobuki

    2015-07-01

    A simple technique designed for visualization of ultrasound fields without Schlieren optics is introduced. An optical system of direct shadowgraphy with diverging light, which consists of a point light source and a shadow screen, constituted the basic system, but the screen was replaced by focusing optics: a camera that makes a virtual screen at its focus plane. The proposed technique visualizes displacement of light deflected by ultrasound, and the use of focusing optics enables flexible settings of the virtual screen position and optical magnification. Insufficient sensitivity of shadowgraphy was overcome by elimination of non-deflecting light using image subtraction of shadowgrams taken with and without ultrasound exposure. A 1-MHz focused transducer for ultrasound therapy and a 20-MHz miniature transducer for intravascular imaging were used for experiments, and alternate pressure change in short-pulsed ultrasound was visualized, indicating the usefulness of the proposed technique for evaluation of medical ultrasound fields. PMID:25842256

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Optical correlator techniques applied to robotic vision

    NASA Technical Reports Server (NTRS)

    Hine, Butler P., III; Reid, Max B.; Downie, John D.

    1991-01-01

    Vision processing is one of the most computationally intensive tasks required of an autonomous robot. The data flow from a single typical imaging sensor is roughly 60 Mbits/sec, which can easily overload current on-board processors. Optical correlator-based processing can be used to perform many of the functions required of a general robotic vision system, such as object recognition, tracking, and orientation determination, and can perform these functions fast enough to keep pace with the incoming sensor data. We describe a hybrid digital electronic/analog optical robotic vision processing system developed at Ames Research Center to test concepts and algorithms for autonomous construction, inspection, and maintenance of space-based habitats. We discuss the system architecture design and implementation, its performance characteristics, and our future plans. In particular, we compare the performance of the system to a more conventional all digital electronic system developed concurrently. The hybrid system consistently outperforms the digital electronic one in both speed and robustness.

  13. 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.

  14. 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.

  15. Advanced Mask Aligner Lithography (AMALITH)

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna

    2015-03-01

    Mask aligner lithography is very attractive for less-critical lithography layers and is widely used for LED, display, CMOS image sensor, micro-fluidics and MEMS manufacturing. Mask aligner lithography is also a preferred choice the semiconductor back-end for 3D-IC, TSV interconnects, advanced packaging (AdP) and wafer-level-packaging (WLP). Mask aligner lithography is a mature technique based on shadow printing and has not much changed since the 1980s. In shadow printing lithography a geometric pattern is transferred by free-space propagation from a photomask to a photosensitive layer on a wafer. The inherent simplicity of the pattern transfer offers ease of operation, low maintenance, moderate capital expenditure, high wafers-per-hour (WPH) throughput, and attractive cost-of-ownership (COO). Advanced mask aligner lithography (AMALITH) comprises different measures to improve shadow printing lithography beyond current limits. The key enabling technology for AMALITH is a novel light integrator systems, referred to as MO Exposure Optics® (MOEO). MOEO allows to fully control and shape the properties of the illumination light in a mask aligner. Full control is the base for accurate simulation and optimization of the shadow printing process (computational lithography). Now photolithography enhancement techniques like customized illumination, optical proximity correction (OPC), phase masks (AAPSM), half-tone lithography and Talbot lithography could be used in mask aligner lithography. We summarize the recent progress in advanced mask aligner lithography (AMALITH) and discuss possible measures to further improve shadow printing lithography.

  16. Some Alignment Considerations for the Next Linear Collider

    SciTech Connect

    Ruland, R

    2004-06-08

    Next Linear Collider type accelerators require a new level of alignment quality. The relative alignment of these machines is to be maintained in an error envelope dimensioned in micrometers and for certain parts in nanometers. In the nanometer domain our terra firma cannot be considered monolithic but compares closer to jelly. Since conventional optical alignment methods cannot deal with the dynamics and cannot approach the level of accuracy, special alignment and monitoring techniques must be pursued.

  17. 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.

  18. Dimensional metrology of large refractive optical components using nonoptical techniques

    NASA Astrophysics Data System (ADS)

    Peggs, Graham

    2002-02-01

    Traditionally, the key component design parameters such as radius, lens thickness, size and shape of most types of optical components are measured using optical techniques. There are several reasons for this, but in particular: the form of the entire surface is generally revealed in one testing set up, the optical functionality of the component is almost always the performance defining factor, and the heritage of many of the optical methods, i.e. the huge investment and expertise that has in the past been brought to bear on perfecting the testing methods. There are however, alternative non-optical instruments, such as CMMs, for measuring the form of optical components that are becoming increasingly attractive for conformal optical components, off-axis optics, and aspherical lenses and components, for example corrector plates, grisms, and so on. The main reasons for the increased acceptance of such techniques are that: the asphericity of some of the surfaces is often too great to be handled satisfactorily by interferometric methods at optical wavelengths, or even at infra-red wavelengths; the probing force of modern, special- purpose probes is remarkably small; the cost of producing computer-generated holograms required for optical testing can be very high and often the numbers of components to be tested do not justify the expense; the speed of production is such that the component cannot be repeatedly removed and replaced in the manufacturing machine and/or the manufacturing process is not so conductive to optical testing because of the presence of cutting fluids etc. and, finally, the level of accuracy required cannot be achieved using optical techniques for unorthodox shapes.

  19. 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

  20. A novel scheme for DVL-aided SINS in-motion alignment using UKF techniques.

    PubMed

    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

  1. Optical metrology techniques and apparatus for lens assembly

    NASA Astrophysics Data System (ADS)

    Wang, Shuping; Zhang, Chi; Davis, Colleen; Alt, Mark; Ji, Zheng; Han, Yue; Gardner, Michael

    2014-11-01

    This paper presents the optical and lens design for alignment to meet the challenging position specifications. Fabrication of the prototypes and testing results and analysis are also presented. The system components as well as their interaction with each other were simulated with Zemax software and tested in an experimental setup in order to conduct tolerance study and provide specifications for the mechanical fixtures used in the system. The epoxy is used to affix the parts together in a cost effective manner for prototyping. The position accuracy of +/-3 μm compared to the golden unit has been achieved.

  2. Phase retrieval techniques for adaptive optics

    SciTech Connect

    Carrano, C. J., LLNL

    1998-03-01

    We have developed and tested a method for minimizing static aberrations in adaptive optics systems. In order to correct the static phase aberrations, we need to measure the aberrations through the entire system. We have employed various phase retrieval algorithms to detect these aberrations. We have performed simulations of our experimental setup demonstrating that phase retrieval can improve the static aberrations to below the 20 nm rms level, with the limiting factor being local turbulence in the A0 system. Experimentally thus far, we have improved the static aberrations down to the 50 nm level, with the limiting factor being the ability to adjust the deformable mirror. This should be improved with better control algorithms now being implemented.

  3. Proposal for using optical transition radiation for electron beam alignment and emittance measurement for the free emittance measurement for the free electron laser experiments at ATF

    SciTech Connect

    Qiu, Xu Z.; Wang, Xijie; Ben-Zvi, I.

    1994-10-01

    Optical transiton radiation (OTR) produced from thin intercepting foils have been employed to image the spatial profile of the electron beam in several free electron laser experiments. It was found that the images from OTR were significantly sharper than the images produced from phosphor screens. Furthermore, OTR`s sensitivity of its angular distribution and polarization to energy and divergence of the electron beam was exploited to diagnose energy and emittance of the electron beam. OTR has been proven to be vital in electron beam alignment in FEL experiments. This report gives a summary of the basic theory of transition radiation and techniques using transition radiation for electron beam imaging and emittance measurement. The possibility was explored for employing these techniques in the HGHG FEL and the visible FEL experiments in ATF (Accelerator Test Facility).

  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. Techniques For Evaluation Of Aircraft Windscreen Optical Distortion

    NASA Astrophysics Data System (ADS)

    Harris, James S.; Hardinci, Kevin G.; Mersch, Steven H.

    1981-02-01

    Results of a program to experimentally evaluate existing techniques and develop new high-speed techniques for evaluation of optical distortion in aircraft windscreens are described. Present techniques for evaluation of air-craft windscreens' optical quality are based on grid board photography and point-by-point measurement of optical deviation errors. Experimental evaluation of the grid board techniques have shown them to be simple and easy to perform, but errors as large as 20 percent occur because of the associated data reduction. The approaches to point-by-point measurement of windscreen deviation errors provide high accuracy, but the time required to evaluate a single windscreen is typically 8 to 24 hours. New techniques were studied, developed, and evaluated in order to permit real-time evaluation of aircraft windscreens. Two approaches described will provide the capability for high-speed evaluation of windscreen optical distortion. These techniques utilize raster-scanned laser probe beams in conjunction with retroreflecting screens and holographic lenses. In addition to high-speed scanning techniques, a speckle photographic technique is described that can be used to evaluate binocular disparity in a transparent aircraft windscreen.

  6. Techniques For Evaluation Of Aircraft Windscreen Optical Distortion

    NASA Astrophysics Data System (ADS)

    Harris, James S.; Harding, Keven G.; Mersch, Steven H.

    1980-05-01

    Results of a program to experimentally evaluate existing techniques and develop new high-speed techniques for evaluation of optical distortion in aircraft windscreens are described. Present techniques for evaluation of aircraft windscreens' optical quality are based on grid board photography and point-by-point measurement of optical deviation errors. Experimental evaluation of the grid board techniques have shown them to be simple and easy to perform, but errors as large as 20 percent occur because of the associated data reduction. The approaches to point-by-point measurement of windscreen deviation errors provide high accuracy, but the time required to evaluate a single windscreen is typically 8 to 24 hours. New techniques were studied, developed, and evaluated in order to permit real-time evaluation of aircraft windscreens. Two approaches described will provide the capability for high speed evaluation of windscreen optical distortion. These techniques utilize raster scanned laser probe beams in conjunction with retro-reflecting screens and holographic lenses. In addition to high-speed scanning techniques, a speckle photographic technique is described that can be used to evaluate binocular disparity in a transparent aircraft windscreen.

  7. Nonlinear optical studies of liquid crystal alignment on a rubbed polyvinyl alcohol surface

    NASA Astrophysics Data System (ADS)

    Wei, Xing; Hong, Seok-Cheol; Zhuang, Xiaowei; Goto, Tomohisa; Shen, Y. R.

    2000-10-01

    Sum-frequency vibrational spectroscopy and second-harmonic generation have been used to measure the orientational distributions of the polymer chains and adsorbed 8CB liquid crystal molecules on a rubbed polyvinyl alcohol surface. Results show that the polymer chains at the surface appear to be well aligned by rubbing, and the adsorbed liquid crystal molecules are aligned, in turn, by the surface polymer chains. Strong correlation exists between the orientational distributions of the polymer chains and the liquid crystal molecules, indicating that the surface-induced bulk alignment of a liquid crystal film by rubbed polymer surfaces is via an orientational epitaxylike mechanism.

  8. Neutron optics requirements for neutron imaging techniques

    NASA Astrophysics Data System (ADS)

    Lehmann, E.; Morgano, M.; Peetermans, S.

    2014-07-01

    The utilization of X-rays for material research is common in many respects since their discovery at the end of the 19th century. New sources as electron synchrotrons or free-electron lasers push the methodology and the application ranges further. A similar approach started 50 years later with neutrons when sources with reasonable high intensity became available. Today, there are many similarities and complementarities visible between X-ray and neutron studies and the involved techniques. Therefore, it is worth to compare and to adapt from the advanced X-ray techniques and to translate it into the neutron world. Despite of the lack of neutron intensities compared to the most brilliant X-ray beams, the specific properties of neutrons (contrast, spin, magnetic moment, penetration power) are utilized and they will further play an important role in non-invasive studies on the micro- and macro scale. This paper wants to encourage to "look over the fence" into activities of the X-ray community as currently running in the COST action MP-1203.

  9. 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.

  10. 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.

  11. 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; Mller, 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.

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

    PubMed

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

    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

  13. Liquidus temperature and optical properties measurement by containerless techniques

    NASA Technical Reports Server (NTRS)

    Anderson, Collin D.

    1993-01-01

    Reactive alloy liquidus temperatures measured by conventional, contained techniques are often in error due to reactions with containers and gaseous impurities. This paper describes a new liquidus temperature measurement technique that avoids these problems by employing containerless processing. This technique relies on precise and accurate noncontact temperature measurements (NCTM), which are made possible by spectral emissivity values. The spectral emissivities, epsilon(sub lambda), are measured along with the optical properties (real, n, and imaginary, k, components of the index of refraction) using polarimetric techniques on electromagnetically levitated specimens. Results from work done at Vanderbilt University and Intersonics on the Ti-Al system are presented to demonstrate the above techniques.

  14. 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).

  15. 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 amplifier for RF power. The advantages are no SLM is required for this approach, and the complete antenna system is capable of full monolithic integration.

  16. Evaluation of Protein Immobilisation Techniques on Optical Fibre Tirf Sensor

    NASA Astrophysics Data System (ADS)

    Tedeschi, L.; Domenici, C.; Ahluwalia, A.; Baldini, F.; Mencaglia, A.

    2000-12-01

    The efficiency of optical immunosensors is highly dependent on the sensitivity of active protein layers anchored to the optical surface. In order to optimise the performance of the sensors, a comparative study of different immobilisation techniques of antibodies on optical surface has been carried out. In particular, experiments of different covalent immobilisation methods on planar quartz surfaces were conducted to enable a choice of the most suitable technique. The two methods resulting in higher surface densities of active sites were selected for further experiments on a fibre optic TIRF immunosensor. In both cases, the antibody coatings gave satisfactory responses to changes in fluorescent analyte concentrations for the tested range (~10-8 M). The capacity of polar organic solvents to dissociate the antigen-antibody complex and hence to regenerate the immunosensor surface has also been evaluated, indicating that DMSO can be used as a regenerating agent.

  17. 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

    2013-01-01

    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. Surface alignment, anchoring transitions, optical properties, and topological defects in the thermotropic nematic phase of organo-siloxane tetrapodes

    NASA Astrophysics Data System (ADS)

    Kim, Young-Ki; Senyuk, Bohdan; Shin, Sung-Tae; Kohlmeier, Alexandra; Mehl, Georg H.; Lavrentovich, Oleg D.

    We perform optical, surface anchoring, and textural studies of an organo-siloxane tetrapode material in the broad temperature range of the nematic phase. The optical, structural, and topological features are compatible with the uniaxial nematic order rather than with the biaxial nematic order, in the entire nematic temperature range -25C < T < 46C studied. For homeotropic alignment, the material experiences surface anchoring transition, but the director can be realigned into an optically uniaxial texture by applying a sufficiently strong electric field. The topological features of textures in cylindrical capillaries, in spherical droplets and around colloidal inclusions are consistent with the uniaxial character of the long-range nematic order. In particular, we observe isolated surface point defect-boojums and bulk point defects-hedgehog that can exist only in the uniaxial nematic.

  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. Wavelength conversion technique for optical frequency dissemination applications.

    PubMed

    Kim, Joonyoung; Marra, Giuseppe; Wu, David S; Richardson, David J; Slavík, Radan

    2016-04-15

    We demonstrate coherent wavelength conversion capable of covering the entire C-band by modulating the incoming optical carrier with a compact Fabry-Perot cavity embedded phase modulator and by optical injection locking a semiconductor laser to a tone of the generated optical frequency comb. The phase noise of the converted optical carrier over 1 THz frequency interval is measured to be -40  dBc/Hz at 10 Hz offset and the frequency stability is better than 2×10-17 level for averaging times >1000  s, making this technique a promising solution for comparisons of state-of-the-art optical clocks over complex fiber networks. PMID:27082327

  1. Study on application of optical clearing technique in skin diseases.

    PubMed

    Shan, Hao; Liang, Yanmei; Wang, Jingyi; Li, Yan

    2012-11-01

    So far, the study of the optical clearing is almost always about healthy tissue. However, the ultimate goal is to detect diseases for clinical application. Optical clearing on diseased skins is explored. The effect is evaluated by applying a combined liquid paraffin and glycerol mixed solution on several kinds of diseased skins in vitro. Scanning experiments from optical coherence tomography show that it has different effects among fibroma, pigmented nevus, and seborrheic keratosis. Based on the results, we conclude that different skin diseases have different compositions and structures, and their optical parameters and biological characteristics should be different, which implies that the optical clearing technique may have selectivity and may not be suitable for all kinds of skin diseases. PMID:23143160

  2. Study on application of optical clearing technique in skin diseases

    NASA Astrophysics Data System (ADS)

    Shan, Hao; Liang, Yanmei; Wang, Jingyi; Li, Yan

    2012-11-01

    So far, the study of the optical clearing is almost always about healthy tissue. However, the ultimate goal is to detect diseases for clinical application. Optical clearing on diseased skins is explored. The effect is evaluated by applying a combined liquid paraffin and glycerol mixed solution on several kinds of diseased skins in vitro. Scanning experiments from optical coherence tomography show that it has different effects among fibroma, pigmented nevus, and seborrheic keratosis. Based on the results, we conclude that different skin diseases have different compositions and structures, and their optical parameters and biological characteristics should be different, which implies that the optical clearing technique may have selectivity and may not be suitable for all kinds of skin diseases.

  3. Selective growth of vertically aligned carbon nanotubes by double plasma chemical vapour deposition technique.

    PubMed

    Cabral, Gil; Titus, Elby; Misra, D S; Gracio, J

    2008-08-01

    The selective growth of vertically aligned carbon nanotubes (VACNTs) on large area copper substrates was carried out using a double plasma hot-filament chemical vapour deposition system. Three independent power supplies were used to produce two glow discharges within the vacuum reactor. The generation of two glow discharges and the efficient utilization of the electric fields, by controlling the key process parameters, enabled the production of VACNTs. Morphology, density and structure of carbon nanotubes were characterized using Scanning Electron Microscopy and Raman Spectroscopy. PMID:19049172

  4. Simple technique to measure toric intraocular lens alignment and stability using a smartphone.

    PubMed

    Teichman, Joshua C; Baig, Kashif; Ahmed, Iqbal Ike K

    2014-12-01

    Toric intraocular lenses (IOLs) are commonly implanted to correct corneal astigmatism at the time of cataract surgery. Their use requires preoperative calculation of the axis of implantation and postoperative measurement to determine whether the IOL has been implanted with the proper orientation. Moreover, toric IOL alignment stability over time is important for the patient and for the longitudinal evaluation of toric IOLs. We present a simple, inexpensive, and precise method to measure the toric IOL axis using a camera-enabled cellular phone (iPhone 5S) and computer software (ImageJ). PMID:25316617

  5. Techniques for analyzing lens manufacturing data with optical design applications

    NASA Astrophysics Data System (ADS)

    Kaufman, Morris I.; Light, Brandon B.; Malone, Robert M.; Gregory, Michael K.; Frayer, Daniel K.

    2015-09-01

    Optical designers assume a mathematically derived statistical distribution of the relevant design parameters for their Monte Carlo tolerancing simulations. However, there may be significant differences between the assumed distributions and the likely outcomes from manufacturing. Of particular interest for this study are the data analysis techniques and how they may be applied to optical and mechanical tolerance decisions. The effect of geometric factors and mechanical glass properties on lens manufacturability will be also be presented. Although the present work concerns lens grinding and polishing, some of the concepts and analysis techniques could also be applied to other processes such molding and single-point diamond turning.

  6. Physical optics of the laser-schlieren shock tube technique.

    PubMed

    Kiefer, J H; Al-Alami, M Z; Hajduk, J C

    1981-01-15

    The physical optics of the laser-schlieren technique for the measurement of rate processes in shock waves is examined in detail. The method utilizes the Kirchhoff-Huygens integral with the usual thin lens, paraxial, and Fresnel approximations, all of which are appropriate for the typical laser schlieren experiment. The resolution and sensitivity of the technique are defined for all detector separations, and a reliable method for locating the time origin in the schlieren signal is provided. Diffraction is found to have a significant effect on the shock front generated signal, and geometrical optics treatments of this signal are shown to be inadequate. PMID:20309094

  7. Color schlieren optics - A review of techniques and applications

    NASA Astrophysics Data System (ADS)

    Settles, G. S.

