Sample records for optical alignment techniques

  1. Alignment technique for polarization-based optical systems

    Microsoft Academic Search

    Lie-Yi Sheng; Bin Lin; Sen-Lu Xu; Lie-Wei Zhu

    1992-01-01

    In this paper, the synthetical analyses on the derivation of alignment in the application of the polarization optical technique are presented upon the main error sources of this technique. Consequently, a novel alignment system is developed to improve the alignment technique, which is composed of a combination of two parallel polarizers, bidirectional-double path, two detectors, and electrical signa processor. Using

  2. Alignment technique for polarization-based optical systems

    NASA Astrophysics Data System (ADS)

    Sheng, Lie-yi; Lin, Bin; Xu, Senlu; Zhu, Lie-wei

    1992-12-01

    In this paper, the synthetical analyses on the derivation of alignment in the application of the polarization optical technique are presented upon the main error sources of this technique. Consequently, a novel alignment system is developed to improve the alignment technique, which is composed of a combination of two parallel polarizers, bidirectional-double path, two detectors, and electrical signa processor. Using this system, we have realized accurate alignments between PM fibers and their in-line devices.

  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. Integration of micro-optics with a fiber array connector using passive alignment technique for parallel optics applications

    Microsoft Academic Search

    Hongtao Han; Jim Morris; Adam Fedor; Bingzhi Su; David Aichele; Eden Chen; Holly Weathersbee; Alexey Semakov

    2004-01-01

    The micro-optic chips are made of glass material using wafer scale photolithography and etching techniques, and micro optical elements are fabricated on both sides. The fiber array connector is an injection molded plastic receptacle, which contains an interface for the MT connector and a precision cavity for passive alignment. For the 12-channel transmitter optical sub-assembly (OSA), we incorporated 12 diffractive

  5. Optical module with MU connector interface using self-alignment technique by solder-bump chip bonding

    Microsoft Academic Search

    Tsuyoshi Hayashi; Hideki Tsunetsugu

    1996-01-01

    We applied a self-alignment technique that uses solder-bump chip bonding for alignment between photonic devices and optical fibers in optical modules, and achieved a compact and simple MU-type connectorized receiver module that requires no optical-axis adjustment. In our scheme, coupling a photonic device to a fiber is basically done by simple butt-joining, which is automatically accomplished by solder-bump bonding the

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

    SciTech Connect

    Gerasimova, N.; Dziarzhytski, S.; Weigelt, H. [Deutsches Electronen-Synchrotron DESY, Notkestrasse 85, 22607 Hamburg (Germany); Chalupsky, J.; Hajkova, V.; Vysin, L.; Juha, L. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic)

    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.

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

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

  10. 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.

  11. Optical analysis and alignment applications using the infrared Smartt interferometer

    SciTech Connect

    Viswanathan, V.K.; Bolen, P.D.; Liberman, I.; Seery, B.D.

    1981-01-01

    The possibility of using the infrared Smartt interferometer for optical analysis and alignment of infrared laser systems has been discussed previously. In this paper, optical analysis of the Gigawatt Test Facility at Los Alamos, as well as a deformable mirror manufactured by Rocketdyne, are discussed as examples of the technique. The possibility of optically characterizing, as well as aligning, pulsed high energy laser systems like Helios and Antares is discussed in some detail.

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

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

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

  13. Fiber optics welder having movable aligning mirror

    DOEpatents

    Higgins, Robert W. (Los Alamos, NM); Robichaud, Roger E. (Jemez Springs, NM)

    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.

  14. Optical and magneto-optical properties of aligned Ni nanowires embedded in polydimethylsiloxane

    NASA Astrophysics Data System (ADS)

    Hamidi, S. M.; Sobhani, A.; Aftabi, A.; Najafi, M.

    2015-01-01

    We report the magnetic, optical and magneto-optical properties of aligned Nickel nanowires embedded in polydimethylsiloxane matrix. The NWs prepared by electrodeposition method in anodic alumina template and then dispersed in ethanol and placed in a heater to evaporate the ethanol and finally dispersed in PDMS matrix to reach to the composite. The used external magnetic field arranges the NWs and our aligned NWs were investigated by magnetic hysteresis loop, surface plasmon resonance and spectral magneto-optical techniques. Our results show that these aligned NWs have a sufficient squareness, a strong increase of the magneto-optical response in visible range and very good surface plasmon resonance.

  15. Optical coupling efficiency studies of passively aligned CWDM optical modules

    Microsoft Academic Search

    A. Priyadarshi; P. V. Ramana; S. G. Mhaisalkar; V. Kripesh; Qingxin Zhang; Anand K. Asundi

    2005-01-01

    A compact low-cost passively aligned optical sub-assembly (OSA) with four different optical transmission channels is fabricated for CWDM transceiver module. A silicon optical bench (SiOB) with V-groove, and U-groove was fabricated with dimensional accuracy of ±1 ?m. A 125 ?m diameter single mode optical fiber (SMF) and a 250×250×100 ?m3 laser diode (LD) was passively aligned on the SiOB using

  16. Optical Alignment Device For Laser Communication

    NASA Technical Reports Server (NTRS)

    Casey, William L.

    1988-01-01

    Optical alignment device under development enables continuous tracking and coalignment of two beams of light. Intended primarily for laser-communication station, in which transmitted beam must be aligned with received beam to ensure transmitted beam falls on receiver at other station. Expected to consume less power and be smaller and less complicated than alignment shutter and drive previously used. Prism and filter separate two overlapping collimated light beams of different wavelength or polarization. Coordinates of two beams tracked on charge-coupled device to determine degree of directional misalignment between two beams.

  17. Computer vision applications for coronagraphic optical alignment and image processing

    E-print Network

    Savransky, Dmitry; Poyneer, Lisa A; Macintosh, Bruce A; 10.1364/AO.52.003394

    2013-01-01

    Modern coronagraphic systems require very precise alignment between optical components and can benefit greatly from automated image processing. We discuss three techniques commonly employed in the fields of computer vision and image analysis as applied to the Gemini Planet Imager, a new facility instrument for the Gemini South Observatory. We describe how feature extraction and clustering methods can be used to aid in automated system alignment tasks, and also present a search algorithm for finding regular features in science images used for calibration and data processing. Along with discussions of each technique, we present our specific implementation and show results of each one in operation.

  18. Optical Techniques Nanomicroscopy

    E-print Network

    Fischer, Wolfgang

    Optical Techniques Nanomicroscopy Drug Development Medicinal Plants Sessions Nanomicroscopy Medical Biophysics Structure and Mechanics of F nction Medicinal Plants Nano Medicine Drug Encapsulation and Deli er

  19. Passive alignment of optical elements in a printed circuit board

    Microsoft Academic Search

    T. Lamprecht; F. Horst; R. Dangel; R. Beyeler; N. Meier; L. Dellmann; M. Gmur; C. Berger; B. J. Offrein

    2006-01-01

    A successful implementation of optics into PCBs (printed circuit boards) requires a precise passive alignment of optical elements relative to the optical waveguides in the board. We tackled this challenge with a novel concept that allows the passive alignment onto a PCB of any optical or optoelectronic building block with a precision of a few micrometers. Markers, structured into a

  20. Automatic Optical Fiber Alignment System Using Genetic Algorithms

    Microsoft Academic Search

    Masahiro Murakawa; Hirokazu Nosato; Tetsuya Higuchi

    2003-01-01

    We propose and demonstrate an automatic optical fiber align- ment system using genetic algorithms. Connecting optical fibers is dif- ficult because the connecting edges should be aligned with sub-micron- meter resolution. It, therefore, takes long time even for a human expert. Although automatic fiber alignment systems are being developed, they cannot be used practically if the degrees of freedom of

  1. AGORA: Assembly Guided by Optical Restriction Alignment

    PubMed Central

    2012-01-01

    Background Genome assembly is difficult due to repeated sequences within the genome, which create ambiguities and cause the final assembly to be broken up into many separate sequences (contigs). Long range linking information, such as mate-pairs or mapping data, is necessary to help assembly software resolve repeats, thereby leading to a more complete reconstruction of genomes. Prior work has used optical maps for validating assemblies and scaffolding contigs, after an initial assembly has been produced. However, optical maps have not previously been used within the genome assembly process. Here, we use optical map information within the popular de Bruijn graph assembly paradigm to eliminate paths in the de Bruijn graph which are not consistent with the optical map and help determine the correct reconstruction of the genome. Results We developed a new algorithm called AGORA: Assembly Guided by Optical Restriction Alignment. AGORA is the first algorithm to use optical map information directly within the de Bruijn graph framework to help produce an accurate assembly of a genome that is consistent with the optical map information provided. Our simulations on bacterial genomes show that AGORA is effective at producing assemblies closely matching the reference sequences. Additionally, we show that noise in the optical map can have a strong impact on the final assembly quality for some complex genomes, and we also measure how various characteristics of the starting de Bruijn graph may impact the quality of the final assembly. Lastly, we show that a proper choice of restriction enzyme for the optical map may substantially improve the quality of the final assembly. Conclusions Our work shows that optical maps can be used effectively to assemble genomes within the de Bruijn graph assembly framework. Our experiments also provide insights into the characteristics of the mapping data that most affect the performance of our algorithm, indicating the potential benefit of more accurate optical mapping technologies, such as nano-coding. PMID:22856673

  2. 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.

  3. Optical coupling efficiency studies of passively aligned CWDM optical modules

    NASA Astrophysics Data System (ADS)

    Priyadarshi, A.; Ramana, P. V.; Mhaisalkar, S. G.; Kripesh, V.; Zhang, Qingxin; Asundi, Anand K.

    2005-04-01

    A compact low-cost passively aligned optical sub-assembly (OSA) with four different optical transmission channels is fabricated for CWDM transceiver module. A silicon optical bench (SiOB) with V-groove, and U-groove was fabricated with dimensional accuracy of ±1 ?m. A 125 ?m diameter single mode optical fiber (SMF) and a 250 × 250 × 100 ?m 3 laser diode (LD) was passively aligned on the SiOB using adhesive and solder preform respectively. Process related coupling losses due to the shifting of fiber during the adhesive attachment and cure process is demonstrated. Analytical studies were carried out to find the effect of parameters such as dimensions of laser diode, SiOB and attachment process on the coupling losses of the module. It was found that dimensional uncertainty of SiOB and the attachment process parameters are the crucial parameters for the coupling loss in passive alignment assembly of CWDM transceiver. An optical coupling loss of 25% was observed due to the shift of fiber during the attachment process and it was in good agreement with the analytical calculated results.

  4. Optical alignment of Centaur's inertial guidance system

    NASA Technical Reports Server (NTRS)

    Gordan, Andrew L.

    1987-01-01

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

  5. An automatic alignment technique for multiple rangefinders

    NASA Astrophysics Data System (ADS)

    Fujiwara, Kenta; Yamauchi, Koichiro; Sato, Yukio

    2008-02-01

    An automatic alignment technique for multiple rangefinders is proposed. We obtain 3D data of object using a rangefinder which is composed of a camera and a projector. Generally, we can only obtain partial figure when we measure an object from one direction. Therefore, we can acquire all around configuration by measuring an object from multiple viewpoint. The data obtained with rangefinder exists independent camera coordinate system each other. It is needed to integrate each range maps to acquire all around figure. Heretofore, we integrate multiple range maps by estimating camera parameter using calibration rig whose scale is known. Calibration rig has many feature points which have world coordinate each. Camera parameter is estimated from the relation between camera coordinate and world coordinate of feature points on the rig. However, we cannot identify the measuring position when we measure a part of the rig, because the pattern painted on the rig is monotonous pattern. In this paper, we use "De Bruijn Sequence pattern" on the calibration rig. This pattern enables us to identify the measuring spot wherever we measure the rig, and enable us to automatically integrate multiple range maps.

  6. Experimental assessment of passive alignment of optical fibers with V-grooves on silicon optical bench

    Microsoft Academic Search

    Jeffery C. C. Lo; S. W. Ricky Lee

    2004-01-01

    Alignment is one of the most critical issues in optoelectronics packaging. A slight offset in any direction will affect the performance of the photonic devices. Nowadays passive alignment of optical fibers is attracting more attention due to its low manufacturing cost and short processing time when compared with active alignment. The position of the optical fiber in passive alignment is

  7. Optical alignment and testing of the Michelle spectrometer

    NASA Astrophysics Data System (ADS)

    Ettedgui-Atad, Eli; Glasse, Alistair C.; Baillie, T. E.; Bryson, Ian R.; Morrison, Garry F.; Murray, J.

    1998-08-01

    We describe the optical alignment and image quality testing of Michelle, the all-reflective mid-IR astronomical spectrometer and imager being built at the Royal Observatory Edinburgh for the UKIRT and GEMINI telescopes. The design strategy called for optical alignment by manufacture, with the only means for adjustment being the machining of sacrificial pads under key optical components. The success of this approach in meeting the alignment error budget is discussed, including the description of a method for identifying the optical axis of the optical train using field rotation. We present the result of image spot and wavefront error measurements and compare them with the instruments opto-mechanical specification.

  8. Low cost packaging of semiconductor laser arrays using passive self-aligned flip-chip technique on Si motherboard

    Microsoft Academic Search

    W. Hunziker; W. Vogt; H. Melchior; R. Germann; C. Harder

    1996-01-01

    A passive self-aligned packaging technique for semiconductor laser arrays has been realized. Alignment trenches on the laser chip are introduced to enable self-alignment to optical fibers during flip-chip mounting on a structured Si motherboard. The use of the etched Si sidewalls for alignment results in a self-positioning effect, reducing device placing precision, and allows larger tolerances in the motherboard processing.

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

    PubMed

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

    2013-01-10

    A method for constructing quasimonolithic, precision-aligned optical assemblies is presented. Hydroxide-catalysis bonding is used, adapted to allow optimization of component fine alignment prior to the bond setting. We demonstrate the technique by bonding a fused silica mirror substrate to a fused silica baseplate. In-plane component placement at the submicrometer level is achieved, resulting in angular control of a reflected laser beam at the sub-10-?rad level. Within the context of the LISA Pathfinder mission, the technique has been demonstrated as suitable for use in space-flight applications. It is expected that there will also be applications in a wide range of areas where accuracy, stability, and strength of optical assemblies are important. PMID:23314633

  10. WFC3: Optical Alignment and Performance

    NASA Astrophysics Data System (ADS)

    Dressel, Linda L.; Hartig, G.; Delker, T.; Sabbi, E.; WFC3 Team

    2010-01-01

    The UVIS and IR channels were aligned to the OTA (Optical Telescope Assembly) using exposures of the open cluster NGC 188. For each channel, an iterative series of focus sweeps and rasters of tip/tilt corrector mechanism settings were performed. Phase retrieval estimation of the low order aberration content and encircled energy measurements of many stars distributed over the field were used to determine the corrector adjustments required to optimize image quality. Assessment of PSF (point spread function) over the field in several filters uses phase retrieval, encircled energy, sharpness, and FWHM. Shallow and deep exposures of the isolated star GD153 are used to evaluate the PSF wings at 5 locations on each detector. Preliminary analysis indicates that the observed metrics are a good match to the model predictions: encircled energy and azimuthally averaged PSFs agree well with model predictions except for the UV (F275W) exposures. The over-prediction of encircled energy from radius 0.2 to 1 arcsec in the UV is being investigated. UVIS shutter vibrations smear the PSF in exposures shorter than 10 seconds, more so for one shutter position than for the other. We have investigated this effect in sequences of repeat exposures of GD153, which also clearly demonstrate the effect of OTA breathing on the PSF as the focus moves in and out of the optimal range. Photometric apertures should be chosen to allow for the effects of this vibration and breathing.

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

    PubMed Central

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

    2013-01-01

    Stimulated emission depletion (STED) microscopy provides diffraction-unlimited resolution in fluorescence microscopy. Imaging at the nanoscale, however, requires precise alignment of the depletion and excitation laser foci of the STED microscope. We demonstrate here that adaptive optics can be implemented to automatically align STED and confocal images with a precision of 4.3 ± 2.3 nm. PMID:23722769

  12. 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.

  13. 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.

  14. Field alignment of bent-core smectic liquid crystals for analog optical phase modulation

    NASA Astrophysics Data System (ADS)

    Shen, Y.; Goodhew, L.; Shao, R.; Moran, M.; Korblova, E.; Walba, D. M.; Clark, N. A.; Maclennan, J. E.; Rudquist, P.

    2015-05-01

    A general method for aligning bent-core smectic liquid crystal materials is described. Alternating electric fields between interdigitated electrodes patterned on one cell surface create torques on the liquid crystal that result in uniform "bookshelf" orientation of the smectic layers. The aligned cell can then be driven in the conventional way by applying an electric field between all of the stripe electrodes connected together and a monolithic electrode on the other cell surface. Fast, analog, optical phase-only modulation is demonstrated in a device containing a polar, bent-core SmAPF material aligned using this technique.

  15. Principles of calculating alignment signals in complex resonant optical interferometers

    Microsoft Academic Search

    Yaron Hefetz; Nergis Mavalvala; Daniel Sigg

    1997-01-01

    In the long baseline laser interferometers, presently under construction to measure gravitational waves (LIGO), the alignment of the optical components with respect to the incoming laser beam is crucial to maintain maximum phase sensitivity. We present a basic formalism to analytically calculate the effects of misalignment and beam distortions in an arbitrarily complex optical system, including coupled cavities and Michelson

  16. 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.

  17. High Speed Alignment Control of an Optical Resonator

    NASA Astrophysics Data System (ADS)

    Amariutei, Daniel

    2014-03-01

    For interferometric gravitational wave detectors, fluctuations in the input laser beam alignment are a critical source of technical noise. In order to maintain optimal sensitivity it is necessary to control the input beam alignment. We introduce a new method for achieving this alignment control using angular actuators based on the electro-optic beam deflection. Compared to piezo-mounted mirror actuators, which have a low bandwidth and intrinsic noise due to moving parts, these actuators promise a much higher bandwidth with no moving parts. This talk presents the experimental demonstration of closed loop alignment control using the electro-optic beam deflectors and report their measured performance. Supported by NSF grant PHY-1205512.

  18. Functional alignments and self-tests for tilted and decentered optics

    SciTech Connect

    Bauke, W.; Cross, E.W.

    1983-01-01

    The alignment of tilted and decentered optics is ordinarily difficult, because such optics have neither simple alignment points amenable to ordinary boresight methods, nor a simple alignment theory. Several different alignment examples which provide insight into a practical universal approach to all such systems are explored. The examples detailed are segments of the Antares Laser Fusion Project's optical train.

  19. Previous R&D of vibrating wire alignment technique for HEPS

    E-print Network

    Wu, Lei; Li, Chunhua; Qu, Huamin

    2014-01-01

    The alignment tolerance of multipoles on a girder is better than 30um in the storage ring of High Energy Photon Source HEPS which will be the next project at IHEP Institute of High Energy Physics. This is difficult to meet the precision only using the traditional optical survey method. In order to achieve this goal, vibrating wire alignment technique with high precision and sensitivity is considered to be used in this project. This paper presents some previous research works about theory, scheme design and achievements.

  20. 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..

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

    SciTech Connect

    Babzien, M.; Ben-Zvi, I.; Fang, J.M. [Brookhaven National Lab., Upton, NY (United States)] [and others

    1995-12-31

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

  2. 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.

  3. Holographic weapons sight as a crew optical alignment sight

    Microsoft Academic Search

    Nujoud Merancy; Brian Dehmlow; Jack P. Brazzel

    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

  4. Call for Papers Optical System Alignment, Tolerancing,

    E-print Network

    Jahns, Jürgen

    . (United States); Daniel G. Smith, Nikon Research Corp. of America (United States); Yana Z. Williams, GE Center · San Diego, CA United States Conference Chairs: José Sasián, College of Optical Sciences, The Univ. of Arizona (United States); Richard N. Youngworth, Light Capture, Inc. (United States) Program

  5. Optimized features allocation technique for improved automated alignment of wafers

    NASA Astrophysics Data System (ADS)

    Parshin, Michael; Zalevsky, Zeev

    2009-02-01

    In this paper we present a new fuzzy logic based approach for automatic optimized features allocation. The technique is used for improved automatic alignment and classification of silicon wafers and chips that are used in the electronic industry. The proposed automatic image processing approach was realized and experimentally demonstrated in real industrial application with typical wafers. The automatic features allocation and grading supported the industrial requirements and could replace human expert based inspection that currently is performed manually.

  6. 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 ?m and over 200 ?m for the transverse and longitudinal directions, respectively. For the TOSA, the tolerance, which is mostly dependent upon the VCSEL alignment, was ~20 ?m and more than 200 ?m 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.

  7. Laser\\/rear Facet Monitor Arrays With Monolithically Integrated V-groove For Passive Optical Fiber Alignment

    Microsoft Academic Search

    Mark A. Rothman; Chan L. Shieh; Alfred J. Negri; John A. Thompson; Craig A. Armiento; Roger P. Holmstrom; Jatinder Kaur

    1992-01-01

    Development of monolithically integrated photonic circuits pramirrcs to enhance the functionality, reliability, and cost effectiveness of optical subsystems. The packa th discrete devices and optoelectronic integrated circuits {OEIG), however, often requires the inco of optic,al-fiber pigtails that substantially increase the cost of such components. Techniques ive Eibcr coupling of lasers, using passive rather than active alignment, have been demonstrated using

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

    SciTech Connect

    Malevich, Y. V., E-mail: malevich@pfi.lt; Adomavi?ius, R.; Krotkus, A. [Center for Physical Sciences and Technology, A. Gostauto 11, 01108 Vilnius (Lithuania); Malevich, V. L. [Institute of Physics, National Academy of Sciences of Belarus, Nezalezhnasti ave., 68, 220072 Minsk (Belarus)

    2014-02-21

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

  9. High contrast and metal-less alignment process for all-polymer optical interconnect devices

    NASA Astrophysics Data System (ADS)

    Ge, Tao; Yang, Jilin; Summitt, Chris; Wang, Sunglin; Johnson, Lee; Zaverton, Melissa; Milster, Tom; Takashima, Yuzuru

    2015-03-01

    A polymer-based flat, flexible and parallel optical interconnect has become an attractive approach for short-range data transfer. For such a device, a low cost fabrication technique is required for light couplers to redirect light from source to waveguides. Recently, we demonstrated a mask-less gray scale lithography process, which used a CMOS compatible polymer for a 45-degree mirror coupler. Polymer materials such as epoclad and AP2210B can be used to fabricate flexible substrates and waveguides, respectively. We propose an all-photopolymer lithography process to fabricate the flexible and parallel optical interconnect in conjunction with the mirror couplers. In the process, a buried polymer structure is used to precisely align the mirror coupler to waveguides, which make it possible to avoid an additional metallization process. However, the contrast of such buried fiducial mark is low since such the structure is a phase structure. As a result, it is not feasible to use the buried polymer structure as an alignment mark with conventional amplitude based imaging modalities. To increase the contrast of these buried alignment marks, we propose a feature specific alignment system for which the shape and depth of the buried alignment marks are optimized for phase-based imaging such as phase contrast and Schlieren imaging. Our results show that an optimized alignment mark provides a significant contrast enhancement while using a phase contrast imaging system compared to that of a conventional imaging system. In addition, we have fabricated an optimized alignment mark specifically for use with a Schlieren imaging system.

  10. Optical Extinction Ratio Monitoring Techniques Using Optical Spectrum Analysis

    Microsoft Academic Search

    Chun-Liang Yang; San-Liang Lee

    2007-01-01

    Abstrac An optical extinction ratio monitoring technique for wavelength-division-multiplexed passive optical network systems is proposed. This technique is based on the optical spectrum analysis. It can accurately measure the optical extinction ratio of optical signals and does not change with the transmission distance. In our experiments, the transient chirp hardly affects the measured results if the optical extinction ratio is

  11. Novel techniques for optical performance monitoring in optical systems

    NASA Astrophysics Data System (ADS)

    Ku, Yuen Ching

    The tremendous increase of data traffic in the worldwide Internet has driven the rapid development of optical networks to migrate from numerous point-to-point links towards meshed, transparent optical networks with dynamically routed light paths. This increases the need for appropriate network supervision methods. In view of this, optical performance monitoring (OPM) has emerged as an indispensable element for the quality assurance of an optical network. This thesis is devoted to the proposal of several new and accurate techniques to monitor different optical impairments so as to enhance proper network management. When the optical signal is carried on fiber links with optical amplifiers, the accumulated amplified spontaneous emission (ASE) noise will result in erroneous detection of the received signals. The first part of the thesis presents a novel, simple, and robust in-band optical signal to noise ratio (OSNR) monitoring technique using phase modulator embedded fiber loop mirror (PM-FLM). This technique measures the in-band OSNR accurately by observing the output power of a fiber loop mirror filter, where the transmittance is adjusted by an embedded phase modulator driven by a low-frequency periodic signal. The robustness against polarization mode dispersion, chromatic dispersion, bit-rate, and partially polarized noise is experimentally demonstrated. Chromatic dispersion (CD) is due to the fact that light with different frequencies travel at different speeds inside fiber. It causes pulse spreading and intersymbol interference (ISI) which would severely degrade the transmission performance. By feeding a signal into a fiber loop which consists of a high-birefringence (Hi-Bi) fiber, we experimentally show that the amount of experienced dispersion can be deduced from the RF power at a specific selected frequency which is determined by the length of the Hi-Bi fiber. Experimental results show that this technique can provide high monitoring resolution and dynamic range. Polarization mode dispersion (PMD) splits an optical pulse into two orthogonally polarized pulses traveling along the fiber at different speeds, causing crosstalk and ISI. The third part of the thesis demonstrates two different PMD monitoring schemes. The first one is based on the analysis of frequency-resolved state-of-polarization (SOP) rotation, with signal spectrum broadened by self-phase modulation (SPM) effect. Experimental results show that the use of broadened signal spectrum induced by SPM not only relaxes the filter requirement and reduces the computational complexity, but also improves the estimation accuracy, and extends the monitoring range of the pulsewidth. The second one is based on the delay-tap asynchronous waveform sampling technique. By examining the statistical distribution of the measured scatter plot, unambiguous PMD measurement range up to 50% of signal bit-period is demonstrated. The final part of the thesis focuses on the monitoring of alignment status between the pulse carver and data modulator in an optical system. We again employ the two-tap asynchronous sampling technique to perform such kind of monitoring in RZ-OOK transmission system. Experimental results show that both the misalignment direction and magnitude can be successfully determined. Besides, we propose and experimentally demonstrate the use of off-center optical filtering technique to capture the amount of spectrum broadening induced by the misalignment between the pulse-carver and the data modulator in RZ-DPSK transmission system. The same technique was also applied to monitor the synchronization between the old and the new data in synchronized phase re-modulation (SPRM) system.

  12. Integration of differential wavefront sampling with merit function regression for efficient alignment of three-mirror anastigmat optical system

    NASA Astrophysics Data System (ADS)

    Oh, Eun-Song; Kim, Seonghui; Kim, Yunjong; Lee, Hanshin; Kim, Sug-Whan; Yang, Ho-Soon

    2010-08-01

    We first studied the characteristics of alignment performances of two computer-aided alignment algorithms i.e. merit function regression (MFR) and differential wavefront sampling (DWS). The initial study shows i) that, utilizing damped least square algorithm, MFR offers accurate alignment estimation to the optical systems with non-linear wavefront sensitivity to changes in alignment parameters, but at the expense of neglecting the coupling effects among multiple optical components, and ii) that DWS can estimate the alignment state while taking the inter-element coupling effects into consideration, but at the expense of increased sensitivity to measurement error associated with experiment apparatus. Following the aforementioned study, we report a new improved alignment computation technique benefitted from modified MFR computation incorporating the concept of standard DWS method. The optical system used in this study is a three-mirror anastignmat (TMA) based optical design for the next generation geostationary ocean color instrument (GOCI-II). Using an aspheric primary mirror of 210 mm in diameter, the F/7.3 TMA design offers good imaging performance such as 80% in 4 um in GEE, MTF of 0.65 at 65.02 in Nyquist frequency. The optical system is designed to be packaged into a compact dimension of 0.25m × 0.55m × 1.050m. The trial simulation runs demonstrate that this integrated alignment method show much better alignment estimation accuracies than those of standard MFR and DWS methods, especially when in presence of measurement errors. The underlying concept, computational details and trial simulation results are presented together with implications to potential applications.

  13. Optical characterization of a dual-frequency hybrid aligned nematic liquid crystal cell

    E-print Network

    Jewell, Sharon

    Optical characterization of a dual-frequency hybrid aligned nematic liquid crystal cell S. A aligned nematic (HAN) cell at various frequencies in both the positive and negative dielectric anisotropy polarization in hybrid aligned nematic cells," J. Appl. Phys. 92, (1) 19 (2002) 6. 6. Y.Q. Lu, X. Liang, Y

  14. Design and alignment strategies of 4f systems used in the vectorial optical field generator.

    PubMed

    Han, Wei; Cheng, Wen; Zhan, Qiwen

    2015-03-20

    In this paper, the design and alignment strategies of 4f systems used in the vectorial optical field generator are described in detail. Reflection-type 4f systems were adopted due to limited spacing. Alignment patterns are designed and introduced as alignment tools so that the optical property (degree of freedom) controlled by each specific spatial light modulator section can be visualized and alignment of the 4f systems can be performed using the CCD image sharpness as the metric. In particular, blurring due to diffraction effects is minimized when the 4f system is fully aligned. PMID:25968510

  15. The technique of coital alignment and its relation to female orgasmic response and simultaneous orgasm

    Microsoft Academic Search

    Edward W. Eichel; Joanne De Simone Eichel; Sheldon Kule

    1988-01-01

    To enhance male-female sexual compatibility, principles of physical alignment were formulated to make clitoral contact possible in coitus. The Coital Alignment technique combines (a) the “riding high” variation of the “missionary” coital posture, with (b) genitally focused pres-sure-counterpressure stimulus applied in the coordination of sexual movement. It was hypothesized that the Alignment technique would correlate with high frequency of female

  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. 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.

  18. On liquid crystal diffractive optical elements utilizing inhomogeneous alignment.

    PubMed

    Valyukh, S; Chigrinov, V; Kwok, H S; Arwin, H

    2012-07-01

    Formation of a desired liquid crystal (LC) director distribution by the use of inhomogeneous anchoring and pre-tilt angle for electrically controlled diffractive optical elements (DOE) is studied. Such LC DOE can have high periodicity and diffraction efficiency. At the same time they are free of constructive regularities, e.g. a periodic arrangement of the electrodes or thickness deviations, which have undesired impact on diffractive characteristics of LC DOE of other types. We focus on evaluation of potential functional abilities of LC DOE with inhomogeneous alignment. The reasons causing restriction of the LC DOE diffraction efficiency and periodicity are considered. Approaches for improvement of characteristics of the LC DOE are discussed. PMID:22772219

  19. Active alignment for interferometric techniques onboard the International Space Station

    NASA Astrophysics Data System (ADS)

    Kebbel, Volker; Becker, Joachim; Jueptner, Werner

    2004-08-01

    Different interferometric techniques are required to cover most of the scientific needs in the field of fluid dynamics science in microgravity research. The Fluid Science Laboratory (FSL), currently under upgrade for the Columbus Orbital Facility of the International Space Station (ISS), shall provide Holographic Interferometry, Digital Holography, Electronic Speckle Pattern Interferometry (ESPI) and Shearing Interferometry among other diagnostic tools. On earth, these highly sensitive interferometers are operated in a thermal and mechanical controlled environment. In opposition to the situation on ground the multi-user facility of the FSL has severe constraints for what concerns volume, mass, modularity, operational needs and its environment. This results in a three-dimensional modular drawer structure for the design of the optical-mechanical set-up, where performance limitations must be expected compared to systems on ground. In a rather uncontrolled thermal environment onboard the ISS this leads to misalignment due to thermo-mechanical changes of the Aluminum structure during experiment runs which finally result in interferogram distortions and therefore to significant measurement errors. In this paper we report about a misalignment detection- and active compensation concept developed on the basis of a thermo-mechanical and optical analysis of the set-up. The detection system is based on a simplified Hartmann-Sensor. It is able to separate wave front tilt and curvature errors due to misalignments of the interferometers itself from the effects caused by the experiment. The closed-loop compensation system uses optical components of the set-up driven by piezoelectric actuators. Due to its active approach this concept allows for the real time accessibility of the experimental effects in the framework of "Telescience." Extensive functional tests as well as representative thermal tests show the suitability of the proposed technique to compensate interferogram distortions due to thermal-mechanical deformations. Thus, it is able to ensure interferometric measurements with sub-wavelength accuracy onboard the ISS.