    The history, underlying principles, and current status of color schlieren techniques are surveyed. The advantages of this optical tool for certain applications are discussed in terms of one- and two-dimensional visualizations, qualitative and quantitative analyses, and system sensitivity, range, and resolution. It is emphasized that schlieren techniques are more firmly rooted in the history of optics than is commonly recognized. A figure is included which illustrates and classifies most of the available color schlieren techniques in terms of source and cutoff masks added to the Toepler schlieren arrangement. Most of the applications cited here take advantage of color coding and color contrast in visualizing complex refractive fields and yielding both qualitative and quantitative results. The purpose is to present a unified framework to help other investigators decide whether color schlieren is useful for particular application and, if so, which technique to use.

  8. Pathfinder first light: alignment, calibration, and commissioning of the LINC-NIRVANA ground-layer adaptive optics subsystem

    NASA Astrophysics Data System (ADS)

    Kopon, Derek; Conrad, Al; Arcidiacono, Carmelo; Herbst, Tom; Viotto, Valentina; Farinato, Jacopo; Bergomi, Maria; Ragazzoni, Roberto; Marafatto, Luca; Baumeister, Harald; Bertram, Thomas; Berwein, Jürgen; Briegel, Florian; Hofferbert, Ralph; Kittmann, Frank; Kürster, Martin; Mohr, Lars; Radhakrishnan, Kalyan

    2014-08-01

    We present descriptions of the alignment and calibration tests of the Pathfinder, which achieved first light during our 2013 commissioning campaign at the LBT. The full LINC-NIRVANA instrument is a Fizeau interferometric imager with fringe tracking and 2-layer natural guide star multi-conjugate adaptive optics (MCAO) systems on each eye of the LBT. The MCAO correction for each side is achieved using a ground layer wavefront sensor that drives the LBT adaptive secondary mirror and a mid-high layer wavefront sensor that drives a Xinetics 349 actuator DM conjugated to an altitude of 7.1 km. When the LINC-NIRVANA MCAO system is commissioned, it will be one of only two such systems on an 8-meter telescope and the only such system in the northern hemisphere. In order to mitigate risk, we take a modular approach to commissioning by decoupling and testing the LINC-NIRVANA subsystems individually. The Pathfinder is the ground-layer wavefront sensor for the DX eye of the LBT. It uses 12 pyramid wavefront sensors to optically co-add light from natural guide stars in order to make four pupil images that sense ground layer turbulence. Pathfinder is now the first LINC-NIRVANA subsystem to be fully integrated with the telescope and commissioned on sky. Our 2013 commissioning campaign consisted of 7 runs at the LBT with the tasks of assembly, integration and communication with the LBT telescope control system, alignment to the telescope optical axis, off-sky closed loop AO calibration, and finally closed loop on-sky AO. We present the programmatics of this campaign, along with the novel designs of our alignment scheme and our off-sky calibration test, which lead to the Pathfinder's first on-sky closed loop images.

  9. 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. PMID:24772009

  10. 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

  11. 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.

  12. 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.

  13. Simulation of a symmetric optical response from a hybrid-aligned structure of a dual-frequency nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Ivanov, A. V.; Vakulin, D. A.

    2015-12-01

    To create a hybrid-aligned structure of a dual-frequency nematic liquid crystal (LC), we have obtained an approximate analytical solution of the system of equations that describes the dynamics of reorientations of the director under the action of a control electric signal of an arbitrary shape. Formulas obtained have been used to simulate a symmetric optical response of the LC structure for a sinusoidal electric pulse. It has been shown that, in terms of the used approximations, the results of the analytical calculation agree well with results of computer simulation and with experiment in the case of small deformations of the LC layer.

  14. 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.

  15. 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.

  16. 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. PMID:21996845

  17. Operation and maintenance manual for the optical alignment system (OAS) system 6250

    SciTech Connect

    Pardini, A.F., Westinghouse Hanford

    1996-07-16

    The OAS is a camera and laser system that will be used as an end effector on the LDUA to properly align the arm with the entry riser. It is attached to the LDUA by means of a Tool Interface Plat (TIP) which provides a feed through for all electrical and pneumatic utilities needed by the end effector to operate.

  18. 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-mean-square difference of 1.6 mrad and 2.1 mrad, respectively. In the field, the Observer method's capability to test collectors in any orientation was demonstrated by mounting the camera on a radio-controlled helicopter and measuring a collector oriented at 90° above the horizon. The absorber measurement capability was demonstrated in the field for a collector facing both horizontally and vertically.

  19. 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.

  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. 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.

  2. 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

  3. 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.

  4. Optical absorption depth profiling of photodegraded poly(vinylchloride) (PVC) films by quantitative photothermal deflection technique

    NASA Astrophysics Data System (ADS)

    Fu, S.-W.; Power, J. F.; Nepotchatykh, O. V.

    2000-05-01

    An improved photothermal beam deflection technique is applied for optical absorption depth profiling of UV photodegraded PVC films, for nondestructive evaluation of their decomposition mechanism. A new model-based on diffraction theory is used to describe the photothermal response (with bicell recording), induced by impulse irradiation of a depth dependent array of thin planar optical absorbers approximating the sample's depth profile. Improved techniques of alignment, sample preparation and quantitative deconvolution of the bicell impulse response have increased the signal repeatability and reduced the principal bias errors affecting this ill posed problem. By this technique and a stable solution of the inverse problem, the absorption coefficient depth profile is accurately reconstructed in PVC films. Experimental depth profiles were confirmed against destructive techniques run on identical samples of the degraded material. An excellent agreement was found between depth profiles recovered using the mirage effect and these reference methods. Observed absorption profiles were fully consistent with known patterns of depth dependent PVC degradation under nitrogen and oxygen atmospheres.

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

    PubMed

    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

  6. Fiber optic remote inspecting technique for caverned large oil tanks

    NASA Astrophysics Data System (ADS)

    Li, Weilai; Jiang, Desheng; Cao, He

    2000-12-01

    In the management of caverned fuel oil inventory, a strict rule of fire control has always been the first priority due to the special conditions. It is always a challenge to perform automatic measurement by means of conventional electrical devices for inspecting oil tank level there. Introduced in this paper is a fiber optic gauging technique with millimeter precision for automatic measurement in caverned tanks. Instead of using any electrical device, it uses optical encoders and optical fibers for converting and transmitting signals. Its principle, specifications, installation and applications are discussed in detail. Theoretical analysis of the factors affecting its accuracy, stability, and special procedures adopted in the installation of the fiber optic gauge are also discussed.

  7. Optical coherence tomography as film thickness measurement technique

    NASA Astrophysics Data System (ADS)

    Manallah, Aissa; Bouafia, Mohamed; Meguellati, Said

    2015-01-01

    Optical coherence tomography (OCT) is a powerful optical method, noninvasive and noncontact diagnostic method. Although it is usually used for medical examinations, particularly in ocular exploration; it can also be used in optical metrology as measure technique. In this work, we use OCT to measure thicknesses of films. In OCT, depth profiles are constructed by measuring the time delay of back reflected light by interferometry measurements. Frequency in k-space is proportional to optical path difference. Then the reflectivity profile is obtained by a Fourier transformation, and the difference between two successive peaks of the resulting spectrum gives the film thickness. Several films, food-type, of different thicknesses were investigated and the results were very accurate.

  8. 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

  9. Benchmarking process integration and layout decomposition of directed self-assembly and self-aligned multiple patterning techniques

    NASA Astrophysics Data System (ADS)

    Chen, Yijian; Zhou, Jun; You, Jun; Liu, Hongyi

    2014-03-01

    In this paper, we present a benchmarking study of directed self-assembly (DSA) and self-aligned multiple patterning (SAMP) techniques for potential applications in manufacturing 10-nm (half-pitch) IC devices. Using the self-aligned quadruple patterning (SAQP) process as an example, we compare their process characteristics and complexity/costs, identify the integration challenges, and propose various patterning solutions for both BEOL and FEOL applications. Major differences in DSA and SAQP mask strategy, layout decomposition algorithm, and pattern-generation modeling are discussed, and critical requirements of overlay accuracy and CD control for implementing a DSA process in NAND wordline patterning are indentified. DSA technique is found to be a complementary solution for certain niche applications and we suggest that our industry should allocate more R and D resources to solve the 2-D SAMP layout decomposition challenges for logic BEOL patterning. We also propose an "out-of-the-box" idea of combining DSA and SADP process to significantly improve the 2-D design flexibility and develop a layout decomposition algorithm for this hybrid process

  10. 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

  11. Radio-Optical Alignment and Recent Star Formation Associated with Ionized Filaments in the Halo of NGC 5128 (Centaurus A)

    NASA Astrophysics Data System (ADS)

    Rejkuba, M.; Minniti, D.; Courbin, F.; Silva, D. R.

    2002-01-01

    We used a direct CCD camera at the Magellan I telescope at Las Campanas Observatory and the Focal Reducer/Low Dispersion Spectrograph (FORS1) at the Antu Very Large Telescope (VLT) ESO Paranal Observatory to image fields centered on the inner and outer optical filaments in the halo of NGC 5128. In the V versus U-V color-magnitude diagrams we have identified young blue supergiants associated with these line-emitting filaments located between the inner radio lobe and the northern middle lobe. Around the outer filament, stars as young as 10 Myr were detected. They are principally aligned with the direction of the radio jet, but a vertical north-south alignment along the edge of the H I cloud is also present. Young stars in the inner filament field are found inside the bright knots of photoionized gas and are strongly aligned in the direction of the center of the galaxy at the same position angle as the inner radio jet. Fitting the Padova isochrones on UV color-magnitude diagrams, we find that blue stars around the inner filaments have ages similar to the ones around the outer filaments ~10-15 Myr and the same abundance of Z=0.004. The presence of young blue supergiants clearly shows that the bright blue knots in the northeastern halo of NGC 5128 are associations of young stars with photoionized gas. The temperature of the brightest stars is T~12,000-16,000 K, insufficient to account alone for the high excitation lines observed in the surrounding ionized gas. Thus, the optical emission jet is principally seen due to its alignment with the radio structure of the active galactic nucleus (AGN). The highly collimated star formation is present only in the northeastern halo of the galaxy, suggesting interaction of the jet with the gas clouds deposited during the last accretion event as the preferred triggering mechanism. From these observations, we infer a lower limit for the age of the NGC 5128 jet at 107 yr. The triggering of the star formation in the dense clouds in the halo of the galaxy by the jet supports the alignment effect observed in high-redshift radio galaxies. It also suggests that radio galaxies should have higher than normal star formation rates. Based on observations collected at the European Southern Observatory, Paranal, Chile, within the Observing Program 63.N-0229, and on observations collected by Magellan I telescope at Las Campanas Observatory, Chile.

  12. 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.

  13. 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. PMID:26560786

  14. Multiple Access Techniques for Fiber-Optic Networks

    NASA Astrophysics Data System (ADS)

    Mestdagh, Denis J. G.

    1996-01-01

    Recent advances and breakthroughs achieved in optical fiber technology have led to the advent of a new generation of fiber systems-Multiaccess Optical Fiber Networks.The huge bandwidth of these networks is revolutionizing the capability of individual nodes, and not surprisingly, multiaccess networks have become the subject of intense activity in the optical fiber communication engineering. The purpose of this tutorial paper is to acquaint the uninitiated reader with the basic concepts as well as the most recent progress of multiple access techniques applied to these networks. It also provides some insights into their characteristics relevant to the design engineer. The four basic multiple access techniques based on wavelength, subcarrier, time, and code degrees of freedom are reviewed theoretically and examples of systems that have been implemented so far are described. However, due to present-day technological limitations, these four basic techniques cannot yet be fully exploited to provide the optimum network performance they can theoretically offer. Therefore,hybridmultiple access schemes that combine these basic techniques in order to benefit from the advantages of each scheme while mitigating the drawbacks of the other ones have been proposed in the professional literature. These hybrid multiple access techniques are also surveyed in this paper.

  15. 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.

  16. 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.

  17. Well-aligned carbon nitride nanorods: the template-free synthesis and their optical and thermal properties

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao; Wu, Si; Zhang, Jian; Tang, Shunxi; Hu, Chunyuan; Li, Yingai; Jiang, Lina; Cui, Qiliang

    2015-06-01

    The fabrication and optical properties of well-aligned graphitic carbon nitride nanorods are demonstrated. The growth strategy involves the polycondensation of ballmilled molecular precursors of melamine and cyanuric chloride at programmed temperatures. The compositional and structural characterizations confirm that the prepared samples are polymeric graphitic carbon nitride with high crystallinity. The morphological studies reveal that the prepared samples consist of nanorods aligning nearly in parallel. The photophysical features of the carbon nitride nanorods can be satisfactorily described by the excitation and radiative recombination of molecular excitons. The significantly improved interlayer stacking, as well as the shifting of optical bandgap to higher energies, may be attributed to the general nanosize effect. Due to the overlap of orbitals induced by the delocalization of electrons in the sp 2 clusters with the higher packing density perpendicular to the layers, a wider bandgap is proposed for this peculiar nanoarchitecture. The luminescent nanorods remain thermally stable up to about 500 °C during calcination under atmospheric conditions, indicating their potential applications as sensors and nanoelectronic and optoelectronic devices.

  18. 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. PMID:27136859

  19. 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.

  20. Hardware accelerated optical alignment of lasers using beam-specific matched filters.

    PubMed

    Awwal, Abdul A S; Rice, Kenneth L; Taha, Tarek M

    2009-09-20

    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 images for thousands of templates in under a second, as may be required in future high-energy laser systems. 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 field programmable gate array (FPGA) hardware implementation processing 32 templates provided a speed increase of about 253 times over an optimized software implementation running on a 2.2 GHz AMD Opteron core. PMID:19767937

  1. 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.

  2. Evaluation of a computerized measurement technique for joint alignment before and during periacetabular osteotomy

    PubMed Central

    ARMIGER, ROBERT S.; ARMAND, MEHRAN; LEPISTO, JYRI; MINHAS, DAVNEET; TALLROTH, KAJ; MEARS, SIMON C.; WAITES, MATTHEW D.; TAYLOR, RUSSELL H.

    2009-01-01

    Periacetabular osteotomy (PAO) is intended to treat a painful dysplastic hip. Manual radiological angle measurements are used to diagnose dysplasia and to define regions of insufficient femoral head coverage for planning PAO. No method has yet been described that recalculates radiological angles as the acetabular bone fragment is reoriented. In this study, we propose a technique for computationally measuring the radiological angles from a joint contact surface model segmented from CT-scan data. Using oblique image slices, we selected the lateral and medial edge of the acetabulum lunate to form a closed, continuous, 3D curve. The joint surface is generated by interpolating the curve and the radiological angles are measured directly using the 3D surface. This technique was evaluated using CT data for both normal and dysplastic hips. Manual measurements made by three independent observers showed minor discrepancies between the manual observations and the computerized technique. Inter-observer error (mean difference±standard deviation) was 0.04±3.53° Observer 1; −0.46±3.13° for Observer 2; and 0.42±2.73° for Observer 3. The measurement error for the proposed computer method was −1.30±3.30°. The computerized technique demonstrates sufficient accuracy compared to manual techniques, making it suitable for planning and intraoperative evaluation of radiological metrics for periacetabular osteotomy. PMID:17786597

  3. Application of techniques for fault localization on optical cable

    NASA Astrophysics Data System (ADS)

    Voronkov, Andrey A.; Morochkovsky, Vladimir V.

    2007-03-01

    For fiber-optic links (FOL), the sufficient time of repairing (removing & reinstalling) fiber-optic cables (FOC) and the natural ageing of optical fibers (OF) have been stipulating and propelling the problems of safe communication. The latters used to and are nowadays resolved by mean of either reserving line, cables, fibers, digital streams or improving quality of FOC grooming. In the latter case, the implementation of a prognostic control of FOC plays sufficient role in fault prediction on maintenance stage of FOL. The prognostic control is performed by mean of Remote Test Fiber Systems (RFTS) on the basis of both direct controlling OF parameters and indirect methods of FOC monitoring, including, being applied at Volgograd City Telephone Network, RLTP Method (Rate Loss Time Prediction) designed for copper/ steel media. Thus for example a prediction method on the basis of protective sheath monitoring results of FOC. This method is very effective when applied for buried long-haul FOC and in widespread use in Russia. One of the problems ofthe method performance is how to maintenance satisfactory sheath condition ofFOC. In general, the main trouble is how to localize faults on the protective sheath. There are however some classical techniques which are similar to the applied techniques in fault localization in copper media, but when applied for FOL, the techniques have specifics. The purpose of the paper is to analyze specifics ofthe classical technique implementation for fault localization ofprotective sheath of FOC.

  4. Application of classical techniques for fault localization on optical cable

    NASA Astrophysics Data System (ADS)

    Platonov, Alexander N.

    2001-10-01

    For fiber-optic links (FOL), the sufficient time of repairing (removing & reinstalling) fiber-optic cables (FOC) and the natural aging of optical fibers (OF) have been stipulating and propelling the problems of safe communication. The latters used to and are nowadays resolved by mean of either reserving line, cables, fibers, digital streams or improving quality of FOC grooming. In the latter case, the implementation of a prognostic control of FOC plays sufficient role in fault prediction on maintenance stage of FOL. The prognostic control is performed by mean of Remote Test Fiber Systems (RFTS) on the basis of both direct controlling OF parameters and indirect methods of FOC monitoring, including, being applied at Vol-gograd City Telephone Network, RLTP Method (Rate Loss Time Prediction) designed for copper/steel media. Thus for example a prediction method on the basis of protective sheath monitoring results of FOC. This method is very effective when applied for buried long-haul FOC and in widespread use in Russia. One of the problems of the method performance is how to maintenance satisfactory sheath condition of FOC. In general, the main trouble is how to localize faults on the protective sheath. There are however some classical techniques which are similar to the applied techniques in fault localization in copper media, but when applied for FOL, the techniques have specifics. The purpose of the paper is to analyze specifics of the classical technique implementation for fault localization of protective sheath of FOC.

  5. 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.

  6. Vertically aligned rolled-up SiO2 optical microcavities in add-drop configuration

    NASA Astrophysics Data System (ADS)

    Böttner, Stefan; Li, Shilong; Jorgensen, Matthew R.; Schmidt, Oliver G.

    2013-06-01

    A significant step towards integrated vertically rolled-up microcavities is demonstrated by interfacing an as-fabricated SiO2 microtube optical ring resonator with tapered fibers. In this transmission configuration, resonant filtering of optical signals at telecommunication wavelengths is shown in subwavelength thick walled microcavities. Moreover, we present a four-port add-drop filter based on a lifted doubly interfaced vertically rolled-up microcavity. Our work opens opportunities for vertical resonant light transfer in 3D multi-level optical data processing as well as for massively parallel optofluidic analysis of biomaterials in lab-on-a-chip systems.

  7. 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 compared with either the G or B method, and it is especially useful when the tumor position varies greatly from its position on the original CT, relative to the rib cage.

  8. Techniques for nonlinear optical characterization of materials: a review

    NASA Astrophysics Data System (ADS)

    de Araújo, Cid B.; Gomes, Anderson S. L.; Boudebs, Georges

    2016-03-01

    Various techniques to characterize the nonlinear (NL) optical response of centro-symmetric materials are presented and evaluated with emphasis on the relationship between the macroscopic measurable quantities and the microscopic properties of photonic materials. NL refraction and NL absorption of the materials are the phenomena of major interest. The dependence of the NL refraction and NL absorption coefficients on the nature of the materials was studied as well as on the laser excitation characteristics of wavelength, intensity, spatial profile, pulse duration and pulses repetition rate. Selected experimental results are discussed and illustrated. The various techniques currently available were compared and their relative advantages and drawbacks were evaluated. Critical comparisons among established techniques provided elements to evaluate their accuracies and sensitivities with respect to novel methods that present improvements with respect to the conventional techniques.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Multistability and non linear dynamics of the optical Fréedericksz transition in homeotropically aligned nematics

    NASA Astrophysics Data System (ADS)

    Abbate, G.; Maddalena, P.; Marrucci, L.; Saetta, L.; Santamato, E.

    1991-05-01

    A new simple model is presented to describe the dynamics of the optical reorientation induced by a laser beam into a homeotropically aligned nematic liquid crystal. Unlike previous models on the subject, we accounted for transfer of angular momentum from light to the sample. A rich and somewhat unexpected dynamics is found also in the case of linear polarization of the incident light. On présente un modèle simple et nouveau pour décrire la dynamique de la réorientation optique obtenue par un rayon laser dans un cristal liquide nématique aligné homéotropiquement. Contrairement aux précédents modèles sur ce sujet, on a rendu compte de l'échange du moment angulaire entre la lumière et le milieu. On a trouvé une dynamique riche et assez inattendue, même dans le cas d'une polarisation linéaire de la lumière incidente.