  20. 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.

  1. Medical image processing with optical Fourier techniques

    Microsoft Academic Search

    Pengfei Wu

    2003-01-01

    Medical image processing is demonstrated by using Fourier techniques. Two optical Fourier systems are designed: the first one is a real-time optical processor with spatial filters and the second one is a self-adaptive optical processor with nonlinear optical films of the biomaterial Bacteriorhodopsin. Medical images including mammograms and Pap smears are investigated by using our optical systems. The desired components

  2. Electronic implementation of optical burst switching techniques

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  3. Bit parallel time-aligned WDM optical communications systems

    NASA Astrophysics Data System (ADS)

    Ruiz, Everardo David

    A high-speed parallel bus technology for grid computing and the clustering of supercomputers at distances of up to 50 kilometers is required to exploit parallelism for solution of computationally challenging numerical simulations. Based on the requirements for low intra-byte (or intra data word) time-skew, high bandwidth, and relatively low latency, a time skew free single optical fiber interconnect is desired. This dissertation presents a feasibility study of such a 'pulse shepherded' wavelength division multiplexed link by analyzing correctable time skew and optical noise multiplication in the presence of amplified spontaneous emission and optical fiber nonlinearities. Bit error rate performance as a function of fiber chromatic dispersion and shepherd pulse peak power show that the range of chromatic dispersion which can be accommodated using this technique is roughly -0.05 to +0.05 ps/(nm-km) using a shepherd pulse with peak power of roughly 20 to 30 milliwatts in a dispersion flattened step index optical fiber with attenuation of 0.2 dB/km, effective area of 55 mum2, and nonlinear coefficient n2 of 3.2 x 10-20 m 2/W. It is also shown that the pulse shepherding technique when applied to ultra long haul optical communications systems limited by Gordon-Haus timing jitter extends the system length. Simulation results suggest that the total system length can be increased by a factor of roughly 2.2.

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

    NASA Astrophysics Data System (ADS)

    Haag, Sebastian; Schranner, Matthias; Müller, Tobias; Zontar, Daniel; Schlette, Christian; Losch, Daniel; Brecher, Christian; Roßmann, Jürgen

    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.

  5. 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 ?m 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 ?m and 150 ?m for the Tx and 50 ?m and over 200 ?m 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

  6. Optical flow techniques in biomimetic UAV vision

    Microsoft Academic Search

    Fouad F. Khalil; Pierre Payeur

    2005-01-01

    Optical flow techniques using grayscale image sequences are known to provide powerful solutions for motion estimation and shape reconstruction applications. In this paper, recent advances in optical flow computation from color image sequences are compared and refined to provide alternative optical flow computation techniques for biomimetic vision and control systems. Experimentation is performed in the specific context of flying insect-inspired

  7. Inverse scattering technique for resonator alignment - Dependence of the accuracy on the finesse and mirror alignment

    Microsoft Academic Search

    S. Solimeno; Fabrizio Barone; Luciano di Fiore; Leopoldo Milano; Innocenzo M. Pinto

    1989-01-01

    The sensitivity of a GW interferometric antenna depends critically on the alignment of the Fabry-Perot (F-P) resonators placed in the two atms of a Michelson interferometer. To this end a servo system can be used for controlling the position and the orientation of the end mirrors by using error signals obtained by analyzing the transverse distribution of the beams reflected

  8. 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

  9. 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.

  10. Constant current corona charging as a technique for poling organic nonlinear optical thin films and the effect of ambient gas

    Microsoft Academic Search

    Phat T. Dao; David J. Williams; William P. McKenna; Kim Goppert-Berarducci

    1993-01-01

    Poling, which involves the alignment of nonlinear optical (NLO) dipolar molecules in the direction of the applied electric field, was carried out using constant current charging, a recently developed corona charging technique. Using this technique, the sample surface voltage buildup, and hence the efficiency of the dipole alignment, can be monitored during the poling process. In addition, it will be

  11. Development of Novel Data Compression Technique for Accelerate DNA Sequence Alignment Based on Smith

    Microsoft Academic Search

    S. A. M. Al Junid; M. A. Haron; Z. Abd Majid; A. K. Halim; F. N. Osman; H. Hashim

    2009-01-01

    This paper presents the development of high performance accelerating technique for DNA sequences alignment. The scope of the paper focuses on speed optimization and memory reduction of the existing technique on initialization module. The novel development of the optimization using data compression technique for accelerates the Smith-Waterman (SW) algorithm has been revealed through this paper. This technique has been implemented

  12. 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.

  13. 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.

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

    PubMed Central

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

    2012-01-01

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

  15. Asynchronous optical performance monitor techniques for DWDM optical networks

    Microsoft Academic Search

    A. L. J. Teixeira; P. S. Andre; M. Lima; J. F. da Rocha; J. L. Pinto

    2002-01-01

    The current techniques of optical system performance monitoring are described and characterized. From the available techniques, we focus our attention on the asynchronous Q method, and it is described and evaluated for several working conditions. This technique allows optical performance monitoring without synchronization, thus allowing the performance monitor to work at a much lower ratio and without performing clock recovery\\/synchronization,

  16. Novel techniques for optical performance monitoring in optical systems

    Microsoft Academic Search

    Chun-Kit Chan; Yuen-Ching Ku; Lian-Kuan Chen

    2006-01-01

    In this paper, different kinds of optical performance monitoring (OPM) techniques, in particular the optical signal-to-noise ratio (OSNR) monitoring and chromatic dispersion (CD) monitoring, are reviewed. Then recent trend of multiple-parameter simultaneous monitoring is examined.

  17. Single actuator alignment control for improved frequency stability of a cavity-based optical frequency reference.

    PubMed

    Dawkins, Samuel T; Luiten, André N

    2008-03-20

    We demonstrate a method of controlling the alignment of a laser beam to a Fabry-Perot resonator through synchronous detection of the misalignment arising from modulating the orientation of a single beam-steering mirror. The horizontal and vertical tilt of the mirror are modulated in quadrature to drive a circular motion of the beam orientation. A corresponding modulation of the intensity of the optical field circulating in the cavity is measured at either the reflected or transmitted port and demodulated synchronously to derive two error signals to indicate the vertical and horizontal misalignment. These signals are fed back to the beam-steering mirror to suppress fluctuations below 30 Hz. This method avoids the complexity of monitoring off-axis cavity modes and is particularly effective in the case where unwanted pointing fluctuations are introduced by one or two elements in the optical setup. We have applied the technique to two Fabry-Perot resonators in use as precision frequency references, delivering a result of 10 dB suppression of alignment fluctuations at 1 Hz and an improvement in frequency stability by up to a factor of 4. PMID:18709070

  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. Automatic alignment of a Kirkpatrick-Baez active optic by use of a soft-x-ray Hartmann wavefront sensor

    NASA Astrophysics Data System (ADS)

    Mercère, Pascal; Idir, Mourad; Moreno, Thierry; Cauchon, Gilles; Dovillaire, Guillaume; Levecq, Xavier; Couvet, Laurent; Bucourt, Samuel; Zeitoun, Philippe

    2006-01-01

    We present what we believe to be the first automatic alignment of a synchrotron beamline by the Hartmann technique. Experiments were performed, in the soft-x-ray range (E=3 keV, lambda=0.414 nm), by using a four-actuator Kirkpatrick-Baez (KB) active optic. A system imaging the KB focal spot and a soft-x-ray Hartmann wavefront sensor were used alternatively to control the KB optic. The beam corrected with the help of the imaging system was used to calibrate the wavefront sensor. With both closed loops, we focused the beam into a 6.8 µm×9 µm FWHM focal spot.

  20. A novel fiber alignment shift measurement and correction technique in laser-welded laser module packaging

    Microsoft Academic Search

    Yi-Cheng Hsu; Ying-Chien Tsai; Yeh-Lin Ho; Maw-Tyan Sheen; Jao-Hwa Kuang; Wood-Hi Cheng

    2005-01-01

    A novel measurement and correction technique employing an ultra-high-precision laser displacement meter (LDM) with a 20-nm resolution to probe the postweld-shift (PWS)-induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by the PWS in laser-welded laser module packaging can be quantitatively determined by four

  1. Surface-tension-driven multi-chip self-alignment techniques for heterogeneous 3D integration

    Microsoft Academic Search

    Fengda Sun; Yusuf Leblebici; Thomas Brunschwiler

    2011-01-01

    Surface-tension-driven self-alignment (SA) is a promising technique for heterogeneous die-level stacking. Multiple dies can be manipulated in parallel at minimal cost. A defined amount of water present between the die and a carrier substrate is used to align the components. The minimization of the water-air interface is the driving force. Most studies were performed with a completely wetted chip surface

  2. Optical alignment of the JWST ISIM to the OTE simulator (OSIM): current concept and design studies

    NASA Astrophysics Data System (ADS)

    Frey, Bradley J.; Davila, Pamela S.; Hagopian, John G.; Marsh, James M.; Ohl, Raymond G.; Wilson, Mark E.; Young, Philip J.

    2007-09-01

    The James Webb Space Telescope's (JWST) Integrated Science Instrument Module (ISIM) contains the observatory's four science instruments and their support subsystems. During alignment and test of the integrated ISIM at NASA's Goddard Space Flight Center (GSFC), the Optical telescope element SIMulator (OSIM) will be used to optically stimulate the science instruments to verify their operation and performance. In this paper we present the design of two cryogenic alignment fixtures that will be used to align the OSIM to the ISIM during testing at GSFC. These fixtures, the Master Alignment Target Fixture (MATF) and the ISIM Alignment Target Fixture (IATF), will provide continuous, six degree of freedom feedback to OSIM during initial ambient alignment as well as during cryogenic vacuum testing. These fixtures will allow us to position the OSIM and detect OSIM-ISIM absolute alignment to better than 180 microns in translation and 540 micro-radians in rotation. We will provide a brief overview of the OSIM system and we will also discuss the relevance of these fixtures in the context of the overall ISIM alignment and test plan.

  3. 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.

  4. Optical ground support equipment for the alignment of JWST-NIRSpec

    Microsoft Academic Search

    J. Schmoll; A. G. Basden; D. G. Bramall; P. Clark; R. E. Cole; G. N. Dodsworth; S. J. Goodsell; A. McCalden; G. J. Murray; R. M. Myers; R. M. Sharples; J. A. Tandy; P. Thomas

    2008-01-01

    The alignment of the JWST NIRSpec spectrograph will use a customised set of optical light sources, imagers and wavefront sensors, which form part of the Optical Ground Support Equipment (OGSE). This has been developed by the Mullard Space Science Laboratory (MSSL) and the Centre for Advanced Instrumentation (CfAI) to be used at the Astrium GmbH, Ottobrunn (Germany) during NIRSpec integration.

  5. 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."

  6. High precision survey and alignment techniques in accelerator construction

    Microsoft Academic Search

    J Gervaise

    1974-01-01

    Basic concepts of precision surveying are briefly reviewed, and an historical account is given of instruments and techniques used during the construction of the Proton Synchrotron (1954-59), the Intersecting Storage Rings (1966-71), and the Super Proton Synchrotron (1971). A nylon wire device, distinvar, invar wire and tape, and recent automation of the gyrotheodolite and distinvar as well as auxiliary equipment

  7. Transparent silicon strip sensors for the optical alignment of particle detector systems

    Microsoft Academic Search

    W. Blum; H. Kroha; P. Widmann

    1996-01-01

    Modern large-area precision tracking detectors require increasing accuracy for the alignment of their components. A novel multi-point laser alignment system has been developed for such applications. The position of detector components with respect to reference laser beams is monitored by semi-transparent optical position sensors which work on the principle of silicon strip photodiodes. Two types of custom designed transparent strip

  8. High precision survey and alignment techniques in accelerator construction

    E-print Network

    Gervaise, J

    1974-01-01

    Basic concepts of precision surveying are briefly reviewed, and an historical account is given of instruments and techniques used during the construction of the Proton Synchrotron (1954-59), the Intersecting Storage Rings (1966-71), and the Super Proton Synchrotron (1971). A nylon wire device, distinvar, invar wire and tape, and recent automation of the gyrotheodolite and distinvar as well as auxiliary equipment (polyurethane jacks, Centipede) are discussed in detail. The paper ends summarizing the present accuracy in accelerator metrology, giving an outlook of possible improvement, and some aspects of staffing for the CERN Survey Group. (0 refs).

  9. X-ray beam metrology and x-ray optic alignment by Hartmann wavefront sensing

    NASA Astrophysics Data System (ADS)

    Mercere, Pascal; Bucourt, Samuel; Cauchon, Gilles; Douillet, Denis; Dovillaire, Guillaume; Goldberg, Kenneth A.; Idir, Mourad; Levecq, Xavier; Moreno, Thierry; Naulleau, Patrick P.; Rekawa, Senajith; Zeitoun, Philippe

    2005-08-01

    In 2002, first experiments at the Advanced Light Source (ALS) at Berkeley, allowed us to test a first prototype of EUV Hartmann wave-front sensor. Wave-front measurements were performed over a wide wavelength range from 7 to 25 nm. Accuracy of the sensor was proved to be better than ?EUV/120 rms (?EUV = 13.4 nm, about 0.1 nm accuracy) with sensitivity exceeding ?EUV/600 rms, demonstrating the high metrological performances of this system. At the Swiss Light Source (SLS), we succeeded recently in the automatic alignment of a synchrotron beamline by Hartmann technique. Experiments were performed, in the hard X-ray range (E = 3 keV, ? = 0.414 nm), using a 4-actuators Kirkpatrick-Baez (KB) active optic. An imaging system of the KB focal spot and a hard X-ray Hartmann wave-front sensor were used alternatively to control the KB. The imaging system used a genetic algorithm to achieve the highest energy in the smallest spot size, while the wave-front sensor used the KB influence functions to achieve the smallest phase distortions in the incoming beam. The corrected beam achieved with help of the imaging system was used to calibrate the wave-front sensor. With both closed loops, we focused the beam into a 6.8x9 ?m2 FWHM focal spot. These results are limited by the optical quality of the imaging system.

  10. 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.

  11. Tear film measurement by optical reflectometry technique

    PubMed Central

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

    2014-01-01

    Abstract. Evaluation of tear film is performed by an optical reflectometer system with alignment guided by a galvanometer scanner. The reflectometer system utilizes optical fibers to deliver illumination light to the tear film and collect the film reflectance as a function of wavelength. Film thickness is determined by best fitting the reflectance-wavelength curve. The spectral reflectance acquisition time is 15 ms, fast enough for detecting film thickness changes. Fast beam alignment of 1 s is achieved by the galvanometer scanner. The reflectometer was first used to evaluate artificial tear film on a model eye with and without a contact lens. The film thickness and thinning rate have been successfully quantified with the minimum measured thickness of about 0.3 ?m. 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 ?m 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

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

    SciTech Connect

    Hurst, P.; Grasz, E.

    1998-05-12

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

  13. 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.

  14. 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.

  15. Noninvasive optical diagnostic techniques for heterogeneous plasma

    Microsoft Academic Search

    A. L. Anisimov; A. V. Bul’ba; L. A. Luizova; A. D. Khakhaev; A. S. Shtykov

    2006-01-01

    Optical techniques that cannot cause any perturbation in plasma are considered for the diagnostics of inhomogeneous plasmas\\u000a (including dust plasma). Versions of experimental data acquisition and processing devices pertinent to optical emission spectroscopy\\u000a of inhomogeneous plasma, in particular, a rational cooperative processing algorithm that allows the stability of results against\\u000a experimental noise to be increased by excluding instrumental disturbance and

  16. A new patterning process concept for large-area transistor circuit fabrication without using an optical mask aligner

    Microsoft Academic Search

    Yoshiro Mikami; Yoshiharu Nagae; Yuji Mori; Kazuhiro Kuwabara; Takeshi Saito; H. Hayama; H. Asada; Y. Akimoto; M. Kobayashi; S. Okazaki; K. Asaka; H. Matsui; K. Nakamura; E. Kaneko

    1994-01-01

    A new concept to produce large thin film transistor liquid crystal displays (TFT-LCD's) without using an optical mask aligner is proposed which emphasizes patterning technology. Some experimental thin film transistors (TFT's) are fabricated according to the concept and operated like conventional transistors fabricated by using an optical mask aligner. The concept includes improvement of printing technology and development of a

  17. Ultrasensitive Absorption Spectroscopy with a High-Finesse Optical Cavity and Off-Axis Alignment

    Microsoft Academic Search

    Joshua B. Paul; Larry Lapson; James G. Anderson

    2001-01-01

    A simple and easy to use method that allows high-finesse optical cavities to be used as absorption cells for spectroscopic purposes is presented. This method introduces a single-mode continuous-wave laser into the cavity by use of an off-axis cavity alignment geometry to eliminate systematically the resonances commonly associated with optical cavities, while preserving the absorption signal amplifying properties of such

  18. Method for angular alignment of birefringent fibers in fiber-optic pressure\\/strain measurement

    Microsoft Academic Search

    Andrzej W. Domanski; T. R. Wolinksi; Wojtek J. Bock

    1992-01-01

    A simple method for angular alignment of principal birefringence axes of a highly birefringent (HB) polarization-maintaining (PM) optical fiber is presented. The method is based on longitudinal strain-induced cross-coupling phenomena which occur in HB fibers and it can be straightforwardly applied to construct a fiber-optic pressure or strain sensor independent of disturbing thermal effects. The method is also particularly suitable

  19. Constellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation

    E-print Network

    Constellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation. ABSTRACT The Constellation-X mission will perform X-Ray science with improvements in energy resolution and effective area over its predecessor missions. The primary instrument on each of the four Constellation

  20. Propagation of partially polarized Gaussian Schell-model beams through aligned and misaligned optical systems

    Microsoft Academic Search

    Di Ge; Yang-Jian Cai; Qiang Lin

    2005-01-01

    By use of a tensor method, the transform formulae for the beam coherence-polarization matrix of the partially polarized Gaussian Schell-model (GSM) beams through aligned and misaligned optical systems are derived. As an example, the propagation properties of the partially polarized GSM beam passing through a misaligned thin lens are illustrated numerically and discussed in detail. The derived formulae provide a

  1. Nonlinear optical techniques for plasma diagnostics

    Microsoft Academic Search

    V. N. Ochkin; S. Y. Savinov; S. N. Tskhai; U. Czarnetzki; V. S. von der Gathen; H. F. Dobele

    1998-01-01

    The application of various nonlinear optical laser spectroscopic techniques to plasma diagnostics are reported. The techniques discussed in this paper are two-photon laser induced fluorescence spectroscopy, double-resonant four-wave mixing, coherent anti-Stokes Raman-scattering (CARS), and a combination of emission spectroscopy and CARS. They are applied to measurements of atomic hydrogen densities, molecular temperature, chemical composition, electric field distributions, and vibrational population

  2. 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.

  3. 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.

  4. Measuring the cryogenic optical alignment between the telescope element and the instruments module of the James Webb Space Telescope

    NASA Astrophysics Data System (ADS)

    Whitman, Tony; Olczak, Eugene

    2011-09-01

    The alignment between the Aft Optical Subsystem (AOS) and the Integrated Science Instruments Module (ISIM) is non-adjustable in orbit, so the alignment must be carefully verified in a cryogenic vacuum environment prior to launch. Optical point source locations calibrated by optical metrology instruments are imaged through the AOS onto the Science Instruments to determine focal, lateral, and clock angle alignment. The pupil image of the AOS is overlaid onto the pupil image of the NIRCam to determine the tip and tilt alignment. In addition, an image from fiducial lights at the Primary Mirror checks the pupil alignment between the telescope entrance pupil, the telescope pupil mask, and the NIRCam aperture stop. The image positions are combined to determine the relative alignment between the Optical Telescope Element (OTE) and the ISIM in all six degrees of freedom with corresponding alignment uncertainties. Uncertainties in the position of focused images of the test sources and images from the pupils are derived from sensitivities of an optical model of the system and the Science Instrument sensing capability. Additional uncertainty in the pupil alignment measurement is due to uncertainty in the analytical removal of gravity effects that simulate the on-orbit alignment environment.

  5. Double Zernike polynomial and its application in optical alignment

    NASA Astrophysics Data System (ADS)

    Tsao, Ming-Sen; Liang, Chao-Wen

    2013-09-01

    Most of the practical optical systems have circular shape lens pupil and rectangular shape image field. This paper proposes a four dimensional polynomial to describe the full-field wavefront with orthogonal polynomials set in both circular pupil and rectangular field. The basic functions of both the pupil wavefront and the field wavefront are Zernike circle polynomials, multiplying each other to a four dimensional double Zernike polynomial (DZP) function. The double Zernike polynomial coefficients of the full-field wavefront represent the global optical aberration of the image system. The misalignment perturbation changes the corresponding least squares fitted DZP coefficients. The changed DZP coefficients shows both linear and nonlinear response to the misalignment status when the misalignment is large. The Tri-Mirror Anastigmatic Telescope is used as one of the implemented example showing the changed DZP due to perturbation.

  6. 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.

  7. Stabilization of laser beam alignment to an optical resonator by heterodyne detection of off-axis modes.

    PubMed

    Sampas, N M; Anderson, D Z

    1990-01-20

    We demonstrate a method for real time alignment of a Gaussian beam to an optical resonator. While thefrequency of a source laser is stabilized to a fundamental cavity mode resonance, phase modulation sidebands are applied at the off-axis mode frequencies. Asymmetrical transmission of the sideband at the frequency of each off-axis mode produces amplitude modulated optical signals and indicates the extent of the misalignments. Phase sensitive detection of these optical signals provides the error signals which are minimized by a control system that steers the input beam. In this way, optimum coupling of an injected source beam can be maintained to the fundamental mode of the resonator. This active alignment technique has demonstrated a sensitivity to tilts of 0.1 nrad/ radicalHz and to lateral beam displacements of 0.08 nm/ radicalHz in the ~1-Hz-1-kHz frequency range. These values correspond to 2 parts in 10(7) radicalHz for both the far-field divergence angle and the beam waist size. Such performance is within a factor of 2 of the shot noise limitation of the error signal measurement for a detected power of 160 microW. PMID:20556119

  8. A grid-alignment finite element technique for incompressible multicomponent flows

    NASA Astrophysics Data System (ADS)

    Bejanov, B.; Guermond, J. L.; Minev, P. D.

    2008-06-01

    We present a numerical method for solving the multicomponent incompressible Navier-Stokes equations. The methods employs a moving grid technique and a projection scheme based on low-order Crouzeix-Raviart and P1 finite elements. The computational grid is aligned with the fluid interface at each time step to keep the interpolation order optimal. The connectivity of the grid is fixed during the entire time simulation to ensure efficient assembling and parallelization. The method is tested on several examples.

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

    DOEpatents

    Johnson, Steve A. (Tracy, CA); Shannon, Robert R. (Tucson, AZ)

    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.

  10. 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.

  11. Redesign of the image processing techniques used for the alignment of the LMJ beams transportation section

    NASA Astrophysics Data System (ADS)

    Hilsz, Laurent; Benoit, Jean-Christophe; Poutriquet, Florence; Bach, Olivier; Nicaise, Frédéric; Adolf, Alain

    2010-08-01

    The Megajoule laser (LMJ) project was launched in 1995 by the French Atomic Energy Commission and is aimed at developing a facility to achieve inertial confinement fusion. The LMJ architecture is based on 176 laser beamlines. To provide these 176 high-powered beams when required for subsequent operations, one of the main issues consists of aligning reliably the laser Transportation Section (TS) not only during the normal operation of the installation but also during the power rising of each laser chain, its initial alignment and after major maintenance. They also must be compatible with the fact that the entire installation should be maintained by a limited staff. Consequently, the goals of the techniques involved in this processing design are essentially robust detection and identification of the relevant items of information present in images, but also the reduction of the number of parameters accessible to the operators. This paper provides a general overview of how the TS is aligned before focusing on the image processing techniques developed to identify and measure the beam centering, since the major difference between the LIL and LMJ TS is the type of centering detector. These techniques have been developed and tested thoroughly against sets of up to 57 images representing both nominal and extreme conditions acquired during recent experiments on the Laser Integration Line (LIL). This facility is fully consistent with the LMJ requirements, a complete laser chain with 4 beamlines. After presenting the basic design principles, we focus on the performances as demonstrated and measured.

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  13. Automatic alignment of a Kirkpatrick-Baez active optic by use of a soft-x-ray Hartmann wavefront sensor.

    PubMed

    Mercère, Pascal; Idir, Mourad; Moreno, Thierry; Cauchon, Gilles; Dovillaire, Guillaume; Levecq, Xavier; Couvet, Laurent; Bucourt, Samuel; Zeitoun, Philippe

    2006-01-15

    We present what we believe to be the first automatic alignment of a synchrotron beamline by the Hartmann technique. Experiments were performed, in the soft-x-ray range (E=3 keV, lambda=0.414 nm), by using a four-actuator Kirkpatrick-Baez (KB) active optic. A system imaging the KB focal spot and a soft-x-ray Hartmann wavefront sensor were used alternatively to control the KB optic. The beam corrected with the help of the imaging system was used to calibrate the wavefront sensor. With both closed loops, we focused the beam into a 6.8 microm x 9 microm FWHM focal spot. PMID:16441029

  14. 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

  15. Optical anisotropy and liquid-crystal alignment properties of rubbed polyimide layers

    E-print Network

    Exeter, University of

    guided mode technique. Results indicate that the effective optical anisotropy of the polyimide layers may polyimide layers and the rubbing process is investigated using the recently developed polarization-conversion extensively in this type of surface study [8­10]. RAS is an optical spectroscopic technique used to measure

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  17. Instrumentation techniques for the automatic alignment of large, tiled fixed matrix displays

    NASA Astrophysics Data System (ADS)

    Marshall, P.

    2005-09-01

    Modern display systems for simulation applications, be they for aviation, naval, automotive or even large visualization and educational/entertainment systems, are all using a tiled approach to achieve high resolution and large fields of view. The aviation applications are particularly demanding, as the fidelity of the matching and blending between the tiled segments needs to be of a high order for flight simulation. This paper looks at the measurement instrumentation techniques that can be used in order to align such large and critical systems. Ultimately such measurement systems allow a fully automatic alignment of color, color uniformity, blending between tiles and gamma to be made. While front- or rear-projected systems are the main references for the analysis, much, if not most, of the principles outlined can apply to tiled large flat panel displays as well.

  18. Self-aligning optical particle sizer for the monitoring of particle growth processes in industrial plants

    NASA Astrophysics Data System (ADS)

    Bassini, A.; Musazzi, S.; Paganini, E.; Perini, U.; Ferri, F.

    1998-06-01

    We describe a diffraction based optical particle sizer to be used on-line in an industrial plant for monitoring the growth process of polystyrene beads in the range (400 ?m-4 mm). The instrument has been designed to perform elastic light scattering measurements at very small angles (from 8×10-5 to 8×10-3 rad) and is provided with an active servo system that controls the beam alignment during operations.

  19. 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.

  20. 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.

  1. Optical Sorting and Alignment of Small Objects in Fluids. Sadik Esener, Mark M. Wang, and Osman Kibar

    E-print Network

    Esener, Sadik C.

    if properties of a cell can be probed in a non-invasive, all-optical fashion. In this paper, a novel, non by an optical beam to study the physical properties of live cells in suspension. Analysis is performedOptical Sorting and Alignment of Small Objects in Fluids. Sadik Esener, Mark M. Wang, and Osman

  2. 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.

  3. Using a two-stage optimization strategy for the active alignment of multifiber optical devices

    NASA Astrophysics Data System (ADS)

    Lin, Tsung Yin

    2010-05-01

    The alignment of optical components is a key factor when designing and manufacturing multifiber optical systems. This problem can be treated as a standard multiobjective optimization problem and solved by numerical optimization methodologies. The core diameter of a single-mode fiber is ~9 ?m, and any slight misalignment during manufacturing will cause signification optical losses in connections. Previous studies have shown that the currently used alignment methods for multifiber devices can increase the optical power summation of all fibers, but the results are not very accurate. This study first compares different numerical optimization methodologies that can be used to find the ideal connection position. Two indices are used to judge the performances of different methods: the required time and the optical power. Next, a two-stage optimization strategy is proposed to obtain a fast and accurate result. In the first stage, the Nelder-Mead simplex method is used to move toward the optimum position quickly. In the second stage, the steepest descent method with polynomial interpolation is applied to improve the accuracy because of the stability of the method.

  4. Technique for measuring the optical phase transfer function

    Microsoft Academic Search

    D. J. Krause; J. C. Cartledge

    2004-01-01

    A technique for directly measuring the optical phase transfer function of optoelectronic devices is presented. The change in the phase of an optical signal is obtained as a function of a time-varying electrical stimulus for electrical-optical devices, or optical stimulus for optical-optical devices. The technique is demonstrated by considering the phase of the output signal from an electroabsorption modulator as

  5. 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.

  6. Optical and structural properties of amorphous SexTe100-x aligned nanorods

    PubMed Central

    2013-01-01

    In the present work, we report studies on optical and structural phenomenon in as-deposited thin films composed of aligned nanorods of amorphous SexTe100-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. PMID:24321447

  7. Study cell invasion by optical techniques

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  8. Electro-optic techniques for VLSI interconnect

    NASA Astrophysics Data System (ADS)

    Neff, J. A.

    1985-03-01

    A major limitation to achieving significant speed increases in very large scale integration (VLSI) lies in the metallic interconnects. They are costly not only from the charge transport standpoint but also from capacitive loading effects. The Defense Advanced Research Projects Agency, in pursuit of the fifth generation supercomputer, is investigating alternatives to the VLSI metallic interconnects, especially the use of optical techniques to transport the information either inter or intrachip. As the on chip performance of VLSI continues to improve via the scale down of the logic elements, the problems associated with transferring data off and onto the chip become more severe. The use of optical carriers to transfer the information within the computer is very appealing from several viewpoints. Besides the potential for gigabit propagation rates, the conversion from electronics to optics conveniently provides a decoupling of the various circuits from one another. Significant gains will also be realized in reducing cross talk between the metallic routings, and the interconnects need no longer be constrained to the plane of a thin film on the VLSI chip. In addition, optics can offer an increased programming flexibility for restructuring the interconnect network.