  14. 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.

  15. Effects of machining parameters and optical alignment in off-centered conic mirrors

    SciTech Connect

    Yoder, R.C.

    1985-12-16

    Expressions are derived in simple, closed form (in terms of the aperture coordinates) for the optical signatures resulting from misalignment and from several controllable machining parameters in the manufacture of diamond-turned mirrors of the type comprising conic sections of revolution. Limited in validity to the lowest order in terms of the magnitudes of both angular misalignment and machining parameters, these wavefront error expressions are generally valid for optics of arbitrarily wide aperture. Through control of these signatures, dynamically induced part distortions can, in some cases, be eliminated.

  16. 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.

  17. 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 the setup is entirely digitally controlled. This measurement method is developed to determine the elasticity parameters of the eardrum in-situ. Other surface shapes however can also be measured.

  18. 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. PMID:22299958

  19. Spartans: Single-Sample Periocular-Based Alignment-Robust Recognition Technique Applied to Non-Frontal Scenarios.

    PubMed

    Juefei-Xu, Felix; Luu, Khoa; Savvides, Marios

    2015-12-01

    In this paper, we investigate a single-sample periocular-based alignment-robust face recognition technique that is pose-tolerant under unconstrained face matching scenarios. Our Spartans framework starts by utilizing one single sample per subject class, and generate new face images under a wide range of 3D rotations using the 3D generic elastic model which is both accurate and computationally economic. Then, we focus on the periocular region where the most stable and discriminant features on human faces are retained, and marginalize out the regions beyond the periocular region since they are more susceptible to expression variations and occlusions. A novel facial descriptor, high-dimensional Walsh local binary patterns, is uniformly sampled on facial images with robustness toward alignment. During the learning stage, subject-dependent advanced correlation filters are learned for pose-tolerant non-linear subspace modeling in kernel feature space followed by a coupled max-pooling mechanism which further improve the performance. Given any unconstrained unseen face image, the Spartans can produce a highly discriminative matching score, thus achieving high verification rate. We have evaluated our method on the challenging Labeled Faces in the Wild database and solidly outperformed the state-of-the-art algorithms under four evaluation protocols with a high accuracy of 89.69%, a top score among image-restricted and unsupervised protocols. The advancement of Spartans is also proven in the Face Recognition Grand Challenge and Multi-PIE databases. In addition, our learning method based on advanced correlation filters is much more effective, in terms of learning subject-dependent pose-tolerant subspaces, compared with many well-established subspace methods in both linear and non-linear cases. PMID:26285149

  20. Understanding and measuring the effects of soft nanopatterning techniques on internal alignment of polymer chains in Poly(3-hexylthiophene) nanolines

    NASA Astrophysics Data System (ADS)

    Lau, Thomas

    We investigate the effects of three h-PDMS stamp-based nanopatterning techniques on the extent of internal alignment of poly(3-hexylthiophene) molecules and crystallite size within the fabricated nanolines. Atomic force phase imaging, x-ray diffraction and thin-film field-effect transistor measurements help provide insight into the kinds of driving forces that promote crystallization of P3HT, which is highly desirable for possible application in various optoelectronic devices. Specifically, we verify that the effects of differing rates of solvent evaporation have a clear but limited role in promoting growth of large crystallites in both unpatterned films and nanolines, which in turn results in an isotropic distribution of chains in the edge-on or face on phase regardless of the patterning technique used or the size of the h-PDMS stamp's lines. Further studies with substrates treated with silanized monolayers are necessary in order to ascertain the possibility of induced crystallite orientation due to nano-confinement by the stamps.

  1. Neurophotonics: non-invasive optical techniques for monitoring brain functions

    PubMed Central

    Torricelli, Alessandro; Contini, Davide; Mora, Alberto Dalla; Pifferi, Antonio; Re, Rebecca; Zucchelli, Lucia; Caffini, Matteo; Farina, Andrea; Spinelli, Lorenzo

    2014-01-01

    Summary The aim of this review is to present the state of the art of neurophotonics, a recently founded discipline lying at the interface between optics and neuroscience. While neurophotonics also includes invasive techniques for animal studies, in this review we focus only on the non-invasive methods that use near infrared light to probe functional activity in the brain, namely the fast optical signal, diffuse correlation spectroscopy, and functional near infrared spectroscopy methods. We also present an overview of the physical principles of light propagation in biological tissues, and of the main physiological sources of signal. Finally, we discuss the open issues in models, instrumentation, data analysis and clinical approaches. PMID:25764252

  2. Techniques for reconfigurable optical add/drop multiplexer

    NASA Astrophysics Data System (ADS)

    He, Chun; Wang, Xinzhong; Li, Yao; Tsay, Wei-Shin

    2004-06-01

    Reconfigurable optical add/drop multiplexer (ROADM) is a next generation critical component that facilitates the network system evolution from a point-to-point transmission-oriented structure to an all-optical, wavelength-flexible, dynamic network. ROADM enables flexible removal and insertion of WDM channels at either a head-end or intermediate nodes-making it possible for true network provisioning and reconfiguration. We will review the pros and cons of each of the techniques for tunable OADM, from their operating principles to their practical implementations with special emphasis on two approaches: a TTF based three-port tunable filter as a basic one-channel tunable add/drop multipexer and a full-scale, MEMS mirror array based 80-channel reconfigurable OADM subsystem. Comparative laboratory experimental results with theoretical calculations are presented.

  3. Optical constants of silicon carbide deposited with emerging PVD techniques

    NASA Astrophysics Data System (ADS)

    Monaco, Gianni; Suman, M.; Pelizzo, M. G.; Nicolosi, P.

    2009-05-01

    Silicon carbide (SiC) is an attractive material for EUV and soft X-ray optics. CVD-deposited silicon carbide (deposited at 1400° C on Si substrate) is the best reflective material in the whole EUV interval (with about the 48% of reflectance at 121.6 nm). Despite of this, SiC thin films deposited with PVD techniques, such as magnetron sputtering, on silicon substrate, do not have the same performances and they undergo to a degradation with time, probably because of some stoichiometry reason (carbon rich). Depositing stable SiC with PVD techniques is crucial in building ML's, like Si/SiC and SiC/Mg for soft X-ray applications (such space telescope and photolithography). We deposited some preliminary samples using the Pulsed Laser Deposition (PLD) and the Pulsed Electron Deposition (PED) techniques achieving a good reflectance in the whole EUV range (27% at near normal incidence at 121.6 nn) on a silicon substrate. The higher energy involved in these deposition processes could lead to a film with a stoichiometry much closer to the target one. The reflectivity of the deposited films has been measured at the BEAR beamline of the ELETTRA synchrotron in Trieste (Italy; the optical constants retrieved at six wavelength from 121.6 nm down to 5 nm.

  4. 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 communicating concurrently. If better BER performance is required, then error correction codes (ECC) using near term electronic technology can be used. For example, the M(8,4,4) optical code together with Reed-Solomon (54,38,8) encoding provides a BER of better than (10 exp -11). The optical transceiver must then operate at 256 Mb/s with pulses of 0.65 ns because the 'bits' are now channel symbols.

  5. Computer-assisted technique versus intramedullary and extramedullary alignment systems in total knee replacement: a radiological comparison.

    PubMed

    Confalonieri, Norberto; Manzotti, Alfonso; Pullen, Chris; Ragone, Vincenza

    2005-12-01

    Malalignment in total knee replacement (TKR) is frequently associated with earlier failure and poor functional results. The authors compare the radiological results achieved in three consecutive series of TKRs using a computer-based alignment system (38 cases), a totally intramedullary alignment system (40 cases) and a totally extramedullary alignment system (37 cases). The frontal-femoral-component angle (FFC), the frontal-tibial-component angle (FTC), the hip-knee-ankle angle (HKA) and the sagittal orientation of the tibial component (slope) were evaluated 12 months after operation. The results did not show any statistically significant differences between the mean values of FFC, FTC, HKA angles and tibial slope among the three groups. However in the extramedullary alignment group there was a statistically higher percentage of TKRs with abnormal FFC and HKA angles. Furthermore all the implants in the computer aligned group were aligned within 4 degrees both of an ideal HKA and tibial slope. PMID:16459861

  6. 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.

  7. Whole optic fiber weighing technique and device of belt conveyor

    NASA Astrophysics Data System (ADS)

    Li, Weilai; Liu, Jie; Pan, Jianjun

    2015-07-01

    Whole optic fiber weighing technique and its device of belt conveyor are developed and put into application. Four FBG stress cells support a frame in a belt conveying line. In each cell, two FBG strain gauges are respectively installed at the stretching and compressing places to get the effects of sensitivity enhancement and temperature compensation. The weighing signals are from both FBG wavelength shift of loading cells and fiber belt speed meter. By means of integral algorithm, the weighing result is obtained. Actual coal weighing test shows that the accuracy of this weighing device is under 0.5%.

  8. 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.

  9. Detecting nanoparticles in tissue using an optical iterative technique

    PubMed Central

    Yariv, Inbar; Rahamim, Gilad; Shliselberg, Elad; Duadi, Hamootal; Lipovsky, Anat; Lubart, Rachel; Fixler, Dror

    2014-01-01

    Determining the physical penetration depth of nanoparticles (NPs) into tissues is a challenge that many researchers have been facing in recent years. This paper presents a new noninvasive method for detecting NPs in tissue using an optical iterative technique based on the Gerchberg-Saxton (G-S) algorithm. At the end of this algorithm the reduced scattering coefficient (µs'), of a given substance, can be estimated from the standard deviation (STD) of the retrieved phase of the remitted light. Presented in this paper are the results of a tissue simulation which indicate a linear ratio between the STD and the scattering components. A linear ratio was also observed in the tissue-like phantoms and in ex vivo experiments with and without NPs (Gold nanorods and nano Methylene Blue). The proposed technique is the first step towards determining the physical penetration depth of NPs. PMID:25426317

  10. Optical momentum alignment and spin orientation of hot electrons in GaAs/AlAs superlattices

    NASA Astrophysics Data System (ADS)

    Sapega, V. F.

    2008-11-01

    Recent studies of dimensionality effects on hot electron photoluminescence (HPL) polarization in GaAs/AlAs superlattices (SLs) are reviewed. The effect of miniband formation in semiconductor superlattices on selection rules for optical transitions has been studied by means of polarized HPL. In the SL parameters two regimes can be distinguished which are characterized by their own selection rules. The peculiarities of selection rules for each of the regimes reveal themselves in linear and circular polarization of photoluminescence, momentum distribution function of photoexcited electrons and their behavior in a magnetic field. It is also demonstrated that the polarized HPL can be successively used in the study of ferromagnetic diluted magnetic semiconductors.

  11. 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.

  12. Experimental comparison of particle interaction measurement techniques using optical traps.

    SciTech Connect

    Koehler, Timothy P.; Grillet, Anne Mary; Brotherton, Christopher M.; Molecke, Ryan A.

    2008-06-01

    Optical tweezers has become a powerful and common tool for sensitive determination of electrostatic interactions between colloidal particles. Recently, two techniques, 'blinking' tweezers and direct force measurements, have become increasingly prevalent in investigations of inter-particle potentials. The 'blinking' tweezers method acquires physical statistics of particle trajectories to determine drift velocities, diffusion coefficients, and ultimately colloidal forces as a function of the center-center separation of two particles. Direct force measurements monitor the position of a particle relative to the center of an optical trap as the separation distance between two continuously trapped particles is gradually decreased. As the particles near each other, the displacement from the trap center for each particle increases proportional to the inter-particle force. Although commonly employed in the investigation of interactions of colloidal particles, there exists no direct comparison of these experimental methods in the literature. In this study, an experimental apparatus was developed capable of performing both methods and is used to quantify electrostatic potentials between particles in several particle/solvent systems. Comparisons are drawn between the experiments conducted using the two measurement techniques, theory, and existing literature. Forces are quantified on the femto-Newton scale and results agree well with literature values.

  13. Nonlinear inverse synthesis technique for optical links with lumped amplification.

    PubMed

    Le, Son Thai; Prilepsky, Jaroslaw E; Turitsyn, Sergei K

    2015-04-01

    The nonlinear inverse synthesis (NIS) method, in which information is encoded directly onto the continuous part of the nonlinear signal spectrum, has been proposed recently as a promising digital signal processing technique for combating fiber nonlinearity impairments. However, because the NIS method is based on the integrability property of the lossless nonlinear Schrödinger equation, the original approach can only be applied directly to optical links with ideal distributed Raman amplification. In this paper, we propose and assess a modified scheme of the NIS method, which can be used effectively in standard optical links with lumped amplifiers, such as, erbium-doped fiber amplifiers (EDFAs). The proposed scheme takes into account the average effect of the fiber loss to obtain an integrable model (lossless path-averaged model) to which the NIS technique is applicable. We found that the error between lossless path-averaged and lossy models increases linearly with transmission distance and input power (measured in dB). We numerically demonstrate the feasibility of the proposed NIS scheme in a burst mode with orthogonal frequency division multiplexing (OFDM) transmission scheme with advanced modulation formats (e.g., QPSK, 16QAM, and 64QAM), showing a performance improvement up to 3.5 dB; these results are comparable to those achievable with multi-step per span digital back-propagation. PMID:25968670

  14. 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 application and will gain widespread acceptance within next few years from bench to bedside as an inexpensive and non-invasive tool compared to the other technologies.

  15. Real-Time Optical Hough Transform and Morphological Inspection Techniques.

    NASA Astrophysics Data System (ADS)

    Richards, Jeffrey Scott

    A real-time optical Hough transform inspection processor is described and applied to the industrial case study of the inspection of cigarette packages. The inspections are performed in real-time using a color Epson liquid crystal television as the input spatial light modulator. A new selective, real-time edge-enhancement technique is used to enhance edges only at the selected orientations which will Hough transform to peaks (this maximizes the signal to noise ratio in the Hough transform output). Several slices of the Hough transform are generated in parallel with a new computer generated hologram utilizing 1D modulated error diffusion. We benchmark our Hough transform processor with the inspection of 100 sample cigarette packages. Correct classification of all the packages (with defects that we intended to inspect for) was attained. We also discuss the confidence with which we can apply our laboratory sample set results to the industrial installation of our inspection processor. Extensions of the Hough transform are also described which generalize the Hough space to recognize shapes other than straight lines (e.g. circles, ellipses). We propose a new high speed acousto-optic architecture to implement these generalized Hough transforms. We also describe how the exact position of input lines can be extracted from Hough transform peak data. Typically, only the contour on which an input line resides is extracted from Hough data. Digital simulations illustrating both generalized Hough transformations and determination of input line position from Hough data are presented. Basic morphological transformations and their real-time optical implementation are discussed. We describe how morphological transformations are useful in inspection and show digital simulations and optical results of an inspection application (string detection in chopped tobacco) where morphological transformations are used.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  17. 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.

  18. 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)

  19. ORFEUS alignment concept

    NASA Astrophysics Data System (ADS)

    Graue, R.; Kampf, D.; Rippel, H.; Witte, G.

    1991-09-01

    The alignment concept of ORFEUS, a short-term scientific space payload scheduled for launching by the STS in January 1993, is discussed. ORFEUS comprises two alternatively operating spectrometers (Echelle and Rowland) implemented in a CFC telescope with a 4-m tube length and an aperture of 1000 mm. The lightweight primary mirror has a focal length of 2426 mm. In order to achieve the required spectrometric high telescope resolution in the UV range (40-125 nm), a sophisticated alignment concept was developed. The centering of the alignment diaphragm (diameter: 15 microns) in the focus of the primary mirror has to be provided in the vertical tube position by means of an autocollimation telescope. The spectrometers have to be integrated into the horizontal telescope aligned within a special antigravity device to reduce optical surface deformations and to ensure the optical performance of the primary. The alignment of all optical components is to be performed in the visible spectral range.

  20. Interstellar Dust Grain Alignment

    NASA Astrophysics Data System (ADS)

    Andersson, B.-G.; Lazarian, A.; Vaillancourt, John E.

    2015-08-01

    Interstellar polarization at optical-to-infrared wavelengths is known to arise from asymmetric dust grains aligned with the magnetic field. This effect provides a potentially powerful probe of magnetic field structure and strength if the details of the grain alignment can be reliably understood. Theory and observations have recently converged on a quantitative, predictive description of interstellar grain alignment based on radiative processes. The development of a general, analytical model for this radiative alignment torque (RAT) theory has allowed specific, testable predictions for realistic interstellar conditions. We outline the theoretical and observational arguments in favor of RAT alignment, as well as reasons the "classical" paramagnetic alignment mechanism is unlikely to work, except possibly for the very smallest grains. With further detailed characterization of the RAT mechanism, grain alignment and polarimetry promise to not only better constrain the interstellar magnetic field but also provide new information on the dust characteristics.

  1. Optical techniques for millimeter-wave detection and imaging

    NASA Astrophysics Data System (ADS)

    Schuetz, Christopher Arnim

    The benefits of imaging using regions of the electromagnetic spectrum outside the visible range have been known for decades. Infrared and radio frequency imaging techniques have achieved great successes in both military and civilian applications. However, there remains a range of the spectrum between these two regimes that remains relatively unexplored. Millimeter waves, or the range of wavelengths between one millimeter and one centimeter, have remained relatively unexplored as an imaging technology, largely due to the lack of sufficiently sensitive, practical detectors for passive imaging in this regime. At these short wavelengths, the diffraction limit imposed by the limited extent of the imaging aperture significantly limits attainable image resolution. Recent developments in semiconductor low-noise amplifiers have demonstrated many desirable applications for such imaging technology, but have, as yet, not been able to demonstrate the economical, small-format imagers necessary to make such imagers practical in most of the conceived applications. In this regard, I present a new approach to millimeter-wave detection based on optical modulation with subsequent carrier suppression. This approach demonstrates promise in achieving the goal of economical, high-resolution imagers with sufficient sensitivity for passive millimeter-wave imaging. In this thesis, I explain the operational requirements of such detectors, provide theoretical background for their operation, and describe current experimental results obtained using commercially available components in the 35 GHz. In addition, I describe successful efforts to fabricate modulators with improved modulation bandwidths for detection in the 95 GHz atmospheric window. These demonstration systems have attained sufficient single pixel performance to detect thermal emission with a noise equivalent temperature difference (NETD) approaching 1K/ Hz at both 35 and 95 GHz. The NETDs attained correspond to sub-picowatt noise equivalent powers which, to the best of my knowledge, have never before been obtained without the use of millimeter-wave low noise amplifiers or cryogenic cooling. The described optically-based detection technique has also demonstrated unique advantages to overcoming the resolution limits imposed by aperture size. Since the optical upconversion process preserves the phase of the collected energy, coherent imaging methods are possible. This enables the use of distributed aperture imaging, which could potentially provide large effective apertures for high resolution without the associated volumetric scaling associated with traditional focal plane arrays. Optical fiber can be utilized to provide low-loss, dispersion-free routing of the upconverted energy and optical lenses and cameras can be used to reconstruct the sampled image in a relatively simple manner. The combination of these factors offers potential for a uniquely capable millimeter-wave imaging technology based on optical upconversion. As part of this dissertation, I describe the relevant parameters that must be considered in designing such an imager and present results from a prototype array that has been successfully demonstrated.

  2. 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.

  3. Manufacturing microcomponents for optical information technology using the LIGA technique

    NASA Astrophysics Data System (ADS)

    Bauer, Hans-Dieter; Ehrfeld, Wolfgang; Hossfeld, Jens; Paatzsch, Thomas

    1999-09-01

    Recently, splices and connectors for fibers ribbons, optical cross connects and especially planar waveguide devices have been fabricated via LIGA in combination with precision engineering techniques. LIGA combines high precision and mass production capability, necessary for products designed for applications in the telecom and datacom market. In this presentation the fabrication of three-level molding and embossing tools is presented, which have been used for the manufacturing of waveguide prestructures consisting of waveguide channels and bier-to-waveguide coupling grooves. The precision of the tools is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, a precision of the tool is better than 1 micrometers in all directions, which allows for simple passive pigtailing. A first product, sixfold array of 4 X 4 multimode star couplers has been realized. The molding behavior of PMMA and COC material has been tested and compared. Production and assembly was tested by fabricating a series of 300 star couplers. The average insertion los has been found better than 9dB, the uniformity better than 3dB, both measured at 830nm. THe device is designed for application in optical backplanes for high-speed computers.

  4. Optimum Character Encryption And Extraction For Optical Correlation Techniques

    NASA Astrophysics Data System (ADS)

    Hawk, James F.; Martin, James C.; Gregory, Don A.; Christens-Barry, William A.

    1990-02-01

    An important subset of pattern recognition applications permit the representation of data by characters which have been optimized for the type of data and the type of search to be performed. An example of this is the search for biologically important patterns within the sequences of nucleotide subunits of deoxyribonucleic acid (DNA). In this case the four distinct subunits of DNA must be represented and "wildcard" or metacharacters are needed to permit flexible searches for sequence patterns. Due to the rapidly increasing availability of DNA sequence information, more rapid and interactive analytical techniques are needed to make full use of this data. This study seeks to design optimal characters for use in an optical correlator recognition device. Characters which are compact, easily distinguishable and compatible with current coherent light modulators have been designed. Preliminary work on these representations has been guided by computer modeling of the optical recognition process. Promising characters have been tested experimentally in a VanderLugt system. The use of laser printers and photo-typesetters to prepare original test images will be discussed.

  5. Technology of alignment mark in electron beam lithography

    NASA Astrophysics Data System (ADS)

    Zhao, Min; Xu, Tang; Chen, Baoqin; Niu, Jiebin

    2014-08-01

    Electron beam direct wring lithography has been an indispensable approach by which all sorts of novel nano-scale devices include many kinds optical devices can be fabricated. Alignment accuracy is a key factor especially to those devices which need multi-level lithography. In addition to electron beam lithography system itself the quality of alignment mark directly influences alignment accuracy. This paper introduces fundamental of alignment mark detection and discusses some techniques of alignment mark fabrication along with considerations for obtaining highly accurate alignment taking JBX5000LS and JBX6300FS e-beam lithography systems for example. The fundamental of alignment mark detection is expounded first. Many kinds of factors which can impact on the quality of alignment mark are analyzed including mark materials, depth of mark groove and influence of multi-channel process. It has been proved from experiments that material used as metal mark with higher average atomic number is better beneficial for getting high alignment accuracy. Depth of mark groove is required to 1.5~5 μm on our experience. The more process steps alignment mark must pass through, the more probability of being damaged there will be. So the compatibility of alignment mark fabrication with the whole device process and the protection of alignment mark are both need to be considered in advance.

  6. Fabricating and aligning pi-conjugated polymer-functionalized DNA nanowires: atomic force microscopic and scanning near-field optical microscopic studies.

    PubMed

    Nakao, Hidenobu; Hayashi, Hideki; Iwata, Futoshi; Karasawa, Hidenori; Hirano, Koji; Sugiyama, Shigeru; Ohtani, Toshio

    2005-08-16

    We report a simple method to functionalize DNA with pi-conjugated polymer, forming highly aligned and integrated arrays of pi-conjugated polymer nanowires of a few nanometers diameter. pi-conjugated polymer, polyphenazasiline, having alkylammonium salts on the N atom (PPhenaz-TMA), synthesized in this study can be directly attached to DNA, which can be organized along stretched and aligned DNA molecules on surfaces as a template. Furthermore, PPhenaz-TMA/DNA nanowires were stretched and aligned on surfaces, even when PPhenaz-TMA/DNA complexes formed in solutions. The resulting PPhenaz-TMA/DNA nanowires could be easily converted to oxidized states or metallic nanowires by using adequate oxidant or metal salts. The direct visualization of PPhenaz-TMA/DNA nanowires and its structural changes have been studied by atomic force microscopy and scanning near-field optical microscopy. PMID:16089403

  7. 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. PMID:27092573

  8. Polymer electro-optic waveguide devices: Low-loss etchless fabrication techniques and passive-to-active integration

    NASA Astrophysics Data System (ADS)

    Geary, Kevin

    The development of high-frequency polymer electro-optic modulators has seen steady and significant progress in recent years, yet applications of these promising materials to more complicated integrated optic structures and arrays of devices have been limited primarily due to high optical waveguide loss characteristics. This is unfortunate since a major advantage of polymers as photonic materials is their compatibility with photolithographic processing of large components. In this Dissertation, etchless waveguide writing techniques are presented in order to improve the overall optical insertion loss of electro-optic polymer waveguide devices. These techniques include poling-induced writing, stress-induced waveguide writing, and photobleaching. Using these waveguide writing mechanisms, we have demonstrated straight waveguides, phase modulators, Mach-Zehnder intensity modulators, variable optical attenuators, and multimode interference (MMI) power splitters, all with improved loss characteristics over their etched rib waveguide counterparts. Ultimately, the insertion loss of an integrated optic device is limited by the actual material loss of the core waveguide material. In this Dissertation, passive-to-active polymer waveguide transitions are proposed to circumvent this problem. These transitions are compact, in-plane, self-aligned, and require no tapering of any physical dimensions of the waveguides. By utilizing both the time-dependent and intensity-dependent photobleaching characteristics of electro-optic polymer materials, adiabatic refractive index tapers can be seamlessly coupled to in-plane butt couple transitions, resulting in losses as low as 0.1 dB per interface. By integrating passive polymer planar lightwave circuits with the high-speed phase shifting capability of electro-optic polymers, active wideband photonic devices of increased size and complexity can be realized. Optical fiber-to-device coupling can also result in significant contributions to the overall insertion loss of an integrated electro-optic polymer device. In this Dissertation, we leverage the photobleached refractive index taper component of our proposed passive-to-active polymer waveguide transitions in order to realize a two-dimensional optical mode transformer for improved overall fiber-to-device coupling of electro-optic polymer waveguide devices.

  9. 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…

  10. 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

  11. 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.

  12. Tumor Functional and Molecular Imaging Utilizing Ultrasound and Ultrasound-Mediated Optical Techniques

    PubMed Central

    Yuan, Baohong; Rychak, Joshua

    2014-01-01

    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. PMID:23219728

  13. Electro-optic characteristics of fringe-field-switching mode with controllable anchoring strength of liquid crystal alignment

    NASA Astrophysics Data System (ADS)

    Lin, T.-C.; Chang, K.-H.; Song, Y.; Hsieh, C.; Lo, C.-C.; Lee, C.; Lien, S.-C. Alan; Hasebe, H.; Takatsu, H.; Chien, L.-C.

    2015-11-01

    A photoalignment technique used in preparation of fringe-field-switching (FFS) mode cells is presented. The azimuthal anchoring energy (AAE) of photoalignment is controllable by tuning the UV exposure and if the value of AAE is as strong as that of the rubbing method. The electro-optical properties of FFS cells are optimized with different electrode configurations and high quality dark states of various types of cells are achieved to create the high contrast ratio. The great thermal stability shown after applying voltage and heat confirms that photoalignment is suitable for FFS mode applications.

  14. Alignment and calibration of high frequency ultrasound (HFUS) and optical coherence tomography (OCT) 1D transducers using a dual wedge-tri step phantom

    NASA Astrophysics Data System (ADS)

    Afsham, N.; Chan, K.; Pan, L.; Tang, S.; Rohling, R. N.

    2011-03-01

    This paper introduces a novel alignment and calibration method for high frequency ultrasound (HFUS) and optical coherence tomography (OCT) 1D transducers. 2D images are constructed by means of translation of the transducers using a linear motor stage. Physical alignment of the transducers is needed in order to capture images of the same crosssectional plane, and calibration is needed to determine the relative coordinates of the images, including the image skew. A dual wedge-tri step phantom is created for both alignment and calibration. This phantom includes two symmetrical wedges and three steps that provide the user with visual feedback on how well the scan plane is aligned with the midplane of the phantom. The phantom image consists of five line segments, each of which corresponds to one of the wedges or steps. The slopes and positions of the lines are extracted from the image and compared with the phantom model. The scan plane parameters are found so that the difference between the model and extracted features is minimized. The main advantage of this phantom is that only one frame is required to determine translations, orientations, and skew parameters of the scan plane with respect to the phantom. Experimental results with ocular imaging show the ability to achieve alignment based on this method and its potential for medical applications.

  15. 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.

  16. 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.

  17. 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.

  18. Measurements of residual stresses and surface topography using optical techniques

    NASA Astrophysics Data System (ADS)

    Wang, Baishi

    The dissertation presents two breakthrough optical interferometric techniques for the measurements of both whole-field residual stresses and surface topography. First, the whole-field residual stress measurement technique is developed for the first time using moire interferometry and Twyman/Green interferometry coupled high temperature resistant grating technique and thermal annealing. In the measurement, a special high temperature resistant cross grating is firstly made on the sample surface, and the whole-field residual stress relief is achieved by thermal annealing. Moire interferometry and Twyman/Green interferometry are then utilized to measure both in-plane and out-of-plane deformations generated by the residual stress relaxation, and then to obtain the whole-field strain redistribution due to the residual stress relief. The technique has been successfully applied to the measurement of the whole-field generalized 2-D residual stresses (i.e. both in-plane stresses and the out-of-plane normal stresses) in the rail using a transverse rail slice based on plausible assumptions. Its comparison to hole-drilling method with moire interferometry shows good quantitative agreement. Some key issues for further development are identified and discussed. Second, a novel polarization phase-stepping shearing interferometry (PPSSI) is presented for the calibration-free measurement of surface topography regardless of any surface reflectivity variation. The PPSSI incorporates the polarization phase modulation and Nomarski shearing interferometry to measure wavefront phase difference, or surface slope, irrespective of any wavefront amplitude change. The principle and theory of the PPSSI are described using Jones matrix method. Experimental results and its applications to the topographic measurements and flat wafers and speckle samples are shown. In addition, the modulation transfer function (MTF) and impulse response of a PPSSI system are studied both analytically and experimentally using Fresnel diffraction integral and edge gradient method, respectively. Comparison results of the system response with different beam truncation ratios, numerical apertures, and beam separations are shown. The results show that system has nearly diffraction limited spatial resolution and height sensitivity is better than 0.1 angstrom. The rule-of-thumb criteria for the system design are also discussed.

  19. 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.

  20. Alignment strategy for metal layers after W-CMP

    NASA Astrophysics Data System (ADS)

    Marokkey, Sajan R.; Tan, Juan Boon; Tak, Yan T.; Cheng, Alex T.

    1999-06-01

    CMP of Tungsten (W) in the wafer process flow pose a major challenge for robust stepper alignment, particularly at tighter design rules for 0.25 micron and beyond. Traditional alignment strategies based on optical diffraction often fail to provide alignment accuracy and consistency, as dictated by the tighter overlay budgets. Intensity based image analysis methods prove to be more successful in the alignment of metal CMP layers. In addition the noise reduction and signal processing capabilities of alignment sensors, the condition of the mark after W-CMP is vital for achieving good alignment. In this paper we report results from various alignment mark designs. The marks are designed to reduce the impact of CMP process variations on stepper alignment. Three types of alignment methods using laser diffraction, bright field imaging and laser interferometry techniques were investigated. The brightfield imaging alignment schemes provide the best results using a narrow trench mark separated by wider islands. Details of stepper alignment signals and overlay measurement results corresponding to some of the relevant mark design sand process variations are included in the paper.

  1. Subwavelength alignment mark signal analysis of advanced memory products

    NASA Astrophysics Data System (ADS)

    Yin, Xiaoming; Wong, Alfred K. K.; Wheeler, Donald C.; Williams, Gary; Lehner, Eric A.; Zach, Franz X.; Kim, Byeong Y.; Fukuzaki, Yuzo; Lu, Zhijian G.; Credendino, Santo; Wiltshire, Timothy J.

    2000-06-01

    The impact of alignment mark structure, mark geometry, and stepper alignment optical system on mark signal contrast was investigated using computer simulation. Several sub-wavelength poly silicon recessed film stack alignment targets of advanced memory products were studied. Stimulated alignment mark signals for both dark-field and bright-field systems using the rigorous electromagnetic simulation program TEMPEST showed excellent agreement with experimental data. For a dark-field alignment system, the critical parameters affecting signal contrast were found to be mark size and mark recess depth below silicon surface. On the other hand, film stack thickness and mark recess depth below/above silicon surface are the important parameters for a bright-field alignment system. From observed simulation results optimal process parameters are determined. Based on the simulation results some signal enhancement techniques will be discussed.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. 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.

  5. 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. PMID:25725877

  6. 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.

  7. All-optical and polarization-independent spatial filter based on a vertically-aligned polymer-stabilized liquid crystal film with a photoconductive layer.

    PubMed

    Huang, Chia-Yi; Ma, Jia-Ming; Mo, Tin-Shan; Lo, Kuo-Ching; Lo, Kuang-Yao; Lee, Chia-Rong

    2009-12-01

    An all-optical and polarization-independent spatial filter was developed in a vertically-aligned (VA) polymer-stabilized liquid crystal (PSLC) film with a photoconductive (PC) layer. This spatial filter is based on the effect of light on the conductivity of PC layer: high (low)-intensity light makes the conductivity of the PC layer high (low), resulting in a low (high) threshold voltage of the PC-coated VA PSLC cell. Experimental results indicate that this spatial filter is a high-pass filter with low optical-power consumption (about 1.11 mW/cm(2)) in an optical Fourier transform system. The high-pass characteristic was confirmed by simulation. Accordingly, the all-optical and polarization-independent spatial filter can be used to enhance the edges of images. PMID:20052162

  8. 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.

  9. A technique for the optical analysis of deformed telescope mirrors

    NASA Technical Reports Server (NTRS)

    Bolton, John F.

    1986-01-01

    The NASTRAN-ACCOS V programs' interface merges structural and optical analysis capabilities in order to characterize the performance of the NASA Goddard Space Flight Center's Solar Optical Telescope primary mirror, which has a large diameter/thickness ratio. The first step in the optical analysis is to use NASTRAN's FEM to model the primary mirror, simulating any distortions due to gravitation, thermal gradients, and coefficient of thermal expansion nonuniformities. NASTRAN outputs are then converted into an ACCOS V-acceptable form; ACCOS V generates the deformed optical surface on the basis of these inputs, and imaging qualities can be determined.

  10. Technique to reduce scattered light in optical systems

    NASA Astrophysics Data System (ADS)

    Wirick, M. P.

    1985-01-01

    In this patent application, in order to reduce the amount of internally scattered radiant energy in an optical system having a collecting optical chamber and a secondary optical chamber, a moving aperture device is positioned in a first focal plane between the chambers; the aperture device has a continuous moving metal band that has staggered slits therein. The band is sprocket driven and cryogenically cooled to reduce thermal emission. The band can be synced with other scanning detectors in the optical system such as one might find in an infrared telescope used in outer space.

  11. Nonlinear optical technique for advanced tunable IR lidar

    NASA Astrophysics Data System (ADS)

    Pasmanik, Guerman A.; Matveyev, Alexander Z.; Peterson, Darrel G.; Shilov, Alexander A.; Yakovlev, Ivan V.

    1998-05-01

    A review of nonlinear optical techniques to be used in tunable far IR lidar, radar and spectrometer system is presented. As an example, a tunable IR remote sensing technology demonstrator system operating at 8-12 μm is described. It includes an OPO and OPA pumped by Nd:YAG laser as well as Raman emitter and receiver pumped by the OPA output. Relatively small variations of an OPA wavelength (1.85-2 μm)provide a broad operative range at far IR (8-12 μm). The unique feature of OPO is pumping by two phase conjugated beams. A pulse from the pump laser is transmitted through the OPO. A portion of the transmitted pulse is reflected in a phase conjugate cell, and the remaining pulse energy is semi- compressed in stimulated Brillouin scattering (SBS) cells. These phase conjugate (PC) cells are filled with highly purified and stable SiCl4 and GeCl4 (R=80%). This process reduces the OPO threshold as well as forms short and narrow linewidth pulses. Being amplified up to 140 mJ in a 2 ns pulse in the OPA, these pulses are directed to a hydrogen Raman emitter. Due to auxiliary pumps at 1064 nm and 1907 nm with total energy approximately 30 mJ providing phonon excitation, the SRS conversion of an OPA output in the Stokes wave starts from a relatively high phonon seed so a quantum efficiency of more than 50 percent at far IR is achieved. The high sensitive detector of far IR weak signals (~1000 photons)is based on a Raman-induced four wave mixing of these signals with a delayed OPA output. A subsequent readout of the Raman grating is performed using a 532 nm pulse. The Raman-shifted 683 nm pulse is proportional to that of a weak IR signal.

  12. Fabrication of nanowire channels with unidirectional alignment and controlled length by a simple, gas-blowing-assisted, selective-transfer-printing technique.

    PubMed

    Kim, Yong-Kwan; Kang, Pil Soo; Kim, Dae-Il; Shin, Gunchul; Kim, Gyu Tae; Ha, Jeong Sook

    2009-03-01

    A printing-based lithographic technique for the patterning of V(2)O(5) nanowire channels with unidirectional orientation and controlled length is introduced. The simple, directional blowing of a patterned polymer stamp with N(2) gas, inked with randomly distributed V(2)O(5) nanowires, induces alignment of the nanowires perpendicular to the long axis of the line patterns. Subsequent stamping on the amine-terminated surface results in the selective transfer of the aligned nanowires with a controlled length corresponding to the width of the relief region of the polymer stamp. By employing such a gas-blowing-assisted, selective-transfer-printing technique, two kinds of device structures consisting of nanowire channels and two metal electrodes with top contact, whereby the nanowires were aligned either parallel (parallel device) or perpendicular (serial device) to the current flow in the conduction channel, are fabricated. The electrical properties demonstrate a noticeable difference between the two devices, with a large hysteresis in the parallel device but none in the serial device. Systematic analysis of the hysteresis and the electrical stability account for the observed hysteresis in terms of the proton diffusion in the water layer of the V(2)O(5) nanowires, induced by the application of an external bias voltage higher than a certain threshold voltage. PMID:19197970

  13. 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.

  14. 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.

  15. 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.

  16. Utilizing vertically aligned CdSe/CdS nanorods within a luminescent solar concentrator

    NASA Astrophysics Data System (ADS)

    Fisher, Martyn; Farrell, Daniel; Zanella, Marco; Lupi, Antonio; Stavrinou, Paul N.; Chatten, Amanda J.

    2015-01-01

    Optical characterisation methodologies are employed to validate a nanorod self-alignment technique for use in luminescent solar concentrators (LSCs). The nanorods utilised in this work were CdSe/CdS core/shell nanorods, and the self-alignment technique relied on the evaporation of a highly concentrated nanorod/xylene solution onto a glass substrate. Position and angular dependent light absorptivity measurements revealed evidence of vertical nanorod alignment over a limited region at the centre of the LSC sample. Vertical nanorod alignment is beneficial for absorbing diffuse/scattered sunlight and provides for a high light trapping efficiency in the LSC.

  17. 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 asymmetries in speed and magnitude of the swimming actions. This procedure should be used to identify and quantify asymmetries that might impair performance. PMID:25983579

  18. 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 in speed and magnitude of the swimming actions.This procedure should be used to identify and quantify asymmetries that might impair performance. PMID:25983579

  19. 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.

  20. Photon Counting Techniques for the Bandlimited Optical Channel

    NASA Technical Reports Server (NTRS)

    Lee, Clement G.; Gray, Andrew A.

    2005-01-01

    Two methods of estimating received photon counts given a realistic noisy and bandlimited optical channel are presented. The function of estimating photon counts is critical in any optical communications receiver. The purpose of this work is to compare two methods, neither of which is generically optimal, with realistic channels-for the purpose of assessing which is more appropriate for application in a hardware receiver given the current state-of-the art.

  1. Frequency Domain Optical Coherence Tomography Techniques in Eye Imaging

    NASA Astrophysics Data System (ADS)

    Wojtkowski, M.; Kowalczyk, A.; Targowski, P.; Gorczyñska, I.

    2000-12-01

    This contribution presents an application of frequency-domain optical tomography to ophthalmology. Essential theoretical foundations of time-domain and frequency-domain optical tomography are presented. Images of sections through the anterior chamber, the corneo-scleral angle and fundus of the eye are reconstructed from the spectral fringes. The morphological information gained by tomograms is important for diagnosing and planning of a treatment of glaucoma.

  2. Simple, low-cost technique for photolithographic self-aligned top metal contacts to nanowires and nanotubes

    NASA Astrophysics Data System (ADS)

    Oon, C. H.; Thong, J. T. L.

    2008-11-01

    We propose a new simple, low-cost method for providing all-round metal contacts to one-dimensional structures such as carbon nanotubes and nanowires on a transparent substrate. The nanostructures are first positioned in place to bridge a electrode gap by dielectrophoresis. The electrode structure is then used as a self-aligned mask during the subsequent photolithography through illumination from the substrate backside. This is followed by metallization and lift-off. Our measurements on multi-walled carbon nanotubes thus contacted show reasonable yield and good electrical contacts for the process carried out on a glass slide as the substrate.