  9. Optical replication techniques for image slicers

    E-print Network

    J. Schmoll; D. J. Robertson; C. M. Dubbeldam; J. Yao; F. Bortoletto; L. Pina; R. Hudec; E. Prieto; C. Norrie; S. Ramsay-Howat; W. Preuss

    2005-09-29

    The Smart Focal Planes (SmartFP) activity is a European Joint Research Activity funded to develop novel optical technologies for future large telescope instrumentation. In this paper, we will discuss the image slicer developments being carried out as part of this initiative. Image slicing technique s have many applications in the plans for instrumentation on Extremely Large Telescopes and will be central to the delivery of the science case. A study of a virtual "multi-object multi-ifu spectrograph and imager" (MOMSI) for a hypothetical OWL-class telescope reveals the need for focal plane splitting, deployable imagers and very small beam steering elements like deployable IFUs. The image slicer workpackage, lead from Durham University in collaboration with LFM Bremen, TNO Delft, UKATC Edinburgh, CRAL Lyon, LAM Marseille, Padua University and REFLEX Prague, is evaluating technologies for manufacturing micro optics in large numbers to enable multi-object integral field spectroscopy.

  10. Simplified optical coupling and alignment scheme for cost effective 10 Gbit\\/s TOSA modules based on edge emitters hermetically packaged in micro-machined silicon structures

    Microsoft Academic Search

    M. Winter; R. Hauffe; A. Kilian

    2005-01-01

    Packaging of opto-electronic components - as opposed to semiconductor or electronics ICs - requires not only hermeticity but also proper alignment of optical elements. Due to tolerances in the range of a few microns at best, conventional technology usually requires laborious active alignment steps to couple light efficiently into the fiber. A simple optical coupling and alignment scheme is presented

  11. Optically stimulated luminescence techniques in retrospective dosimetry

    NASA Astrophysics Data System (ADS)

    Bøtter-Jensen, L.; Murray, A. S.

    2001-06-01

    Optically stimulated luminescence signals from natural quartz and feldspar are now used routinely in dating geological and archaeological materials. More recently they have also been employed in accident dosimetry, i.e. the retrospective assessment of doses received as a result of a nuclear accident. Since 1990 the exploration of this wide variety of applications has driven an intensive investigation and development programme at Risø, in measurement facilities and techniques. This paper reviews some of the outcomes of this programme, including (i) optimisation of stimulation and emission windows, and detection sensitivity, (ii) experience with various stimulation light sources, including filtered incandescent lamps (420-550 nm) and high intensity light emitting diodes (470 nm) and laser diodes (830-850 nm). We also discuss recently developed high-precision single-aliquot measurement protocols. These offer exciting possibilities in dating and accident dosimetry, and are already leading to new demands on measurement techniques and facilities.

  12. Magneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading magnetic flux

    NASA Astrophysics Data System (ADS)

    Shaver, J.; Crooker, S. A.; Fagan, J. A.; Hobbie, E. K.; Ubrig, N.; Portugall, O.; Perebeinos, V.; Avouris, Ph.; Kono, J.

    2008-08-01

    We have investigated excitons in highly aligned single-walled carbon nanotubes (SWCNTs) through optical spectroscopy at low temperatures down to 1.5 K and high magnetic fields (B) up to 55 T. SWCNT/polyacrylic acid films were stretched, giving SWCNTs that are highly aligned along the direction of stretch (n?) . Utilizing two well-defined measurement geometries, n??B and n??B , we provide unambiguous evidence that the photoluminescence energy and intensity are only sensitive to the B -component parallel to the tube axis. A theoretical model of one-dimensional magnetoexcitons, based on exchange-split “bright” and “dark” exciton bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfully reproduces our observations and allows determination of the splitting between the two bands as ˜4.8meV for (6,5) SWCNTs.

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

    PubMed

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

    2006-01-14

    The influence of the charge separation during the trans-cis conformational change on the surface of azobenzene 6Az10PVA monolayer on the polar liquid-crystal monolayer film, such as 4-n-pentyl-4'-cyanobiphenyl(5CB), is investigated. The effective anchoring energy (in the Rapini-Papolar form) is phenomenologically described in the framework of the molecular model, which takes into account the interaction between the surface polarization and surface electric field, for number of conformational states of the boundary surface. It is shown, using the experimental data for the voltage across the 6Az10PVA+5CB film, provided by the surface-potential technique, that the charge separation during the conformational changing, caused by the UV irradiation, may lead to changing of the surface alignment of liquid-crystalline molecules. The influence of the photoisomerization process on the orientational order parameter S2(t) using the optical polarized absorption measurement is also investigated. PMID:16422620

  14. 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.

  15. 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 ?m 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 ?m, 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.

  16. Self-Calibration Technique for 3-point Intrinsic Alignment Correlations in Weak Lensing Surveys

    E-print Network

    M. A. Troxel; Mustapha Ishak

    2011-12-23

    The intrinsic alignment (IA) of galaxies has been shown to be a significant barrier to precision cosmic shear measurements. (Zhang, 2010, ApJ, 720, 1090) proposed a self-calibration technique for the power spectrum to calculate the induced gravitational shear-galaxy intrinsic ellipticity correlation (GI) in weak lensing surveys with photo-z measurements which is expected to reduce the IA contamination by at least a factor of 10 for currently proposed surveys. We confirm this using an independent analysis and propose an expansion to the self-calibration technique for the bispectrum in order to calculate the dominant IA gravitational shear-gravitational shear-intrinsic ellipticity correlation (GGI) contamination. We first establish an estimator to extract the galaxy density-density-intrinsic ellipticity (ggI) correlation from the galaxy ellipticity-density-density measurement for a photo-z galaxy sample. We then develop a relation between the GGI and ggI bispectra, which allows for the estimation and removal of the GGI correlation from the cosmic shear signal. We explore the performance of these two methods, compare to other possible sources of error, and show that the GGI self-calibration technique can potentially reduce the IA contamination by up to a factor of 5-10 for all but a few bin choices, thus reducing the contamination to the percent level. The self-calibration is less accurate for adjacent bins, but still allows for a factor of three reduction in the IA contamination. The self-calibration thus promises to be an efficient technique to isolate both the 2-point and 3-point intrinsic alignment signals from weak lensing measurements.

  17. Pupil alignment reference (PAR) for the Mid-Infrared Instrument (MIRI) for optical alignment and verification on the Integrated Science Instrument Module (ISIM) in James Webb Space Telescope (JWST)

    Microsoft Academic Search

    Cagatay Aymergen; Phillip Driggers; Raymond Ohl IV; Ray Lundquist; Pam Davila; Brent Bos; Scott Antonille; David Kubalak; Suong Le; Leonard Hanssen; Vilem Mikula; Claef Hakun; Corina Guishard; Jeffrey Guzek; Joe Connelly; Joseph McMann

    2009-01-01

    The Mid Infrared Instrument (MIRI), one of the four instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST), supports all of the science objectives of the observatory. MIRI optical alignment is an important step in the verification process, directly affecting mission success. The MIRI optical alignment is verified on the ground at the integrated

  18. TiO? 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 TiO? 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

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

    Microsoft Academic Search

    S. A. Johnson; R. R. Shannon

    1985-01-01

    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.

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

    Microsoft Academic Search

    Steve A. Johnson; Robert R. Shannon

    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.

  1. 39.2 / B. L. Zhang 39.2: Optical Analysis of Vertical Aligned Mode on Color Filter

    E-print Network

    39.2 / B. L. Zhang 39.2: Optical Analysis of Vertical Aligned Mode on Color Filter Liquid of Science and Technology, Clear Water Bay, Hong Kong Y. C. Chen Himax Display, No.12, Nanke 8th Road, Tainan on color filter liquid-crystal-on-silicon microdisplay. Three-dimensional optical analyses were performed

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

    PubMed

    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

  3. Fabrication of optical mosaic gratings: a self-referencing alignment method.

    PubMed

    Shi, Lei; Zeng, Lijiang

    2011-05-01

    We propose and demonstrate a self-referencing alignment technique to conveniently enlarge fabricated grating area. The latent image gratings are used as the reference objects to align (adjust and lock) the attitude and position of the substrate relative to the exposure beams between and during consecutive exposures. The adjustment system and the fringe-locking system are combined into the exposure system, eliminating the drift errors between them and making the whole system low-cost and compact. For the fabricated 1 × 4 mosaics of 50 × (30 + 30 + 30 + 30) mm(2) area and 1 × 2 mosaics of 90 × (80 + 80) mm(2) area, the typical peak-valley -1st-order wavefront errors measured by a 100-mm-diameter interferometer are not more than 0.06 ? and 0.09 ?, respectively. PMID:21643151

  4. Optical replication techniques for image slicers

    NASA Astrophysics Data System (ADS)

    Schmoll, J.; Robertson, D. J.; Dubbeldam, C. M.; Bortoletto, F.; Pina, L.; Hudec, R.; Prieto, E.; Norrie, C.; Ramsay-Howat, S.

    2006-06-01

    The smart focal planes (SmartFP) activity is an European Joint Research Activity funded to develop novel optical technologies for future large telescope instrumentation [Cunningham C.R., et al., 2004. SPIE 5382, 718-726]. In this paper, we will discuss the image slicer developments being carried out as part of this initiative. Image slicing techniques have many applications in the plans for instrumentation on extremely large telescopes and will be central to the delivery of the science case. A study of a virtual multi-object multi-ifu spectrograph and imager (MOMSI) for a hypothetical OWL-class telescope reveals the need for focal plane splitting, deployable imagers and very small beam steering elements like deployable IFUs. The image slicer workpackage, lead from Durham University in collaboration with LFM Bremen, TNO Delft, UKATC Edinburgh, CRAL Lyon, LAM Marseille, Padua University and REFLEX Prague, is evaluating technologies for manufacturing micro optics in large numbers to enable multi-object integral field spectroscopy.

  5. Wireless optical transceiver design, link analisys and alignment control for mobile communication

    NASA Astrophysics Data System (ADS)

    Zhou, Dayong

    Pointing, acquisition and tracking of a free-space optical node in a mobile network experiencing misalignment due to adverse factors including vibration, motion and atmospheric turbulence requires a different approach than traditional free-space optical transceivers. A recent fiber-bundle approach for beam steering at the transmitter was investigated to provide continuous beam coverage at the receiver without the application of mechanical devices. Utilizing multiple fibers-lenses sets at the receiver was also proposed to enhance the tolerance of optical link misalignment. In this work, both laboratory experiments and software simulation were implemented to evaluate the optical link performance for different fiber-bundle-based transceiver setups as the link parameters were varied. The performance was evaluated in terms of the coverage area at the receiver, which is a measure of misalignment tolerance and is dependent not only on wavelength but on other key parameters such as link length, transmitted power, the pattern of transmitters, beam divergence, and the receiver construction. The results showed that fiber-bindle-based transceivers reveal significant potential to maximize the up time of the link, and the results also provide guidance on the further development of the overall system. To incorporate the proposed transceiver designs, an alignment control system was developed and evaluated as well. The laboratory results show that the optical control system successfully recovered and maintained the link while the receiver was in motion and the signal coverage at the target area was enhanced significantly.

  6. Fiber optic diagnostic techniques for the electrical discharge machining process 

    E-print Network

    Pillans, Brandon William

    1998-01-01

    Plasma sparks from an electrical discharge machining phics. (EDM) process were observed using fiber optics positioned the dielectric oil. New measurement techniques were developed to observe the spark in the extremely noisy environment. Optical data...

  7. Stabilized Ultrafast Pulse Generation and Optical Frequency Combs Techniques

    E-print Network

    Van Stryland, Eric

    Stabilized Ultrafast Pulse Generation and Optical Frequency Combs ­ Techniques and Applications Length, Intracavity Power, PDH · Applications ­ Optical Sampling (ADC's), Waveform Generation (DAC Gold wire Ceramic stand Gold coated copper stud Copper block Thermoelectric cooler + I 4mm Mounted

  8. 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…

  9. Thermal Annealing Effects on Optical Anisotropy of Aligned Thiophene-Based ?-Conjugated Polymer Films Fabricated by Capillary Action

    NASA Astrophysics Data System (ADS)

    Higashi, Takuya; Yamasaki, Naoyuki; Utsumi, Hideyuki; Yoshida, Hiroyuki; Fujii, Akihiko; Ozaki, Masanori

    2012-02-01

    Thermal annealing effects of the aligned thiophene-based polymer films were studied. Aligned poly2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene (pBTTT) and poly2,5-bis(3-alkylthiophene-2-yl)thieno[2,3-b]thiophene (pBTCT) films were fabricated by utilizing capillary actions of polymer solutions. The optical anisotropies of the aligned films were enhanced by thermal annealing at temperatures below the phase transition. The differences in the optical anisotropies between pBTTT and pBTCT were discussed by taking the lamellar stacking structures in the aligned films and phase transition into consideration.

  10. 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

  11. Advanced molding technique for optical transceivers

    Microsoft Academic Search

    S. D. Robinson; F. C. J. Anigbo; G. J. Shevchuk

    1996-01-01

    With the growing use of fiber optics in Local Area Networks (LANs), efforts to cost reduce the optical components has intensified. In general, optoelectronic components for Fiber Distributed Data Interface (FDDI) and Fiber Channel LANs have been LED-based Optical Data Links (ODLs). Due to the bi-directional nature of most links, the trend has been towards the integration of simplex optical

  12. Optical access and diagnostic techniques for internal combustion engine devlopment

    NASA Astrophysics Data System (ADS)

    Winklhofer, Ernst

    2001-07-01

    Methods for optical access to combustion chambers of internal combustion engines are shown. The optical access is either maximized to allow application of complex optical diagnostic techniques while maintaining minimum necessary operability of the engine or engine components, or full engine operability is maintained while optical access and diagnostic techniques are tailored to the diagnostic demand and the restraints of engine operation. As full optical access allows a wide range of diagnostics to be applied, it puts the emphasis on organizing and extending realistic engine operation conditions. Full engine operability, however, challenges the optical access and the design of diagnostic systems. The paper gives examples for diagnostic applications for both of these situations.

  13. Nova laser alignment control system

    SciTech Connect

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

    1984-03-29

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

  14. Design, alignment and applications of optical systems for parallel processing with ultra-short laser pulses

    NASA Astrophysics Data System (ADS)

    Büsing, L.; Eifel, S.; Loosen, Peter

    2014-05-01

    During the last years, the average power of commercial ultra-short pulsed laser sources increased significantly. The efficient utilization of the high average laser power in the field of material processing requires an effective distribution of the laser power onto the work piece. One approach to increase the efficiency is the application of beam splitting devices to enable parallel processing. But the shaping and steering of multiple beams requires particular optical systems which are not state of the art today. Limitations for large spot arrays are evaluated and considered for the design concept of appropriate optical systems. For the purpose of micro structuring with high demands on the spatial accuracy, an optical system based on a diffractive 14×14 beam splitter (DOE) is designed and set up. All partial beams are coupled into a scanner device by using a relay lens system. Furthermore, this relay lens system offers a practicable solution to remove higher diffraction orders of the DOE. Due to the scanner a highly dynamic, simultaneous deflection of all partial laser beams can be achieved. For the alignment and the experimental evaluation of the complex optical system appropriate measurement devices are necessary. The simultaneous determination of several spot positions is realized by a camera system and adapted evaluation software. First experiments of large-area processing metal foils show promising results.

  15. 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

  16. Self-Calibration Technique for 3-point Intrinsic Alignment Correlations in Weak Lensing Surveys

    E-print Network

    Troxel, M A

    2011-01-01

    The intrinsic alignment (IA) of galaxies has been shown to be a significant barrier to precision cosmic shear measurements. Zhang [P. Zhang, Astrophys. J. 720, 1090 (2010)] proposed a self-calibration technique for the power spectrum to calculate the induced gravitational shear-galaxy intrinsic ellipticity correlation (GI) in weak lensing surveys with photo-z measurements which is expected to reduce the IA contamination by at least a factor of 10 for currently proposed surveys. We confirm this using an independent analysis and propose an expansion to the self-calibration technique for the bispectrum in order to calculate the dominant IA gravitational shear-gravitational shear-intrinsic ellipticity correlation (GGI) contamination. We first establish an estimator to extract the galaxy density-density-intrinsic ellipticity (ggI) correlation from the galaxy ellipticity-density-density measurement for a photo-z galaxy sample. We then develop a relation between the GGI and ggI bispectra, which allows for the estima...

  17. 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.

  18. IEEE Communications Magazine January 2001136 Techniques for Optical Packet Switching

    E-print Network

    IEEE Communications Magazine · January 2001136 Techniques for Optical Packet Switching and Optical of the Internet. Several differ- ent technologies have been developed so far for the transfer of data over WDM. In this article we survey two new technologies which are still in the experimental stage -- optical packet switch

  19. Cryogenic Optical Alignment Stability Test (COAST) of the Composite Infrared Spectrometer (CIRS) engineering unit for the Cassini mission to Saturn

    NASA Astrophysics Data System (ADS)

    Hagopian, John G.

    1996-10-01

    The composite infrared spectrometer (CIRS) of the Cassini mission to Saturn has two interferometers covering the far- IR (FIR) and mid-IR (MIR) wavelength region. The instrument is aligned at ambient temperature, but operates at 170 Kelvin and has challenging interferometric alignment tolerances. Interferometric alignment sensitivity tests of the CIRS FIR breadboard indicated that the instrument was sensitive to alignment perturbations in the few arc second regime; therefore, a cryogenic alignment stability test was designed and implemented to determine the stability of the CIRS optics module. Test beamsplitters were installed in the instrument to allow transmission of HeNe laser beams through both channels of the instrument onto test focal planes consisting of position sensing photodiodes to measure the actual shear and boresight change in the focal planes. Cryogenic vacuum compatible shutters were designed and fabricated to allow separate measurements of the reflected and transmitted components of the test beam. The test determined that the optics bench was distorting an unacceptable amount between ambient and operating temperature, but that the distortion was very repeatable, opening the possibility of performing an interferometric alignment at cryogenic temperature.

  20. Flight data evaluation of a technique for payload inertial reference alignment transfer from the Shuttle navigation system

    Microsoft Academic Search

    K. L. Meldahl; R. E. Norris; J. P. Clarke

    1987-01-01

    An attitude update (AU) technique is described which was designed for use with the Air Force IUS space transportation vehicle while carried by the Shuttle. The AU consists of an alignment transfer from the Orbiter's navigation system to that of the IUS by comparing attitude data gathered during deliberate or incidental maneuvers. Ensemble results from IUS flights are shown, with

  1. A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the

    E-print Network

    Geddes, Cameron Guy Robinson

    , and the Defense Advanced Research Projects Agency (DARPA) Currently at Peking University, Beijing, 100871, P. RAbstract A technique has been developed to accurately align a laser beam through a plasma channel by minimizing the shift in laser centroid and angle at the channel outptut. If only the shift in centroid

  2. A New Technique for Finding the Optical Center of Cameras

    Microsoft Academic Search

    Guruprasad Shivaram; Guna Seetharaman

    1998-01-01

    We present a new technique for finding the optical center of a camera. We usespheres as calibration objects. Our approach is based on a new key result that themajor axis of the ellipse image resulting from the perspective projection of a spherewould pass through the optical center of the image. The presented technique hasbeen applied on large number of images.

  3. 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.

  4. Novel techniques for optical performance monitoring in optical systems

    Microsoft Academic Search

    Yuen Ching Ku

    2007-01-01

    The tremendous increase of data traffic in the worldwide Internet has driven the rapid development of optical networks to migrate from numerous point-to-point links towards meshed, transparent optical networks with dynamically routed light paths. This increases the need for appropriate network supervision methods. In view of this, optical performance monitoring (OPM) has emerged as an indispensable element for the quality

  5. 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

  6. Propagating a partially coherent radially polarized beam through aligned and misaligned ABCD optical systems

    NASA Astrophysics Data System (ADS)

    Ma, Yuzhao

    2012-05-01

    In the present work the propagation of a partially coherent radially polarized beam through aligned and misaligned ABCD optical systems is discussed. The elements of the beam coherence-polarization matrix for a partially coherent radially polarized beam propagating through these systems are derived for the first time. Using the derived analytical results the intensity distribution of the focused partially coherent radially polarized beam after a low-NA lens is investigated. It is shown that the coherence of the light source affects the beam intensity profile at the focal plane significantly, while for the given coherence of the light source the focal length of the used lens does not affect the beam intensity profile at the focal plane. This is consistent with the case of a partially coherent Hermite-Gaussian beam, as expected.

  7. 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.

  8. Basic Concepts of Optical Mapping Techniques in Cardiac Electrophysiology

    PubMed Central

    Attin, Mina; Clusin, William T.

    2011-01-01

    Optical mapping is a tool used in cardiac electrophysiology to study the heart's normal rhythm and arrhythmias. The optical mapping technique provides a unique opportunity to obtain membrane potential recordings with a higher temporal and spatial resolution than electrical mapping. Additionally, it allows simultaneous recording of membrane potential and calcium transients in the whole heart. This article presents the basic concepts of optical mapping techniques as an introduction for students and investigators in experimental laboratories unfamiliar with it. PMID:19617237

  9. Three-dimensional optical analyses and optimizations of a vertical alignment color-filters-embedded liquid-crystal-on-silicon microdisplay

    E-print Network

    Three-dimensional optical analyses and optimizations of a vertical alignment color-filters-dimensional optical analyses and optimizations of a vertical alignment color-filters-embedded liquid of China 2 Center for Display Research, The Hong Kong University of Science and Technology, Clear Water Bay

  10. Electro-optical systems to accurately align (boresight) laser designator, FLIR, and CCD on the ground before the mission

    NASA Astrophysics Data System (ADS)

    Cabib, Dario; Segal, Alon; Dolev, Jacob

    2008-10-01

    CI Systems has been involved in the development and production of in-flight boresight equipment since 19891,2, by pioneering the field with innovative laser-FLIR and laser-CCD alignment solutions. In addition, over the years we have developed a number of systems for use on the ground to align the various electro-optical instrumentation to a common Line of Sight (LOS) before the mission. This adjustment is very important for the success of the mission: the more accurate the alignment and its retention during the flight, the better the chance of a precise hit. In this paper we describe various systems developed and built at CI for use with EO pods mounted on aircraft, especially UAV's. The most important engineering tasks are design for small size and convenient mechano-optical interfaces for different pods allowing system compactness, low weight and easy operation. Some of the design considerations to meet these challenges will be given here.

  11. Phase-Noise Analysis of Optically Generated Millimeter-Wave Signals With External Optical Modulation Techniques

    Microsoft Academic Search

    Guohua Qi; Jianping Yao; Joe Seregelyi; Stéphane Paquet; Claude Bélisle; Xiupu Zhang; Ke Wu; Raman Kashyap

    2006-01-01

    In this paper, the phase-noise performance of optically generated electrical signals based on external optical modulation techniques is investigated theoretically and experimentally. Mathematical models are developed to represent perturbations on the transmitted optical signal caused by the phase fluctuations of the electrical drive signal applied to the external modulator and the optical carrier that feeds the external modulator. Closed-form expressions

  12. On-wafer process for mass production of hybrid integrated optical components using passive alignment on silicon motherboard

    Microsoft Academic Search

    Han-Jun Koh; Min-Ho Choi; Hong-Jun Chun; Joon-Suk Song; Jong-Uk Bu

    1999-01-01

    In recent years the widespread use of optoelectronic components has been restricted by their high cost. The major reasons come from the facts that the active alignment of optical fibers to laser diodes takes lengthy tact time and makes its automation for production extremely difficult, and that facilities needed to manufacture require a considerable investment with a reasonably large volume

  13. 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

  14. Optical performance monitoring techniques for high capacity optical networks

    Microsoft Academic Search

    Chao Lu; Alan Pak Tao Lau; F. N. Khan; Qi Sui; Jian Zhao; Zhaohui Li; H. Y. Tam; P. K. A. Wai

    2010-01-01

    Optical performance monitoring is an important function for high capacity optical transmission system. In this paper, we summarize some of the recent work we have carried out in this area. In particular, PMD independent OSNR monitoring, OSNR monitoring using half symbol delay for SNR monitoring of RZ-DQPSK signal and signed residue dispersion monitoring of CSRZ-DQPSK signal using delay tap sampling

  15. Tissue image contrasting using optical immersion technique

    NASA Astrophysics Data System (ADS)

    Tuchin, Valery V.

    2000-10-01

    Experimental data for in vitro and in vivo studies of various solutions action on optical properties of human tissues is presented. The dynamics of tissue optical properties depending on matter diffusion rate within tissue is studied. The possible application of refractive index matching effect for tissue imaging is discussed. Results on optical properties control of the human sclera, skin, connective tissue membranes, such as dura mater, muscle and blood due to their impregnation by the osmotically active chemicals, such as trazograph, glucose, propylene glycol, glycerol are presented.

  16. Photoresponsive carbohydrate-based giant surfactants: automatic vertical alignment of nematic liquid crystal for the remote-controllable optical device.

    PubMed

    Kim, Dae-Yoon; Lee, Sang-A; Kang, Dong-Gue; Park, Minwook; Choi, Yu-Jin; Jeong, Kwang-Un

    2015-03-25

    Photoresponsive carbohydrate-based giant surfactants (abbreviated as CELAnD-OH) were specifically designed and synthesized for the automatic vertical alignment (VA) layer of nematic (N) liquid crystal (LC), which can be applied for the fabrication of remote-controllable optical devices. Without the conventional polymer-based LC alignment process, a perfect VA layer was automatically constructed by directly adding the 0.1 wt % CELA1D-OH in the N-LC media. The programmed CELA1D-OH giant surfactants in the N-LC media gradually diffused onto the substrates of LC cell and self-assembled to the expanded monolayer structure, which can provide enough empty spaces for N-LC molecules to crawl into the empty zones for the construction of VA layer. On the other hand, the CELA3D-OH giant surfactants forming the condensed monolayer structure on the substrates exhibited a planar alignment (PA) rather than a VA. Upon tuning the wavelength of light, the N-LC alignments were reversibly switched between VA and PA in the remote-controllable LC optical devices. Based on the experimental results, it was realized that understanding the interactions between N-LC molecules and amphiphilic giant surfactants is critical to design the suitable materials for the automatic LC alignment. PMID:25738306

  17. 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.

  18. Antares automatic beam alignment system

    SciTech Connect

    Appert, Q.; Swann, T.; Sweatt, W.; Saxman, A.

    1980-01-01

    Antares is a 24-beam-line CO/sub 2/ laser system for controlled fusion research, under construction at Los Alamos Scientific Laboratory (LASL). Rapid automatic alignment of this system is required prior to each experiment shot. The alignment requirements, operational constraints, and a developed prototype system are discussed. A visible-wavelength alignment technique is employed that uses a telescope/TV system to view point light sources appropriately located down the beamline. Auto-alignment is accomplished by means of a video centroid tracker, which determines the off-axis error of the point sources. The error is nulled by computer-driven, movable mirrors in a closed-loop system. The light sources are fiber-optic terminations located at key points in the optics path, primarily at the center of large copper mirrors, and remotely illuminated to reduce heating effects.

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

    SciTech Connect

    Klingsporn, P.E.

    1997-06-01

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

  20. Optical alignment of the airborne laser laboratory's gas dynamic laser cavity

    Microsoft Academic Search

    J. P. Mills; C. E. Moeller

    1980-01-01

    A design approach for an alignment system for an unstable resonator is presented. A description of the Air Force airborne gas-dynamic laser resonator is followed by the results of a paraxial ray trace, including aperture stops, of the images used in the alignment method. An analysis of these results led to the design of the resonator alignment system.

  1. On numerical techniques for the transformation to an orthogonal coordinate system aligned with a vector field

    SciTech Connect

    CASTILLO,JOSE E.; OTTO,JAMES S.

    2000-02-11

    The authors explore the use of variational grid-generation to perform alignment of a grid with a given vector field. Variational methods have proven to be a powerful class of grid-generators, but when they are used in alignment, difficulties may arise in treating boundaries due to an incompatibility between geometry and vector field. In this paper, a refinement of the procedure of iterating boundary values is presented. It allows one to control the quality of the grid in the face of the above-mentioned incompatibility. This procedure may be incorporated into any variational alignment algorithm. The authors demonstrate its use with respect to a new quasi-variational alignment method having a particularly simple structure. The latter method is comparable to Knupp's method (see [7]), but avoids use of the Winslow equations.

  2. Vertically Aligned Carbon Nanotubes at Different Temperatures by Spray Pyrolysis Techniques

    Microsoft Academic Search

    Rakesh A. Afre; T. Soga; T. Jimbo; Mukul Kumar; Y. Ando; M. Sharon

    2006-01-01

    Vertically aligned arrays of multi-walled carbon nanotubes (VACNTs) were grown by spray pyrolysis of turpentine oil and ferrocene mixture at temperatures higher than 700°C. Using this simple method, we report the successful growth of vertically aligned nanotubes of ~300mum length and diameter in the range of ?20-80nm on Si(100) substrate. The ferrocene acts as an in situ Fe catalyst precursor,

  3. 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

  4. Study of microfluidic measurement techniques using novel optical imaging diagnostics 

    E-print Network

    Park, Jaesung

    2007-04-25

    Novel microscale velocity and temperature measurement techniques were studied based on confocal laser scanning microscopy (CLSM) and optical serial sectioning microscopy (OSSM). Two microscopic measurement systems were developed, 1) a CLSM micro...

  5. Study of microfluidic measurement techniques using novel optical imaging diagnostics

    E-print Network

    Park, Jaesung

    2007-04-25

    Novel microscale velocity and temperature measurement techniques were studied based on confocal laser scanning microscopy (CLSM) and optical serial sectioning microscopy (OSSM). Two microscopic measurement systems were developed, 1) a CLSM micro...

  6. The Virgo automatic alignment system

    Microsoft Academic Search

    F. Acernese; P. Amico; M. Al-Shourbagy; S. Aoudia; S. Avino; D. Babusci; G. Ballardin; R. Barillé; F. Barone; L. Barsotti; M. Barsuglia; F. Beauville; M. A. Bizouard; C. Boccara; F. Bondu; L. Bosi; C. Bradaschia; S. Braccini; A. Brillet; V. Brisson; L. Brocco; D. Buskulic; E. Calloni; E. Campagna; F. Cavalier; R. Cavalieri; G. Cella; E. Chassande-Mottin; C. Corda; A.-C. Clapson; F. Cleva; J.-P. Coulon; E. Cuoco; V. Dattilo; M. Davier; R. De Rosa; L. Di Fiore; A. Di Virgilio; B. Dujardin; A. Eleuteri; D. Enard; I. Ferrante; F. Fidecaro; I. Fiori; R. Flaminio; J.-D. Fournier; S. Frasca; F. Frasconi; A. Freise; L. Gammaitoni; A. Gennai; A. Giazotto; G. Giordano; L. Giordano; R. Gouaty; D. Grosjean; G. Guidi; S. Hebri; H. Heitmann; P. Hello; L. Holloway; S. Kreckelbergh; P. La Penna; V. Loriette; M. Loupias; G. Losurdo; J.-M. Mackowski; E. Majorana; C. N. Man; M. Mantovani; F. Marchesoni; F. Marion; J. Marque; F. Martelli; A. Masserot; M. Mazzoni; L. Milano; C. Moins; J. Moreau; N. Morgado; B. Mours; A. Pai; C. Palomba; F. Paoletti; S. Pardi; A. Pasqualetti; R. Passaquieti; D. Passuello; B. Perniola; F. Piergiovanni; L. Pinard; R. Poggiani; M. Punturo; P. Puppo; K. Qipiani; P. Rapagnani; V. Reita; A. Remillieux; F. Ricci; I. Ricciardi; P. Ruggi; G. Russo; S. Solimeno; A. Spallicci; R. Stanga; R. Taddei; D. Tombolato; M. Tonelli; A. Toncelli; E. Tournefier; F. Travasso; G. Vajente; D. Verkindt; F. Vetrano; A. Viceré; J.-Y. Vinet; H. Vocca; M. Yvert; Z. Zhang

    2006-01-01

    The automatic alignment system of the Virgo interferometer differs substantially from those used in similar experiments, since it uses a variant of the Anderson technique. This implies a completely different control topology with respect to other detectors, and the main feature is a strong coupling of different degrees of freedom in the optical signals. It also provides two extra output

  7. 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.