  3. 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.

  4. Evaluation of Mechanical Modal Characteristics Using Optical Techniques

    NASA Technical Reports Server (NTRS)

    Lekki, John; Adamovsky, Grigory; Flanagan, Patrick; Weiland, Ken

    2002-01-01

    In this paper the sensitivity of embedded fiber optic sensors to changes in modal characteristics of plates is discussed. In order to determine the feasibility of embedded fiber Bragg gratings for the detection of modal shapes and modal frequencies, a comparison of holographically imaged modes and the detected dynamic strain from embedded fiber optic Bragg gratings is made. Time averaged optical holography is used for the detection of mechanical defects, or damage, in various aerospace components. The damage is detected by measuring an alteration in structural dynamics, which is visually apparent when using time-averaged holography. These shifts in the mode shapes, both in frequency of the resonance and spatial location of vibration nodes, are caused by changes in parameters that affect the structure's mechanical impedance, such as stiffness, mass and damping, resulting from cracks or holes. It is anticipated that embedded fiber optic sensor arrays may also be able to detect component damage by sensing these changes in modal characteristics. This work is designed to give an initial indication to the feasibility of damage detection through the monitoring of modal frequencies and mode shapes with fiber optic sensors.

  5. Weather watch studies by means of an optical technique

    NASA Technical Reports Server (NTRS)

    Turner, R. E. (Editor)

    1974-01-01

    A series of articles is presented on a passive, optical, cross beam system. The passive, optical, cross beam system was evaluated as a remote sensor of atmospheric conditions. The system employed the light scattered from natural aerosols to sense atmospheric mean and turbulent motion. A space-time correlation of the output of two optical sensors was used to evaluate the mean convective wind speed. In approximately 20% of the tests, signal-to-noise levels were sufficient to allow estimation of convective wind speeds. The feasibility of employing intersecting beams to evaluate the atmospheric turbulent motion was also investigated. The intersecting beams produced maximums in the space-time correlation curves for other than zero delay. The non-zero time delay maximums indicate the cross beam system was detecting aerosol layers in the atmosphere, rather than information from the common intersecting volume.

  6. A preferential coating technique for fabricating large, high quality optics

    NASA Astrophysics Data System (ADS)

    Alcock, S. G.; Cockerton, S.

    2010-05-01

    A major challenge facing optic manufacturers is the fabrication of large mirrors (>1 m) with minimal residual slope errors (<0.5 μrad rms). We present a differential coating method with the potential to satisfy such exacting technical demands. Iterative cycles of measurement using the Diamond-NOM, followed by preferential deposition, were performed on a 1200 mm long, silicon mirror. The applied coatings were observed to reduce the optical slope and figure errors from 1.62 to 0.44 μrad rms, and from 208 to 13 nm rms, respectively. It is hoped that this research will lead to commercially available products, of direct benefit to the Synchrotron, Free Electron Laser, Astronomy, Space, and Laser communities, who all require state-of-the-art optics.

  7. Ultrafast optical technique for the characterization of altered materials

    DOEpatents

    Maris, H.J.

    1998-01-06

    Disclosed herein is a method and a system for non-destructively examining a semiconductor sample having at least one localized region underlying a surface 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. 22 figs.

  8. 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.

  9. Amplitude independent instantaneous frequency measurement using all optical technique.

    PubMed

    Bui, Lam Anh; Mitchell, Arnan

    2013-12-01

    A novel all-optical system which independently measures both the amplitude and frequency of an RF signal is proposed and demonstrated. A photonic Hilbert transformer provides two orthogonal measurements of an RF signal. These are compared using four wave mixing in a highly nonlinear fiber, producing two independent outputs enabling determination of both signal frequency and amplitude. This all optical approach requires only simple, low cost DC electronics at the receiver. The system is demonstrated up to 20 GHz but can be scaled to 40 GHz and beyond. PMID:24514511

  10. Using quantum memory techniques for optical detection of ultrasound

    NASA Astrophysics Data System (ADS)

    McAuslan, D. L.; Taylor, L. R.; Longdell, J. J.

    2012-11-01

    Quantum memories are inherently highly efficient and display low noise, making them particularly suitable for the optical detection of ultrasound. Here, we use an atomic-frequency-comb based quantum memory to demonstrate sensitive ultrasound detection, realising a 49 dB discrimination between the sidebands and the carrier. The method remains valid in the case of optically thin samples and thus represents a significant improvement over other ultrasound detection methods based on rare-earth-ion-doped crystals. Furthermore, we show that this non-destructive non-contact approach is also compatible with highly scattering samples and suggest its particular suitability for the real-time imaging of biological tissues.

  11. 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

  12. Space diversity techniques in indoor broadband optical wireless communications

    NASA Astrophysics Data System (ADS)

    Alqudah, Yazan A.

    Wireless optical (infrared) link provides a secure and a promising alternative to radio for wireless indoor connectivity, be it for terminals or sensors. The large spectrum of unregulated band enables a link to provide broadband access needed for multimedia and other bandwidth demanding applications. The spatial confinement of infrared light provides interference-free bandwidth-reuse in adjacent rooms. The ability to create spatially independent channels in a small physical space holds the promise of large link capacity. The main challenges in the design of an infrared link include: susceptibility to shadowing, multipath dispersion, and limited range resulting from noise generated by ambient light. Shadowing caused by benign objects blocking signal path results in service degradation, if not complete interruption. Configurations employing wide beam transmitter to service many receiver locations suffer multipath. Noise at receiver is generated by ambient light. Even in a uniformly lit environment, noise generated by natural and artificial light varies depending on receiver location and orientation. To combat the adverse effects of temporal dispersion in high-speed applications, an accurate channel impulse response is needed. The impulse response is used to analyze and to compensate for the effects of multipath dispersion. In this work, a new approach for obtaining the channel impulse response is presented resulting in tremendous savings in calculation time and bringing insight into the channel behavior. The ability to create spatially independent channels has motivated a new configuration called Multi-Spot Diffusing (MSD) configuration. In which, a transmitter acts as an array antenna, with each element transmitting data over an independent channel. A multibranch receiver is employed to receive independent copies of transmitted data through each of its branches. In our research, we analyze MSD link with the objective of determining the optimal number of branches that results in maximum signal-to-noise ratio, minimum probability of error and minimum outage probability. The MSD configuration increases link capacity and reliability by providing a multi-input multi-output channel between transceivers. The availability of N spatial channels implies the possibility of increasing data rate by N folds compared to a single channel. In order to improve link reliability, our research considers novel spatial diversity coding techniques. In orthogonal spatial coding, each channel is responsible for carrying one of N symbols. The receiver decides on a transmitted symbol by comparing received signals on its branches and selects the branch corresponding to maximum signal. In another proposed scheme, a symbol is represented by N bit code word. Each bit is transmitted through a separate channel. The diversity receiver decides on a symbol that corresponds to the highest correlation with a received code word. Thus, information is transmitted not only through signal shapes, but also through branches that receive them. (Abstract shortened by UMI.)

  13. 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.

  14. Extramedullary versus intramedullary tibial alignment technique in total knee arthroplasty: A meta-analysis of randomized controlled trials

    PubMed Central

    Zeng, Huan Bei; Ying, Xiao Zhou; Chen, Guang Jun; Yang, Xia Qing; Lin, Duo Duo; Li, Zhi Jie; Liu, Hai Xiao

    2015-01-01

    The aim of this study was to establish whether the use of an extramedullary or intramedullary tibial cutting guide leads to superior mechanical leg axis and implant positioning. A meta-analysis of six randomized controlled trials including 350 knees was performed. For the mechanical axis, frontal tibial component angle and tibial slope, there were no significant differences in the mean values or the number of outliers (±3°) between the extramedullary and intramedullary groups. A reduced tourniquet time was associated with the intramedullary guide. No significant difference in the complication rate was noted between the two groups. Neither extramedullary nor intramedullary tibial alignment was more accurate in facilitating the tibial cut. Use of an intramedullary guide results in a shorter tourniquet time and exhibits a similar complication rate as the extramedullary guide. PMID:26598086

  15. Review of grazing incidence optics fabrication techniques for X-ray astronomy

    NASA Technical Reports Server (NTRS)

    Ulmer, Melville P.

    1990-01-01

    This paper covers the various techniques that are currently being used and developed to fabricate grazing incidence X-ray optics for the energy range from about 0.2 to 20 keV. Techniques covered will include diamond turning, thin foils, epoxy/carbon-fiber replication, electroforming replication, and float glass/Kirkpatrick-Baez techniques.

  16. Review of grazing incidence optics fabrication techniques for X-ray astronomy

    NASA Astrophysics Data System (ADS)

    Ulmer, Melville P.

    1990-08-01

    This paper covers the various techniques that are currently being used and developed to fabricate grazing incidence X-ray optics for the energy range from about 0.2 to 20 keV. Techniques covered will include diamond turning, thin foils, epoxy/carbon-fiber replication, electroforming replication, and float glass/Kirkpatrick-Baez techniques.

  17. Infrared optical element mounting techniques for wide temperature ranges

    SciTech Connect

    Saggin, Bortolino; Tarabini, Marco; Scaccabarozzi, Diego

    2010-01-20

    We describe the optimization of a mounting system for the infrared (IR) optics of a spaceborne interferometer working in the temperature range between -120 deg. C and +150 deg. C. The concept is based on an aluminum alloy frame with designed mechanical compliance, which allows for compensation of the different coefficient of thermal expansion between the optics and the holder; at the same time, the system provides for the high stiffness required to reach natural frequencies above 200 Hz, which are mandatory in most space missions. Thermal adapters with properly chosen thermomechanical characteristics are interposed between the metallic structure and the lens, so as to reduce the interface stresses on the mechanically weak IR material, due to both the thermoelastic and acceleration loads. With the proposed mount, the competitive requirements of stiffness and stress-free mounting can be matched in wide temperature ranges. The case study of the interferometer of a miniaturized Fourier transform IR spectrometer is presented.

  18. Improving optical measurement accuracy using multi-technique nested uncertainties

    NASA Astrophysics Data System (ADS)

    Silver, R. M.; Zhang, N. F.; Barnes, B. M.; Zhou, H.; Heckert, A.; Dixson, R.; Germer, T. A.; Bunday, B.

    2009-03-01

    This paper compares and contrasts different combinations of scatterfield and scatterometry optical configurations as well as introduces a new approach to embedding atomic force microscopy (AFM) or other reference metrology results directly in the uncertainty analysis and library-fitting process to reduce parametric uncertainties. We present both simulation results and experimental data demonstrating this new method, which is based on the application of a Bayesian analysis to library-based regression fitting of optical critical dimension (OCD) data. We develop the statistical methods to implement this approach of nested uncertainty analysis and give several examples, which demonstrate reduced uncertainties in the final combined measurements. The approach is also demonstrated through a combined reference metrology application using several independent measurement methods.

  19. Optical Properties of Astronomical Silicates with Infrared Techniques

    NASA Astrophysics Data System (ADS)

    Cataldo, Giuseppe; Rinehart, S. A.; Benford, D.; Dwek, E.; Kinzer, R. E.; Nuth, J.; Silverberg, R.; Wollack, E.

    2011-05-01

    Infrared observations are uniquely able to observe the astrophysical processes deep within dusty regions and to provide key information on the characteristics of the dust itself. This information is critical for learning the role of dust in gas physics, for exploring how dust processing occurs, and for understanding the formation and destruction mechanisms of dust grains. Though relevant astronomical and ground-based observations already exist, the properties of dust at these long wavelengths are poorly known, and since observed spectral features of dust are used to infer characteristics of the surrounding neighborhood, these large uncertainties lead to ambiguity in interpretation. The OPASI-T program addresses the need for high fidelity optical characterization data in the far and mid infrared, aiming at the creation of a unique library of the optical properties of metal-enriched silicate condensates. Such database will cover a wide wavelength range connecting numerical data with laboratory and astronomical spectra in the mid infrared, while providing new data in the unexplored far-infrared and millimeter regime. Both new and established experiments are used to measure the transmission and reflection properties of amorphous silicates across the infrared, which are then analyzed by way of numerical methods in order to determine the variations of their optical constants and complex dielectric function as a function of wavelength. I will present room-temperature measurements of SiO in a KBr matrix from 5 to 25 μm and its optical properties as derived from a least-squares nonlinear fit applied to a mixed approach coupling the Maxwell-Garnett theory, the Lorentz dispersive model for mixtures, and the averaged equation for transmission. This material is based upon work supported by NASA through the ROSES/APRA program. This research was supported by an appointment (Cataldo) at the Goddard Space Flight Center administered by Universities Space Research Association through a contract with NASA.

  20. Optical correlation technique for cement particle size measurements

    NASA Astrophysics Data System (ADS)

    Gorsky, M. P.; Maksimyak, P. P.

    2015-11-01

    Article describes optical correlation method of cement particle size distribution definition. It based on transverse coherent function definition. It has been shown that set of particles with random shapes and orientations produces correlation function which is almost the same as a function for round particles set. Measurements of coherence function are performed using polarization transverse shearing interferometer. Described method allows fast and high reliable definition of cement particle distribution by sizes.

  1. Segmentation of the optic tracts using graph-based techniques

    NASA Astrophysics Data System (ADS)

    Noble, Jack H.; D'Haese, Pierre-Franois; Dawant, Benoit M.

    2012-02-01

    In DBS surgery, electrodes are implanted in specific nuclei of the brain to treat several types of movement disorders. Pre-operative knowledge of the location of the optic tracts may prove useful for pre-operative planning assistance or intra-operative target refinement. In this article we present a semi-automated method to localize the optic tracts in MR. As opposed to previous approaches presented to identify these structures, our methods are able to recover the eccentric shape of the optic tracts. This approach consists of two parts: (1) automatic model construction from manually segmented exemplars and (2) segmentation of structures in unknown images using these models. The segmentation problem is solved by finding an optimal path in a graph. The graph is designed with novel structures that permit the incorporation of prior information from the model into the optimization process and account for several weaknesses of traditional graph-based approaches. The approach achieved mean and maximum surface errors of 0.35 and 1.9 mm in a validation study on 10 images. The results from all experiments were considered acceptable.

  2. ATLAS Muon Endcap Alignment

    NASA Astrophysics Data System (ADS)

    Bensinger, James R.

    2006-01-01

    To align the endcap muon chambers of the ATLAS experiment, an optical grid is set up between aluminum "alignment bars" nested in each layer of chambers. Optical lines are made of laser diodes and CCD cameras that form an alignment grid. The alignment bars are self-aligning. They are then carefully measured using a large coordinate measuring machine (CMM). The subsequent shape changes of the bar are determined by calculations that are corrected by the readings of the internal monitors. The relationship between the bars is then established by a network of sensors that measure the bearing angle of light sources on the other parts of the system. The system is over-determined and the location and orientation of each bar is determined using a fitting program. Chambers are then referenced to the alignment grid using proximity sensors. This information is used to provide corrections to the nominal chamber positions before calculating track momentum. The performance of the system has been validated in a test beam at CERN. We have been able to track changes in muon sagitta's to an accuracy of about 15 microns under normal temperature variation and controlled movements. The system is stable over a period of months.

  3. 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)

  4. Design Considerations For An Automated Fibre Optics Aided Remote Condition Monitoring Technique

    NASA Astrophysics Data System (ADS)

    Nwagboso, Christopher O.; Whomes, Terence L.; Davies, P. B.

    1990-04-01

    Recent years have seen progression in the use of fibre optic aided remote condition monitoring techniques which was once reserved for medical application. The use of such systems provides important and useful information on the operational status of components and equipment in their normal remote operating condition and environment. Their application in a specific area usually requires some innovative design work, that utilises the basic fibre optic system for the required tasks. The remote condition monitoring technique requires the automated system of fibre optics probe and Charge Couple Device camera as means of visually monitoring the component insitu. This paper presents some of the difficulties and constraints encountered in the conceptualisation of an automated remote condition monitoring technique. It deals mainly with the optical aspects of the technique. This includes the results of some experimental work, and the problems that are inherent in the development of the concept of a computer controlled camera orbital scanning system.

  5. 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.

  6. Polarisation control through an optical feedback technique and its application in precise measurements

    PubMed Central

    Chen, Wenxue; Zhang, Shulian; Long, Xingwu

    2013-01-01

    We present an anisotropic optical feedback technique for controlling light polarisation. The technique is based on the principle that the effective gain of a light mode is modulated by the magnitude of the anisotropic feedback. A new physical model that integrates Lamb's semi-classical theory and a model of the equivalent cavity of a Fabry-Perot interferometer is developed to reveal the physical nature of this technique. We use this technique to measure the phase retardation, optical axis, angle, thickness and refractive index with a high precision of λ/1380, 0.01°, 0.002°, 59 nm and 0.0006, respectively. PMID:23771164

  7. Multimodal optogenetic neural interfacing device fabricated by scalable optical fiber drawing technique.

    PubMed

    Davey, Christopher J; Argyros, Alexander; Fleming, Simon C; Solomon, Samuel G

    2015-12-01

    We present a novel approach to the design and manufacture of optrodes for use in the biomedical research field of optogenetic neural interfacing. Using recently developed optical fiber drawing techniques that involve co-drawing metal/polymer composite fiber, we have assembled and characterized a novel optrode with promising optical and electrical functionality. The fabrication technique is flexible, scalable, and amenable to extension to implantable optrodes with high-density arrays of multiple electrodes, waveguides, and drug delivery channels. PMID:26836662

  8. Fiber-optic sensor integration and multiplexing techniques for smart skin applications

    SciTech Connect

    Muhs, J.D.; Allison, S.W.; Janke, C.J.; Kercel, S.; Smith, D.B.

    1991-01-01

    Integration and multiplexing techniques for smart skin applications using optical fibers has become an increasingly important topic of research in recent years. This paper reviews the initial stages of research in this area at the Oak Ridge National Laboratory (ORNL). Specifically, results from first generation fiber-optic temperature and strain sensor development efforts are given, along with a discussion of various integration and multiplexing techniques proposed for future development.

  9. Fiber-optic sensor integration and multiplexing techniques for smart skin applications

    SciTech Connect

    Muhs, J.D.; Allison, S.W.; Janke, C.J.; Kercel, S.; Smith, D.B.

    1991-12-31

    Integration and multiplexing techniques for smart skin applications using optical fibers has become an increasingly important topic of research in recent years. This paper reviews the initial stages of research in this area at the Oak Ridge National Laboratory (ORNL). Specifically, results from first generation fiber-optic temperature and strain sensor development efforts are given, along with a discussion of various integration and multiplexing techniques proposed for future development.

  10. Antares alignment gimbal positioner

    SciTech Connect

    Day, R.D.; Viswanathan, V.K.; Saxman, A.C.; Lujan, R.E.; Woodfin, G.L.; Sweatt, W.C.

    1981-01-01

    Antares is a 24-beam 40-TW carbon-dioxide (CO/sub 2/) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, and wavefront optical path difference, as well as aberration information at both helium-neon (He-Ne) and CO/sub 2/ wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1-cm cube to a tolerance of 10 ..mu..m.

  11. Optical Trapping Techniques Applied to the Study of Cell Membranes

    NASA Astrophysics Data System (ADS)

    Morss, Andrew J.

    Optical tweezers allow for manipulating micron-sized objects using pN level optical forces. In this work, we use an optical trapping setup to aid in three separate experiments, all related to the physics of the cellular membrane. In the first experiment, in conjunction with Brian Henslee, we use optical tweezers to allow for precise positioning and control of cells in suspension to evaluate the cell size dependence of electroporation. Theory predicts that all cells porate at a transmembrane potential VTMof roughly 1 V. The Schwann equation predicts that the transmembrane potential depends linearly on the cell radius r, thus predicting that cells should porate at threshold electric fields that go as 1/r. The threshold field required to induce poration is determined by applying a low voltage pulse to the cell and then applying additional pulses of greater and greater magnitude, checking for poration at each step using propidium iodide dye. We find that, contrary to expectations, cells do not porate at a constant value of the transmembrane potential but at a constant value of the electric field which we find to be 692 V/cm for K562 cells. Delivering precise dosages of nanoparticles into cells is of importance for assessing toxicity of nanoparticles or for genetic research. In the second experiment, we conduct nano-electroporation—a novel method of applying precise doses of transfection agents to cells—by using optical tweezers in conjunction with a confocal microscope to manipulate cells into contact with 100 nm wide nanochannels. This work was done in collaboration with Pouyan Boukany of Dr. Lee's group. The small cross sectional area of these nano channels means that the electric field within them is extremely large, 60 MV/m, which allows them to electrophoretically drive transfection agents into the cell. We find that nano electroporation results in excellent dose control (to within 10% in our experiments) compared to bulk electroporation. We also find that, unlike bulk electroporation, nano-electroporation directly injects nanoparticles, such as quantum dots, to the cell interior, bypassing the cell membrane without the need for endocytosis. The aging of RBC's can render them rigid, an issue for the survivability of transfusion patients. This rigidity can be assessed by examining the fluctuations in the cell membrane. In the third experiment, we use back focal plane detection—an interferometric detection scheme using an optical tweezers setup—to measure the membrane fluctuations of RBC's and K562 cells. Membrane fluctuations have long been observed in RBC's and a well developed theory exists linking them to the cells internal viscosity η, the membrane bending modulus k and the surface tension of the membrane σ. We use back focal plane detection to measure the effect of ascorbic acid treatment on RBC aging and find no improvement in cell flexibility. K562 cells differ from RBC's in that they possess an actin cortex which the membrane attaches to. We demonstrate that K562 cells exhibit as much as an order of magnitude more variation in their fluctuations than RBC's do.

  12. Optical coherent reflectometry: a new technique to guide invasive procedures.

    PubMed

    Yamashita, T; Kasaoka, S; Son, R; Gordon, I L; Khan, R; Neet, J; Hedrick, A D; Tobis, J M

    2001-10-01

    The success rate of percutaneous transluminal coronary angioplasty for chronic total arterial occlusions is still unsatisfactory. Inability to cross the lesion with a guidewire is a major cause of failure. Optical coherent reflectometry (OCR) is a new method of using laser light to measure the depth of tissue from the end of an optic fiber. This study tests whether an OCR prototype guidewire provides a guidance system that might be useful to assist reopening chronic total arterial occlusions. An OCR fiber optic within a 0.014" hypotube was developed using the interference pattern of two reflected light beams (wave length 1,300 nm). To determine if OCR can distinguish different tissue types, plaques of human lower extremity arterial segments were visually divided into three types (calcified, white, or yellow). The slope of the initial reflectance of the OCR curve was calculated and compared between the three groups. In six other arteries, the OCR wire was advanced longitudinally through occluded human artery segments in vitro. Guidewire position was determined by OCR and compared to the position of the guidewire tip observed simultaneously by intravascular ultrasound (IVUS) imaging. In 16 arterial surface segments, calcified plaques had a significantly steeper slope than white or yellow plaques (-227.2 +/- 82.2; -81.5 +/- 12.9; -103.6 +/- 19.6 dB/mm; P < 0.01). For the determination of the guidewire position, IVUS and OCR corresponded correctly in 82% of 28 measurements. Sensitivity and specificity of OCR for detection of plaque versus the media/adventitia boundary were 79% and 89%, respectively (P < 0.001). OCR can distinguish calcified from noncalcified plaque and may distinguish plaque from the media/adventitia boundary. This technology may be useful as a means to help navigate a guidewire safely through an occluded artery. PMID:11590695

  13. X-ray optics - A technique for high resolution imaging

    NASA Technical Reports Server (NTRS)

    Cash, Webster

    1987-01-01

    Both scattering and figure errors in grazing incidence optics are larger in the plane of incidence than out-of-plane by a factor equal to 1/sin theta, where theta is the graze angle. When the full annular aperture of a grazing incidence telescope is stopped down, the point spread function becomes highly elliptical with a width as much as sin theta times narrower than the full image. In practice, this means that improvements in resolution of up to 100 times can be achieved, and effective resolution can approach the diffraction limit. Laboratory data demonstrating the effect are presented.

  14. Visual cryptography based on optical interference encryption technique

    NASA Astrophysics Data System (ADS)

    Seo, Dong-Hoan; Kim, Jong-Yun; Lee, Sang-Su; Park, Se-Joon; Cho, Woong H.; Kim, Soo-Joong

    2001-07-01

    In this paper, we proposed a new visual cryptography scheme based on optical interference that can improve the contrast and signal to noise ratio of reconstructed images when compared to conventional visual cryptography methods. The binary image being encrypted is divided into any number of n slides. For encryption, randomly independent keys are generated along with another random key based on a XOR process of random keys. The XOR process between each divided image and each random key produces the encryption of n encrypted images. These encrypted images are then used to make encrypted binary phase masks. For decryption, the phase masks are placed on the paths of a Mach-Zehnder interferometer.

  15. PAPR reduction techniques for asymmetrically clipped optical OFDM communication system

    NASA Astrophysics Data System (ADS)

    Wang, Yong; Zhang, Zhaojun; Sun, Lu

    2014-07-01

    In the ultraviolet communication system, ACO-OFDM technology can effectively suppress inter-symbol interference on the system performance, and further improve the transmission rate of the system. However, ACO-OFDM has a high peak to average power ratio (PAPR), and high PAPR not only reduces the power efficiency of the optical modulator, but also bring damage to the human eye or skin. In order to solve the above problem, according to ACO-OFDM signal characteristics, two clipping and filtering algorithms are used, and its performance is simulated, the simulations show that the two algorithms are able to inhibit well the PAPR of ACO-OFDM system.

  16. Search for nearly massless, weakly coupled particles by optical techniques

    SciTech Connect

    Cameron, R.; Cantatore, G.; Melissinos, A.C.; Ruoso, G.; Semertzidis, Y. ); Halama, H.J.; Lazarus, D.M.; Prodell, A.G. ); Nezrick, F. ); Rizzo, C.; Zavattini, E. )

    1993-05-01

    We have searched for light scalar and/or pseudoscalar particles that couple to two photons by studying the propagation of a laser beam ([lambda]=514 nm) through a transverse magnetic field. A limit of 3.5[times]10[sup [minus]10] rad was set on a possible optical rotation of the beam polarization for an effective path length of 2.2 km in a 3.25 T magnetic field. We find that the coupling [ital g][sub [alpha][gamma][gamma

  17. 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.

  18. Alignment reference device

    DOEpatents

    Patton, Gail Y. (Sunnyvale, CA); Torgerson, Darrel D. (Palo Alto, CA)

    1987-01-01

    An alignment reference device provides a collimated laser beam that minimizes angular deviations therein. A laser beam source outputs the beam into a single mode optical fiber. The output end of the optical fiber acts as a source of radiant energy and is positioned at the focal point of a lens system where the focal point is positioned within the lens. The output beam reflects off a mirror back to the lens that produces a collimated beam.

  19. Detecting concentrations of milk components by an iterative optical technique.

    PubMed

    Yariv, Inbar; Kapp-Barnea, Yaara; Genzel, Eran; Duadi, Hamootal; Fixler, Dror

    2015-11-01

    This paper introduces a theoretical and practical model for reconstructing the scattering properties of a participating media. Our theory is based on a robust generalization of the Gerchberg-Saxton (G-S) algorithm. At the end of this algorithm the reduced scattering coefficient μ's of a given substance, can be estimated from the standard deviation (STD) of the retrieved phase of the remitted light. We use the theory to compute the phase's STD that directly correlated to the optical properties for different types of milk components, and we derive a novel appearance model for milk parameterized by the lactose and protein contents. Our results show that we are able to detect the possibility of lactose and milk proteins' quantitative signature by the G-S optical tool, en route to the design of a novel milk-content-monitoring tool. Sketch of the experimental setup for light intensity measurements and reduced scattering coefficient reconstruction. The samples were prepared from various milk components: whey protein, sodium casienate and lactose, at different concentrations. PMID:25727334

  20. A technique for multiplexing 3x3-coupler terminated interferometric fiber-optic sensors

    NASA Astrophysics Data System (ADS)

    Reid, Gregory J.

    1993-12-01

    This thesis investigates the multiplexing of Mach-Zehnder type 3x3 terminated fiber-optic sensors demodulated by either 'quadrature' or 'symmetric' methods using intensity modulation of the source. 3x3-couplers produce signals that permit unmodulated passive demodulation of interferometric signals. The theory is described and the results of a 2x1 element array optical demonstration are presented. Possible architectures using this demultiplexing technique are presented for several applications with different return line requirements. The technique was successfully demonstrated and warrants further investigation to increase the number of sensors and reduce the number of return lines for specific applications. The multiplexing technique presents the opportunity for possible cost savings over other phase generated carrier techniques, which require wavelength modulation of the source and significant optical path differences in the interferometers, and are therefore constrained to presently very expensive sources. The technique presented uses compatible low coherent laser sources such as Compact Disc quality (830 nm) devices.

  1. MOLECULAR OPTICAL SPECTROSCOPIC TECHNIQUES FOR HAZARDOUS WASTE SITE SCREENING

    EPA Science Inventory

    The U.S. Environmental Protection Agency is interested in field screening hazardous waste sites for contaminants in the soil and surface and ground water. his study is an initial technical overview of the principal molecular spectroscopic techniques and instrumentation currently ...

  2. Optical fringe reduction technique for FM laser spectroscopy

    NASA Technical Reports Server (NTRS)

    Chou, Nee-Yin; Sachse, Glen W.; Wang, Liang-Guo; Gallagher, Thomas F.

    1989-01-01

    A simple fringe reduction method for FM diode laser spectroscopy is discussed. The fringes can be effectively suppressed by using a modulation frequency that is an integral multiple of the free spectral range of the fringes. The technique is experimentally confirmed by two-tone FM spectroscopy of water vapor absorption lines. A factor of 20 fringe reduction is observed.

  3. 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. PMID:20357871

  4. Solar experiment alignment system

    NASA Technical Reports Server (NTRS)

    Fain, D. L.

    1972-01-01

    Sensor system determines absolute alignment of optical axis of experiment package relative to solar vector and provides control information to permit pointing experiment anywhere on solar disc to absolute accuracy of the order of two arc seconds in center and five arc seconds on limb.

  5. Orientation and alignment effects for one-electron transfer processes in ion-atom collisions involving an optically prepared target

    NASA Astrophysics Data System (ADS)

    Dowek, D.; Houver, J. C.

    1997-04-01

    Recent aspects in the study of the role of electronic orbital alignment and orientation in one-electron transfer processes induced in atomic collisions are reviewed. We focus on the study of collisions involving a laser prepared target, in the range where the collision velocity ?c and the velocity of the active electron ?e are of comparable magnitude. Results obtained in the recent years, both for total electron capture cross sections and for angular scattering analysis, are presented and discussed in terms of simple models.

  6. 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.

  7. 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 deterministic effects pose for long-haul optical data transmission. Experimental results which demonstrate the possibility to digitally mitigate both dispersion and nonlinearity are presented. Impairment compensation is achieved using backward propagation by implementing the split-step method. Efficient realizations of the dispersion compensation operator used in this implementation are considered. Infinite-impulse response and wavelet-based filtering are both investigated as a means to reduce the required computational load associated with signal backward-propagation. Possible future research directions conclude this dissertation.

  8. 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.

  9. 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.

  10. 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.

  11. Frequency-Shifted Interferometry — A Versatile Fiber-Optic Sensing Technique

    PubMed Central

    Ye, Fei; Zhang, Yiwei; Qi, Bing; Qian, Li

    2014-01-01

    Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI). This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented. PMID:24955943

  12. Frequency-shifted interferometry--a versatile fiber-optic sensing technique.

    PubMed

    Ye, Fei; Zhang, Yiwei; Qi, Bing; Qian, Li

    2014-01-01

    Fiber-optic sensing is a field that is developing at a fast pace. Novel fiber-optic sensor designs and sensing principles constantly open doors for new opportunities. In this paper, we review a fiber-optic sensing technique developed in our research group called frequency-shifted interferometry (FSI). This technique uses a continuous-wave light source, an optical frequency shifter, and a slow detector. We discuss the operation principles of several FSI implementations and show their applications in fiber length and dispersion measurement, locating weak reflections along a fiber link, fiber-optic sensor multiplexing, and high-sensitivity cavity ring-down measurement. Detailed analysis of FSI system parameters is also presented. PMID:24955943

  13. Actively stabilized optical fiber interferometry technique for online/in-process surface measurement

    SciTech Connect

    Wang Kaiwei; Martin, Haydn; Jiang Xiangqian

    2008-02-15

    In this paper, we report the recent progress in optical-beam scanning fiber interferometry for potential online nanoscale surface measurement based on the previous research. It attempts to generate a robust and miniature measurement device for future development into a multiprobe array measurement system. In this research, both fiber-optic-interferometry and the wavelength-division-multiplexing techniques have been used, so that the optical probe and the optical interferometer are well spaced and fast surface scanning can be carried out, allowing flexibility for online measurement. In addition, this system provides a self-reference signal to stabilize the optical detection with high common-mode noise suppression by adopting an active phase tracking and stabilization technique. Low-frequency noise was significantly reduced compared with unstabilized result. The measurement of a sample surface shows an attained repeatability of 3.3 nm.

  14. Synthesis, transfer printing, electrical and optical properties, and applications of materials composed of self-assembled, aligned single-walled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Pint, Cary L.

    Super growth of single-walled carbon nanotubes (SWNTs) has emerged as a unique method for synthesizing self-assembled, pristine, aligned SWNT materials composed of ultra-long (millimeter-long) nanotubes. This thesis focuses on novel routes of synthesizing such self-assembled SWNTs and the challenges that arise in integrating this material into next-generation applications. First of all, this work provides unique insight into growth termination of aligned SWNTs, emphasizing the mechanism that inhibits the growth of infinitely long nanotubes. Exhaustive real-time growth studies, combined with ex-situ and in-situ TEM characterization emphasizes that Ostwald ripening and subsurface diffusion of catalyst particles play a key role in growth termination. As a result, rational steps to solving this problem can enhance growth, and may ultimately lead to the meter or kilometer-long SWNTs that are necessary for a number of applications. In addition, other novel synthesis routes are discussed, such as the ability to form macroscopic fibrils of SWNTs, called "flying carpets" from 40 nm thick substrates, and the ability to achieve supergrowth of SWNTs that are controllably doped with nitrogen. In the latter case, molecular heterojunctions of doped and undoped sections in a single strand of ultralong SWNTs are demonstrated Secondly, as supergrowth is conducted on alumina coated SiO2 substrates, any applications will require that one can transfer the SWNTs to host surfaces with minimal processing. This work demonstrates a unique contact transfer route by which both patterned arrays of SWNTs, or homogenous SWNT carpets, can be transferred to any host surface. In the first case, the SWNTs are grown vertically aligned, and transferred in patterns of horizontally aligned SWNT. This transfer process relies on simple water-vapor etching of amorphous carbons at the catalyst following growth, and strong van der Waals adhesion of the high surface-area SWNT to host surfaces (gecko effect). Next, as the SWNTs produced in supergrowth are notably large in diameter (2-5 nm), this work provides the first characterization of these SWNTs using combined microscopy and infrared polarized absorption studies. Perfectly aligned SWNTs are transferred to infrared optical windows and mounted in a rotatable vacuum cell in which polarization dependent characterization is carried out. By modeling features observed in absorption to expected optical excitonic transition energies, diameter distributions are rapidly extracted. In addition, other concepts of optical characterization in ultra-long aligned SWNTs are explored. For example, the concept of using polarized near-IR characterization for such SWNT samples is inadequate to characterize the bulk alignment due to the mismatch of the excitation wavelength and the SWNT length. Therefore, comparing anisotropy in polarized near-IR Raman or absorption gives substantially different results than anisotropic electrical transport measurements. In addition to optical characterization, this work uniquely finds that the electrical transport properties of SWNTs is ultimately limited by SWNT-SWNT junctions. This is evident in temperature-dependent DC and AC conductivity measurements that emphasize localization-induced transport characteristics. A number of non-classical electrical transport features are observed that can simply be related to the sensitivity of electrical transport to SWNT-SWNT junctions. This means that despite the incredible electrical properties of individual SWNTs, it is necessary to focus on the growth and processing of ultra-long SWNTs in order to realistically make nanotube-based materials comparable in transport characteristics to conventional materials. Finally, this work concludes by demonstrating progress on the fabrication of new SWNT-based applications. First of all, a new type of solid-state supercapacitor material is fabricated where vertically aligned SWNT are coated with metal-oxide dielectric and counterelectrode layers to form efficient supercapacitors. This design benefits from the ultra-high surface area available in SWNT arrays, the intrinsic ultra-high current carrying capacity of ultra-long SWNT (1000 times copper), the high breakdown voltages one can achieve using solid dielectric layers, and the lightweight and temperature insensitive design of this capacitor. As a result, performance comparable to current electric-double layer capacitor devices is reported, and energy densities significant larger are predicted by material optimization. In addition, progress on other applications are discussed, including devices utilizing self-assembled molecular heterojunction arrays, and terahertz polarizers made from perfectly aligned transferred SWNT films. This work demonstrates a bottom-up route toward the synthesis of new materials for novel characterization and applications.

  15. Z-scan: A simple technique for determination of third-order optical nonlinearity

    NASA Astrophysics Data System (ADS)

    Singh, Vijender; Aghamkar, Praveen

    2015-08-01

    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 (?(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 (?=532 nm) at 5 ns pulse. The values of nonlinear absorption coefficient (?), nonlinear refractive index (n2) and third-order nonlinear optical susceptibility (?(3)) of permethylazine were found to be 9.64 10-7 cm/W, 8.55 10-12 cm2/W and 5.48 10-10 esu, respectively.

  16. Radiation-hardening techniques of dedicated optical fibres used in plasma diagnostic systems in ITER

    NASA Astrophysics Data System (ADS)

    Brichard, B.; Fernandez Fernandez, A.; Ooms, H.; Berghmans, F.; Decréton, M.; Tomashuk, A.; Klyamkin, S.; Zabezhailov, M.; Nikolin, I.; Bogatyrjov, V.; Hodgson, E.; Kakuta, T.; Shikama, T.; Nishitani, T.; Costley, A.; Vayakis, G.

    2004-08-01

    This paper addresses the particular need to develop suitable fabrication techniques of glasses to improve the radiation-resistance and extend the lifetime of optical fibres in high radiation background. Two radiation hardening techniques based on hydrogen and fluorine doping of glass have been applied on step index pure silica core optical fibres. The radiation-induced optical absorption and luminescence have been measured in gamma and fission reactor irradiation conditions at SCKCEN, Mol Belgium. The experimental results show that the lowest optical absorption is achieved in the hydrogen-treated fibre sample. However, the luminescence effect remains significant in any type of fibre and cannot be reduced by the investigated radiation hardening techniques.

  17. 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.

  18. Investigation of in vitro dental erosion by optical techniques.

    PubMed

    Thomas, Shiny S; Mallia, Rupananda J; Jose, Mini; Subhash, Narayanan

    2008-07-01

    Nitrogen laser-induced fluorescence (LIF) and tungsten halogen lamp excited diffuse reflectance spectra were recorded in 350- to 700-nm range on a miniature fiber-optic spectrometer from in vitro premolar tooth during various stages of artificial erosion with 36% phosphoric acid. Both the LIF spectral intensity and the diffuse reflectance intensity gradually increased during tooth erosion. The LIF spectra were analyzed by curve fitting using Gaussian spectral functions to determine the true contribution of different bands in the spectra during erosion. Thus, the broad bands at 440 and 490 nm in the LIF spectra of sound enamel were resolved into four peaks centered at 409.1, 438.1, 492.4 and 523.1 nm and of sound dentin into peaks at 412.0, 440.1, 487.8 and 523.4 nm. The F410/F525 ratios derived from curve-fitted Gaussian peak amplitudes and curve areas were found to be more sensitive to erosion as compared to the diffuse reflectance ratio R500/R700 or the raw LIF spectral ratio F440/F490. PMID:17786500

  19. 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.

  20. Processing speech for analysis using optical Fourier techniques

    NASA Astrophysics Data System (ADS)

    Jones, D. L.