  8. Optically stimulated luminescence techniques in retrospective dosimetry

    Microsoft Academic Search

    L. Bøtter-Jensen; A. S. Murray

    2001-01-01

    Optically stimulated luminescence signals from natural quartz and feldspar are now used routinely in dating geological and archaeological materials. More recently they have also been employed in accident dosimetry, i.e. the retrospective assessment of doses received as a result of a nuclear accident. Since 1990 the exploration of this wide variety of applications has driven an intensive investigation and development

  9. Microwave generation and transmission using optical heterodyning or optical upconversion technique

    Microsoft Academic Search

    R. P. Braun; N. Grosskopf; F. Rohde; E. Schmidt

    1996-01-01

    Two optical\\/microwave generation techniques are discussed. 140 Mbit\\/s transmissions with optically generated microwaves at frequencies at of 18 and 60-70 GHz are reported. Quartz accuracy and sub-Hertz linewidths of an optical microwave generator signal are demonstrated

  10. Alignment technology for backside integration

    NASA Astrophysics Data System (ADS)

    Bauer, J.; Kulse, P.; Haak, U.; Old, G.; Scheuring, G.; Döbereiner, St.; Hillmann, F.; Brück, H.-J.; Kaynak, M.; Ehwald, K.-E.; Marschmeyer, St.; Birkholz, M.; Schulz, K.

    2011-03-01

    This paper presents a backside-to-frontside alignment technique for the backside processing of Si wafers. Integrated MEMS components like BiCMOS-embedded RF-MEMS switches require accurate (1-2?m) alignment. We demonstrate an alignment technique providing overlay values of less than 500 nm by using a backside alignment layer. The approach is enabled by a new non-contact wafer pre-alignment system of the Nikon Scanner S207D allowing precise loading (<5?m) of the wafer onto the exposure stage. Before starting the back-side MEMS process, the misalignment between frontside devices and backside alignment layer has to be measured. The alignment errors are applied as lithography overlay corrections to the backside MEMS process. For the specific application of deep Si etching (Bosch process), moreover, one has to consider the etch profile angle deviation across the wafer (tilting), which turned out in our experiments to amount up to 8 ?m. During initial experiments with a Nikon i-line stepper NSR-2205 i- 11D the overlay has been corrected by the stepper offset parameters. These parameters have been obtained by summing up both the wafer and intra-field scaling errors caused by deep Si etching and backside-to-frontside alignment errors. Misalignments and tilting errors were all measured with a MueTec MT 3000 IR optical metrology system using overlay marks. The developed alignment technique is applied to BiCMOS-embedded MEMS devices, i.e. mm-wave RF switches and a viscosity sensor chip based on the IHP's high-speed SiGe technology. It turned out to be very promising for backside processed MEMS components with critical alignment requirements.

  11. 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.

  12. Optical ranging techniques in turbid waters

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    In this paper simulation and experimental results are presented for two hybrid lidar-radar modulation techniques for underwater laser ranging. Both approaches use a combination of multi-frequency and single frequency modulation with the goal of simultaneously providing good range accuracy, unambiguous range, and backscatter suppression. The first approach uses a combination of dual and single frequency modulation. The performance is explored as a function of increasing average frequency while keeping the difference frequency of the dual tones constant. The second approach uses a combination of a stepped multi-tone modulation called frequency domain reflectometry (FDR) and single frequency modulation. The FDR technique is shown to allow simultaneous detection of the range of both the volumetric center of the backscattered "clutter" signal and the desired object. Experimental and simulated results are in good agreement for both techniques and performance out to ten attenuations lengths is reported.

  13. Optical metrology of Ni and NiSi thin films used in the self-aligned silicidation process

    Microsoft Academic Search

    V. K. Kamineni; M. Raymond; E. J. Bersch; B. B. Doris; A. C. Diebold

    2010-01-01

    The thickness-dependent optical properties of nickel metal and nickel monosilicide (NiSi) thin films, used for self-aligned silicidation process, were characterized using spectroscopic ellipsometry. The thickness-dependent complex dielectric function of nickel metal films is shown to be correlated with the change in Drude free electron relaxation time. The change in relaxation time can be traced to the change in grain boundary

  14. 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

  15. 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.

  16. 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.

  17. Optical image segmentation using wavelet filtering techniques

    NASA Astrophysics Data System (ADS)

    Veronin, Christopher P.

    1990-12-01

    This research effort successfully implemented an automatic, optically based image segmentation scheme for locating potential targets in a cluttered FLIR image. Such a design is critical to achieve real-time segmentation and classification for machine vision applications. The segmentation scheme used in this research was based on texture discrimination and employs orientation specific, bandpass spatial filters as its main component. The orientation specific, bandpass spatial filters designed during this research include symmetrically located circular apertures implemented on heavy, black aluminum foil; cosine and sine Gabor filters implemented with detour-phase computer generated holography photoreduced onto glass slides; and symmetrically located circular apertures implemented on a liquid crystal television (LCTV) for real-time filter selection. The most successful design was the circular aperture pairs implemented on the aluminum foil. Segmentation was illustrated for simple and complex texture slides, glass template slides, and static and real-time FLIR imagery displayed on an LCTV.

  18. Self-aligned optical couplings by self-organized waveguides toward luminescent targets in organic/inorganic hybrid materials.

    PubMed

    Yoshimura, Tetsuzo; Iida, Makoto; Nawata, Hideyuki

    2014-06-15

    Self-organization of optical waveguides is observed between two opposed optical fibers placed in a photosensitive organic/inorganic hybrid material, Sunconnect. A luminescent target containing coumarin 481 was deposited onto the edge of one of the two fibers at the core. When a 448-nm write beam was introduced from the other fiber, the write beam and the luminescence from the photoexcited target increased the refractive index of Sunconnect to induce self-focusing. Traces of waveguides were seen to grow from the cores of both fibers and merged into a single self-aligned optical coupling between the fibers. This optical solder functionality enabled increases in both coupling efficiency and tolerance to lateral misalignment of the fibers. PMID:24978520

  19. 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.

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

    PubMed Central

    2013-01-01

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

  1. Optical-fiber finger photo-plethysmograph using digital techniques

    Microsoft Academic Search

    John N. Lygouras; Philippos G. Tsalides

    2002-01-01

    This paper presents digital techniques to design an optical-fiber photo-plethysmograph. This noninvasive method is based on the measurement of the intensity of an infrared-light beam, which penetrates the index finger. Sinusoidal modulation of the light-beam by driving an infrared LED is proposed. The method of direct digital synthesis is used to produce a very stable sinusoidal waveform. Optical fibers are

  2. 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.

  3. 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.

  4. A comparative study of self-aligned quadruple and sextuple patterning techniques for sub-15nm IC scaling

    NASA Astrophysics Data System (ADS)

    Chen, Yijian; Kang, Weiling; Zhang, Pan

    2013-04-01

    Self-aligned multiple patterning (SAMP) techniques can potentially scale integrated circuits down to half-pitch 7nm. In this paper, we present a comparative analysis of self-aligned quadruple (SAQP) and sextuple (SASP) techniques by investigating their technological merits and limitations, process complexity and cost structures, strategy of layout decomposition/synthesis, and yield impacts. It is shown that SASP process complexity is comparable to that of SAQP process, while it offers 50% gain in feature density and may be extended for one more node. The overlay yield of cut process is identified to be a challenge when the minimum device feature is scaled to half-pitch 7nm. The mask design issues for various applications using each technique are discussed, and the corresponding layout decomposition/synthesis strategy for complex 2D patterning is proposed. Although the high-dose EUV single-cut process can save significant costs when applied to replace the 193i multiple-cut process to form fin/gate structures, our cost modeling results show that SADP+EUV approach is still not cost effective for patterning other critical layers that generally require the same mask number (and lithographic steps) as the non-EUV schemes.

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

    PubMed Central

    2012-01-01

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

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

    Microsoft Academic Search

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

    1987-01-01

    The long-recognized association of brighter aurora with more deeply penetrating, and hence more energetic electrons is examined. Using the Knight (1973) relation between the magnetic field aligned current density j{sub parallel} and potential drop V{sub parallel}, derived from the theory of single particle motion in the presence of a magnetic field-aligned electric field, an approximate expression relating the energy flux

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

    Microsoft Academic Search

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

    1987-01-01

    The long-recognized association of brighter aurora with more deeply penetrating, and hence more energetic, electrons is examined. Using the Knight (1973) relation between the magnetic-field-aligned current density and potential drop (derived from the theory of single-particle motion in the presence of a magnetic-field-aligned electric field), an approximate expression relating the energy flux of the precipitating electrons over discrete aurora and

  8. Alignment tolerance measurements and optical coupling modeling for optoelectronic array interface assemblies

    Microsoft Academic Search

    J. Sutherland; G. George; S. van der Green; J. P. Krusius

    1996-01-01

    Alignment tolerance measurements for flip-chip mounted optoelectronic device substrates have been performed, including separation, tilt, and lateral misalignments. A test assembly was fabricated by joining two metallized and lithographically patterned glass substrates with an array of 76 ?m dia. 63%Sn-37%Pb solder balls. Measurements indicated poorer alignment than expected, with an average lateral misalignment of 9 ?m, and worst case height

  9. Ultraviolet imprinting and aligned ink-jet printing for multilayer patterning of electro-optic polymer modulators.

    PubMed

    Lin, Xiaohui; Ling, Tao; Subbaraman, Harish; Zhang, Xingyu; Byun, Kwangsub; Guo, L Jay; Chen, Ray T

    2013-05-15

    The present work demonstrates an electro-optic polymer-based Mach-Zehnder (MZ) modulator fabricated utilizing advanced ultraviolet (UV) imprinting and aligned ink-jet printing technologies for patterning and layer deposition. The bottom electrode layer is designed and directly ink-jet printed on the substrate to form the patterned layer. The waveguide structure is formed into a bottom cladding polymer using a transparent flexible mold-based UV imprinting method. All other layers can be ink-jet printed. The top electrode is aligned and printed over the MZ arm. The modulator demonstrates a V-pi of 8 V at 3 kHz. This technology shows great potential in minimizing the fabrication complexity and roll-to-roll compatibility for manufacturing low cost, lightweight, and conformal modulators at high throughput. PMID:23938881

  10. Performance and characterization of a MEMS-based device for alignment and manipulation of x-ray nanofocusing optics

    NASA Astrophysics Data System (ADS)

    Xu, Weihe; Lauer, Kenneth; Yan, Hui; Milanovic, Veljko; Lu, Ming; Nazaretski, Evgeny

    2015-03-01

    X-ray microscopy is a powerful, non-invasive tool used for nanometer-scale resolution imaging, and it is widely applied in various areas of science and technology. To push the spatial resolution of x-ray microscopy studies in the hard x-ray regime below 10 nm, Multilayer Laue Lenses (MLL) can be used as nanofocusing elements. To ensure distortion-free x-ray imaging, high-stability microscopy systems are required. MEMS-based manipulators are a promising route to achieve high stability when used for alignment and manipulation of nanofocusing optics. In this work, we present a tip-tilt MEMS-based device suitable for MLL alignment. We fully characterize the device and demonstrate better-than 10 millidegree angular positioning resolution when utilizing capacitive displacement sensors, and better-than 0.8 millidegree resolution when using laser interferometry.

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

    NASA Technical Reports Server (NTRS)

    Lee, George

    1992-01-01

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

  12. Surface Alignment, Anchoring Transitions, Optical Properties, and Topological Defects in the Thermotropic Nematic Phase of an Organo-Siloxane Tetrapodes

    E-print Network

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

    2013-11-02

    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.

  13. Surface Alignment, Anchoring Transitions, Optical Properties, and Topological Defects in the Thermotropic Nematic Phase of an Organo-Siloxane Tetrapodes

    E-print Network

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

    2013-01-01

    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.

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

    PubMed

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

    2014-01-21

    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 -25 °C < T < 46 °C 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 defects - boojums and bulk point defects - hedgehogs that can exist only in the uniaxial nematic liquid crystal. PMID:24651889

  15. 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

  16. 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

  17. 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.

  18. 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

  19. Integrated Acousto-Optic Correlator Using The Proton Exchange Technique

    NASA Astrophysics Data System (ADS)

    Varasi, Mauro; Vanucci, Antonello; Reid, Stuart A.

    1990-02-01

    The proton exchange technique has been used to realise monomode waveguide lenses and Bragg cells in Y-cut lithium niobate. These results are discussed, and the performance of a fully packaged integrated acousto-optic correlator fabricated using the above components is presented. Recent experiments to further optimise, device performance are described.

  20. Quantitative analyses of pyrite in coal by optical image techniques

    Microsoft Academic Search

    L. A. Harris; T. Rose; L. DeRoos; J. Greene

    1977-01-01

    In this study we have demonstrated that quantitative analyses of pyrite in coal can be achieved by means of optical image analysis techniques. However, it is necessary to measure a large sample surface since selected area analyses may lead to erroneous values. The roots of this problem stem from the nonuniform distribution of pyrite throughout a coal briquet. In addition,

  1. Technique developed for measuring transmittance of optical birefringent networks

    NASA Technical Reports Server (NTRS)

    Ammann, E. O.; Yarborough, J. M.

    1968-01-01

    The transmission characteristics of synthesized optical single-pass and double-pass birefringent networks is obtained by measuring network transmission as a function of network temperature. This technique is most useful for testing those birefringent networks whose bandwidths and periods are very small.

  2. 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

  3. 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.

  4. Near-infrared optical properties of ex vivo human skin and subcutaneous tissues measured using the Monte Carlo inversion technique

    NASA Astrophysics Data System (ADS)

    Simpson, C. Rebecca; Kohl, Matthias; Essenpreis, Matthias; Cope, Mark

    1998-09-01

    The absorption and transport scattering coefficients of caucasian and negroid dermis, subdermal fat and muscle have been measured for all wavelengths between 620 and 1000 nm. Samples of tissue 2 mm thick were measured ex vivo to determine their reflectance and transmittance. A Monte Carlo model of the measurement system and light transport in tissue was then used to recover the optical coefficients. The sample reflectance and transmittance were measured using a single integrating sphere `comparison' method. This has the advantage over conventional double-sphere techniques in that no corrections are required for sphere properties, and so measurements sufficiently accurate to recover the absorption coefficient reliably could be made. The optical properties of caucasian dermis were found to be approximately twice those of the underlying fat layer. At 633 nm, the mean optical properties over 12 samples were ALIGN="MIDDLE"/> and ALIGN="MIDDLE"/> for absorption coefficient and ALIGN="MIDDLE"/> and ALIGN="MIDDLE"/> for transport scattering coefficient for caucasian dermis and the underlying fat layer respectively. The transport scattering coefficient for all biological samples showed a monotonic decrease with increasing wavelength. The method was calibrated using solid tissue phantoms and by comparison with a temporally resolved technique.

  5. 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.

  6. Optical Turbulence in High Angular Resolution Techniques in Astronomy

    NASA Astrophysics Data System (ADS)

    Beckers, Jacques M.

    2009-09-01

    All astronomical observations are done best from space where the absorption by and turbulence in the Earth atmosphere are absent. One has access to the entire electromagnetic radiation spectrum and the absence of seeing allows unlimited angular resolution. However, the cost of facilities in space and their operation is 3 orders of magnitude of similar sized facilities on Earth. Experimental astrophysicists have therefore in the past decades pursued the development of techniques to overcome the seeing limitations by the atmosphere. So far they have been very successful at this and much more is almost certain to come. Adaptive Optics (AO) will make very large (8 - 10-meters diameter) and extremely large (30 - 42 meters diameter) telescopes diffraction limited first at infrared wavelengths and eventually at visible wavelengths. The development of fast optical turbulence/seeing wavefront sensing techniques using artificial sources (Laser Beacons) will enable doing that over the entire sky. Atmospheric Tomography (AT) needed for Multi-Conjugate Adaptive Optics (MCAO) will give 3D maps of the rapidly variable atmospheric turbulence. Large interferometers with baselines of hundreds of meters will further enhance the angular resolution using fringe tracking for both co-phasing and coherent operation. Ground-based astronomy is therefore entering a new era in which milli-arcsecond observations and better are foreseen even of objects at the edge of the universe. The astronomical techniques will result in information of atmospheric optical turbulence which is likely to be of interest for meteorologists.

  7. Controlling the optical dipole force for molecules with field-induced alignment

    SciTech Connect

    Purcell, S. M.; Barker, P. F. [Department of Physics and Astronomy, University College London, London, WC1E 6BT (United Kingdom)

    2010-09-15

    We measure the role of field-induced alignment on the dipole force for molecules using a single focused nonresonant laser beam. We show that through the alignment process we can modify the effective polarizability by field polarization and thus control the center-of-mass motion of the molecule. We observe a maximum change of 20% in the dipole force on CS{sub 2} molecules when changing from linearly to circularly polarized light. Additionally, the effect of the dipole force on different vibrational states is also studied.

  8. A novel fiber alignment shift measurement technique employing an ultra high precision laser displacement meter in laser-welded laser module packaging

    Microsoft Academic Search

    Yi-Cheng Hsu; Yue-Lin He; Maw-Tyan Sheen; Ying-Chien Tsai; Jao-Hwa Kuang; Wood-Hi Cheng

    2004-01-01

    A novel measurement technique employing an ultra high precision laser displacement meter (LDM) with a 20 nm resolution for probing the post-weld-shift (PWS) induced fiber alignment shifts in laser-welded laser module packaging is presented. The results show that the direction and magnitude of the fiber alignment shifts induced by PWS in laser-welded laser module packaging can be determined and measured

  9. A novel technique for optical header multiplexing using coded Frequency Division Multiplexing in optical packet switching networks

    Microsoft Academic Search

    Dulal Hossain; Jae Jeung Rho; Junghoon Moon

    2009-01-01

    The typical labeled optical packet switching requires only the header separation at the core node without touching a payload. Thus labeled optical switching is a promising approach to switch and route optical packets in optical packet switching networks. This paper proposes a novel optical header multiplexing technique by coded frequency division multiplexing (CFDM) with the biased 8B\\/10B coding system. The

  10. Clinical detection of optic nerve damage: measuring changes in cup steepness with use of a new image alignment algorithm.

    PubMed

    Burk, R O; Rendon, R

    2001-05-01

    The purpose of this study was to study the effect of a subpixel image alignment algorithm on the standard deviation (SD) of mean topography images obtained by laser scanning tomography and to evaluate changes of the cup shape measure parameter (CSM) over time based upon the individual parameter variability using the new algorithm. Triple measurements from optic nerve heads of 132 eyes of 132 subjects were obtained using the Heidelberg Retina Tomograph HRT. To calculate a mean topography image from three single topography images, alignment of the raw optical section image data was performed with the standard software and again with a new subpixel-based image alignment algorithm. The effect on the averaged (SD) of the mean topography images was evaluated. CSM was evaluated in 15 eyes of 15 normal subjects (N) and 28 eyes of 14 glaucoma patients (G) over a period of 28.6 +/- 4.6 months (N) and 28.56 +/- 5.2 months (G) respectively. A change in the CSM value over time was considered significant if CSM measurements exceeded two standard deviations of this variable determined for the individual eye. Mean-topography image SD was 22.86 +/- 8.2 microns (min. 9.5 microm; max. 47.8 microm) with the standard alignment procedure and 15.46 +/- 6.8 microm (min. 6.8 microm; max. 42.8 microm) with the new algorithm. The average SD improvement was 7.46 +/- 3.9 microns (min. -8.1 microm; max. 28.7 microm). The coefficient of correlation of both methods was R(2) = 0.77 (p < 0.0001). No control group eye demonstrated significant changes of CSM in the follow-up period. The CSM indicated an increase in cup steepness in 4 eyes of 4 glaucoma patients. In one of these four eyes, a deterioration of the visual field was identified by white on white perimetry. The new image alignment algorithm significantly reduces the SD of mean topography images calculated from identical raw data. If topometric variables are evaluated over time, the individual variability of data should be taken into account. PMID:11377453

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

    E-print Network

    Yang, Changhuei

    | DOI:10.1364/OE.22.014054 | OPTICS EXPRESS 14054 #12;5. D. M. Pepper, D. Fekete, and A. Yariv, "Observation of amplified phase-conjugate reflection and optical parametric oscillation by degenerate four

  12. 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.

  13. Hermetic fiber optic-to-metal connection technique

    DOEpatents

    Kramer, Daniel P. (Centerville, OH)

    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.

  14. 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.

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

    SciTech Connect

    Schley, R. S.; Hurley, D. H. [Dept. of Materials Science, Idaho National Laboratory, Idaho Falls, Idaho 83415 (United States); Hua, Z. A. [Dept. of Materials Science, Idaho National Laboratory, Idaho Falls, Idaho 83415 (United States) and Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States)

    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.

  16. 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.

  17. All-optical clock and data separation technique for asynchronous packet-switched optical time-division-multiplexed networks

    Microsoft Academic Search

    Paul Toliver; Ivan Glesk; Paul R Prucnal

    2000-01-01

    We propose and experimentally demonstrate an all-optical technique for separating a clock synchronization pulse from an optical time-division-multiplexed (OTDM) 100 Gb\\/s data packet. The technique is based on an all-optical switching device combined with optical feedback. This approach removes limitations found in other techniques such as those that are sensitive to long strings of zeroes in the data packet.

  18. Optical modulation techniques for underwater detection, ranging and imaging

    NASA Astrophysics Data System (ADS)

    Mullen, Linda; Cochenour, Brandon; Laux, Alan; Alley, Derek

    2011-06-01

    The focus of this paper is to describe research being conducted at NAVAIR in Patuxent River, MD to improve optical detection, ranging and imaging in the underwater environment through the use of optical modulation techniques. The modulation provides a way to discriminate against unwanted scattered light that would otherwise reduce detection sensitivity. Another benefit of modulating the transmitted light is that coherent detection of the modulation envelope results in the ability to accurately measure the range to the underwater object. Ways to use the hardware and methods developed for the detection, ranging, and imaging scenario to satisfy other mission requirements are also being investigated. The requirements for the modulation scheme, modulation frequency, and laser characteristics (pulsed, continuous, optical power level) depend on the targeted application. The implementation of this optical modulation technique in a variety of underwater sensors has become possible due to recent advances in laser and receiver technology. A review of the work being done in this area of research will be presented, and results from laboratory experiments will be discussed.

  19. Probing Molecular Dynamics with Non-linear Optical Techniques

    NASA Astrophysics Data System (ADS)

    Lausten, Rune

    The dynamics of molecules in the gas and liquid phase is investigated using ultrafast optical techniques. The development of sub-25 fs ultrafast sources using noncollinear optical parametric amplification is discussed. These intense pulses are utilized in coherent anti-Stokes Raman scattering to investigate vibrational motion in I2 Br2 and IBr. For larger bio-molecules relevant dynamics may not be related to the absorption of light. Here, a new technique is introduced, in which an optically excitable molecule is incorporated into the bio-molecule. Photoisomerization of the trigger molecule initiates structural rearrangement in the larger system. To demonstrate this approach, azobenzene was synthesized into short strands of DNA to time-resolve base pair destacking dynamics and DNA melting. The isomerization of azobenzene in thin polymer films (and their corresponding change in optical properties) was also used to write birefringence and surface relief gratings. This method was used to demonstrate a rewritable Bragg filter for telecom wavelengths. Lastly, an alternative to typical crystal based wavemixing is presented for the generation of ultrafast tunable ultraviolet and deep ultraviolet pulses. The approach utilizes difference frequency four wave mixing in hollow waveguides filled with noble gas.

  20. Optical fiber modulation techniques for single mode fiber sensors

    Microsoft Academic Search

    R. P. Tatam

    \\u000a In order to be able to implement the signal processing techniques discussed in Chapter 5 a means is required of measuring\\u000a changes in one or more of the parameters describing the optical beam: amplitude, phase, direction and frequency of the light\\u000a wave. Temporal modulation of one, or more, of these parameters enables information to be encoded onto or extracted from

  1. Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique

    PubMed Central

    Tang, Jianyong; Germain, Ronald N.; Cui, Meng

    2012-01-01

    Biological tissues are rarely transparent, presenting major challenges for deep tissue optical microscopy. The achievable imaging depth is fundamentally limited by wavefront distortions caused by aberration and random scattering. Here, we report an iterative wavefront compensation technique that takes advantage of the nonlinearity of multiphoton signals to determine and compensate for these distortions and to focus light inside deep tissues. Different from conventional adaptive optics methods, this technique can rapidly measure highly complicated wavefront distortions encountered in deep tissue imaging and provide compensations for not only aberration but random scattering. The technique is tested with a variety of highly heterogeneous biological samples including mouse brain tissue, skull, and lymph nodes. We show that high quality three-dimensional imaging can be realized at depths beyond the reach of conventional multiphoton microscopy and adaptive optics methods, albeit over restricted distances for a given correction. Moreover, the required laser excitation power can be greatly reduced in deep tissues, deviating from the power requirement of ballistic light excitation and thus significantly reducing photo damage to the biological tissue. PMID:22586078

  2. Fiber distributed Brillouin sensing with optical correlation domain techniques

    NASA Astrophysics Data System (ADS)

    Hotate, Kazuo

    2013-12-01

    Fiber distributed Brillouin sensing is discussed, focusing mainly on optical correlation domain techniques. By synthesizing a delta-function like optical coherence function between pump and probe lightwave traveling along an optical fiber in opposite directions, which is realized by modulating laser source frequency by an appropriate waveform, stimulated Brillouin scattering can be selectively excited at one specific position along the fiber. The selected position can easily be swept by changing the modulation frequency, so the distributed measurement can be achieved. In the system, Brillouin Optical Correlation Domain Analysis (BOCDA), the position to be measured can be selected randomly along the fiber, which is a special feature of the system. Spatial resolution of 1.6 mm and measurement speed of 1000 samples/s have already been demonstrated. With a similar way, distribution of spontaneous Brillouin scattering can also be measured along the fiber. Spatial resolution of 10 mm and measurement speed of 50 samples/s have already been demonstrated in the system, Brillouin Optical Correlation Domain Reflectometry (BOCDR). Brillouin dynamic grating (BDG), which is acoustic-wave generated refractive-index grating caused in the stimulated Brillouin scattering process, was found to cause a Bragg reflection for the orthogonally polarized lightwave in an polarization maintaining fiber. By measuring both the BDG and the Brillouin scattering, discriminative distributed measurement of strain and temperature has been realized by the BOCDA scheme with a 10 mm spatial resolution.

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

    PubMed Central

    2014-01-01

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

  4. 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

  5. Review of optical multiple-input-multiple-output techniques in multimode fiber

    NASA Astrophysics Data System (ADS)

    Amphawan, Angela

    2011-10-01

    The success of optical multiple-input-multiple output (MIMO) systems in wireless communications has motivated interesting investigations of MIMO in optical fiber communications. This paper reviews various optical MIMO techniques in multimode fiber.

  6. Review of optical multiple-input-multiple-output techniques in multimode fiber

    Microsoft Academic Search

    Angela Amphawan

    2011-01-01

    The success of optical multiple-input-multiple output (MIMO) systems in wireless communications has motivated interesting investigations of MIMO in optical fiber communications. This paper reviews various optical MIMO techniques in multimode fiber.

  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 [Department of Radiation Oncology, University of Florida College of Medicine, Gainesville, Florida 32610 (United States)

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

    PubMed

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

    2015-08-01

    The present study was to examine the distribution of lymphatic vessels in the penis of normal adult males, which could provide an anatomical basis for improvement of incisions in penile lengthening surgery, and may also help to prevent postoperative refractory edema. Thirteen normal adult male volunteers were recruited for this study. Contrast agent was injected subcutaneously in the foreskin of the penis, and after two minutes magnetic resonance lymphangiography (MRL) was performed. The acquired magnetic resonance images were analyzed to determine the changes in the number and diameter of lymphatic vessels in different parts of the penis. Maximum intensity projections (MIP) and materializes interactive medical image control system (MIMICS) were applied to analyze the overall distribution of lymphatic vessels in the penis. Magnetic resonance imaging (MRI) showed that the lymphatic vessels were in conspicuous contrast with surrounding tissues and could be clearly identified. Penile lymphatic vessels were clearly visible in the root of the penis. At the junction of the penis and the abdominal wall, all lymphatic vessels were found to be concentrated in the dorsal part of the penis. MIP two-dimensional reconstruction showed that the overall distribution of relatively large lymphatic vessels in the dorsal and ventral parts of the penis could be seen clearly on bilateral 45° position, but not inside the abdominal wall because some of lymphatic vessels were overlapped by other tissues in the abdomen. MIMICS three-dimensional reconstruction was able to reveal the overall spatial distribution of lymphatic vessels in the penis from any angle. The reconstruction results showed that there were 1-2 main lymphatic vessels on the root of dorsal penis, which coursed along the cavernous to the first physiological curvature of the penis. Lymphatic vessels merged on both sides of the ventral penis. At the root of the penis, lymphatic vessels gradually coursed to the dorsal surface of the penis and folded at the abdominal wall to the outside, and finally merged into the inguinal lymph nodes. The changes in distribution, number and diameter of the lymphatic vessels in the penis were observed by MRI. MIP and MIMICS reconstructions directly revealed the anatomical features of penile lymphatic vessels such as spatial distribution, overall alignment, and the relations to adjacent structures, drainage and reflux. The study will provide the anatomical basis for penile surgery, penile lymphatic reflux disorders caused by trauma or lymphatic vessels obstruction, and lymph node metastasis in penile cancer. Anat Rec, 298:1465-1471, 2015. © 2014 Wiley Periodicals, Inc. PMID:25403330

  9. Advances in polymer optical devices and waveguide fabrication techniques

    NASA Astrophysics Data System (ADS)

    Herman, Warren N.; Chen, Wei-Yen; Kim, Younggu; Hutchinson, Glenn; Cao, Wei Lou; Leng, Yongzhang; Yun, Victor; Liang, Hongye; Peng, Yi-Hsing; Du, Min; Lucas, Lisa; Ho, Ping-Tong; Goldhar, Julius; Lee, Chi H.

    2004-10-01

    We report progress in the development of polymer waveguides and devices for photonic applications in three areas: non-photolithographic techniques for polymer waveguide fabrication, bistability in laterally-coupled polymer microring resonators, and ultrafast photoconductive switches fabricated from semiconducting polymers. The non-photolithographic techniques for waveguide fabrication under development include laser milling with an excimer laser and programmable automatic dispensing of multimode polymer waveguides using an Essemtech automatic dispenser. Asymmetric diffraction gratings fabricated using phase masks and the interference of two excimer laser beams have exhibited concentration of optical power into the 1st diffraction order. Polymer micro-ring resonators laterally coupled to a bus line were fabricated by lithography from benzocyclobutene with radii as small as 10 ?m and free spectral ranges on the order of 20 nm. These devices exhibit bistability in the frequency domain which can arise from thermal or nonlinear optical changes in refractive index and that may have application for all-optical switching. Metal-polymer-metal switches fabricated with interdigitated electrodes in an inverted structure exhibited fast transient photoconductive pulsewidths under 20 ps in response to femtosecond pump laser pulses, but the measurement was bandwidth limited by the oscilloscope. Here we report pump-probe measurements that indicate carrier lifetimes on the order of 2 ps.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. 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 ?m 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.

  12. Optical velocity-measurement techniques for supersonic surfaces.

    SciTech Connect

    Briggs, M,E. (Matthew E.); Hemsing, W. F. (Willard F.); Shinas, M. A. (Michael A.)

    2004-01-01

    Interferometric techniques have been used routinely for more than 20 years to measure velocities of explosive shock-fronts. Recently, structured-light measurements have been used for the same purpose. Explosions accelerate surfaces to as much as 15 km/sec in a nanosecond or less, often generating much light, large changes in reflectivity, and ejecting particles or layers at different speeds. I will describe the current performance of fiber-optic displacement-interferometers, Fabret-Perot inteferometers, velocity interferometers (VISAR), and structured light, in this interesting physical space. We have designed and used for several years a 1/4 inch OD optical probe with large depth of field that both illuminates and returns the image from a surface inside a confined geometry. We report on its design and performance. The increased information from the surface requires greater automation from the analysis software. We report our software automation and analysis improvements.

  13. Current modulation technique used in resonator micro-optic gyro.

    PubMed

    Lei, Ming; Feng, Lishuang; Zhi, Yinzhou; Liu, Huilan; Wang, Junjie; Ren, Xiaoyuan; Su, Ni

    2013-01-10

    Resonator micro-optic gyro (RMOG) is a promising candidate for the next generation inertial rotation sensor based on the Sagnac effect. A current modulation technique used in an external cavity laser diode is proposed to construct the gyroscope system for the first time. The resonance curves before and after eliminating accompanying amplitude modulation are theoretically analyzed, calculated, and simulated; the demodulation curves with different modulation currents are formulated theoretically; and the optimum modulation current corresponding to the maximum sensitivity is obtained. The experiment results from the established RMOG experimental setup demonstrate that a bias stability of 2.7 deg/s (10 s integrated time) over 600 s, and dynamic range of ±500 deg/s are demonstrated in an RMOG with a silica optical waveguide ring resonator having a ring length of 12.8 cm. PMID:23314650

  14. 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.

  15. Construction, alignment, and implementation of an acousto-optical deflector-based system for patterned uncaging with ultraviolet light.

    PubMed

    Civillico, Eugene F; Shoham, Shy; O'Connor, Daniel H; Sarkisov, Dmitry V; Wang, Samuel S-H

    2012-08-01

    The method of patterned photoactivation is a natural fit for the study of neuronal dendritic integration. Photoactivatable molecules that influence a wide range of extracellular and intracellular neurophysiological functions are available. The choice of photosensitive molecules depends on the research question and will influence the design of the experimental apparatus. An acousto-optical deflector (AOD)-based system can be used for rapid ultraviolet (UV) photolysis in arbitrary spatial and temporal patterns. Photolysis-activated "caged" diffusible molecules or newer light-sensitive membrane proteins can be used in this system. This protocol describes the addition of a UV beam for uncaging to a homebuilt two-photon microscope. The goal is to get UV light from the light source (laser) to the approximate center of the objective's back aperture, passing through a pair of perpendicularly oriented AODs along the way. The protocol also describes the fine alignment of the UV beam and the implementation of AOD-based beam steering. Performing the final alignment with the beam passing through the AODs will ensure that the system is optimized for the idiosyncrasies of the crystals. PMID:22854574

  16. Differences in optical properties of normal and tumoral tissues: a comparison to accuracy limits in laser techniques for optical imaging

    NASA Astrophysics Data System (ADS)

    Falco, Maria D.; Lepore, Maria; Indovina, Pietro L.

    2000-11-01

    The use of optical techniques for diagnostic purpose relies on the capability to measure the optical properties of healthy and pathological tissues and in appreciating their relative differences. In fact, a degree of contrast must exist between absorption and scattering coefficients for effective detection of a tissue alteration using optical imaging. In this contest, it is important to study the accuracy limits of different optical measurement techniques in order to establish their performances in recovering the optical parameters. The accuracy limit of laser techniques in the determination of optical methods have been recovered partly from literature and, as far as concerns time-resolved techniques, from experimental work carried on in our laboratory using a conventional time-resolved system. The results from this analysis allow us to better identify the role of different experimental techniques, which are generally proposed in optical imaging for diagnostic purpose.

  17. Broadband, Polarization-Sensitive Photodetector Based on Optically-Thick Films of Macroscopically Long, Dense, and Aligned Carbon Nanotubes

    PubMed Central

    Nanot, Sébastien; Cummings, Aron W.; Pint, Cary L.; Ikeuchi, Akira; Akiho, Takafumi; Sueoka, Kazuhisa; Hauge, Robert H.; Léonard, François; Kono, Junichiro

    2013-01-01

    Increasing performance demands on photodetectors and solar cells require the development of entirely new materials and technological approaches. We report on the fabrication and optoelectronic characterization of a photodetector based on optically-thick films of dense, aligned, and macroscopically long single-wall carbon nanotubes. The photodetector exhibits broadband response from the visible to the mid-infrared under global illumination, with a response time less than 32??s. Scanning photocurrent microscopy indicates that the signal originates at the contact edges, with an amplitude and width that can be tailored by choosing different contact metals. A theoretical model demonstrates the photothermoelectric origin of the photoresponse due to gradients in the nanotube Seebeck coefficient near the contacts. The experimental and theoretical results open a new path for the realization of optoelectronic devices based on three-dimensionally organized nanotubes. PMID:23443054

  18. Low-Cost, Precision, Self-Alignment Technique for Coupling Laser and Photodiode Arrays to Polymer Waveguide Arrays on Multilayer PCBs

    Microsoft Academic Search

    Ioannis Papakonstantinou; David R. Selviah; Richard C. A. Pitwon; Dave Milward

    2008-01-01

    The first, to our knowledge, passive, precision, self-alignment technique for direct coupling of vertical cavity surface emitting laser (VCSEL) and photodiode (PD) arrays to an array of polymer buried channel waveguides on a rigid printed circuit board (PCB) is reported. It gives insertion losses as good as the best achieved previously, to within experimental measurement accuracy, but without the need

  19. 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.

  20. 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

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

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

    SciTech Connect

    Tang, Runsheng; Yu, Yamei [Education Ministry Key Laboratory of Advanced Technology and Preparation for Renewable Energy Materials, Yunnan Normal University, Kunming 650092 (China)

    2010-09-15

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

  3. PARAMAGNETIC RESONANCE FINE STRUCTURES OF OPTICALLY ALIGNED Cs¹³³, Rb⁸⁷ AND Rb⁸⁵ VAPOUR

    Microsoft Academic Search

    Ando

    1963-01-01

    The optical pumping principle, with the observation of the circularly ; polarized D⁠radiation that was transmitted through the vapor, was used to ; obtain the paramagnetic resonance fine structures of optically aligned Cs¹³³; , Rb⁸⁵, and Rb\\/sup 87. In Cs¹³³ and Rb⁸⁷ there are two peaks ; corresponding to F = 3,4 and 1,2 respectively. In Rb⁸⁵ the peak

  4. 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.

  5. Studies of ferroelectric materials using novel optical techniques

    NASA Astrophysics Data System (ADS)

    Yang, Xi

    Morphotropic phase boundary (MPB) lead barium niobate (PBN) thin films are potentially important for optical and electronic applications due to their high switchable polarizability, thus giving large electro-optic and peizoelectric coefficients, and readily engineered tuning characteristics. The focus of this research was to fabricate high quality PBN thin films and to characterize their piezoelectric and electrostrictive properties using both transmission and reflection methods. We successfully grew PBN:65 thin films using pulsed laser deposition (PLD). Interdigital capacitors (IDC), consisting of with 10-pm conducting lines separated by 10-mum spaces, were deposited on top of the film to allow us to apply an external electric field. This dissertation presents two optical models to analyze our results. Optical model I was developed for characterization of electro-optic properties. New peaks in the diffraction were predicted due to the field induced period doubling. Optical model II was based upon the experimental observation that a superposition of a diffraction pattern, interference pattern and grating images was obtained when a grating sample was illuminated by a divergent beam. A combination of the geometrical rays and boundary diffraction waves was used to qualitatively reconstruct the superposed patterns. The field-induced bending of the PBN:65 thin film sample, resulting from its piezoelectric properties, was measured in both transmission and reflection experiments. A bending model was used to obtain the strain from the bending angle measurement. Either a piezoelectric constant of 1750 +/- 0.0002 (pC/N) or an electrostrictive constant of 0.000875 +/- 0.00005 (mum 2/V2) was calculated using the IEEE standard model. We believe, however, that electrostriction better describes the experimental results. In addition, three different types of strain-electric field hysteresis was measured in this PBN:65 thin film sample in the reflection experiment. A LiNbO3 sample with an IDC consisting of 7-mum lines and 8-mum spaces was used to observe the new peaks that were predicted in optical model II. These new peaks were observed in both the transmission and reflection experiments. In the transmission experiment, a sample scan technique was developed to examine the electric field distribution in the grating spaces in order to improve the accuracy of the electro-optic measurement. This same sample could be applied to examine experimentally electronic defects in thin film devices. The major contributions resulting from using a divergent beam to illuminate the grating sample in the transmission experiment are: (1) a magnification of more than 100 of the grating images is obtained; (2) the superposition of three different patterns provides a new method to calibrate the piezoelectric and electrostrictive properties of ferroelectric thin films; (3) a field imaging technique is developed for electronic defect examination and electric field distribution measurement. These results are experimentally observed and theoretically verified.

  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. Single point active alignment method (SPAAM) for optical see-through HMD calibration for AR

    Microsoft Academic Search

    Mihran Tuceryan; Nassir Navab

    2000-01-01

    Augmented reality (AR) is a technology in which a user's view of the real world is enhanced or augmented with additional information generated from a computer model. In order to have a working AR system, the see-through display system must be calibrated so that the graphics is properly rendered. The optical see-through systems present an additional challenge because we do

  8. In situ measurement of misalignment errors in free-space optical interconnects

    Microsoft Academic Search

    G. C. Boisset; D. R. Rolston; B. Robertson; Y. S. Liu; R. Iyer; D. Kabal; D. V. Plant

    1998-01-01

    A nonobtrusive technique for measuring misalignment errors in multistage free-space optical interconnects is proposed. The technique makes use of dedicated microoptics to relay higher order dedicated alignment beams generated by an optical power supply onto alignment detectors located on the periphery of a smart pixel chip. An implementation of this technique for measuring lateral (x-y) misalignment error in a multistage

  9. Hybrid technique for enhanced optical ranging in turbid water environments

    NASA Astrophysics Data System (ADS)

    Lee, Robert W.; Laux, Alan; Mullen, Linda J.

    2014-05-01

    A hybrid approach is described that enhances the performance of an underwater optical ranging system. This approach uses high-frequency modulation and a spatial delay line filter to suppress unwanted backscatter. A dual frequency approach is also implemented to reduce the effects of forward scatter and remove the ambiguity associated with using the phase of the single, high-frequency modulation envelope to measure range. Controlled laboratory experiments were conducted to evaluate the effectiveness of the hybrid technique to reject multiple scattered light and improve range precision. The experimental results were compared with data generated from a theoretical model developed to predict the performance of the technique as a function of system and environmental variables. Model and experimental results are shown that reveal the ability of the approach to provide accurate ranging to an underwater object in a variety of water environments. Model predictions also indicate that advancements in transmitter and receiver technology will extend the range and improve the accuracy of the technique beyond what has been achieved thus far.

  10. Unstable confocal resonator cavity alignment system

    Microsoft Academic Search

    R. Guthrie; T. B. Mc Donald; D. Anafi

    1987-01-01

    An optical alignment system is described for controlling the relative orientation of a second mirror with respect to the orientation of a convex cavity surface of a first mirror in a high-power optical cavity. The system comprises: an alignment laser for generating an alignment beam; a controlled steering mirror for adjusting the direction of propagation of the alignment beam; first

  11. CLASP (Capture and Locking alignment Spring Positioner): A micromachined fiber auto-positioning device

    SciTech Connect

    Kravitz, S.H.; word, J.C.; Bauer, T.M.; Seigal, P.K.; Armendariz, M.G.

    1996-03-01

    This work provides a method of mechanical alignment of an array of single mode fibers to an array of optical devices. The technique uses a micromachined metal spring, which captures a vertical, pre- positioned fiber, moves it into accurate alignment, and holds it for attachment. The spring is fabricated from electroplated mickel, using photodefined polyimide as a plating mask. The nickel is plated about 80 {mu}m thick, so that a large fiber depth is captured. In one application, the nickel springs can be aligned to optics on the back side of the substrate. This entire concept is referred to as CLASP (Capture and Locking Alignment Spring Positioner). These springs can be used for general alignment and capture of any fiber to any optical input or output device. Passive alignment of fiber arrays to {plus}/{minus} 2{mu}m accuracy has been demonstrated, with a clear path to improved accuracy.

  12. Effect of SRS on pilot-tone-based monitoring technique in DWDM optical communication system

    Microsoft Academic Search

    Zhiguo Gao; Jiangang Jin; Minghua Chen; Shizhong Xie

    2002-01-01

    Optical performance monitoring is an important issue for the design, operation and maintenance of optical transport networks (OTN). Pilot tone detection is a simple technique for optical performance monitoring, which could monitor both the optical paths ans switch failures in networks. The effect of Stimulated Roman Scattering (SRS) could produce ghost tone that will suppress the capability of pilot-tone based

  13. 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…

  14. 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.

  15. 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

  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. Survey of interferometric techniques used to test JWST optical components

    Microsoft Academic Search

    H. Philip Stahl; Chris Alongi; Andrea Arneson; Rob Bernier; Bob Brown; Dave Chaney; Glen Cole; Jay Daniel; Lee Dettmann; Ron Eng; Ben Gallagher; Robert Garfield; James Hadaway; Patrick Johnson; Allen Lee; Doug Leviton; Adam Magruder; Michael Messerly; Ankit Patel; Pat Reardon; John Schwenker; Martin Seilonen; Koby Smith; W. Scott Smith

    2010-01-01

    JWST optical component in-process optical testing and cryogenic requirement compliance certification, verification & validation is probably the most difficult metrology job of our generation in astronomical optics. But, the challenge has been met: by the hard work of dozens of optical metrologists; the development and qualification of multiple custom test setups; and several new inventions, including 4D PhaseCam and Leica

  18. Precision alignment device

    DOEpatents

    Jones, Nelson E. (Huntington Beach, CA)

    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.

  19. 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.

  20. Optical constants of Zn 1? x Li x O films prepared by chemical bath deposition technique

    Microsoft Academic Search

    A. Abu EL-Fadl; Galal A. Mohamad; A. B. Abd El-Moiz; M. Rashad

    2005-01-01

    Zn1?xLixO films of different Li concentrations x=0.0–0.5 were successfully deposited on glass substrates using chemical bath deposition (CBD) technique. Optical properties of the films were studied extensively in the wavelength range 190–800nm from the measurements of the optical transmittance (T) and optical reflectance (R). The mechanism of the optical absorption follows the rule of direct allowed transition. Both the optical

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  2. Measurement of laser frequency response through heterodyne technique using optical modulation 

    E-print Network

    Ahmed, Syed Faisal

    1994-01-01

    An optical modulation technique for measuring the parasitic-free frequency response of high frequency semiconductor lasers is demonstrated. In this technique, we heterodyne light from two continuously tunable external cavity travelling wave ring...

  3. Measurement of laser frequency response through heterodyne technique using optical modulation

    E-print Network

    Ahmed, Syed Faisal

    1994-01-01

    An optical modulation technique for measuring the parasitic-free frequency response of high frequency semiconductor lasers is demonstrated. In this technique, we heterodyne light from two continuously tunable external cavity travelling wave ring...

  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. 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.

  7. Novel technique for solar power illumination using plastic optical fibres

    NASA Astrophysics Data System (ADS)

    Munisami, J.; Kalymnios, D.

    2008-09-01

    Plastic Optical Fibres (POF) were developed almost 3 decades ago. They are mainly used for short haul data communications (up to 1 km with data rates up to 1 Gbps). Over the years, POF has found applications in many other areas including solar energy transport for illumination. In such an application, light is collected from the sun and is directed into a space which needs to be illuminated. The use of fibres and more specifically POF, in daylighting systems, started only a few years ago. Several approaches have been investigated and we have seen the development of a few commercial products. The market however, has not really taken off for these technologies simply because of their enormous price tags. It is important to note that the use of POF in these designs has been limited to the function of POF as the transmission medium only. We propose a novel solar illumination technique using POF as both the light collecting/concentrating mechanism and the transmission medium. By modifying the structure of the fibre, solar light can be directed into the fibre by using an analogous process to fibre side emission but, in the reverse. We shall report on the solar light capturing efficiency of POF as modified by several types of external imperfections introduced onto the fibre. One major advantage of our proposed approach lies in the fact that we aim to eliminate at least one of the two axes of sun tracking that is currently used in existing solar illumination systems.

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

    PubMed

    Piper, T; Piper, J

    2012-09-01

    Axial phase-darkfield-contrast (APDC) has been developed as an illumination technique in light microscopy which promises significant improvements and a higher variability in imaging of several transparent 'problem specimens'. With this method, a phase contrast image is optically superimposed on an axial darkfield image so that a partial image based on the principal zeroth order maximum (phase contrast) interferes with an image, which is based on the secondary maxima (axial darkfield). The background brightness and character of the resulting image can be continuously modulated from a phase contrast-dominated to a darkfield-dominated character. In order to achieve this illumination mode, normal objectives for phase contrast have to be fitted with an additional central light stopper needed for axial (central) darkfield illumination. In corresponding condenser light masks, a small perforation has to be added in the centre of the phase contrast providing light annulus. These light modulating elements are properly aligned when the central perforation is congruent with the objective's light stop and the light annulus is conjugate with the phase ring. The breadth of the condenser light annulus and thus the intensity of the phase contrast partial image can be regulated with the aperture diaphragm. Additional contrast effects can be achieved when both illuminating light components are filtered at different colours. In this technique, the axial resolution (depth of field) is significantly enhanced and the specimen's three-dimensional appearance is accentuated with improved clarity as well as fine details at the given resolution limit. Typical artefacts associated with phase contrast and darkfield illumination are reduced in our methods. PMID:22906013

  9. Low cost optical interconnects

    NASA Astrophysics Data System (ADS)

    Palen, Edward

    2007-02-01

    Optical interconnects to couple light from single mode fiber to waveguides and photonic elements have remained expensive due to tight alignment tolerances, materials choices, fabrication methods and assembly processing techniques. Methods that have been used to lower the cost of optical interconnects will be reviewed and compared to current and future market application demands. Design approaches, fabrication methodologies, and assembly processing techniques for optical interconnects to meet future lower cost market application demands will be shared.

  10. 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

  11. Silicon wafer board alignment of laser arrays to single-mode optical fiber for analog optoelectronic module applications

    Microsoft Academic Search

    Paul O. Haugsjaa; Craig A. Armiento; A. J. Negri; Joseph Mehr; Marvin J. Tabasky; Hui-Pin Hsu; Willie W. Ng; Daniel Yap; Huan-Wun Yen

    1996-01-01

    This paper describes the development of laser transmitter arrays for analog optoelectronic link applications up to 2 GHz. These modules have been developed in an attempt to utilize passive assembly and alignment operations for the purpose of reducing costs. To this end, silicon waferboard integration platforms and semiconductor laser arrays have been fabricated with special alignment features that allow passive

  12. Optical and surface morphological properties of polarizing films fabricated from a chromonic dye by the photoalignment technique.

    PubMed

    Ruslim, Christian; Hashimoto, Masanori; Matsunaga, Daisaku; Tamaki, Takashi; Ichimura, Kunihiro

    2004-01-01

    The inherent chromonic lyotropic liquid crystalline properties of a dye have been manipulated to fabricate multi-axial micropolarizing thin films by means of the photoalignment technique. The dye aqueous solution is deposited on a photopatterned polymer film to result in the macroscopic alignment of the dye molecules, followed by drying at ambient temperature. The solid polarizing dye layers thus produced exhibit very a high contrast ratio and degree of polarization in the region of visible light. Addition of a small amount of surfactant to the dye solution is a prerequisite for the generation of a nematic chromonic phase and for the formation of homogeneous thin dye layers on the polymer film. The correlation between the optical and surface morphological properties of the dye layers is discussed. PMID:15745005

  13. An Optical Imaging Technique Using Deep Illumination in the Angular Domain

    Microsoft Academic Search

    Fartash Vasefi; Paulman K. Y. Chan; Bozena Kaminska; Glenn H. Chapman; Nick Pfeiffer

    2007-01-01

    This paper describes a novel optical imaging method, deep illumination angular domain imaging (ADI), for detecting micron-scale objects within highly scattering media. The new optical imaging is a much simpler and less expensive solution as compared to other available optical imaging techniques. In principle, deep illumination ADI uses collimation detection capabilities of small acceptance angle devices to extract photons emitted

  14. A Robust Continuous-Time Multi-Dithering Technique for Laser Communications using Adaptive Optics

    E-print Network

    Cauwenberghs, Gert

    A Robust Continuous-Time Multi-Dithering Technique for Laser Communications using Adaptive Optics-dither algorithm for adaptive optics robustly and in continuous-time. Similar architectures have been The inherent decades, significant work has been done in the field of adaptive optics in order to alleviate or at least

  15. 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.

  16. Developments in on-line, electron-beam emittance measurements using optical transition radiation techniques

    SciTech Connect

    Feldman, R.B.; Lumpkin, A.H. (Los Alamos National Lab., NM (USA)); Rule, D.W.; Fiorito, R.B. (Naval Surface Warfare Center, Silver Spring, MD (USA))

    1989-01-01

    We have developed image analysis software to facilitate the analysis of optical transition radiation (OTR) patterns generated by the electron beam from the Los Alamos free-electron laser facility. The software can be used for beam alignment, beam profile and angular divergence measurements, and the programs run on an IBM AT microcomputer. The programs and their use are described and some results shown. 2 refs., 17 figs.

  17. Frequency-Domain Techniques Enhance Optical Mammography: Initial Clinical Results

    Microsoft Academic Search

    Maria Angela Franceschini; K. Thomas Moesta; Sergio Fantini; Gerhard Gaida; Enrico Gratton; Helge Jess; William W. Mantulin; Marcel Seeber; Peter M. Schlag; Michael Kaschke

    1997-01-01

    We present a novel approach to optical mammography and initial clinical results. We have designed and developed a frequency-domain (110-MHz) optical scanner that performs a transillumination raster scan of the female breast in approximately 3 min. The probing light is a dual-wavelength (690 and 810 nm, 10-mW average power), 2-mm-diameter laser beam, and the detection optical fiber is 5 mm

  18. Recent advances in optical processing techniques using highly nonlinear bismuth oxide fiber

    Microsoft Academic Search

    Mable P. Fok; Chester Shu

    2008-01-01

    We report our recent studies on nonlinear processing of optical signals using a 35-cm highly nonlinear bismuth oxide fiber (Bi-NLF). Our findings are based on self-phase modulation, cross-phase modulation, and four-wave mixing in the Bi-NLF. We demonstrate applications of the nonlinear techniques in optical signal regeneration, tunable optical delay, stabilization of multiwavelength laser source, tunable optical pulse generation, microwave photonic

  19. Optical constants of Zn1-xLixO films prepared by chemical bath deposition technique

    Microsoft Academic Search

    A. Abu El-Fadl; Galal A. Mohamad; A. B. Abd El-Moiz; M. Rashad

    2005-01-01

    Zn1-xLixO films of different Li concentrations x=0.0 0.5 were successfully deposited on glass substrates using chemical bath deposition (CBD) technique. Optical properties of the films were studied extensively in the wavelength range 190 800 nm from the measurements of the optical transmittance (T) and optical reflectance (R). The mechanism of the optical absorption follows the rule of direct allowed transition.

  20. 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

  1. 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

  2. Smectic Layer Structure of Thin Ferroelectric Liquid Crystal Cells Aligned by SiO Oblique Evaporation Technique

    Microsoft Academic Search

    Yukio Ouchi; Ji Lee; Hideo Takezoe; Atsuo Fukuda; Katsumi Kondo; Teruo Kitamura; Akio Mukoh

    1988-01-01

    Smectic layer structures were studied by high-resolution X-ray analysis for two kinds of cells aligned on SiO obliquely evaporated film; the glass plates were fabricated for the evaporation direction to be the same (parallel) or to be the opposite (antiparallel). For parallel cells, a chevron layer structure was formed. The temperature dependence was similar to that of a rubbing cell,

  3. Molecular alignment in submicron patterned polymer matrix using nanoimprint lithography

    E-print Network

    Molecular alignment in submicron patterned polymer matrix using nanoimprint lithography Jian Wang important examples are the electro-optical modulator5,6 and the frequency converter sum frequency generation or chro- mophores in a polymer matrix. Poling by electrical field5­7 or laser10 is a widely used technique

  4. Performance of synchronous optical receivers using atmospheric compensation techniques

    E-print Network

    Kahn, Joseph M.

    . Barros, and J. M. Kahn, "Coherent detection in optical fiber systems," Opt. Express 16, 753-791 (2008). 9. M. P. Cagigal and V. F. Canales, "Speckle statistics in partially corrected wave fronts," Opt. Lett. 23, 1072- 1074 (1998). 10. J. W. Goodman, Speckle Phenomena in Optics. Theory and Applications (Ben

  5. Stream Processing Techniques for High Performance Optical Flow Approximation

    Microsoft Academic Search

    David Dobson; Andrew Strelzoff

    Optical flow in vision systems is the identification of apparent motion of objects or visual features in a scene observed from a fixed point. For scenes with either large numbers of objects or complex moving surfaces this problem is quite computationally challenging. In ocean modeling there is a need for optical flow approximations of wave motion but current implementations are

  6. Vibration suppression techniques for optical inter-satellite communications

    Microsoft Academic Search

    Tong Luo; Yu Hu

    2002-01-01

    Optical inter-satellite communications is a promising method in space-based communications. In order to communicate between satellites, the laser beam of the communication partner must be acquired, pointed and tracked. The optical communication transceiver is impacted by the host platform vibration and space environment as payload of the satellite. This paper summarily explains the design requirements of acquisition, pointing and tracking

  7. Nonlinear optical Fourier filtering technique for medical image processing

    E-print Network

    Rao, D.V.G.L.N.

    optical filtering; optical Fourier processing; bacteriorhodopsin film; breast cancer; mammography. Paper. 3, 2005; published online Jul. 15, 2005. 1 Introduction Breast cancer is still one of the leading causes of mortality in women.1 Early detection of the cancer is extremely important for successful

  8. On the alignment for precession electron diffraction.

    PubMed

    Liao, Yifeng; Marks, Laurence D

    2012-06-01

    Precession electron diffraction has seen a fast increase in its adoption as a technique for solving crystallographic structures as well as an alternative to conventional selected-area and converged-beam diffraction methods. One of the key issues of precession is the pivot point alignment, as a stationary apparent beam does not guarantee a fixed pivot point. A large precession tilt angle, along with pre-field and post-field misalignment, induces shift in the image plane. We point out here that the beam should be aligned to the pre-field optic axis to keep the electron illumination stationary during the rocking process. A practical alignment procedure is suggested with the focus placed on minimizing the beam wandering on the specimen, and is demonstrated for a (110)-oriented silicon single crystal and for a carbide phase (?20nm in size) within a cast cobalt-chromium-molybdenum alloy. PMID:22634134

  9. On the alignment for precession electron diffraction

    PubMed Central

    Liao, Yifeng; Marks, Laurence D.

    2013-01-01

    Precession electron diffraction has seen a fast increase in its adoption as a technique for solving crystallographic structures as well as an alternative to conventional selected-area and converged-beam diffraction methods. One of the key issues of precession is the pivot point alignment, as a stationary apparent beam does not guarantee a fixed pivot point. A large precession tilt angle, along with pre-field and post-field misalignment, induces shift in the image plane. We point out here that the beam should be aligned to the pre-field optic axis to keep the electron illumination stationary during the rocking process. A practical alignment procedure is suggested with the focus placed on minimizing the beam wandering on the specimen, and is demonstrated for a (110)-oriented silicon single crystal and for a carbide phase (~20 nm in size) within a cast cobalt–chromium–molybdenum alloy. PMID:22634134

  10. MP-Align: alignment of metabolic pathways

    PubMed Central

    2014-01-01

    Background Comparing the metabolic pathways of different species is useful for understanding metabolic functions and can help in studying diseases and engineering drugs. Several comparison techniques for metabolic pathways have been introduced in the literature as a first attempt in this direction. The approaches are based on some simplified representation of metabolic pathways and on a related definition of a similarity score (or distance measure) between two pathways. More recent comparative research focuses on alignment techniques that can identify similar parts between pathways. Results We propose a methodology for the pairwise comparison and alignment of metabolic pathways that aims at providing the largest conserved substructure of the pathways under consideration. The proposed methodology has been implemented in a tool called MP-Align, which has been used to perform several validation tests. The results showed that our similarity score makes it possible to discriminate between different domains and to reconstruct a meaningful phylogeny from metabolic data. The results further demonstrate that our alignment algorithm correctly identifies subpathways sharing a common biological function. Conclusion The results of the validation tests performed with MP-Align are encouraging. A comparison with another proposal in the literature showed that our alignment algorithm is particularly well-suited to finding the largest conserved subpathway of the pathways under examination. PMID:24886436

  11. Optical 8-channel, 10 Gb\\/s MT pluggable connector alignment technology for precision coupling of laser and photodiode arrays to polymer waveguide arrays for optical board-to-board interconnects

    Microsoft Academic Search

    Ioannis Papakonstantinou; David R. Selviah; Kai Wang; Richard A. Pitwon; Ken Hopkins; Dave Milward

    2008-01-01

    The paper introduces a low cost, precision alignment technique designed to be unaffected by temperature or process variations in the thickness of the PCB FR4 board, the thickness of the lower cladding between the PCB board and the waveguide core, the thickness of the upper cladding above the waveguide core, the relative lateral position of waveguides across the PCB, and

  12. 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

  13. Guided scrambling: a new line coding technique for high bit rate fiber optic transmission systems

    Microsoft Academic Search

    I. J. Fair; W. D. Grover; W. A. Krzymien; R. I. MacDonald

    1991-01-01

    The technique introduced has relatively simple encoding and decoding procedures which can be implemented at the high bit rates used in optical fiber communication systems. Because it is similar to the established technique of self-synchronizing scrambling but is also capable of guiding the scrambling process to produce a balanced encoded bit stream, the technique is called guided scrambling, (GS). The

  14. Kerr electro-optic measurement technique for determination of nonuniform electric fields

    Microsoft Academic Search

    A. Ustundag; T. J. Gung; M. Zalin

    1996-01-01

    Use of the ac modulation technique which has an ac high voltage superposed onto a dc high voltage has increased the sensitivity of Kerr electro-optic measurements. The technique has been used when the electric field magnitude and direction have been constant along the light path. Recently the technique was extended with use of the Abel transformation to recover the non-uniform

  15. Evaluation of spectrally efficient indoor optical wireless transmission techniques 

    E-print Network

    Fath, Thilo Christian Martin

    2014-06-30

    Optical wireless communications (OWC) has the potential to become a remedy for the shortage of the radio frequency (RF) spectrum. Especially in indoor environments, OWC could enable wireless home networking systems which offload data traffic from...

  16. 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.