    1984-12-01

    In this thesis a system for displaying speech as a two dimensional video image is presented. The speech is pre-processed by compressing its dynamic range and filtering to emphasize frequencies above 500 Hz. Blanking and sync pulses are inserted to put the signal in standard video format, and every other field is blanked to prevent interference between fields in the interlaced display. Two dimensional variation is achieved by modulating the baseband audio signal up in the spectrum near a multiple of the video scan rate. The relationship between input frequency and pattern angle of the display is derived, and it is shown that the set of frequencies near a multiple of the video scan rate have points in the spatial frequency domain which lie in a straight line at a distance from the origin proportional to the scan rate multiple. Two modulation frequencies are selected to display in the spatial frequencies domain the location of the first and second formant peaks. The two modulated signals are mixed with the baseband audio and displayed simultaneously in a single image. The images are digitized and an optical Fourier transform is simulated on the computer by creating the image which would appear in the Fourier transform plane. Entire words are processed by assembling individual frames on video tape.

  1. Optical waveguides in Er:LiNbO3 fabricated by different techniques - A comparison

    NASA Astrophysics Data System (ADS)

    Cajzl, Jakub; Nekvindová, Pavla; Macková, Anna; Malinský, Petr; Oswald, Jiří; Staněk, Stanislav; Vytykáčová, Soňa; Špirková, Jarmila

    2016-03-01

    We report on the comparison of three techniques used for the fabrication of optical waveguides in erbium doped lithium niobate crystal substrates (Er:LiNbO3). The techniques include ion in-diffusion from a titanium metal layer, annealed proton exchange (APE), and He+ ion implantation. The main focus of the work was placed on the investigation of the influence of the used optical waveguides fabrication techniques on the structural and luminescence properties of Er:LiNbO3 substrates. The results have shown that none of the used optical-waveguide-fabrication techniques significantly affect the position of erbium in the host crystal structure. It turned out, however, that the fabrication process affected luminescence intensities of the characteristic luminescence bands of erbium ions - the most significant decrease in the luminescence intensity was observed in the Ti-indiffused waveguides.

  2. Spatial resolution of confocal XRF technique using capillary optics

    PubMed Central

    2013-01-01

    XRF (X-ray fluorescence) is a powerful technique for elemental analysis with a high sensitivity. The resolution is presently limited by the size of the primary excitation X-ray beam. A test-bed for confocal-type XRF has been developed to estimate the ultimate lateral resolution which could be reached in chemical mapping using this technique. A polycapillary lens is used to tightly focus the primary X-ray beam of a low power rhodium X-ray source, while the fluorescence signal is collected by a SDD detector through a cylindrical monocapillary. This system was used to characterize the geometry of the fluorescent zone. Capillary radii ranging from 50 μm down to 5 μm were used to investigate the fluorescence signal maximum level This study allows to estimate the ultimate resolution which could be reached in-lab or on a synchrotron beamline. A new tool combining local XRF and scanning probe microscopy is finally proposed. PMID:23758858

  3. 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.

  4. Structural and optical characteristics of graphene quantum dots size-controlled and well-aligned on a large scale by polystyrene-nanosphere lithography

    NASA Astrophysics Data System (ADS)

    Duck Oh, Si; Kim, Jungkil; Lee, Dae Hun; Kim, Ju Hwan; Jang, Chan Wook; Kim, Sung; Choi, Suk-Ho

    2016-01-01

    Graphene quantum dots (GQDs) are one of the most attractive graphene nanostructures due to their potential optoelectronic device applications, but it is a challenge to accurately control the size and arrangement of GQDs. In this report, we fabricate well-aligned GQDs on a large area by polystyrene (PS)-nanosphere (NS) lithography and study their structural and optical properties. Single-layer graphene grown on a Cu foil by chemical vapour deposition is patterned by reactive ion etching employing aligned PS-NS arrays as an etching mask. The size (d) of the GQDs is controlled from 75 to 23 nm by varying the etching time, as proved by scanning electron microscopy and atomic force microscopy. This method is well valid for both rigid/flexible target substrates and even for multilayer graphene formed by piling up single layers. The absorption peak of the GQDs is blue-shifted with respect to that of a graphene sheet, and is sequentially shifted to higher energies by reducing d, consistent with the quantum confinement effect (QCE). The Raman D-to-G band intensity ratio shows an almost monotonic increase with decreasing d, resulting from the dominant contribution of the edge states at the periphery of smaller GQDs. The G-band frequency shows a three-step size-dependence: initial increase, interim saturation, and final decrease with decreasing d, thought to be caused by the competition between the QCE and edge-induced strain effect.

  5. 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

    2015-08-01

    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. PMID:26737728

  6. 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.

  7. Optical and imaging techniques for in-vivo sunscreens investigation

    NASA Astrophysics Data System (ADS)

    Utz, Sergei R.; Knuschke, Peter; Sinichkin, Yurii 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.

  8. Minimum detectable phase shift in spectrum-analysis techniques of optical interferometric vibration detection.

    PubMed

    Sudarshanam, V S

    1992-10-01

    The minimum detectable phase shift indicated in recent experimental reports of new linear spectrumanalysis techniques of optical interferometric vibration detection is established as the direct consequence of the 1/f noise voltage in the system components. The dynamic range and inaccuracy predicted by the simple theoretical model presented is in good agreement with experimental measurements. The conclusions of the analysis are compared with experimental reports of heterodyne shot-noise-limited optical systems. With this effective tool the generic class of spectrum-analysis techniques can be analyzed and relatively weighed to assess the effect of noise. This analysis is applicable to optical interferometry in general, although the experiments specifically involved fiber-optic modulators. PMID:20733800

  9. Comparative study of optical-digital vs all-digital techniques in textural pattern recognition

    NASA Astrophysics Data System (ADS)

    Otoole, R. K.; Stark, H.

    1980-08-01

    The application of both optical-digital and all-digital techniques in textural pattern recognition is examined and a comparison of the two approaches is made. The optical-digital scheme makes use of an optical-digital computer to generate textural measurements based on the 2-D irradiance spectrum. The all-digital scheme produces measurements based on gray-tone spatial-dependence matrices. In both cases two feature extraction algorithms were employed: the Hotelling trace method and the Foley-Sammon discriminant vector analysis. Classification was accomplished using the k-nearest neighbor decision rule. The performance of these techniques was evaluated in an experiment involving the classification of four texture patterns. The results show that, for the textures chosen, both approaches give high classification accuracy with the optical-digital method performing somewhat better.

  10. Technique for in situ measurement of free spectral range and transverse mode spacing of optical cavities.

    PubMed

    Stochino, Alberto; Arai, Koji; Adhikari, Rana X

    2012-09-20

    Length and g-factor are fundamental parameters that characterize optical cavities. We developed a technique to measure these parameters in situ by determining the frequency spacing between the resonances of fundamental and spatial modes of an optical cavity. Two laser beams are injected into the cavity, and their relative frequency is scanned by a phase-lock loop, while the cavity is locked to either laser. The measurement of the amplitude of their beat note in transmission reveals the resonances of the longitudinal and the transverse modes of the cavity and their spacing. This method proves particularly useful to characterize complex optical systems, including very long and/or coupled optical cavities, as in gravitational-wave interferometers. This technique and the results of its application to the coupled cavities of a 40 m-long gravitational-wave interferometer prototype are presented here. PMID:23033027

  11. MOSAIC - A space-multiplexing technique for optical processing of large images

    NASA Technical Reports Server (NTRS)

    Athale, Ravindra A.; Astor, Michael E.; Yu, Jeffrey

    1993-01-01

    A technique for Fourier processing of images larger than the space-bandwidth products of conventional or smart spatial light modulators and two-dimensional detector arrays is described. The technique involves a spatial combination of subimages displayed on individual spatial light modulators to form a phase-coherent image, which is subsequently processed with Fourier optical techniques. Because of the technique's similarity with the mosaic technique used in art, the processor used is termed an optical MOSAIC processor. The phase accuracy requirements of this system were studied by computer simulation. It was found that phase errors of less than lambda/8 did not degrade the performance of the system and that the system was relatively insensitive to amplitude nonuniformities. Several schemes for implementing the subimage combination are described. Initial experimental results demonstrating the validity of the mosaic concept are also presented.

  12. Hybrid SCM SAC-OCDMA System Employing New Optical Spectral Amplitude Direct Decoding Detection Technique

    NASA Astrophysics Data System (ADS)

    Sahbudin, R. K. Z.; Abdullah, M. K.; Samad, M. D. A.; Mahdi, M. A.; Ismail, M.

    In this research, a hybrid subcarrier multiplexed spectral-amplitude-coding optical code-division-multiple-access (SCM SAC-OCDMA) system is proposed for the purpose of combining the advantages of both techniques. SAC-OCDMA is employed because of its ability to eliminate the Multiple Access Interference (MAI) when code sequences with fixed in-phase cross correlation are used. In order to enhance the channel data rate of the OCDMA systems, the SCM technique is used. As a result, the hybrid system is robust against interference and is much more spectrally efficient. The system utilizes double weight (DW) code that has a weight W equal to two, code length N equal to six and cross correlation λ equal to 1. A simple and new detection technique called optical spectral amplitude direct decoding is proposed. Based on the theory and experimental simulation results obtained, the new proposed detection technique provides a better performance than the conventional balanced detection technique.

  13. Study on Third-Order Optical Nonlinearity of BIS(TETRABUTYLAMMONIUM)-Hg(dmit)2 by Femtosecond Optical Kerr Gate Technique

    NASA Astrophysics Data System (ADS)

    Yang, Hongliang; Wang, Xinqiang; Ren, Quan; Zhang, Fujun; Zhang, Guanghui; Xu, Dong; Wang, Shufeng; Wang, Zhenwei

    Bis(tetrabutylammonium)-Hg(dmit)2 was synthesized and its sample solution's optical Kerr Effect (OKE) signal was measured by the femtosecond optical Kerr gate technique. With the concentration of 9.27 × 10-4 M, the sample solution's third-order optical susceptibility was obtained to be 2.53 × 10-14 esu by using the CS2 OKE signal as reference signal measured under identical conditions. The second-order hyperpolarizability for the bis(tetrabutylammonium)-Hg(dmit)2 molecular was estimated to be 1.7 × 10-32 esu. Its response time was about 226 fs, which is believed to be the contribution from the delocalized electrons.

  14. 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.

  15. Optical properties of surface modified polypropylene by plasma immersion ion implantation technique

    SciTech Connect

    Ahmed, Sk. Faruque; Moon, Myoung-Woon; Kim, Chansoo; Lee, Kwang-Ryeol; Jang, Yong-Jun; Han, Seonghee; Choi, Jin-Young; Park, Won-Woong

    2010-08-23

    The optical band gap and activation energy of polypropylene (PP) induced by an Ar plasma immersion ion implantation technique were studied in detail. It was revealed that the structural alternation with an increase in polymer chain cross-linking in the ion beam affected layer enhanced the optical properties of PP. The optical band gap, calculated from the transmittance spectra, decreased from 3.44 to 2.85 eV with the Ar plasma ion energy from 10 to 50 keV. The activation energy, determined from the band tail of the transmittance spectra, decreased while the electrical conductivity increased with the Ar plasma ion energy.

  16. PAPR reduction in optical OFDM systems using asymmetrically clipping and signal scrambling technique

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Fang, Yong; Huang, Qinghua; Sun, Yanzan

    2015-08-01

    Optical orthogonal frequency division multiplexing (OOFDM) is a promising technology in the next generation of high-speed and long-haul optical transmission, due to its high spectral efficiency, high speed of data transmission and strong ability of anti-dispersion. But optical OFDM system has a very high peak-to-average power ratio (PAPR). High PAPR will bring instantaneous high optical power to the optical OFDM system. Asymmetrically clipping and signal scrambling based on fast Hartley transform for PAPR reduction is proposed in optical OFDM system. Firstly, IFFT/FFT module in each sub-block of traditional signal scrambling technique is replaced with inverse fast Hartley transform (IFHT) and fast Hartley transform (FHT) module, which yield to the real signal in OOFDM system. Then, asymmetrically clipping technique is applied to turn it into a positive and real signal. Finally, the signal with the minimum PAPR is selected for transmission in the fiber channel. The PAPR of the optical OFDM signal can be reduced effectively. And without the Hermitian symmetry, the space and computational complexity are reduced accordingly.

  17. 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.

  18. Toward photonic DNA computing: developing optical techniques for parallel manipulation of DNA

    NASA Astrophysics Data System (ADS)

    Ogura, Yusuke; Beppu, Taro; Sumiyama, Fumika; Tanida, Jun

    2005-09-01

    We have proposed the concept of photonic DNA computing, which utilizes light and DNA, as a new evolution of parallel computing technology. The scheme has potential for achieving ingenious information processing by use of the properties of light including spatial parallelism and visibility, and the nature of DNA such as reaction parallelism and capability for autonomous reactions. We are developing optical techniques to realize this idea. An important example is the parallel optical manipulation technique that uses vertical-cavity surface-emitting laser (VCSEL) array sources. One can generate various optical field distributions by directly modulating the optical outputs of individual VCSELs, and it is possible to achieve manipulation of microscopic objects without physical contact based on compact hardware and a simple control method. We demonstrated parallel translation and fabrication of a stacked structure of microscopic particles, on the surfaces of which a lot of DNA molecules are bound. A method for reactions of DNA using an optical technique has also being developed. The method is based on control of the temperature of a local small volume of a DNA solution, which is put on a substrate coated with light-absorbing material, by irradiating with laser beams. We irradiated the substrate or a bead, on which DNA molecules were attached by hybridization, and succeeded in detaching DNA from the substrate or the bead. These techniques are expected to contribute miniaturization and weight-reduction of information systems for computing, genome analyses, and other applications.

  19. Investigation of a novel slumping technique for the manufacturing of stiff and lightweight optical mirrors

    NASA Astrophysics Data System (ADS)

    Canestrari, R.; Ghigo, M.; Pareschi, G.; Basso, S.; Proserpio, L.

    2008-07-01

    The Astronomical Observatory of Brera (INAF-OAB) is investigating a novel slumping technique for the manufacturing of stiff and lightweight optical segments. We propose a 2-steps technique: initially the procedure foresees to manufacture a mirror segment using the hot slumping technique. This step produces a thin and floppy Borofloat glass shell using the slumping of a glass sheet onto a ceramic mould that has a surface with a high optical quality. After this step, this curved shell is assembled and glued to a stiff substrate made in foamed and pre-shaped material. On the back of the substrate it is also glued a flat sheet of the same glass. This procedure combine the good optical performances achievable on optics produced by means of the hot slumping technique with the lightweight and stiffness of the foamed material and, finally, the good structural properties achievable in sandwich-like structures. This approach could be in principle used for the production of mirrors for a number of applications, from the primary segmented mirror for large telescopes to the mirrors for the future Cherenkov telescopes nowadays under development. This paper describes the process of production of a prototype optical segment and the status of the investigation.

  20. 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.

  1. FMIT alignment cart

    SciTech Connect

    Potter, R.C.; Dauelsberg, L.B.; Clark, D.C.; Grieggs, R.J.

    1981-01-01

    The Fusion Materials Irradiation Test (FMIT) Facility alignment cart must perform several functions. It must serve as a fixture to receive the drift-tube girder assembly when it is removed from the linac tank. It must transport the girder assembly from the linac vault to the area where alignment or disassembly is to take place. It must serve as a disassembly fixture to hold the girder while individual drift tubes are removed for repair. It must align the drift tube bores in a straight line parallel to the girder, using an optical system. These functions must be performed without violating any clearances found within the building. The bore tubes of the drift tubes will be irradiated, and shielding will be included in the system for easier maintenance.

  2. Implementation of pulse interval modulation based on dualmapping technique for optical wireless communications

    NASA Astrophysics Data System (ADS)

    Zhang, Tie-Ying; Wang, Hong-Xing; Hu, Hao; Cong, Pei-Sheng

    2009-11-01

    Aiming at implementing the digital pulse interval modulation (DPIM) for optical wireless communications (OWC), a dualmapping technique is presented. The scheme of DPIM train based upon the dual-mapping technique is given. Its slot error rate is derived for the avalanche photonic diode (APD) receiver model, and is compared with that of classical DPIM. Simulation results show that the dual-mapping DPIM (D-DPIM), which has a fixed slot length, only has marginally inferior error performance, but can solve waiting slots or buffer overflowing in comparison with DPIM. Hence, it is suitable for the optical wireless communication systems.

  3. Development and evaluation of techniques for using combined microwave and optical image data for vegetation studies

    NASA Technical Reports Server (NTRS)

    Paris, J. F.; Rock, B. N.; Hsu, S. Y.

    1984-01-01

    Techniques for using combined image data from the Shuttle Imaging Radar (SIR-B) and the LANDSAT Thematic Mapper (TM) or Multispectral Scanner (MSS) for studies of irrigated crops, and boreal and deciduous forests are developed and evaluated. The effects of the structure and composition of crop canopies and soil surfaces on multiangle L-band HH (Horizontal polarization for transmission and reception) backscattering and on optical reflectance (in TM or MSS bands viewed at the nadir) are investigated. The relative accuracy of digital, calibrated SIR-B image data and LANDSAT TM or MSS image data is evaluated. Textural information extraction-techniques are developed for radar and optical image analysis.

  4. Real-time quantitative fluorescence imaging using a single snapshot optical properties technique for neurosurgical guidance

    NASA Astrophysics Data System (ADS)

    Valdes, Pablo A.; Angelo, Joseph; Gioux, Sylvain

    2015-03-01

    Fluorescence imaging has shown promise as an adjunct to improve the extent of resection in neurosurgery and oncologic surgery. Nevertheless, current fluorescence imaging techniques do not account for the heterogeneous attenuation effects of tissue optical properties. In this work, we present a novel imaging system that performs real time quantitative fluorescence imaging using Single Snapshot Optical Properties (SSOP) imaging. We developed the technique and performed initial phantom studies to validate the quantitative capabilities of the system for intraoperative feasibility. Overall, this work introduces a novel real-time quantitative fluorescence imaging method capable of being used intraoperatively for neurosurgical guidance.

  5. Study of Structural, Optical and Electrical Properties of InAs/InAsSb Superlattices Using Multiple Characterization Techniques

    NASA Astrophysics Data System (ADS)

    Shen, Xiaomeng

    InAs/InAsSb type-II superlattices (T2SLs) can be considered as potential alternatives for conventional HgCdTe photodetectors due to improved uniformity, lower manufacturing costs with larger substrates, and possibly better device performance. This dissertation presents a comprehensive study on the structural, optical and electrical properties of InAs/InAsSb T2SLs grown by Molecular Beam Epitaxy. The effects of different growth conditions on the structural quality were thoroughly investigated. Lattice-matched condition was successfully achieved and material of exceptional quality was demonstrated. After growth optimization had been achieved, structural defects could hardly be detected, so different characterization techniques, including etch-pit-density (EPD) measurements, cathodoluminescence (CL) imaging and X-ray topography (XRT), were explored, in attempting to gain better knowledge of the sparsely distributed defects. EPD revealed the distribution of dislocation-associated pits across the wafer. Unfortunately, the lack of contrast in images obtained by CL imaging and XRT indicated their inability to provide any quantitative information about defect density in these InAs/InAsSb T2SLs. The nBn photodetectors based on mid-wave infrared (MWIR) and long-wave infrared (LWIR) InAs/InAsSb T2SLs were fabricated. The significant difference in Ga composition in the barrier layer coupled with different dark current behavior, suggested the possibility of different types of band alignment between the barrier layers and the absorbers. A positive charge density of 1.8 x 1017/cm3 in the barrier of MWIR nBn photodetector, as determined by electron holography, confirmed the presence of a potential well in its valence band, thus identifying type-II alignment. In contrast, the LWIR nBn photodetector was shown to have type-I alignment because no sign of positive charge was detected in its barrier. Capacitance-voltage measurements were performed to investigate the temperature dependence of carrier densities in a metal-oxide-semiconductor (MOS) structure based on MWIR InAs/InAsSb T2SLs, and a nBn structure based on LWIR InAs/InAsSb T2SLs. No carrier freeze-out was observed in either sample, indicating very shallow donor levels. The decrease in carrier density when temperature increased was attributed to the increased density of holes that had been thermally excited from localized states near the oxide/semiconductor interface in the MOS sample. No deep-level traps were revealed in deep-level transient spectroscopy temperature scans.

  6. Pairwise Sequence Alignment Library

    Energy Science and Technology Software Center (ESTSC)

    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 footprintmore » 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.« less

  7. 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.

  8. 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.

  9. A comparison of image processing techniques for optical interference fringe analysis

    NASA Astrophysics Data System (ADS)

    Farooq, Muhammad; Aslam, Aasma; Hussain, Babar; Hussain, Ghazanfar; Ikram, Masroor

    2015-12-01

    We present a comparison of different techniques for the analysis of the shift and tilt in optical interference fringes. Fringe center, Radon transform, and Gaussian approximation methods are used for fringe analysis. We have measured the tilt and shift between two relevant fringe patterns. The error in tilt measurement was about 2%, and the displacement of the order of few nanometers was measured by the fringe shift analysis. The comparison between the techniques is analyzed with respect to percentage error.

  10. Proposal to develop techniques using magneto-optic and electro-optic effects in optical fiber for CTR diagnostics

    SciTech Connect

    Chandler, G.I.; Jahoda, F.C.

    1982-02-01

    We discuss the developing technology of measuring electric and magnetic fields with optical fibers using the Faraday and Kerr effects, magnetostriction, and Sagnac interferometry. We review the measurement of induced birefringence in the presence of natural birefringence. We propose the use of these effects in making measurements in the fusion research program, with ZT-40 as an example.

  11. 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.

  12. Study on adjustment technique of optical-axis parallelism in multibeam axes optoelectronic system

    NASA Astrophysics Data System (ADS)

    Han, Jun; Wang, Jing; Chen, Wen-jiang; Yu, Xun

    2009-05-01

    A kind of adjustment on the complicated Optoelectronic system with visible, laser, and rotative mechanical axis is discussed in this paper. This is the adjustment of multispectral spatial rotation optical axis, the characteristics is not only the parallelism adjustment of optical axis where relative rotaton movement occurs, but also the danger of invisible highenergy laser, the harmful invisible laser is simulated by the visible light camera aimed at the danger; the principle and method of the optical axis calibration finely with dual-optical wedge for guaranteeing the high parallelism depth between laser and visible optical axis in the discretional azimuth is introduced in this paper: the special rotative adjustment pedestal and the reference light source is designed and processed, the error of the different spatial relative position between camera axis and visual axis is detected by turning the rotative pedestal; In this work, the mathematical model aiming at the dual-optical wedge adjustment technique is constructed ,in which the rationality is confirmed by MATLAB program, and the convenience, the maneuverability and the useful value of the adjustment technique is also illustrated for the parallel precision of 0.1mrad in between laser and visible light axis.

  13. [Optical coherence tomography. Bases and applications of a new intravascular imaging technique].

    PubMed

    Macías, Enrico; Medina, Miguel Ángel; Gonzalo, Nieves; del Angel, Juan; Escaned, Javier

    2013-01-01

    Coronary angiography is the reference technique for the diagnosis of coronary disease. However, the majority of acute coronary syndromes involve angiographically non-significant lesions. It is also the technique of choice for guiding the implantation of endovascular prostheses and their later monitoring. Optical coherence tomography is an interferometric imaging technique that penetrates tissue approximately 2-3mm and provides axial and lateral resolution. It is able to distinguish different tissue types, such as fibrous, lipid-rich, necrotic, or calcified tissue. Optical coherence tomography is able to recognize a variety of features of atherosclerotic plaques that have been associated with rapid lesion progression and clinical events, such as thin cap fibroatheroma, fibrous cap thickness, dense macrophage infiltration, and thrombus formation. Currently, there is growing interest in the value of optical coherence tomography in the area of coronary intervention, where the technique offers significant advantages over more widespread intravascular diagnostic techniques such as intravascular ultrasound. Its higher resolution permits to recognize periprocedural complications, such as microdissection of the coronary artery, stent malapposition, and neointimal hyperplasia, making this tool one of the most promising techniques in the intravascular diagnosis. PMID:23648202

  14. Alignment fixture

    DOEpatents

    Bell, Grover C.; Gibson, O. Theodore

    1980-01-01

    A part alignment fixture is provided which may be used for precise variable lateral and tilt alignment relative to the fixture base of various shaped parts. The fixture may be used as a part holder for machining or inspection of parts or alignment of parts during assembly and the like. The fixture includes a precisely machined diameter disc-shaped hub adapted to receive the part to be aligned. The hub is nested in a guide plate which is adapted to carry two oppositely disposed pairs of positioning wedges so that the wedges may be reciprocatively positioned by means of respective micrometer screws. The sloping faces of the wedges contact the hub at respective quadrants of the hub periphery. The lateral position of the hub relative to the guide plate is adjusted by positioning the wedges with the associated micrometer screws. The tilt of the part is adjusted relative to a base plate, to which the guide plate is pivotally connected by means of a holding plate. Two pairs of oppositely disposed wedges are mounted for reciprocative lateral positioning by means of separate micrometer screws between flanges of the guide plate and the base plate. Once the wedges are positioned to achieve the proper tilt of the part or hub on which the part is mounted relative to the base plate, the fixture may be bolted to a machining, inspection, or assembly device.

  15. Characterization and Processing of Organic Nonlinear Optical Materials using Ellipsometric, Waveguiding, and Absorption Spectroscopy Techniques

    NASA Astrophysics Data System (ADS)

    Olbricht, Benjamin C.

    The first focus of this work is to describe methods for characterizing organic electro-optic materials. Teng-Man Ellipsometry and Attenuated Total Internal Reflection are reviewed. Experimental techniques for these instruments are described and the calculation of an electro-optic activity is derived. The two techniques are compared; it has been found that in Situ Teng-Man ellipsometry is useful to determine poling conditions but not for reliably evaluating electro-optic activity. Attenuated Total Internal Reflection is found to provide very reliable and precise measurements of electro-optic activity and linear optical constants. As a reference, many materials systems have been evaluated and their electro-optic activities are recorded herein. Methods for fabricating devices for test by Teng-Man ellipsometry and Attenuated Total Internal Reflection are presented. A process for inducing Pockel's response via contact-geometry electric field poling is also described, along with modifications to the simple slab dielectric device to enhance the efficacy of poling. An additional method for enhancing the efficiency of poling is presented. This technique relies on the photoisomerization of azobenzene dyes under 532nm radiation to reduce the dimensionality accessible to chromophores doped into the azobenzene matrix. This effect is known as "Laser Assisted Poling" and is shown to increase poling efficiency by more than two fold. The second purpose of this work is to present an experimental technique to measure the order parameter = 3cos 2q -12 . This method is known as Variable-Angle Polarization-Referenced Absorption Spectroscopy (VAPRAS). The experimental apparatus used for VAPRAS introduces small alterations to a UV/Vis Spectrophotometer and an order parameter is derived by exclusively using classical models for transmittance. VAPRAS provides an effective refractive index for the electro-optic material film which is used to calculate the order of absorbers in the film. The results of the VAPRAS method are compared with rigorous (Jones Matrix) simulations of absorbance and Monte Carlo simulations of poling. Both comparisons conclude that the order is low, ≈ 0.05, and their agreement with theory is within experimental error. Theoretical simulations of poling are employed to relate the results of VAPRAS to a noncentrosymmetric order parameter . Finally, a solid-state first molecular hyperpolarizability is calculated from these values, measurements of electro-optic activity, linear optical constants and other secondary properties of the electro-optic material.

  16. Iterative deconvolution technique for measurements of diffraction-limited images on optical microscopes

    PubMed Central

    Lu, Wenlong; Chang, Ming; Chen, Po-Cheng; Luo, Wun-Mao

    2014-01-01

    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. PMID:25774075

  17. 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.

  18. Electrical and Optical Properties of Copper Oxide Thin Films by Sol-Gel Technique

    NASA Astrophysics Data System (ADS)

    Hashim, H.; Shariffudin, S. S.; Saad, P. S. M.; Ridah, H. A. M.

    2015-11-01

    Copper oxide were prepared by sol-gel technique and deposited onto quartz substrates as thin films using spin coating method. The aim of this research was to study the effects of different spin coating speeds of copper oxide thin films on the electrical and optical properties of the thin films. Five samples of copper oxide thin films with different spin coating speeds of 1000, 1500, 2000, 2500 and 3000 rpm were annealed at 600°C for 30 minutes. UV-Vis spectrophotometer and two-point probe technique were used to characterize the optical and electrical properties of the deposited films. Based on the results obtained, it revealed that the electrical conductivity of the copper oxide thin films reduce as the spin coating speeds increase. The calculated optical band gap and the resistivity of the copper oxide thin films also decrease when the spin coating speeds are increased.

  19. 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.

  20. Optical self-absorption technique for qualitative measurement of excited-state densities in plasma reactors

    SciTech Connect

    Miller, P.A.; Hebner, G.A.; Jarecki, R.L. Jr.; Ni, T.

    1998-11-01

    Measurements of excited-state populations in processing plasmas can be useful because those populations often are indicators of, or participants in, chemical reactions. An optical self-absorption technique has been used to measure the relative densities of species in long-lived excited states in high-density plasma reactors. The technique is advantageous because it is simple and inexpensive compared to many laboratory diagnostic techniques, and thus it has potential for industrial manufacturing applications. The technique is useful when absorption strength and wavelength are in acceptable ranges. This paper describes the technique, compares its performance to a more sophisticated laser-absorption technique, and presents self-absorption data from a laboratory reactor and from a 300 mm production-prototype reactor. {copyright} {ital 1998 American Vacuum Society.}

  1. Optical performance monitoring technique using software-based synchronous amplitude histograms.

    PubMed

    Choi, H G; Chang, J H; Kim, Hoon; Chung, Y C

    2014-10-01

    We propose and demonstrate a simple technique to monitor both the optical signal-to-noise ratio (OSNR) and chromatic dispersion (CD) by using the software-based synchronous amplitude histogram (SAH) analysis. We exploit the software-based synchronization technique to construct SAHs from the asynchronously sampled intensities of the signal. The use of SAHs facilitates the accurate extraction of the monitoring parameters at the center of the symbol. Thus, unlike in the case of using the technique based on the asynchronous amplitude histogram (AAH), this technique is not affected by the transient characteristics of the modulated signals. The performance of the proposed monitoring technique is evaluated experimentally by using 10-Gbaud quadrature phase-shift keying (QPSK) and quadrature amplitude modulation (QAM) signals over wide ranges of OSNR and CD. We also evaluate the robustness of the proposed technique to the signal's transient characteristics. PMID:25321978

  2. 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.

  3. Monitoring the stress build-up in dental cements: a novel optical characterization technique

    NASA Astrophysics Data System (ADS)

    Ottevaere, Heidi; Tabak, M.; Bartholomees, F.; de Wilde, Willy P.; Veretennicoff, Irina P.; Thienpont, Hugo

    2001-01-01

    It is well known that during the curing of dental cements, polymerization shrinkage induces unacceptable stresses, which can result into cracks and an over-sensitivity of the teeth. We demonstrate that polarimetric optical fiber sensors can be used to characterize this shrinkage quantitatively. To determine the time evolution and the amount of shrinkage we embed a highly birefringent optical fiber in the dental cement and analyze the change in optical polarization at its output. This change is a measure for the dynamic stress-build up. We also demonstrate the repeatability of our characterization method for these cements. Moreover we given indications that this technique allows for in- vivo monitoring of the stress build-up dynamics between dentine and porcelain facings. This may bring durable all-ceramic restorations closer to reality. In this paper we present the principle of this original optical fiber sensor, its practical implementation and the experimental results we obtained for this application.

  4. Self-normalized photoacoustic technique for thermo-optical characterization of samples mounted between transparent media

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.; Díaz-Reyes, J.; Jaime-Fonseca, M. R.; Martínez-Pérez, L.; Pescador-Rojas, J. A.

    2016-03-01

    A self-normalized photoacoustic technique for thermo-optical characterization of materials, mounted between transparent media, is presented. It involves a complex ratio of photoacoustic signals in transmission and front configurations, taking the modulation frequency as the only variable. The analytical solutions for the corresponding 1D heat diffusion problems are analyzed to provide suitable methodologies for measuring the optical absorption coefficients and thermal diffusivity of such samples. This methodology was tested by measuring the optical absorption coefficient, at 660 nm, of methylene blue solutions at various concentrations and the thermal diffusivity of a black drawing ink sample. In addition, an approximated range of optical absorption coefficients, where this photoacoustic methodology is adequate, was established.

  5. Frequency-derived distributed optical-fiber sensing technique: theory and characterization.

    PubMed

    Parvaneh, F; Handerek, V A; Rogers, A J

    2000-06-20

    Frequency-derived distributed optical-fiber sensing is a method for remote measurement of the spatial distribution of linear birefringence in an optical fiber, allowing a corresponding measurement of those external measurands that influence this birefringence. The method employs a pump-probe scheme, which, by use of the optical Kerr effect, generates an optical modulation of the probe beam, with a modulation frequency whose temporal variation maps the spatial distribution of birefringence. We provide a complete theoretical analysis of this method by using Jones calculus and graphic representation on the Poincaré sphere. The relevant characterization of the technique and some experimental results are also presented; these show good agreement with the theory. PMID:18345229

  6. Practical and cost-effective high-fidelity optical carrier dissemination using coherent communication techniques.

    PubMed

    Sooudi, Ehsan; O'Gorman, James; Gunning, Paul; Ellis, Andrew D; Gunning, Fatima C Garcia; Manning, Robert J

    2015-08-24

    We report a unidirectional frequency dissemination scheme for high-fidelity optical carriers deployable over telecommunication networks. For the first time, a 10 Gb/s Binary Phase Shift Keying (BPSK) signal from an ultra-narrow linewidth laser was transmitted through a field-installed optical fibre with round-trip length of 124 km between Cork City and town of Clonakilty, without inline optical amplification. At the receiver, using coherent communication techniques and optical injection-locking the carrier was recovered with noise suppression. The beat signal between the original carrier at the transmitter and recovered carrier at the receiver shows a linewidth of 2.8 kHz. Long term stability measurements revealed fractional instabilities (True Allan deviation) of 3.3 10(-14) for 1 s averaging time, prior to phase noise cancellation. PMID:26368147

  7. Fan-out routing and optical splitting techniques for compact optical interconnects using single-mode polymer waveguides

    PubMed Central

    Kruse, Kevin L.; Middlebrook, Christopher T.

    2015-01-01

    Polymer waveguide (WG) S-bends are necessary for fan-out routing techniques and optical splitting in high-density optical interconnects. Designing and manufacturing of optimal S-bends are critical for minimizing optical link loss while maintaining overall size and layout constraints. Complete structural loss analysis is demonstrated theoretically and shown experimentally utilizing both radial and transitional loss in single-mode (SM) polymer WG radial arc, cosine, and raised-sine S-bend profiles. SM polymer WG straights were first fabricated to measure standard propagation loss. SM WG S-bends were fabricated incorporating straight lead-in and lead-out sections to incorporate transitional loss present in workable designs. S-bend designs were measured at different dimensions and matched to theoretical losses. Compact cosine and radial arc S-bends exhibited the lowest structure loss for low and high NA WGs, respectively. High-speed performance of SM WG straights and S-bends was measured at 10 Gbit/s demonstrating low error rate. Optical splitters designed with S-bends and tapers were also evaluated and fabricated. Trade-off between optimal loss and minimal device size is discussed. PMID:25892851

  8. A precise technique for measurement of optical-fiber hole concentricity in the ferrule of an optical connector

    SciTech Connect

    Klingsporn, P.E.

    1996-12-01

    A precise optical method was developed for measuring the concentricity of a longitudinal hole in a cylinder relative to the outer cylindrical surface. The work was done to provide improved accuracy over existing methods for measuring the concentricity ofan optical fiber relative to the outer ferrule diameter in an optical connector. Fiber concentricity is very important for reliable coupling of high optical power densities from one connectorized fiber cable to another. The technique involves the use of a laser interferometer to measure the passage of the ferrule into and out of a light beam whose attenuated energy is measured simultaneously to high precision. Combined measurements of the passage of a precisely fit pin or fiber in the ferrule hole through the light beam allow the concentricity of the fiber hole to be measured relative to the outer ferrule diameter. Repeatability measurements were made under different experimental arrangements, with both a collimated light beam and a slightly convergent light beam. Depending on the particular arrangement, the standard deviation for concentricity measurement in a given plane of the ferrule ranged from 2.37 microinches to 4.19 microinches.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Molecular imaging with optics: primer and case for near-infrared fluorescence techniques in personalized medicine

    PubMed Central

    Sevick-Muraca, Eva M.; Rasmussen, John C.

    2010-01-01

    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. PMID:19021311

  15. Image segmentation using a hybrid technique by combining optical and digital methods

    NASA Astrophysics Data System (ADS)

    Aguayo Adame, Juan Pablo; Flores, Jorge L.; Ferrari, José A.; García-Torales, Guillermo

    2011-08-01

    We present an image segmentation method based on the use of an optical technique for detection of contours (as a preprocessing stage) and a posterior digital segmentation algorithms. The contouring technique is utilized to find an accurate contour and it is based on the polarization features of the twisted-nematic liquid-crystal displays (TNLCDs). TN-LCDs are manufactured to work between a crossed polarizer-analyzer pair. When the analyzer is at 45 deg (instead of 90 deg) with respect to the polarizer, one obtains an optically processed image with pronounced outlines (dark contours) at middle intensity. On other hand, the segmentation algorithms are based on active shape models or snakes. Experimental results show that the proposed technique yields accurate segmentation for low-contrast images. Also, we demonstrate that this hybrid-system has a better performance than purely digital algorithms.

  16. Neutron, fluorescence, and optical imaging: An in situ combination of complementary techniques

    NASA Astrophysics Data System (ADS)

    Wagner, D.; Brgardts, M.; Grnzweig, C.; Lehmann, E.; Mller, T. J. J.; Egelhaaf, S. U.; Hermes, H. E.

    2015-09-01

    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.

  17. Layer-to-layer alignment for step and flash imprint lithography

    NASA Astrophysics Data System (ADS)

    Choi, Byung J.; Meissl, Mario J.; Colburn, Matthew; Bailey, Todd C.; Ruchhoeft, Paul; Sreenivasan, S. V.; Prins, F.; Banerjee, Sanjay K.; Ekerdt, John G.; Willson, C. Grant

    2001-08-01

    The Step and Flash Imprint Lithography (SFIL) process is a low-cost, high-throughput patterning technique with a sub- 100 nm resolution capability. Investigation by this group and others indicates that the resolution of replication by imprint lithography is limited only by the size of the structures that can be created on the template. It has also been demonstrated that the SFIL process is capable of eliminating contaminants from the template (master) during a step and repeat imprinting process. The low pressure, room temperature nature of SFIL and the transparent imprint templates make it particularly attractive for high- resolution layer-to-layer alignment. Another aspect of SFIL that assists in the layer to layer alignment is the presence of a thin layer of low viscosity liquid between the template and wafer prior to UV curing. The liquid maintains a small gap (~0.2 micrometers ) and acts as lubrication and damping agents, which allows for accurate in situ error measurement and compensation. In this paper, we present results from overlay alignment experiments using the SFIL process. A Canon mask aligner was modified to implement a layer-to-layer alignment scheme for SFIL. The objective of this research was to achieve alignment accuracy of about 0.5 micrometers , which is the practical limit of the X-Y stage in the mask aligner. The overlay alignment error measurements and the corresponding corrections in X,Y and Theta were performed using the modified mask aligner. In its current state, the alignment resolution appears to be limited by the resolution of the mask aligner stage. It is expected that other high resolution alignment techniques have been developed for optical projection lithography and X-ray lithography processes can be adapted to the SFIL process to significantly improve the alignment resolution.

  18. 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.

  19. 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

  20. Application of nondestructive optical techniques in the detection of surface and subsurface defects in sapphire

    NASA Astrophysics Data System (ADS)

    Akwani, Ikerionwu A.; Hibbard, Douglas L.; Jacoby, Keith T.

    2007-04-01

    Advancements in optical manufacturing and testing technologies for sapphire material are required to support the increasing use of large aperture sapphire panels as windscreens for various electro-optical system applications. It is well known that the grinding and polishing operations employed to create optical surfaces leads to the introduction of surface stress and sub-surface damage which can affect critical opto-mechanical performance characteristics such as strength and durability. Traditional methods for measuring these defects are destructive and, therefore, unsuitable as in-process, high volume inspection tools. A number of non-destructive optical techniques were investigated at Exotic Electro-Optics under funding by the Office of Naval Research and the Air Force Research Laboratory including Raman spectroscopy, laser polarimetry and the Twyman effect to characterize process-induced defects in sapphire panels. Preliminary experimental results using these techniques have shown that surface stress and sub-surface damage may be non-destructively measured. Raman spectroscopy has shown promise in quantifying surface stress, laser polarimetry is of questionable utility and the Twyman effect may be used qualitatively to monitor relative stress and sub-surface damage. This information will ultimately provide a better understanding of the overall manufacturing process leading to optimized process time and cost.