  17. Optical fiber packaging for MEMS interfacing

    NASA Astrophysics Data System (ADS)

    Mireles, Jose, Jr.; Garcia, Miguel A.; Ambrosio, Roberto C.; Garcia, Ernest J.; Calleja, Wilfrido; Reyes, Claudia

    2009-02-01

    An investigation study concerning positioning, alignment, bonding and packaging of optical fibers for interfacing with optical MEMS devices is being reviewed in this paper. The study includes a review of techniques and critical issues for optical fiber positioning, alignment, bonding, optical improvements, and coupling and interfacing through micro-lenses and waveguides. Also, we present a packaging design structure for hermetic sealing of optical MEMS devices requiring interfacing through optical fibers which considers aspects such as processes, assemble schemes and bonding techniques for Optical Fibers, which are briefly reviewed in this work. This packaging design considers the following conditions: hermeticity of the MEMS devices, optical fiber and MEMS die alignment and positioning, assembly process, and Simachined fixturing design for final assembly and positioning.

  18. 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.

  19. 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.

  20. Validation and qualification of surface-applied fibre optic strain sensors using application-independent optical techniques

    NASA Astrophysics Data System (ADS)

    Schukar, Vivien G.; Kadoke, Daniel; Kusche, Nadine; Münzenberger, Sven; Gründer, Klaus-Peter; Habel, Wolfgang R.

    2012-08-01

    Surface-applied fibre optic strain sensors were investigated using a unique validation facility equipped with application-independent optical reference systems. First, different adhesives for the sensor's application were analysed regarding their material properties. Measurements resulting from conventional measurement techniques, such as thermo-mechanical analysis and dynamic mechanical analysis, were compared with measurements resulting from digital image correlation, which has the advantage of being a non-contact technique. Second, fibre optic strain sensors were applied to test specimens with the selected adhesives. Their strain-transfer mechanism was analysed in comparison with conventional strain gauges. Relative movements between the applied sensor and the test specimen were visualized easily using optical reference methods, digital image correlation and electronic speckle pattern interferometry. Conventional strain gauges showed limited opportunities for an objective strain-transfer analysis because they are also affected by application conditions.

  1. Performance enhancement of multiple-gate ZnO metal-oxide-semiconductor field-effect transistors fabricated using self-aligned and laser interference photolithography techniques.

    PubMed

    Lee, Hsin-Ying; Huang, Hung-Lin; Tseng, Chun-Yen

    2014-01-01

    The simple self-aligned photolithography technique and laser interference photolithography technique were proposed and utilized to fabricate multiple-gate ZnO metal-oxide-semiconductor field-effect transistors (MOSFETs). Since the multiple-gate structure could improve the electrical field distribution along the ZnO channel, the performance of the ZnO MOSFETs could be enhanced. The performance of the multiple-gate ZnO MOSFETs was better than that of the conventional single-gate ZnO MOSFETs. The higher the drain-source saturation current (12.41 mA/mm), the higher the transconductance (5.35 mS/mm) and the lower the anomalous off-current (5.7 ?A/mm) for the multiple-gate ZnO MOSFETs were obtained. PMID:24948884

  2. Performance enhancement of multiple-gate ZnO metal-oxide-semiconductor field-effect transistors fabricated using self-aligned and laser interference photolithography techniques

    PubMed Central

    2014-01-01

    The simple self-aligned photolithography technique and laser interference photolithography technique were proposed and utilized to fabricate multiple-gate ZnO metal-oxide-semiconductor field-effect transistors (MOSFETs). Since the multiple-gate structure could improve the electrical field distribution along the ZnO channel, the performance of the ZnO MOSFETs could be enhanced. The performance of the multiple-gate ZnO MOSFETs was better than that of the conventional single-gate ZnO MOSFETs. The higher the drain-source saturation current (12.41 mA/mm), the higher the transconductance (5.35 mS/mm) and the lower the anomalous off-current (5.7 ?A/mm) for the multiple-gate ZnO MOSFETs were obtained. PMID:24948884

  3. Comparison of Computational and Optical Techniques for Image Processing

    NASA Astrophysics Data System (ADS)

    Unger, Blair; Bunton, Patrick

    2003-03-01

    This project will demonstrate complementary methods of image analysis using Fourier transforms. The computational components will use MathCAD® to calculate the Fourier transforms (FTs), while optical components will use a HeNe laser and a long focal length lens to process the FTs. The project will begin with use of simple shapes (a.k.a. -the aperture shape) to test the programming and optical outputs of the respective methods. In addition, starting with simple shapes allows for easy and straight forward conceptualization of the 2D FTs. From simple shapes, we will move to increasingly more complex apertures, until finally holograms of complex shapes (dendritic crystals and other objects) can be both optically and computationally processed (creating the FTs) and enhanced (for image clarity).

  4. New edge-blackening techniques for refractive optical elements

    NASA Astrophysics Data System (ADS)

    Eberhardt, Ramona; Gebhardt, A.; Weber, C.; Risse, Stefan; Guyenot, Volker

    1996-08-01

    There is a trend in the optical industry to automate the edge-blackening of optical components. The goal of edge- blackening is to coat the areas outside the functional region of optical components, namely the peripheral areas including the surface edge or 'diaphragm' and apertures, with light absorbing, index-matched material to minimize scattering light. The common method today is the manual application with brush or ink-writer of quick-drying liquid pigmented synthetic resin. The lenses are fitted at a rotary table with a vacuum-pump or with considerable disadvantage inhibiting the automation. Another problem is the use of a high number of lacquers with different or partly unknown properties, due to varying chemical bases.

  5. 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.

  6. COMPUTING OPTICAL FLOW VIA VARIATIONAL TECHNIQUES G. AUBERT y , R. DERICHE z , AND P. KORNPROBST y

    E-print Network

    Aubert, Gilles

    COMPUTING OPTICAL FLOW VIA VARIATIONAL TECHNIQUES G. AUBERT y , R. DERICHE z , AND P. KORNPROBST y ­ 2004 Route des Lucioles, BP 93 ­ 06902 Sophia­Antipolis Cedex ­ FRANCE 1 #12; 2 G. Aubert, R. Deriche

  7. Development of X-ray lithography and nanofabrication techniques for III-V optical devices

    E-print Network

    Lim, Michael H. (Michael Hong)

    2002-01-01

    This dissertation covers the development of fabrication techniques for Bragg-grating-based integrated optical devices in III-V materials. Work on this rich family of devices has largely been limited to numerical analysis ...

  8. 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

  9. 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 ?/1380, 0.01°, 0.002°, 59?nm and 0.0006, respectively. PMID:23771164

  10. Optical nonlinear properties of PbS nanoparticles studied by the Z-scan technique

    Microsoft Academic Search

    Baolong Yu; Guosheng Yin; Congshan Zhu; Fuxi Gan

    1998-01-01

    The optical nonlinear properties of PbS nanoparticles in polyvinyl alcohol (PVA) sol were studied by the Z-scan technique with 50 ps pulses at 530 and 1060 nm, respectively. The sample under these two excitations shows quite contrasting nonlinear optical responses. The saturation absorption at 520 nm is observed while at 1060 nm the two-photon absorption. The optical limiting of PbS

  11. Air pollution monitoring with two optical remote sensing techniques in Mexico City

    Microsoft Academic Search

    Michel Grutter; Edgar Flores-Jardines

    2004-01-01

    An open-path Fourier Transform Infrared (FTIR) and a Differential Optical Absorption Spectrometer (DOAS) were installed and simultaneously operated along a 426 m optical path in downtown Mexico City. O3 and SO2 were measured by both optical remote sensing techniques and the results from the comparison are presented. The instruments presented comparable sensitivities for O3 and an excellent agreement (R2 >

  12. IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1 Optical Spatial Quantization for Higher

    E-print Network

    Miller, David A. B.

    . Index Terms--Analog-to-digital conversion, mode-locked lasers, optical sampling, phase modulationIEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES 1 Optical Spatial Quantization for Higher Performance Analog-to-Digital Conversion Mona Jarrahi, Student Member, IEEE, R. Fabian W. Pease, Fellow, IEEE

  13. Visualization of magnetization processes of soft magnetic composites by the magneto-optical imaging technique

    E-print Network

    Johansen, Tom Henning

    Visualization of magnetization processes of soft magnetic composites by the magneto-optical imaging of electromagnetic devices. This paper presents the magnetization processes in a SMC sample in micron scale by means of the magneto-optical imaging technique. The sample was magnetized by magnetic fields tangential

  14. 0.18-?m CMOS equalization techniques for 10Gb\\/s fiber optical communication links

    Microsoft Academic Search

    Moonkyun Maeng; Franklin Bien; Youngsik Hur; Hyoungsoo Kim; Soumya Chandramouli; Edward Gebara; Joy Laskar

    2005-01-01

    Limitations in data transmission caused by modal dispersion in fiber-optic links can be significantly improved using equalization techniques. In this paper, two different equalizer implementation approaches are proposed to extend the transmission capacities of existing fiber-optic links. The building blocks of the equalizer including a multiplier cell, a delay line, and an output buffer stage are fully integrated on a

  15. Performance analysis of space time block coding techniques for indoor optical wireless systems

    Microsoft Academic Search

    Georgia Ntogari; Thomas Kamalakis; Thomas Sphicopoulos

    2009-01-01

    Indoor optical wireless systems provide an attractive alternative for realizing next generation wireless local area networks (WLANs). In this paper, the performance of diffuse optical wireless systems, employing space time block coding (STBC) techniques, is numerically investigated, accurately taking into account, the indoor channel impulse response and the characteristics of ambient light and thermal noises at the receiver. Discrete multitone

  16. Laser pointing stability measured by an oblique-incidence optical transmittance difference technique

    E-print Network

    Zhu, Xiangdong

    Laser pointing stability measured by an oblique-incidence optical transmittance difference an oblique-incidence optical transmittance technique for determining the pointing stability of a laser in transmittance through a parallel fused quartz window for s and p polarized components of the beam in response

  17. Laser pointing stability measured by an oblique-incidence optical transmittance difference technique

    E-print Network

    Zhu, Xiangdong

    Laser pointing stability measured by an oblique-incidence optical transmittance difference 95616, U.S.A. ABSTRACT We describe an oblique incidence optical transmittance difference technique laser beam by measuring the relative changes in transmittance through a parallel fused quartz window

  18. A new technique of real-time monitoring of fiber optic cable networks transmission

    Microsoft Academic Search

    A. A. A. Bakar; M. Z. Jamaludin; F. Abdullah; M. H. Yaacob; M. A. Mahdi; M. K. Abdullah

    2007-01-01

    A new technique of fiber-break detecting and monitoring in optical communication network systems is proposed and experimentally demonstrated. The subsystem, namely fiber-break monitoring system is designed to be simpler, significantly less expensive and yet gives an appropriate measurement to the distance break in place of the optical time domain reflectometer. This new approach has a bright prospect to be utilized

  19. Chromatic dispersion monitoring technique using sideband optical filtering and clock phase-shift detection

    Microsoft Academic Search

    Qian Yu; Zhongqi Pan; Lian-Shan Yan; Alan Eli Willner

    2002-01-01

    We propose and demonstrate a novel technique for 40- and 10-Gb\\/s chromatic dispersion monitoring that uses an optical filter to select the upper and lower vestigial-sideband (VSB) signals in the transmitted optical data and determine the relative clock phase shift caused by dispersion. Without modification of transmitters, this technique provides low cost chromatic dispersion monitoring for WDM systems, <3 ps\\/nm

  20. 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.

  1. 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.

  2. Acousto-optic spectrum and Fourier analysis techniques

    Microsoft Academic Search

    D. L. Hecht; P. S. Guilfoyle

    1979-01-01

    The paper examines two major classes of acousto-optic analog processors for implementation of the Fourier transform. Attention is given to the first, termed space integrating processors, which relies on dispersive spatial frequency characteristics of free space propagation combined with lenses as space quadratic phase multipliers, noting that in this case the spatial integration is the diffraction integral. Further, the second

  3. Laboratory Comparison of Aerosol Optical Property Measurement Techniques

    NASA Astrophysics Data System (ADS)

    Massoli, P.; Baynard, T.; Lack, D.; Ravishankara, A.; Lovejoy, E.

    2006-12-01

    Aerosol particles influence the global radiative balance with their optical properties, i.e., the ability of scattering and/or absorbing the incoming solar radiation (aerosol direct effect). Because this ability depends on aerosol characteristics such as composition, size distribution and mixing state, it is critical to link aerosol optical,physical and chemical properties to emissions for better assessing the regional and global impact of different aerosol types. During 2006, NOAA ERSL/CSD performed a series of laboratory based comparison studies to address the performance, uncertainties, and biases of both existing and newly developed instruments to measure aerosol optical properties. These investigations included measurements of extinction using cavity ring-down spectrometers (CRD-AES),scattering by a TSI nephelometer, and absorption by a Photoacoustic spectrometer (PAS) and a Radiance Research Particle Soot Absorption Photometer (PSAP). In this work we compare the optical properties derived for several aerosol types and mixtures by using various combinations of CRD-AES, nephelometer, and PSAP measurements. Our results indicate that such properties significantly depend on composition and mixing state of aerosols. We complete the study with top-of-the-atmosphere radiative forcing estimates and we compare the newly obtained values with what has been reported in past calculations.

  4. A new technique for hardening optically-triggered thyristors

    SciTech Connect

    Carson, R.F.; Hughes, R.C.; Weaver, H.T.; Brennan, T.M.; Hammons, B.E.

    1990-01-01

    Optically-triggered thyristors are hardened to high x-ray dose rates by the addition of a monolithically integrated compensating photodetector. Tests of discrete device arrangements show radiation-induced switching is completely inhibited up to 1.4 {times} 10{sup 9} rad (Si)/sec. 1 ref., 4 figs.

  5. ULTRADEEP OPTICAL SPECTROSCOPY using the NodandShuffle Technique

    E-print Network

    in the optical, optimized for good transmission and high image quality from 350nm to 1µm. We present our plan strategically chosen to fall in a gap between two strong OH night sky emission bands ( note that the sky lines) flux re­ sults in systematic errors which propagate multiplicatively. Contrary to pho­ ton shot noise

  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. An optical image segmentor using neural based wavelet filtering techniques

    NASA Astrophysics Data System (ADS)

    Veronin, Christopher P.; Rogers, Steven K.; Kabrisky, Matthew; Priddy, Kevin L.; Ayer, Kevin W.

    1991-10-01

    This paper presents a neural based optical image segmentation scheme for locating potential targets in cluttered FLIR images. The advantage of such a scheme is speed, i.e., the speed of light. Such a design is critical to achieve real-time segmentation and classification for machine vision applications. The segmentation scheme used was based on texture discrimination and employed biologically based orientation specific filters (wavelet filters) as its main component. These filters are well understood impulse response functions of mammalian vision systems from input to striate cortex. By using the proper choice of aperture pair separation, dilation, and orientation, targets in FLIR imagery were optically segmented. Wavelet filtering is illustrated for glass template slides, as well as segmentation for static and real-time FLIR imagery displayed on a liquid crystal television.

  8. Optical image segmentation using neural-based wavelet filtering techniques

    NASA Astrophysics Data System (ADS)

    Veronin, Christopher P.; Priddy, Kevin L.; Rogers, Steven K.; Ayer, Kevin W.; Kabrisky, Matthew; Welsh, Byron M.

    1992-02-01

    This paper presents a neural based optical image segmentation scheme for locating potential targets in cluttered FLIR images. The advantage of such a scheme is speed, i.e., the speed of light. Such a design is critical to achieve real-time segmentation and classification for machine vision applications. The segmentation scheme used was based on texture discrimination and employed biologically based orientation specific filters (wavelet filters) as its main component. These filters are well understood impulse response functions of mammalian vision systems from input to striate cortex. By using the proper choice of aperture pair separation, dilation, and orientation, targets in FLIR imagery were optically segmented. Wavelet filtering is illustrated for glass template slides, as well as segmentation for static and real-time FLIR imagery displayed on a liquid crystal television.

  9. Optical image encryption based on multistage fractional Fourier transforms and pixel scrambling technique

    NASA Astrophysics Data System (ADS)

    Zhao, Jianlin; Lu, Hongqiang; Song, Xiaoshan; Li, Jifeng; Ma, Yanghua

    2005-05-01

    A novel encryption for optical image based on multistage fractional Fourier transforms (FRTs) and pixel scrambling technique is presented in this paper. The principle of pixel scrambling is described and an optical approach to realize the pixel scrambling and decoding is also proposed. Numerical simulation results are given to verify the algorithm, and relative error (RE) between the decoded images and the original image versus the deviation of fractional orders is discussed. Comparing with single FRT encryption, the security using this method for optical image encryption is greatly improved due to the introduction of the pixel scrambling technique.

  10. Flipped-exponential Nyquist pulse technique to optimize the PAPR in optical direct detection OFDM system

    NASA Astrophysics Data System (ADS)

    Xiao, Jiangnan; Yu, Jianjun; Cao, Zizheng; Li, Fan; Chen, Lin

    2013-01-01

    In this paper, a novel technique based on flipped-exponential (FE) Nyquist pulse method is proposed for peak-to-average power ratio (PAPR) reduction in optical direct detection orthogonal frequency-division multiplexing (DD-OFDM) system. The method is based on a proper selection of the FE Nyquist pulses for shaping the different subcarriers of the OFDM. We experimentally demonstrated an optical DD-OFDM transmission system with this novel technique to achieve significant improvement in PAPR reduction in the optical OFDM system. The received sensitivity of the OFDM signal after suffered from strong nonlinear effects in standard single-mode fiber (SMF) has been experimentally investigated.

  11. Characterization of the optical constants of As 2Se 3 thin films using a fiber optic technique

    NASA Astrophysics Data System (ADS)

    Inci, M. N.; Yaradanakul, M. A.; Gül?en, G.; Akta?, G.

    1997-06-01

    The optical constants of amorphous As 2Se 3 chalcogenide thin films were determined over the range 600 to 1100 nm from the transmittance versus wavelength spectrum, using a fiber optic technique. Chalcogenide thin films were deposited directly onto the cleaved-end-faces of multimode fused silica optical fibers in a vacuum chamber. Optical constants, namely the index of refraction (n), the extinction coefficient ( k) and the optical band-gap ( Eg were measured before and after annealing of the films. A stabilization in optical constants occurred after annealing the thin films at a fixed temperature of 100°C for 2 h. The optical band-edge shifted towards longer wavelengths and, consequently, the optical band-gap decreased by a fraction, between approximately 0.7 and 3.5%. The transmission measurements of the chalcogenide thin films were performed only on films coated onto a fiber core of 50 ?m diameter, therefore the influence of thickness non-uniformity was significantly reduced.

  12. Precision alignment device

    SciTech Connect

    Jones, N.E.

    1990-03-13

    This patent describes an 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 servo-motor operated adjustment screws to adjust the position of elements of the structure associated with the main beam to maintain alignment of the main beam.

  13. [Optical colonoscopy and virtual colonoscopy: the current role of each technique].

    PubMed

    Bouzas Sierra, R

    2015-01-01

    The importance of optical or conventional colonoscopy in diagnosing colon disease is undisputed. In this context, optical colonoscopy is the gold standard against which other techniques must be validated. Apart from enabling direct inspection of the colonic mucosa, optical colonoscopy enables biopsies and techniques to treat and prevent colorectal cancer. Virtual colonoscopy or CT colonography has been validated in multicenter studies; virtual colonoscopy is as sensitive as optical colonoscopy for the detection of polyps and colon cancer. It is currently the only valid alternative to optical colonoscopy. Its role in patients with medium or high risk of colon cancer is in the process of being defined as multidisciplinary teams gain experience. This article aims to discuss the usefulness of virtual colonoscopy in different clinical situations, emphasizing the situations in which there is enough scientific evidence, and to discuss the controversies surrounding its possible use for population-based screening. PMID:25066725

  14. 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

  15. 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

  16. Heterodyne technique for measuring the amplitude and phase transfer functions of an optical modulator

    Microsoft Academic Search

    Francis P. Romstad; D. Birkedal; J. Mork; J. A. Hvam

    2002-01-01

    We propose a technique based on heterodyne detection for accurately and simultaneously measuring the amplitude and phase transfer functions of an optical modulator. The technique is used to characterize an InGaAsP multiple quantum-well electroabsorption modulator. From the measurements we derive the small-signal ?-parameter and the time-dependent chirp for different operation conditions

  17. Stable Materials and Bonding Techniques for Space-Based Optical Systems

    Microsoft Academic Search

    Alix Preston; Benjamin Balaban; Gabriel T. Boothe; Guido Mueller

    Advances in material science have expanded the list of materials and bonding techniques available that can be used to design complex structures with exceptional quality and reliability for use in space-based missions such as LISA, TPF, SIM, BBO, or the GRACE follow-on mission. These missions require complex optical systems made from materials and bonding techniques that must meet unprecedented dimensional

  18. A novel technique to improve the performance in optical amplifier WDM transmission systems

    Microsoft Academic Search

    T. Kawazawa; T. Otani; K. Goto; M. Tanaka

    1996-01-01

    Summary form only given. We proposed a novel technique of nonlinear suppression using nonlinear suppression lights (NSL), and confirmed the improvement of the system performance in a long-haul optical amplifier system. It is important to load the NSL with proper wavelength and level in order to obtain the best system performance. For example, this technique is applicable to improve system

  19. Manufacturing technique for embedding detachable fiber-optic connections in aircraft composite components

    Microsoft Academic Search

    Anders Sjögren

    2000-01-01

    This paper describes a manufacturing technique for embedding standard fiber-optic connection hardware in aircraft composite components. The manufacturing technique is simple and robust and enables trimming of the composite parts. Three different concepts for edge connections are presented. The usual problem with trimming composite parts with edge connections is solved by using polytetra-fluoroethylene dummies during manufacture.

  20. OPTICALLY STIMULATED ELECTRON EMISSION (OSEE): A NON-INVASIVE TECHNIQUE FOR CONTAMINATION DETECTION

    Microsoft Academic Search

    George Epstein; Susan S. Shlanger

    Optically Stimulated Electron Emission (OSEE) is a unique technique for non-invasive inspection of surfaces for molecular contamination. This technique utilizes a tool which utilizes ultraviolet radiation to create electron emission from a surface, resulting in a small current detected by the tool. Electron emission is dependent on the substrate's surface chemistry; hence the electron emission characteristics will change with the

  1. Optical 3D Measurement Techniques in Archaeology: Recent Developments and Applications

    Microsoft Academic Search

    Karsten Lambers; Fabio Remondino

    2007-01-01

    This paper is intended to give an overview on current surveying techniques that use remotely sensed data, and their applications in archaeology. The focus is on optical 3D measurement techniques based on image and range sensors. Data and methods are briefly reviewed, whereas data processing and related problems are only touched in passing. For the purpose of this review we

  2. Planar waveguide based optical performance monitoring techniques and their applications in all-optical networks

    Microsoft Academic Search

    Shan Zhong

    2001-01-01

    Over the past few years, DWDM has been widely adopted across the telecommunications industry to expand capacity in telecommunication infrastructure. The success of DWDM in increasing raw capacity on point-to-point fiber routes and the rapid growth of data communications accelerates the pace to all-optical networking. The goal of all- optical networking is to create a transparent optical layer that can

  3. Multimode fiber-optic hydrophone based on a schlieren technique.

    PubMed

    Spillman, W B

    1981-02-01

    A multimode fiber-optic hydrophone is described which is based upon a schlieren acoustooptic intensity modulation mechanism. Computer modeling of critical device parameters was experimentally verified and used to indicate ultimate attainable device performance. The device was shown to be able to detect the Knudsen noise level for frequencies up to 1 kHz, to have a dynamic range of 125 dB, to have an omnidirectional receiving response, and to be able to detect displacements as small as 3.4 x 10(-3) A. The device is not susceptible to phase noise, is relatively insensitive to static pressure head variations and is electrically passive. PMID:20309136

  4. Ion beam induced defects in solids studied by optical techniques

    NASA Astrophysics Data System (ADS)

    Comins, J. D.; Amolo, G. O.; Derry, T. E.; Connell, S. H.; Erasmus, R. M.; Witcomb, M. J.

    2009-08-01

    Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems. X- and Y-cut LiNbO 3 crystals implanted with 8 MeV Au 3+ ions with a fluence of 1 × 10 17 ions/cm 2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie theory provide the average nanoparticle sizes. TEM studies are in reasonable agreement and confirm a near-spherical nanoparticle shape but with surface facets. Large temperature differences in the nanoparticle creation in the X- and Y-cut crystals are explained by recrystallisation of the initially amorphised regions so as to recreate the prior crystal structure and to result in anisotropic diffusion of the implanted gold. Defect formation in alkali halides using ion beam irradiation has provided new information. Radiation-hard CsI crystals bombarded with 1 MeV protons at 300 K successfully produce F-type centres and V-centres having the I3- structure as identified by optical absorption and Raman studies. The results are discussed in relation to the formation of interstitial iodine aggregates of various types in alkali iodides. Depth profiling of I3- and I5- aggregates created in RbI bombarded with 13.6 MeV/A argon ions at 300 K is discussed. The recrystallisation of an amorphous silicon layer created in crystalline silicon bombarded with 100 keV carbon ions with a fluence of 5 × 10 17 ions/cm 2 during subsequent high temperature annealing is studied by Raman and Brillouin light scattering. Irradiation of tin-doped indium oxide (ITO) films with 1 MeV protons with fluences from 1 × 10 15 to 250 × 10 15 ions/cm -2 induces visible darkening over a broad spectral region that shows three stages of development. This is attributed to the formation of defect clusters by a model of defect growth and also high fluence optical absorption studies. X-ray diffraction studies show evidence of a strained lattice after the proton bombardment and recovery after long period storage. The effects are attributed to the annealing of the defects produced.

  5. 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.

  6. 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 ...

  7. An optical technique to detect the degradation of electrical insulation

    Microsoft Academic Search

    S. S. Bamji; A. T. Bulinski; J. Shen

    1993-01-01

    An experimental technique which can simultaneously measure the amplitude and phase of the electroluminescence (EL) pulses emitted prior to electrical tree inception is described. A digital oscilloscope is used to acquire the light pulses and 3-D plots of the number of light pulses versus their amplitude, and phase with respect to the AC waveform are obtained. Long-term aging tests are

  8. Fiber-optical cable television system performance improvement employing light injection and optoelectronic feedback techniques

    Microsoft Academic Search

    Hai-Han Lu; Yao-Wei Chuang; Guan-Lin Chen; Che-Wei Liao; Yu-Chieh Chi

    2006-01-01

    A split-band directly modulated fiber-optical cable television system employing light injection and optoelectronic feedback techniques is proposed and demonstrated. The light injection technique enhances the laser resonance frequency, and the optoelectronic feedback technique further enhances it, leading to an improvement in the systems' overall performances. Good performances of carrier-to-noise ratio, composite second order, and composite triple beat were achieved for

  9. A technique for extracting and analyzing the polarization aberration of hyper-numerical aperture image optics

    NASA Astrophysics Data System (ADS)

    Li, Yanqiu; Guo, Xuejia; Liu, Xiaolin; Liu, Lihui

    2013-12-01

    For hyper-numerical aperture (NA) lithographic optics, one of the design goals is to minimize polarization aberration (PA). However PA represented by Jones pupil can not be acquired by design software CODE V™ directly. And most researchers generate PA by computer randomly in study of various presentation of PA. Optical designers and instrument developers should analyze the realistic PA in optical design procedure, which is most important for controlling the PA before the optics is fabricated. This work presents a technique for extracting and analyzing the realistic PA caused by large incident angle of light, film coatings and intrinsic birefringence of lens materials in hyper-NA optics. The PA and its decomposition is obtained and analyzed for optics with different coatings using the technology in this paper. The results show that the subset aberrations of PAs can compensate each other via different coatings on the PO. The results also reveal that coating design should balance the transmission and its aberration (apodization).

  10. Comparative study of optical coherence tomography, photoacoustic technique, and time-of-flight technique in phantom measurements

    NASA Astrophysics Data System (ADS)

    Kinnunen, Matti; Myllylä, Risto

    2006-08-01

    of biomedical imaging techniques, the optical coherence tomography (OCT), photoacoustic (PA) and time-of-flight (TOF) techniques are among the most researched and, consequently, increasingly broadly applied. This article reviews their basic principles, compares their technical aspects and discusses their ability to determine optical parameters. Also studied is their applicability to non-invasive glucose monitoring in Intralipid TM phantom measurements, followed by a discussion of some detected problems. Although suffering from a limited probing depth, OCT was found to have the best capacity for detecting changes in the light scattering properties of Intralipid TM. Photon migration studies with the TOF technique showed changes in pulse amplitude, pulse width and arrival time of the pulse maximum as a function of changes in Intralipid TM concentration, whereas the sensitivity of the PA technique for detecting changes in scattering was less pronounced. However, each technique showed changes in the registered signals when measuring large glucose concentrations in Intralipid TM phantoms. Measurement results were also affected by the varying measurement geometries and the photon energies of the light sources.

  11. Simple, generalizable route to highly aligned block copolymer thin films

    NASA Astrophysics Data System (ADS)

    Qiang, Zhe; Cavicchi, Kevin; Vogt, Bryan

    2015-03-01

    Macroscopic alignment of block copolymer domains in thin films is desired for many applications, such as cell responsive surfaces or optical polarizers. Alignment generally requires specialized tools that apply external fields, shear force gradient, or produce topological patterned substrates. This requirement limits the broad academic application of aligned BCPs. Here, we describe a simple modification of commonly utilized solvent vapor annealing (SVA) process for macroscopic alignment of BCPs. Adhering a flat, crosslinked elastomer pad to the BCP film leads to differential swelling between the elastomer pad and BCP to produce a shear force that aligns the ordered BCP domains. The role of elastomer properties, solvent quality, drying rate and degree of segregation of the block copolymer will be discussed to provide generalized rules for alignment with this technique. Cylindrical nanostructures formed in polystyrene-block-polydimethylsiloxane can be transformed into arrays of silica lines and increasing the thickness from a monolayer to bilayer can effectively halve the spacing of the lines. These results illustrate a generalized method for BCP alignment and a potential route for the generation of complex hierarchical assembled structures.

  12. Cognition-enabling techniques in heterogeneous and flexgrid optical communication networks

    NASA Astrophysics Data System (ADS)

    Tafur Monroy, Idelfonso; Caballero, Antonio; Saldaña Cercós, Silvia; Borkowski, Robert

    2012-12-01

    High degree of heterogeneity of future optical networks, such as services with different quality-of-transmission requirements, modulation formats and switching techniques, will pose a challenge for the control and optimization of different parameters. Incorporation of cognitive techniques can help to solve this issue by realizing a network that can observe, act, learn and optimize its performance, taking into account end-to-end goals. In this letter we present the approach of cognition applied to heterogeneous optical networks developed in the framework of the EU project CHRON: Cognitive Heterogeneous Reconfigurable Optical Network. We focus on the approaches developed in the project for optical performance monitoring and power consumption models to implement an energy efficient network.

  13. Optical techniques for remote and in-situ characterization of particles pertinent to GEOTRACES

    NASA Astrophysics Data System (ADS)

    Boss, Emmanuel; Guidi, Lionel; Richardson, Mary Jo; Stemmann, Lars; Gardner, Wilford; Bishop, James K. B.; Anderson, Robert F.; Sherrell, Robert M.

    2015-04-01

    Field and laboratory characterization of marine particles is laborious and expensive. Proxies of particle properties have been developed that allow researchers to obtain high frequency distributions of such properties in space or time. We focus on optical techniques used to characterize marine particles in-situ, with a focus on GEOTRACES-relevant properties, such as bulk properties including particle mass, cross-sectional area, particle size distribution, particle shape information, and also single particle optical properties, such as individual particle type and size. We also address the use of optical properties of particles to infer particulate organic or inorganic carbon. In addition to optical sensors we review advances in imaging technology and its use to study marine particles in situ. This review addresses commercially available technology and techniques that can be used as a proxy for particle properties and the associated uncertainties with particular focus to open ocean environments, the focus of GEOTRACES.

  14. Transfer Matrix Technique for Interface Optical Phonon Modes in Multiple Interface Heterostructures Systems

    Microsoft Academic Search

    Segi Yu; K. W. Kim; Michael A. Stroscio; J.-P. Sun; G. I. Haddad

    1997-01-01

    Interactions of carriers with interface optical phonons dominate over other carrier-phonon interactions in quantum well structures for the case where well widths are less than about 30 ÅHerein, the transfer matrix technique is used to establish a formalism for determining the electrostatic potentials and dispersion relations of the interface-optical phonons for multiple-interface heterostructure systems within the framework of the the

  15. A novel local area network emulation technique on passive optical networks

    Microsoft Academic Search

    Nishaanthan Nadarajah; Manik Attygalle; Ampalavanapillai Nirmalathas; Elaine Wong

    2005-01-01

    An optical layer solution for intercommunication between customers in a passive optical network by placing a narrow-band fiber Bragg grating close to the star coupler in the feeder fiber is proposed. The local area network (LAN) emulation technique is experimentally demonstrated with 1.25-Gb\\/s upstream transmission to the central office and with 155 Mb\\/s customer data transmission that is multiplexed on

  16. Onorbit IMU alignment error budget

    NASA Technical Reports Server (NTRS)

    Corson, R. W.

    1980-01-01

    The Star Tracker, Crew Optical Alignment Sight (COAS), and Inertial Measurement Unit (IMU) from a complex navigation system with a multitude of error sources were combined. A complete list of the system errors is presented. The errors were combined in a rational way to yield an estimate of the IMU alignment accuracy for STS-1. The expected standard deviation in the IMU alignment error for STS-1 type alignments was determined to be 72 arc seconds per axis for star tracker alignments and 188 arc seconds per axis for COAS alignments. These estimates are based on current knowledge of the star tracker, COAS, IMU, and navigation base error specifications, and were partially verified by preliminary Monte Carlo analysis.

  17. 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

  18. Inkjet printing techniques for the fabrication of polymer optical waveguides

    NASA Astrophysics Data System (ADS)

    Vacirca, Nicholas A.; Kurzweg, Timothy P.

    2010-02-01

    A great deal of attention in recent years has been given to inkjet printing as an alternative to traditional lithographic techniques due to its potential for low cost and rapid turnaround fabrication. A Dimatix DMP-2831 materials printer is used to inkjet print polymer waveguides of SU-8 negative photoresist. Several obstacles must be overcome for the technology to be feasible on a large scale including the development of capable print devices, suitable materials for printing, and the ability to consistently and precisely print high-aspect-ratio geometries. We will discuss the inkjet printing fabrication process, explore some of the difficulties encountered through the method, present several of our first prototype waveguides, and report some preliminary results on waveguide characterization.

  19. Optical fibre techniques for use within tamper indicating enclosures designed for arms control verification purposes

    NASA Astrophysics Data System (ADS)

    Dyer, Thomas C.; Thompson, Alexander W. J.; Wynn, Paul; White, Helen

    2014-10-01

    Ensuring that a future nuclear arms control agreement can be verified is a complex technical challenge. Tamper Indicating Enclosures (TIEs) are likely to be deployed as part of a chain of custody regime, providing an indication of an unauthorised attempt to access an item within the agreement. This paper focuses on the assessment of optical fibre techniques for ensuring boundary control as part of a TIE design. The results of optical fibre damage, subsequent repair attempts, enclosure construction considerations and unique identification features have been evaluated for a selection of fused-silica optical fibres. This paper focuses on detecting a fibre repair attempt, presents a method for increasing repair resistance and a method for uniquely identifying an enclosure using the optical signature from the embedded optical fibre.

  20. Technique for stabilizing the phase of the reference signals in analog fiber-optic links.

    PubMed

    Shadaram, M; Medrano, J; Pappert, S A; Berry, M H; Gookin, D M

    1995-12-20

    The effects of temperature and longitudinal stress on the phase delay of reference signals in a fiber-optic link are discussed. A feedback system that uses a fiber-optic phase modulator is used to compensate for the phase fluctuations of a reference signal in the link. The phase deviations of a 50-MHz reference frequency that are caused by temperature variations of the link is reduced by more than 95% on optimization of the correction system. The advantages of this technique are that the fiber-optic phase modulator has a greater stability compared with the electronic phase modulators, and signal conversions from electric to optic and optic to electric are avoided. PMID:21068946

  1. Optical Limiting in TeO2-ZnO Glass from Z-Scan Technique

    NASA Astrophysics Data System (ADS)

    Thomas, Rose Leena; Vasuja; Hari, Misha; Nithyaja, B.; Mathew, S.; Rejeena, I.; Thomas, Sheenu; Nampoori, V. P. N.; Radhakrishnan, P.

    TeO2-ZnO glasses were prepared by conventional melting procedure, and their optical properties were determined. In the present work, we measured the optical non-linearity of the glass. The measurement was carried out using a single beam z-scan technique given by Sheike Bahe et al. We could observe that the material exhibits reverse saturable absorption, and the effective nonlinear absorption coefficients are numerically evaluated. This study is important in identifying the nonlinear material as a Reverse Saturable Absorption (RSA) based optical limiter.

  2. 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 [Convergence Technology Laboratory, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of); Jang, Yong-Jun [Environment and Energy Research Team, Central Advanced Research and Engineering Institute for Hyundai Motor Company and Kia Motors Corporation, Gyeonggi-Do 437-040 (Korea, Republic of); Han, Seonghee; Choi, Jin-Young; Park, Won-Woong [Materials Science and Technology Division, Korea Institute of Science and Technology, P.O. Box 131, Cheongryang, Seoul 130-650 (Korea, Republic of)

    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.

  3. Optical image encryption based on multichannel fractional Fourier transform and double random phase encoding technique

    NASA Astrophysics Data System (ADS)

    Jin, Weimin; Yan, Caijie

    2007-01-01

    The optical image encryption based on multichannel fractional Fourier transform (FRT) and double random phase encoding technique is proposed. Optical principles of encoding and decoding are analyzed in detail. With this method, one can encrypt different parts of input image, respectively. The system security can be improved to some extent, not only because fractional orders and random phase masks in every channel can be set with freedom, but also because the system parameters among all channels are independent. Numerical simulation results of optical image encryption based on four channel FRT and double random phase encoding are given to verify the feasibility of the method.

  4. Dynamic interferometer alignment and its utility in UV Fourier transform spectrometer systems

    NASA Technical Reports Server (NTRS)

    Dorval, Rick K.; Engel, James R.; Wyntjes, Geert J.

    1993-01-01

    Dynamic alignment has been demonstrated as a practical approach to alignment maintenance for systems in the infrared region of the spectrum. On the basis of work done by OPTRA, this technique was introduced in commercial Fourier transform spectrometer systems in 1982 and in various forms is now available from a number of manufacturers. This paper reports on work by OPTRA to extend the basic technique to systems operating in the ultraviolet. In addition, this paper reports the preliminary results of the development of an alignment system using a laser diode in place of a gas laser normally found in dynamic alignment systems. A unique optical system and spatial heterodyne technique allows for achievement of a metrology system with characteristics that fully satisfy the requirements of an ultraviolet spectrometer system.

  5. 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.

  6. Electrical signal processing techniques in long-haul fiber-optic systems

    Microsoft Academic Search

    J. H. Winters; R. D. Gitlin

    1990-01-01

    The potential for electrical signal processing to mitigate the effect of intersymbol interference in long-haul fiber-optic systems is discussed. Intersymbol interference can severely degrade performance and consequently limit both the maximum distance and data rate of the system. Several techniques for reducing intersymbol interference in single-mode fiber systems with single-frequency lasers are presented, and those techniques which are appropriate at

  7. Gracilis tendon transfer associated with distal alignment for patella alta with recurrent dislocations: an original surgical technique.

    PubMed

    Marteau, E; Burdin, P; Brilhault, J-M

    2011-06-01

    Many surgical techniques for the medial patellofemoral ligament have recently been suggested, all of which included problems identifying the femoral anchorage point and determining the proper extent of knee flexion for the transplant. P. Burdin proposed a different and original approach consisting in performing a gracilis muscle transfer to the medial edge of the patella, thus obtaining progressive tension of the transfer during knee flexion by means of the myotatic reflex. We report the results herein. We retrospectively assessed 17 knees treated for patellofemoral instability using this technique. Two cases presented subjective patellofemoral instability and 15 presented objective patellofemoral instability. The patients' mean age was 17.4 years (range, 8-47 years) during the first episode of dislocation. Two cases of instability were secondary to advanced neuromuscular disease. Two knees had already undergone two stabilization attempts. Fifteen knees presented trochlear dysplasia (four stage A, eight stage B, and three stage C). The mean age at surgery was 28.2 years (range, 16-47 years). In 15 cases, the gracilis transfer was associated with lowering the anterior tibial tuberosity (mean, 10mm). No patellar fracture occurred. A persistent sensory deficit of the anterior branch of the internal saphenous nerve was observed in 15 cases. One knee remained painful and retained subjective instability; total knee arthroplasty was performed 3 years after the intervention. The mean follow-up at revision was 5.5 years (range, 1.5-16.5 years). No recurrence of dislocation was reported. Eight cases retained subjective instability. The SF-36 and IKDC scores were good or excellent in 12 cases and the KOOS was good or excellent in 13 cases. Radiologically, patellar tilt persisted in six cases out of 14, translation persisted in two cases out of 14, and secondary patella baja was observed in one. Medial patellofemoral osteoarthritis was observed in five cases: one case IWANO stage I and four cases IWANO stage II. These satisfactory results seem stable over time and were acquired using a simple procedure with reduced morbidity, making it possible to avoid significant displacement of the anterior tibial tuberosity and stabilize the extensor apparatus. It can also be hoped that the onset of secondary patellofemoral osteoarthritis, undoubtedly inevitable, has been delayed. PMID:21530441

  8. 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.

  9. REPAIR PATCH MONITORING WITH EMBEDDED OPTICAL SENSORS BYA RESIDUAL STRAIN RELEASE TECHNIQUE

    E-print Network

    Boyer, Edmond

    REPAIR PATCH MONITORING WITH EMBEDDED OPTICAL SENSORS BYA RESIDUAL STRAIN RELEASE TECHNIQUE Malte (FBGSs) embedded in the CFRP-patch. Temperature compensation has been introduced to enable that are instrumented with two or four embedded FBGS. The results of the tests show that the embedded sensors can indeed

  10. A Survivable WDM-PON Architecture Using Optical Carrier Suppression Technique

    NASA Astrophysics Data System (ADS)

    Song, Yingxiong; Gan, Chaoqin; Gong, Yan; Chen, Benyang

    2013-12-01

    In this paper, we propose and demonstrate a novel survivable WDM-PON architecture using Optical Carrier Suppression (OCS) technique. It can provide protection against the feeder fiber failure. The simulation results for the scheme at 2.5 Gbit/s downstream signals and 2.5 Gbit/s upstream signals are presented to verify the feasibility of system.

  11. Measurement of Temperature Change in Nonlinear Optical Materials by Using the Z-Scan Technique

    Microsoft Academic Search

    Shu-Guang Dong; Jun-Yi Yang; Min Shui; Chuan-Xiang Yi; Zhong-Guo Li; Ying-Lin Song

    2011-01-01

    Spatial and temporal changes of temperature in a novel polymer are investigated by using the Z-scan technique under ns laser pulse excitation. According to the open aperture Z-scan experimental results, the nonlinear absorption coefficient of the polymer is determined. By solving the diffusion equation of heat conduction induced by optical absorption, the spatial and temporal changes in temperature are obtained.

  12. Quantitative analyses of pyrite in coal by optical image techniques. [7 references

    Microsoft Academic Search

    L. A. Harris; T. Rose; L. DeRoos; J. Greene

    1977-01-01

    It has been demonstrated that quantitative analyses of pyrite in coal can be achieved by means of optical image analysis techniques. However, it is necessary to measure the total sample surface since selected area analyses may lead to erroneous values. The roots of this problem stem from the nonuniform distribution of pyrite throughout a coal briquet. In addition, the inability

  13. Growth of Nd2TiO5 single crystal using optical floating zone technique

    NASA Astrophysics Data System (ADS)

    Murugesan, G.; Nithya, R.; Kalainathan, S.; Ravindran, T. R.

    2015-06-01

    Single crystals of Nd2TiO5 were grown using Optical Floating zone technique in oxygen atmosphere by spontaneous nucleation. Powder X-ray diffraction pattern showed that the grown single crystal is of homogeneous composition. Laue diffraction was recorded in both transmission and backscattering geometries to check the crystal quality. Vibrational properties were analyzed using Raman measurements.

  14. Analysis of diffuse optical wireless channels employing spot-diffusing techniques, diversity receivers, and combining schemes

    Microsoft Academic Search

    Abdullah G. Al-ghamdi; Jaafar M. H. Elmirghani

    2004-01-01

    In this letter, the performance of an indoor optical wireless spot-diffusing system using various multibeam transmitter configurations, in association with direction diversity and combining techniques, is assessed and compared under the impact of multipath dispersion and ambient light noise through theoretical analysis and computer simulation. Computer simulation for three different multibeam transmitter configurations and a conventional diffuse transmitter is carried

  15. Multimodal imaging of vascular network and blood microcirculation by optical diagnostic techniques

    Microsoft Academic Search

    Yu L. Kuznetsov; V. V. Kalchenko; I. V. Meglinski

    2011-01-01

    We present a multimodal optical diagnostic approach for simultaneous non-invasive in vivo imaging of blood and lymphatic microvessels, utilising a combined use of fluorescence intravital microscopy and a method of dynamic light scattering. This approach makes it possible to renounce the use of fluorescent markers for visualisation of blood vessels and, therefore, significantly (tenfold) reduce the toxicity of the technique

  16. Optical smoothing techniques for shock wave generation in laser-produced plasmas

    Microsoft Academic Search

    Michel Koenig; Bernard Faral; Jean Michel Boudenne; Dimitri Batani; Alessandra Benuzzi; Simone Bossi

    1994-01-01

    Shock wave experiments have been performed at the Laboratoire pour l'Utilisation des Lasers Intenses in a regime of interest for inertial confinement fusion and equation of state measurements. Laser beams have been optically smoothed either with random phase plates or with phased zone plates. This last technique allowed the production of a flat-top intensity distribution in the focal spot and

  17. Masking technique for coating thickness control on large and strongly curved aspherical optics

    E-print Network

    Paris-Sud XI, Université de

    to deposit a reflective interferential coating over a spherical substrate with a 500 mm diameter clear1 Masking technique for coating thickness control on large and strongly curved aspherical optics B.sassolas@lma.in2p3.fr I. Abstract This paper discusses a method to control the coating thickness deposited onto

  18. The Direct Optical Transition Line Shape Function from the Equilibrium Density Projection Operator Technique

    Microsoft Academic Search

    J. Y. Sug; S. G. Jo; S. D. Choi

    1999-01-01

    Using the equilibrium density projection operator technique (EDPT), we calculate the lineshape function for the magneto-optical direct interband transition in an electron-phonon system. We present the calculation processes for obtaining the scattering factor using the EDPT. We introduce two useful identities necessary to expand the elements of the scattering factor. We derive a cancellation relation which simplifies the expansion of

  19. Resonator micro optic gyro with double phase modulation technique using an FPGA-based digital processor

    Microsoft Academic Search

    Huilian Ma; Hui Mao; Yan Chen; Zhonghe Jin

    2011-01-01

    A resonator micro optic gyro (RMOG) with the proposed FPGA-based digital processor is set up. The double phase modulation technique is applied to achieve high total carrier suppression. Rotation tests from +\\/-0.1 °\\/s to +\\/-5 °\\/s are tested, where the processing circuit of RMOG is implemented by the instruments. The rotation test over a range of +\\/-550 °\\/s has been

  20. Investigation of adsorption reactions on gold and tantalum using electrochemical techniques and optical second harmonic generation

    Microsoft Academic Search

    Michael John Walters

    2003-01-01

    Techniques of electrochemical impedance spectroscopy (EIS), potential step (PS), and optical second harmonic generation (SHG) are used to study a selected set of electrochemical systems. These model experimental systems have potential applications in areas of corrosion, catalysis, and SAM stabilization. Nonfaradaic anion adsorption on gold is used to develop a method where differential capacitance can be measured in situ with

  1. A novel broadband asynchronous histogram technique for optical performance monitoring [optical fibre communication

    Microsoft Academic Search

    Sarah D. Dods; Don F. Hewitt; P. M. Farrell; Kerry Hinton

    2005-01-01

    We combine tunable narrowband filtering with asynchronous sampling to produce broadband histograms that measure frequency-resolved signal distortion. We demonstrate the technique using chirped WDM signals affected by filter detuning, dispersion and nonlinear effects.

  2. A technique for the optical characterization of imaging air-Cherenkov telescopes

    NASA Astrophysics Data System (ADS)

    Arqueros, F.; Ros, G.; Elorza, G. R.; García-Pinto, D.

    2005-09-01

    A procedure for the optical characterization of imaging air-Cherenkov telescopes IACTs is discussed. The method relies in simple principles of geometrical optics. A CCD camera provided with a lens and located at (or near) the telescope focus records images of the mirror while the pointing direction of the telescope moves around a star. For each image, the slope of those mirror points which are recorded bright, due to the light star, can be accurately measured by the simple application of the reflection law. This procedure allows the reconstruction of the slope map of the mirror and thus it provides a full optical characterization. The applicability of this technique to typical IACTs is discussed by means of a simple simulation. The slope map could be reconstructed with an uncertainty better than 0.1 mrad. Many geometrical features of the mirror like facet misalignment and structure deformations could be measured with this technique.

  3. Scanning second harmonic microscopy techniques with monomode and near field optical fibers

    NASA Astrophysics Data System (ADS)

    Adameck, M.; Blum, R.; Eich, M.

    1998-11-01

    Extending our scanning second harmonic microscopy (SSHM) technique for the detection of lateral orientational inhomogeneities in high field poled polymer films, we present results with considerably improved lateral resolution by using optical fiber technology. Two experimental setups for measuring the ?(2) susceptibility of thin films are introduced. The first setup uses a standard monomode infrared-fiber with 10 ?m core that carries the coherent fundamental infrared wave to the surface of a poled polymer film (illumination mode). The generated doubled frequency wave behind the nonlinear optical sample is detected by a photomultiplier tube. In the second setup a lens focuses the fundamental wave into the poled film. The resulting second harmonic wave is coupled into a 2.5 ?m single mode fiber. SSHM micrographs of high field poled nonlinear optical polymer films were obtained with lateral resolutions of <3.5 ?m. SSHM was also realized with a scanning near field optical microscopy fiber in pick up mode.

  4. Surface alignment, anchoring transitions, optical properties, and topological defects in the nematic phase of thermotropic bent-core liquid crystal A131

    NASA Astrophysics Data System (ADS)

    Senyuk, B.; Wonderly, H.; Mathews, M.; Li, Q.; Shiyanovskii, S. V.; Lavrentovich, O. D.

    2010-10-01

    We study optical, structural, and surface anchoring properties of thermotropic nematic bent-core material A131. The focus is on the features associated with orientational order as the material has been reported to exhibit not only the usual uniaxial nematic but also the biaxial nematic phase. We demonstrate that A131 experiences a surface anchoring transition from a perpendicular to tilted alignment when the temperature decreases. The features of the tilted state are consistent with surface-induced birefringence associated with smectic layering near the surface and a molecular tilt that changes along the normal to the substrates. The surface-induced birefringence is reduced to zero by a modest electric field that establishes a uniform uniaxial nematic state. Both refractive and absorptive optical properties of A131 are consistent with the uniaxial order. We found no evidence of the “polycrystalline” biaxial behavior in the cells placed in crossed electric and magnetic fields. We observe stable topological point defects (boojums and hedgehogs) and nonsingular “escaped” disclinations pertinent only to the uniaxial order. Finally, freely suspended films of A131 show uniaxial nematic and smectic textures; a decrease in the film thickness expands the temperature range of stability of smectic textures, supporting the idea of surface-induced smectic layering. Our conclusion is that A131 features only a uniaxial nematic phase and that the apparent biaxiality is caused by subtle surface effects rather than by the bulk biaxial phase.

  5. 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.

  6. The new BL Lacertae objects discovered by an efficient X-ray/radio/optical technique

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.; Stocke, John T.; Perlman, Eric; Elvis, Martin; Remillard, Ron; Granados, Arno; Luu, Jane; Huchra, John P.; Humphreys, Roberta; Urry, C. M.

    1993-01-01

    We report the recent discovery of ten BL Lac objects in the Einstein IPC Slew Survey by means of X-ray/radio versus X-ray/optical color-color diagrams and confirming optical spectroscopy. These ten BL Lac objects were discovered using a technique proposed by Stocke et al. (1989) which exploits the characteristic broad-band spectra of BL Lac objects. New VLA detections provide accurate fluxes (limiting f(6 cm) about 0.5 mJy) and about 1 arcsec positions, facilitating the determination of an optical counterpart. All ten new BL Lac objects show essentially featureless optical spectra and lie within the range of radio/X-ray/optical colors of known X-ray-selected BL Lac objects, when about 1 mag optical variability is included. We expect about 50 new BL Lac objects in total, from complete optical follow-up of our now completed VLA work and recent Australia Telescope observations, yielding a complete Slew Survey sample of about 90 BL Lac objects.

  7. Study on the absorption uniformity of optical thin films based on the photothermal detuning technique.

    PubMed

    Hao, Honggang; Zhou, Ao; Rao, Min

    2012-10-01

    Absorption loss in optical components, particularly in optical coatings, is a limiting factor in high-power laser applications. The uniformity of optical coatings becomes more and more important as large-diameter optical devices are used widely. In this paper, the photothermal detuning technique used for absorption uniformity measurement of optical thin films is developed for the first time. Experiments are conducted with a highly reflective coating used in 514 nm to measure the photothermal detuning signal and to evaluate the absorption at 514 nm by detecting the spectral shift with a probe beam at a wavelength of 632.8 nm. The relative absorption at different points on the sample surface can be measured by moving the sample two-dimensionally, and we use the measured data to make the absorption image. The results show that the designed experimental system can be used to analyze the absorption uniformity of optical coatings. The obtained images reflect the absorption uniformity of the sample well. The absorption uniformities of the two samples analyzed in this experiment are different. The film coated on fused silica is better. The research provides a powerful and convenient tool for absorption uniformity measurement of optical thin film. PMID:23033101

  8. 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.

  9. 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

  10. 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

  11. 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.

  12. Optical gratings induced by field-free alignment of molecules A.Rouzee, V.Renard, S.Guerin, O.Faucher, and B.Lavorel

    E-print Network

    Paris-Sud XI, Université de

    gratings with aligned molecules were performed in CO2 at room temperature in a static cell and at 30 KOptical gratings induced by field-free alignment of molecules A.Rouz´ee, V.Renard, S.Gu´erin, O Dijon Cedex, France (Dated: June 19, 2009) We analyze the alignment of molecules generated by a pair

  13. 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.

  14. 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

  15. Radio frequency phototube and optical clock: High resolution, high rate and highly stable single photon timing technique

    SciTech Connect

    Amur Margaryan

    2011-10-01

    A new timing technique for single photons based on the radio frequency phototube and optical clock or femtosecond optical frequency comb generator is proposed. The technique has a 20 ps resolution for single photons, is capable of operating with MHz frequencies and achieving 10 fs instability level.

  16. Simple fiber-optic technique for in-situ corrosion sensing in structures

    NASA Astrophysics Data System (ADS)

    Singh, Nahar; Jain, Subhash C.; Aggarwal, Anil K.; Singla, Madan L.; Singh, Mewa

    2000-05-01

    Corrosion of structures is a serious problem involving man and material safety. Over the years, though several methods of monitoring corrosion have been devised with some success, but there is a persistent need for devising non-destructive and in-situ techniques for monitoring corrosion in structures. Fiber optic techniques are capable of meeting these requirements, besides offering several other important advantages. Fiber optic corrosion sensors have thus become quite attractive and are currently being investigated to address the high costs associated with the existing structural maintenance procedures. Fiber optics based direct absorption spectroscopic techniques investigated by some groups for estimating corrosion have used single fiber elements for recording the signal reflected from specimen at different wavelengths. As the light coupling efficiency of the single fiber elements is relatively poor in comparison with that of fiber bundles and the signal available for processing is weak, the paper presents a simple and alternate technique based on the color matching principle of fiber optic colorimetry to detect corrosion induced color changes. It employs a thin Y- shaped fiber optic bundle which increases the quantity of light energy coupled from a whitelight source. The light reflected off the sample is made incident on a PIN photo- detector through a complementary filter. A series of such probes can be safety embedded and or bonded to structures at pre-determined locations. The experimental set up for this sensor was implemented and feasibility of in-situ corrosion detection in structures demonstrated. Measurement data was acquired for steel samples corroded both in concrete embedded and open ambience conditions and results analyzed.

  17. Auto-aligning and splicing PM-fibers of different types with a passive method

    Microsoft Academic Search

    Wenxin Zheng

    1996-01-01

    Many different types of polarization maintaining (PM) fibers and polarizing (PZ) fibers are playing important roles in most of fiber optical gyros and high speed communication networks. A new method for passively aligning and fusion- splicing those fiber types are developed with the help of the lens-effect tracing technique. Instead of calculating the correlation directly between the two POL profiles

  18. Modeling of Optical Resonators Using Gaussian Beams and Ray Tracing Techniques

    NASA Astrophysics Data System (ADS)

    Ruiz, Liliana; Cantu, Sergio; Quetschke, Volker; Rakhmanov, Malik

    2011-10-01

    One of the main components in the laser stabilization subsystem in the Laser Interferometer Gravitational-Wave Observatory (LIGO) is a triangular ring resonator, which filters out high order Hermite-Gaussian modes in the laser beam. We developed a model to study the optical properties of such resonators and investigate their performance. The propagation of the laser beam is modeled by combining ray tracing techniques with wave optics. The model can be used to analyze various effects due to mirror misalignments and fluctuations of the laser beam pointing.

  19. UMBCUMBCUMBC Protein Image Alignment

    E-print Network

    Potra, Florian

    . Gels must be aligned before comparison. Bottleneck: Gel Alignment Protein Image Alignment via Quadratic (Compugen) All are deficient on gel alignment Protein Image Alignment via Quadratic Programming ­ p.3/47 #12 (2) , I (3) , I (4) Aligned gels Protein Image Alignment via Quadratic Programming ­ p.5/47 #12

  20. A Review of the Polarization-Nulling Technique for Monitoring Optical-Signal-to-Noise Ratio in Dynamic WDM Networks

    Microsoft Academic Search

    J. H. Lee; H. Y. Choi; S. K. Shin; Y. C. Chung

    2006-01-01

    The polarization-nulling technique utilizes the different properties of optical signal and amplified spontaneous emission (ASE) noise for accurate monitoring of the optical-signal-to-noise ratio (OSNR) in dynamic optical networks. However, the performance of this technique is bound to be deteriorated if the signal is depolarized by polarization-mode dispersion and\\/or nonlinear birefringence or the ASE noise is partially polarized due to polarization-dependent

  1. In-line particle sizing for real-time process control by fibre-optical spatial filtering technique (SFT)

    Microsoft Academic Search

    Petrak Dieter; Dietrich Stefan; Eckardt Günter; Köhler Michael

    2011-01-01

    Sizing of particles in industrial processes is of great technical interest and therefore different physical-based techniques have been developed. The objective of this study was to review the characteristics of modern sizing instruments based on a modified fibre-optical spatial filtering technique (SFT). Fibre-optical spatial filtering velocimetry was modified by fibre-optical spot scanning in order to determine simultaneously the size and

  2. Alignment fixture

    DOEpatents

    Bell, Grover C. (Norris, TN); Gibson, O. Theodore (Lenoir City, TN)

    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.

  3. Thirteen new BL Lacertae objects discovered by an efficient x ray/radio/optical technique

    NASA Technical Reports Server (NTRS)

    Schachter, Jonathan F.; Stocke, John T.; Perlman, Eric; Elvis, Martin S.; Luu, Jane; Huchra, John P.; Humphreys, Roberta; Remillard, Ron; Wallin, John

    1992-01-01

    The discovery of 13 serendipitous BL Lac objects in the Einstein IPC Slew Survey by means of x ray/radio vs. x ray/optical color-color diagrams and confirmation by optical spectroscopy are reported. These 13 BL Lacs were discovered using a technique which exploits the characteristic broad band spectra of BL Lacs. New VLA detections provide accurate fluxes (f(6 cm) is approximately 0.5 mJy) and 2 in. positions, facilitating the determination of an optical counterpart. All 13 new BL Lacs show essentially featureless optical spectra. Nine of these lie within the range of colors of known x ray selected BL Lacs. Of the remaining four, one is apparently x ray louder (by a factor of 1.5) or optically quieter (by 0.8 mags); and three are optically louder (by 1-1.3 mags) than x ray selected BL Lacs. Approximately 50 new BL Lacs in total are expected from VLA work and upcoming Australia Telescope observations, yielding a complete Slew Survey sample of approximately 90 BL Lacs.

  4. Identification of cataract and post-cataract surgery optical images using artificial intelligence techniques.

    PubMed

    Acharya, Rajendra Udyavara; Yu, Wenwei; Zhu, Kuanyi; Nayak, Jagadish; Lim, Teik-Cheng; Chan, Joey Yiptong

    2010-08-01

    Human eyes are most sophisticated organ, with perfect and interrelated subsystems such as retina, pupil, iris, cornea, lens and optic nerve. The eye disorder such as cataract is a major health problem in the old age. Cataract is formed by clouding of lens, which is painless and developed slowly over a long period. Cataract will slowly diminish the vision leading to the blindness. At an average age of 65, it is most common and one third of the people of this age in world have cataract in one or both the eyes. A system for detection of the cataract and to test for the efficacy of the post-cataract surgery using optical images is proposed using artificial intelligence techniques. Images processing and Fuzzy K-means clustering algorithm is applied on the raw optical images to detect the features specific to three classes to be classified. Then the backpropagation algorithm (BPA) was used for the classification. In this work, we have used 140 optical image belonging to the three classes. The ANN classifier showed an average rate of 93.3% in detecting normal, cataract and post cataract optical images. The system proposed exhibited 98% sensitivity and 100% specificity, which indicates that the results are clinically significant. This system can also be used to test the efficacy of the cataract operation by testing the post-cataract surgery optical images. PMID:20703916

  5. Performance comparison of asynchronous and synchronous code-division multiple-access techniques for fiber-optic local area networks

    Microsoft Academic Search

    Wing C. Kwong; Philippe A. Perrier; Paul R. Prucnal

    1991-01-01

    Synchronous code-division multiple access (S\\/CDMA) is investigated for fiber-optic local area networks. It is shown that the large bandwidth expansion required by spread-spectrum techniques, such as CDMA, can be accommodated by using a fiber-optic channel for transmission and incoherent optical signal processing for code generation and correlation. Prime sequence codes, previously developed for a fiber-optic network using (asynchronous) CDMA, are

  6. Novel technique to predict dry-band arcing failure of fiber-optic cables installed on high voltage lines

    Microsoft Academic Search

    G. G. Karady; S. Devarajan; M. Tuominen

    1999-01-01

    Utilities frequently use ADSS (all dielectric self-supporting) fiber-optic cables installed on transmission lines. Dry-band arcing occurs on the fiber-optic cables when they are polluted and wet. The objective of this paper is to present a technique to predict dry-band arcing in fiber-optic cables. An equivalent circuit is used to represent the polluted fiber-optic cable. The effect of pollution levels on

  7. A Wafer-Bonded, Floating Element Shear-Stress Sensor Using a Geometric Moire Optical Transduction Technique

    NASA Technical Reports Server (NTRS)

    Horowitz, Stephen; Chen, Tai-An; Chandrasekaran, Venkataraman; Tedjojuwono, Ken; Cattafesta, Louis; Nishida, Toshikazu; Sheplak, Mark

    2004-01-01

    This paper presents a geometric Moir optical-based floating-element shear stress sensor for wind tunnel turbulence measurements. The sensor was fabricated using an aligned wafer-bond/thin-back process producing optical gratings on the backside of a floating element and on the top surface of the support wafer. Measured results indicate a static sensitivity of 0.26 microns/Pa, a resonant frequency of 1.7 kHz, and a noise floor of 6.2 mPa/(square root)Hz.

  8. Bandwidth-efficient phase modulation techniques for stimulated Brillouin scattering suppression in fiber optic parametric amplifiers.

    PubMed

    Coles, J B; Kuo, B P-P; Alic, N; Moro, S; Bres, C-S; Chavez Boggio, J M; Andrekson, P A; Karlsson, M; Radic, S

    2010-08-16

    Two novel bandwidth efficient pump-dithering Stimulated Brillouin Scattering (SBS) suppression techniques are introduced. The techniques employ a frequency-hopped chirp and an RF noise source to impart phase modulation on the pumps of a two pump Fiber Optical Parametric Amplifier (FOPA). The effectiveness of the introduced techniques is confirmed by measurements of the SBS threshold increase and the associated improvements relative to the current state of the art. Additionally, the effect on the idler signal integrity is presented as measured following amplification from a two pump FOPA employing both techniques. The measured 0.8 dB penalty with pumps dithered by an RF noise source, after accruing 160 ps/nm of dispersion with 38 dB conversion gain in a two-pump FOPA is the lowest reported to date. PMID:20721202

  9. High finesse pulsed optical cavity locking by tilt-locking technique.

    PubMed

    You, Y; Chiche, R; Yan, L X; Huang, W H; Tang, C X; Zomer, F

    2014-03-01

    We report the Tilt-Locking (TL) technique applied to lock a laser in pulsed regime to a 28,000 high finesse Fabry-Perot cavity. Preliminary experimental results show that TL technique is comparable with the well-known Pound-Drever-Hall technique. This study is the first to implement the TL technique to lock a pulsed laser to a high-finesse optical cavity. Very high and stable coupling is obtained. The coupling rate is ~80%, and locking can last for more than 1 h. Furthermore, while previously published papers have focused on near field case, in this study we will give the error signal shape simulation for the far field case. We will show that for different types of error sources, the split photodiode transverse position can be carefully adjusted to obtain a symmetrical error signal. Our experimental results are consistent with the simulations. PMID:24689559

  10. High finesse pulsed optical cavity locking by tilt-locking technique

    NASA Astrophysics Data System (ADS)

    You, Y.; Chiche, R.; Yan, L. X.; Huang, W. H.; Tang, C. X.; Zomer, F.

    2014-03-01

    We report the Tilt-Locking (TL) technique applied to lock a laser in pulsed regime to a 28 000 high finesse Fabry-Perot cavity. Preliminary experimental results show that TL technique is comparable with the well-known Pound-Drever-Hall technique. This study is the first to implement the TL technique to lock a pulsed laser to a high-finesse optical cavity. Very high and stable coupling is obtained. The coupling rate is ˜80%, and locking can last for more than 1 h. Furthermore, while previously published papers have focused on near field case, in this study we will give the error signal shape simulation for the far field case. We will show that for different types of error sources, the split photodiode transverse position can be carefully adjusted to obtain a symmetrical error signal. Our experimental results are consistent with the simulations.

  11. Crystallography of ordered colloids using optical microscopy. 1. Parallel-beam technique.

    PubMed

    Rogers, Richard B; Lagerlöf, K Peter D

    2008-01-10

    A technique is described for determining the reciprocal lattice basis vectors of randomly oriented colloidal crystals from optical Fourier transform images using a parallel incident beam. This approach is demonstrated by comparing information gathered using this technique with results from real-space images for a single colloidal crystal grain with a random hexagonal close-packed structure. The reciprocal space and available real-space results agreed to within experimental error. The complete set of reciprocal lattice basis vectors was determined using the proposed technique in contrast to the partial lattice information available from real-space images. This technique appears to be generally capable of measuring lattice parameters to within 1% and orientation to better than 1 degrees . PMID:18188211

  12. Preventing Technique of Metal Deposition on Optical Devices in Space Diode Laser Welding for Space Applications

    NASA Astrophysics Data System (ADS)

    Suita, Yoshikazu; Tanaka, Kenji; Ohtani, Masato; Shobako, Shinichiro; Terajima, Noboru; Hiraoka, Nobuaki

    In future space developments, the welding in space may be required for the repairs of the ISS and the constructions of lunar base and space structures. The authors have studied the space Gas Hollow Tungsten Arc (GHTA) welding process since 1993. This paper describes the results for space applying the space Diode Laser (DL) welding process which the authors proposed in 2002. It is necessary to prevent the metal deposition on optical devices in order to utilize the space DL welding process in space. The authors studied the preventing technique of metal deposition which covered optical devices with the nozzle and blew the shielding gas out from nozzle outlet. The metal deposition can be reduced by supplying the nozzle with inert gas and blowing the gas out from nozzle outlet. The shielding gas argon perfectly prevents the metal deposition on optical devices when argon pressurizes the nozzle to over 19.9 Pa and spouts out from the nozzle outlet.

  13. MUSE alignment onto VLT

    NASA Astrophysics Data System (ADS)

    Laurent, Florence; Renault, Edgard; Boudon, Didier; Caillier, Patrick; Daguisé, Eric; Dupuy, Christophe; Jarno, Aurélien; Lizon, Jean-Louis; Migniau, Jean-Emmanuel; Nicklas, Harald; Piqueras, Laure

    2014-07-01

    MUSE (Multi Unit Spectroscopic Explorer) is a second generation Very Large Telescope (VLT) integral field spectrograph developed for the European Southern Observatory (ESO). It combines a 1' x 1' field of view sampled at 0.2 arcsec for its Wide Field Mode (WFM) and a 7.5"x7.5" field of view for its Narrow Field Mode (NFM). Both modes will operate with the improved spatial resolution provided by GALACSI (Ground Atmospheric Layer Adaptive Optics for Spectroscopic Imaging), that will use the VLT deformable secondary mirror and 4 Laser Guide Stars (LGS) foreseen in 2015. MUSE operates in the visible wavelength range (0.465-0.93 ?m). A consortium of seven institutes is currently commissioning MUSE in the Very Large Telescope for the Preliminary Acceptance in Chile, scheduled for September, 2014. MUSE is composed of several subsystems which are under the responsibility of each institute. The Fore Optics derotates and anamorphoses the image at the focal plane. A Splitting and Relay Optics feed the 24 identical Integral Field Units (IFU), that are mounted within a large monolithic structure. Each IFU incorporates an image slicer, a fully refractive spectrograph with VPH-grating and a detector system connected to a global vacuum and cryogenic system. During 2012 and 2013, all MUSE subsystems were integrated, aligned and tested to the P.I. institute at Lyon. After successful PAE in September 2013, MUSE instrument was shipped to the Very Large Telescope in Chile where that was aligned and tested in ESO integration hall at Paranal. After, MUSE was directly transported, fully aligned and without any optomechanical dismounting, onto VLT telescope where the first light was overcame the 7th of February, 2014. This paper describes the alignment procedure of the whole MUSE instrument with respect to the Very Large Telescope (VLT). It describes how 6 tons could be move with accuracy better than 0.025mm and less than 0.25 arcmin in order to reach alignment requirements. The success of the MUSE alignment is demonstrated by the excellent results obtained onto MUSE image quality and throughput directly onto the sky.

  14. Grain alignment in starless cores

    SciTech Connect

    Jones, T. J.; Bagley, M. [Minnesota Institute for Astrophysics, University of Minnesota, Minneapolis, MN 55455 (United States); Krejny, M. [Cree Inc., 4600 Silicon Dr., Durham, NC (United States); Andersson, B.-G. [SOFIA Science Center, USRA, Moffett Field, CA (United States); Bastien, P., E-mail: tjj@astro.umn.edu [Centre de recherche en astrophysique du Québec and Départment de Physique, Université de Montréal, Montréal (Canada)

    2015-01-01

    We present near-IR polarimetry data of background stars shining through a selection of starless cores taken in the K band, probing visual extinctions up to A{sub V}?48. We find that P{sub K}/?{sub K} continues to decline with increasing A{sub V} with a power law slope of roughly ?0.5. Examination of published submillimeter (submm) polarimetry of starless cores suggests that by A{sub V}?20 the slope for P versus ? becomes ??1, indicating no grain alignment at greater optical depths. Combining these two data sets, we find good evidence that, in the absence of a central illuminating source, the dust grains in dense molecular cloud cores with no internal radiation source cease to become aligned with the local magnetic field at optical depths greater than A{sub V}?20. A simple model relating the alignment efficiency to the optical depth into the cloud reproduces the observations well.

  15. Optical encryption by combining image scrambling techniques in fractional Fourier domains

    NASA Astrophysics Data System (ADS)

    Liu, Shi; Sheridan, John T.

    2013-01-01

    In this paper, we propose a novel scheme for optical information hiding (encryption) of two-dimensional images by combining image scrambling techniques in fractional Fourier domains. The image is initially randomly shifted using the jigsaw transform algorithm, and then a pixel scrambling technique based on the Arnold transform (ART) is applied. The scrambled image is then encrypted in a randomly chosen fractional Fourier domain. These processes can then be iteratively repeated. The parameters of the architecture, including the jigsaw permutation indices, Arnold frequencies, and fractional Fourier orders, form a very large key space enhancing the security level of the proposed encryption system. Optical implementations are discussed as numerical implementation algorithms. Numerical simulation results are presented to demonstrate the system's flexibility and robustness.

  16. Phased-array beam steering using optical true time delay technique

    NASA Astrophysics Data System (ADS)

    Yang, Dong-Hua; Lin, Wen-Piao

    2015-09-01

    An optical dispersion technique for phased-array beam steering is proposed and analyzed. Optical true time delay using a high-dispersion compensation fiber (HDCF) and a phased array antenna (PAA) can provide a continuous radio-frequency squint-free beam scanning. When the dispersion of the fabricated DCF-C band is as high as -1020±31 ps/nm/km, the laser wavelength can be tuned from 1549.95 to 1550.2 nm. The experimental results confirmed that the scanning angle of far field radiation patterns for proposed technique can be tuned to have a range 51° (from -22° to +29°) at frequency of 5.9, 12.7 and 17 GHz.

  17. Optical Fourier techniques for medical image processing and phase contrast imaging

    PubMed Central

    Yelleswarapu, Chandra S.; Kothapalli, Sri-Rajasekhar; Rao, D.V.G.L.N.

    2008-01-01

    This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764

  18. Optical and Thermal Analysis of the Time Evolution of Curing in Resins by Photothermal Techniques

    NASA Astrophysics Data System (ADS)

    Martínez-Torres, P.; Zambrano-Arjona, M.; Aguilar, G.; Alvarado-Gil, J. J.

    2012-11-01

    Four shades of a commercial visible-light curing dental resin are analyzed using photothermal techniques. The thermal effusivities of the dental resin shades before curing are measured using a variant of the conventional photoacoustic technique. The thermal diffusivities before and after curing are measured using infrared photothermal radiometry in the forward emission configuration. The time evolution process of the photocuring resin is monitored by photothermal radiometry in the forward and backward emission configurations. Inversion of the time evolution signal of the different configurations used permits one to obtain the time evolution of the thermal and optical properties during the photocuring. The thermal effusivity and thermal diffusivity exhibit exponential growth, while the optical absorption decreases exponentially due to the curing process. The relationship of these phenomena with the decrease of monomer concentration induced by the curing is discussed.

  19. Influence of aluminum on doping of ytterbium in optical fiber synthesized by vapor phase technique

    NASA Astrophysics Data System (ADS)

    Saha, Maitreyee; Pal, Atasi; Pal, Mrinmay; Sen, Ranjan

    2015-01-01

    The process conditions of vapor phase doping technique for fabricating rare earth (RE) doped optical fiber have been systematically investigated to achieve better control over RE incorporation. Experimental results showed that the amount of RE incorporation can be precisely controlled by adjusting Al ion concentration in the inlet gas mixture. The extent of RE incorporation can also be predicted for any composition of inlet gas mixture if all other process parameters remain constant. The investigation helps to obtain the optimum conditions necessary to produce fibers of given specification and thus achieve greater reproducibility. For the first time co-operative phenomenon has been established through gas phase technique.

  20. DSP-based optical modulation technique for long-haul transmission

    NASA Astrophysics Data System (ADS)

    Yoshida, T.; Sugihara, T.; Uto, K.

    2015-01-01

    Fiber nonlinearity and equalization-enhanced phase noise (EEPN) generate rapid perturbations and critically limit the system capacity and range of long-haul optical transmission. It is possible to cancel the rapid perturbations by introducing a particular correlation between multiple signals at the transmitter and analyzing the received signals using digital signal processing. In this paper, we review our proposed techniques to cancel rapid perturbations of polarization multiplexed signals due to fiber nonlinearity and EEPN. Numerical simulation of quaternary phase-shift keying based signals shows 1.2 dB and 0.5 dB improvement respectively from the proposed cancellation techniques for fiber nonlinearity and EEPN.

  1. Study of optical techniques for the Ames unitary wind tunnel: Digital image processing, part 6

    NASA Technical Reports Server (NTRS)

    Lee, George

    1993-01-01

    A survey of digital image processing techniques and processing systems for aerodynamic images has been conducted. These images covered many types of flows and were generated by many types of flow diagnostics. These include laser vapor screens, infrared cameras, laser holographic interferometry, Schlieren, and luminescent paints. Some general digital image processing systems, imaging networks, optical sensors, and image computing chips were briefly reviewed. Possible digital imaging network systems for the Ames Unitary Wind Tunnel were explored.

  2. Theoretical investigation of the off-axis z-scan technique for nonlinear optical refraction measurement.

    PubMed

    Ryasnyansky, Aleksandr I; Palpant, Bruno

    2006-04-20

    The theoretical investigation of the off-axis z-scan technique for the measurement of nonlinear optical refraction in materials is presented. The normalized transmittance is calculated for different aperture radii and positions. The dependence of both the normalized transmittance amplitude (DeltaT(pv)) and the distance between maximum and minimum (Deltaz(pv)) on the aperture radius is analyzed. A condition for the applicability of the pinhole approximation is given. PMID:16633429

  3. Technique and Apparatus for Accurate Cross-Sectional Stress Profiling of Optical Fibers

    Microsoft Academic Search

    Michael R. Hutsel; R. Reeve Ingle; Thomas K. Gaylord

    2011-01-01

    The design and performance of a technique for de- termining 2-D cross-sectional stress distributions in optical fibers and fiber-based devices is described. The Brace-Köhler phase com- pensation method is implemented on a commercial polarization microscope to perform full-field measurements of the transverse retardations induced by the low levels of birefringence in opti- cal fibers. Analysis of the region surrounding the

  4. A simple optical encryption based on shape merging technique in periodic diffraction correlation imaging.

    PubMed

    Sun, Mengjie; Shi, Jianhong; Li, Hu; Zeng, Guihua

    2013-08-12

    In Periodic diffraction correlation imaging (PDCI), the images of several objects located in different spatial positions can be integrated into one image following certain rules, which is named shape merging. In this paper, we proposed and demonstrated this new technique. It can be realized without SLM or beam-splitter. And this effect can find novel application in optical encryption, enabling transmission of object information to a remote place secretly. PMID:23938855

  5. ITO films on glass substrate by sol–gel technique: synthesis, characterization and optical properties

    Microsoft Academic Search

    E. Celik; U. Aybarc; M. F. Ebeoglugil; I. Birlik; O. Culha

    2009-01-01

    The present paper extensively demonstrates synthesis, characterization and optical properties of semiconductor indium tin\\u000a oxide (ITO) thin films on glass substrate using sol–gel technique for gas sensor applications. Turbidity, pH values, wettability\\u000a and rheological properties of the prepared solutions were measured to determine solution characteristics by turbidimeter,\\u000a pH meter, contact angle goniometer and rheometer machines prior to coating process. Thermal,

  6. Application of the optically stimulated luminescence (OSL) technique in space dosimetry

    Microsoft Academic Search

    E. G. Yukihara; G. O. Sawakuchi; S. Guduru; S. W. S. McKeever; R. Gaza; E. R. Benton; N. Yasuda; Y. Uchihori; H. Kitamura

    2006-01-01

    This paper reviews the state of the optically stimulated luminescence (OSL) technique for space dosimetry applications, focusing on the properties of carbon-doped aluminum oxide (Al2O3:C). New data presented include the most complete and recent values for the relative efficiency ?HCP,? for heavy charged particles as a function of the incident radiation's linear energy transfer (LET), obtained through ground-based experiments at

  7. Radio-over-fiber techniques and demonstration for in-building optical-wireless access networks

    Microsoft Academic Search

    Kun Xu; Jie Yin; Xiaoqiang Sun; Jianqiang Li; Hao Huang; Jian Wu; Xiaobing Hong; Jintong Lin

    2009-01-01

    This paper presents our recent progress on advanced radio-over-fiber (ROF) technologies for in-building optical-wireless access networks, including multi-service, full duplex and polarization diversity ROF systems design, and experimental delivery of uncompressed HDTV signals. The novel polarization diversity technique is proposed to improve receiving sensitivity and increase anti-interference capacity of the wireless transmission at the in-building environment.

  8. Frequency doubling technique perimetry and spectral domain optical coherence tomography in patients with early glaucoma

    Microsoft Academic Search

    F K Horn; C Y Mardin; D Bendschneider; A G Jünemann; W Adler; R P Tornow

    2011-01-01

    PurposeTo assess the combined diagnostic power of frequency-doubling technique (FDT)-perimetry and retinal nerve fibre layer (RNFL) thickness measurements with spectral domain optical coherence tomography (SDOCT).MethodsThe study included 330 experienced participants in five age-related groups: 77 ‘preperimetric’ open-angle glaucoma (OAG) patients, 52 ‘early’ OAG, 50 ‘moderate’ OAG, 54 ocular hypertensivepatients, and 97 healthy subjects. For glaucoma assessment in all subjects conventional

  9. Characterization of thermo-oxidative stability of polymer optical fibers using chemiluminescence technique

    Microsoft Academic Search

    Anilkumar Appajaiah; Volker Wachtendorf; Werner Daum

    2006-01-01

    The thermo-oxidative stability of commercially available polymer optical fibers (POFs) and their components (cores and claddings) was investigated. All the bare POFs (core and cladding only) studied here were based on poly(methyl methacrylate) (PMMA) core. The fibers were exposed to 100°C\\/low humidity for about 4200h. Chemiluminescence (CL) technique was applied to investigate the thermo-oxidative stability and for measuring the transmission

  10. Low temperature cavity ring down spectroscopy with off-axis alignment: application to the A- and gamma-bands of O2 in the visible at 90 K

    Microsoft Academic Search

    Y. Perez-Delgado; C. E. Manzanares

    2011-01-01

    The cavity ring down (CRD) technique presented here involves an optical cavity attached to a cryostat. The static cell and mirrors of the optical cavity are all inside a vacuum chamber at the same temperature of the cryostat. The temperature of the cell can be changed between 77 K and 298 K. An off-axis alignment of the laser beam into

  11. Optical coherence tomography: a non-invasive technique applied to conservation of paintings

    NASA Astrophysics Data System (ADS)

    Liang, Haida; Gomez Cid, Marta; Cucu, Radu; Dobre, George; Kudimov, Boris; Pedro, Justin; Saunders, David; Cupitt, John; Podoleanu, Adrian

    2005-06-01

    It is current practice to take tiny samples from a painting to mount and examine in cross-section under a microscope. However, since conservation practice and ethics limit sampling to a minimum and to areas along cracks and edges of paintings, which are often unrepresentative of the whole painting, results from such analyses cannot be taken as representative of a painting as a whole. Recently in a preliminary study, we have demonstrated that near-infrared Optical Coherence Tomography (OCT) can be used directly on paintings to examine the cross-section of paint and varnish layers without contact and the need to take samples. OCT is an optical interferometric technique developed for in vivo imaging of the eye and biological tissues; it is essentially a scanning Michelson's interferometer with a "broad-band" source that has the spatial coherence of a laser. The low temporal coherence and high spatial concentration of the source are the keys to high depth resolution and high sensitivity 3D imaging. The technique is non-invasive and non-contact with a typical working distance of 2 cm. This non-invasive technique enables cross-sections to be examined anywhere on a painting. In this paper, we will report new results on applying near-infrared en-face OCT to paintings conservation and extend the application to the examination of underdrawings, drying processes, and quantitative measurements of optical properties of paint and varnish layers.

  12. Generalized 1D photopyroelectric technique for optical and thermal characterization of liquids

    NASA Astrophysics Data System (ADS)

    Balderas-López, J. A.

    2012-06-01

    The analytical solution for the one-dimensional heat diffusion problem for a three-layer system, in the Beer-Lambert model for light absorption, is used for the implementation of a photopyroelectric (PPE) methodology for thermal and optical characterization of pigments in liquid solution, even for those ones potentially harmful to the pyroelectric sensor, taking the liquid sample's thickness as the only variable. Exponential decay of the PPE amplitude followed by a constant PPE phase for solutions at low pigment concentration, and exponential decay of the PPE amplitude but a linear decrease of the PPE phase for the concentrated ones are theoretically shown, allowing measurements of the optical absorption coefficient (at the wavelength used for the analysis) and the thermal diffusivity for the liquid sample, respectively. This PPE methodology was tested by measuring the thermal diffusivity of a concentrated solution of methylene blue in distilled water and the optical absorption coefficient, at two wavelengths (658 and 785 nm), of water solutions of copper sulfate at various concentrations. These optical parameters were used for measuring the molar absorption coefficient of this last pigment in water solution at these two wavelengths. This last optical property was also measured using a commercial spectrometer, finding very good agreement with the corresponding ones using this PPE technique.

  13. An optically controlled microwave phase shifter based on self-heterodyning technique using chirped fiber gratings and an optical frequency shifter

    Microsoft Academic Search

    Wataru Chujo; Yoshihiro Tomiyama

    2000-01-01

    A novel optically controlled microwave phase shifter based on self-heterodyne technique using chirped fiber gratings (CFG's) and optical frequency shifter (OFS) is demonstrated experimentally. The phase shifter is able to provide a wide bandwidth and beam scanning capability over a wide angle. Calculated results of an investigation into the beam scanning properties of a nine-element phased array antenna at 5

  14. A review of high-grade imaging of diatoms and radiolarians in light microscopy optical- and software-based techniques

    Microsoft Academic Search

    Jörg Piper

    2011-01-01

    Several optical- and software-based techniques for light microscopy are presented, which can be suggested as suitable means for the enhancement of image quality in observations and photomicrography of 3D specimens, especially diatoms and radiolarians. Sandwich illumination techniques, condenser aperture reduction darkfield, condenser aperture reduction phase contrast, axial darkfield (luminance contrast), traditional incident light and monochromatic illumination techniques can be used

  15. A 3D optical deformation measurement system supported by knowledge-based and learning techniques

    NASA Astrophysics Data System (ADS)

    Reiterer, Alexander; Lehmann, Martin; Miljanovic, Milos; Ali, Haider; Paar, Gerhard; Egly, Uwe; Eiter, Thomas; Kahmen, Heribert

    2009-03-01

    High accuracy 3D representation and monitoring of objects is receiving increasing interest both in science and industrial applications. Up to now tasks like monitoring of building displacements or deformations were solved by means of artificial targets on the objects of interest, although mature optical 3D measurement and laser scanning techniques are available. Such systems can perform their measurements even without targeting. This paper presents a new optical 3D measurement system, based on the fusion between a geodetic image sensor and a laser scanner. The main goal of its development was the automation of the whole measurement process, including the tasks of point identification and measurement, deformation analysis, and interpretation. This was only possible by means of new methods and techniques originally developed in the area of Artificial Intelligence; both point detection and deformation analysis are supported by decision systems that use such techniques. The resulting complex multi-sensor system is able to measure and analyse the deformation of objects, as shown in experiments. In this article we focus on specific key components and novel techniques that have been developed, and briefly report on the current stage of the whole system.

  16. Combining optical and radio techniques for high-resolution ionospheric specification

    NASA Astrophysics Data System (ADS)

    Coker, C.; Dymond, K. F.; Thonnard, S. E.

    2003-12-01

    With the proliferation of satellite-based ionospheric measurement systems, opportunities exist for high-resolution ionospheric specification. These systems utilize optical and radio-based techniques. The optical techniques include, UV limb scanning, UV disk scanning, and UV disk imaging. The radio techniques include, radio occultations, radio beacon tomography, and radar altimetry. While assimilative models seek to routinely ingest these data and produce a global or regional specification of the ionosphere, coincident measurements from more than one technique provide frequent opportunities to directly reconstruct the ionospheric densities with a high spatial resolution. The concept is demonstrated by using coincident UV limb scan data from LORAAS with radar altimetry data from TOPEX. The limb scans provide vertical information and the altimetry data provides horizontal information. When combined a 2D reconstruction of the ionosphere is obtained over a large geographic region with high spatial resolution. Additional combination of existing satellites can be used to produce high-resolution ionospheric specifications. In the future, multiple sensors on the same satellite will routinely provide such opportunities. Examples of these satellites include COSMIC and NPOES.

  17. Advanced Electro-Optic Surety Devices

    SciTech Connect

    Watterson, C.E.

    1997-05-01

    The Advanced Electro-Optic Surety Devices project was initiated in march 1991 to support design laboratory guidance on electro-optic device packaging and evaluation. Sandia National Laboratory requested AlliedSignal Inc., Kansas City Division (KCD), to prepare for future packaging efforts in electro-optic integrated circuits. Los Alamos National Laboratory requested the evaluation of electro-optic waveguide devices for nuclear surety applications. New packaging techniques involving multiple fiber optic alignment and attachment, binary lens array development, silicon V-groove etching, and flip chip bonding were requested. Hermetic sealing of the electro-optic hybrid and submicron alignment of optical components present new challenges to be resolved. A 10-channel electro-optic modulator and laser amplifier were evaluated for potential surety applications.

  18. High Field Magneto-Optical Spectroscopy of Highly Aligned Individual and Ensemble Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Shaver, J.; Srivastava, A.; Kono, J.; Crooker, S. A.; Htoon, H.; Klimov, V. I.; Fagan, J. A.; Hobbie, E. K.; Ubrig, N.; Portugall, O.; Perebeinos, V.; Avouris, Ph.

    The tubular nature of single-walled carbon nanotube (SWCNT) crystals allows them to exhibit non-intuitive quantum phenomena when threaded by a magnetic flux, which breaks the time reversal symmetry and adds an Aharonov-Bohm phase to the circumferential boundary conditions on the electronic wave function. We demonstrate that such a symmetry-breaking magnetic field can dramatically "brighten" an optically-inactive, or dark, exciton state at low temperature. This phenomenon, magnetic brightening, can be understood as a consequence of interplay between the strong intervalley Coulomb mixing and field-induced lifting of valley degeneracy. Most recently, we made the direct observation of the dark excitonic state in individual SWCNTs using low-temperature micro-photoluminescence (PL) and and verified the importance of a parallel, tube-threading magentic field with ensemble spectroscopy. For micro-PL, a magnetic field up to 5 T, applied along the nanotube axis, brightened the dark state, leading to the emergence of a new emission peak. The peak rapidly grew in intensity with increasing field at the expense of the originally-dominant bright exciton peak and finally became dominant at fields > 3 T. The directly measured dark-bright splitting values were 1-4 meV for tube diameters 1.0-1.3 nm. For ensemble PL, we used fields up to 55 T in two collection geometries to demonstrate the importance of the tube-threading component. These experiments have provided one of the most critical tests for recently-proposed theories of 1-D excitons taking into account the strong 1-D Coulomb interactions and unique band structure on an equal footing.

  19. IUS prerelease alignment

    NASA Technical Reports Server (NTRS)

    Evans, F. A.

    1978-01-01

    Space shuttle orbiter/IUS alignment transfer was evaluated. Although the orbiter alignment accuracy was originally believed to be the major contributor to the overall alignment transfer error, it was shown that orbiter alignment accuracy is not a factor affecting IUS alignment accuracy, if certain procedures are followed. Results are reported of alignment transfer accuracy analysis.

  20. The electro-optical characteristics and applicability evaluation of a photo-induced vertical alignment negative-type liquid crystal\\/photo-curable acrylic prepolymer mixture system mixed with chiral smectic A phase liquid crystal

    Microsoft Academic Search

    Czung-Yu Ho; Jiunn-Yih Lee

    2011-01-01

    In this study, we have investigated newly synthesised chiral smectic A (SmA*) liquid crystals (LCs) with a lactic acid structure with polarised optical microscopy (POM). We started cooling from the clear point until a SmA* phase emerged as the temperature dropped to the range 55.7–88.6°C. At this point, the alignment of the LC molecules resulted in a homeotropic texture. To

  1. New Active Optical Technique Developed for Measuring Low-Earth-Orbit Atomic Oxygen Erosion of Polymers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; deGroh, Kim K.; Demko, Rikako

    2003-01-01

    Polymers such as polyimide Kapton (DuPont) and Teflon FEP (DuPont, fluorinated ethylene propylene) are commonly used spacecraft materials because of desirable properties such as flexibility, low density, and in the case of FEP, a low solar absorptance and high thermal emittance. Polymers on the exterior of spacecraft in the low-Earth-orbit (LEO) environment are exposed to energetic atomic oxygen. Atomic oxygen reaction with polymers causes erosion, which is a threat to spacecraft performance and durability. It is, therefore, important to understand the atomic oxygen erosion yield E (the volume loss per incident oxygen atom) of polymers being considered in spacecraft design. The most common technique for determining E is a passive technique based on mass-loss measurements of samples exposed to LEO atomic oxygen during a space flight experiment. There are certain disadvantages to this technique. First, because it is passive, data are not obtained until after the flight is completed. Also, obtaining the preflight and postflight mass measurements is complicated by the fact that many polymers absorb water and, therefore, the mass change due to water absorption can affect the E data. This is particularly true for experiments that receive low atomic oxygen exposures or for samples that have a very low E. An active atomic oxygen erosion technique based on optical measurements has been developed that has certain advantages over the mass-loss technique. This in situ technique can simultaneously provide the erosion yield data on orbit and the atomic oxygen exposure fluence, which is needed for erosion yield determination. In the optical technique, either sunlight or artificial light can be used to measure the erosion of semitransparent or opaque polymers as a result of atomic oxygen attack. The technique is simple and adaptable to a rather wide range of polymers, providing that they have a sufficiently high optical absorption coefficient. If one covers a photodiode with a uniformly thick sheet of semitransparent polymer such as Kapton H polyimide, then as atomic oxygen erodes the polymer, the short-circuit current from the photodiode will increase in an exponential manner with fluence. This nonlinear response with fluence results in a lack of sensitivity for measuring low atomic oxygen fluences. However, if one uses a variable-thickness polymer or carbon sample, which is configured as shown in the preceding figure, then a linear response can be achieved for opaque materials using a parabolic well for a circular geometry detector or a V-shaped well for a rectangular-geometry detector. Variable-thickness samples can be fabricated using many thin polymer layers. For semitransparent polymers such as Kapton H polyimide, there is an initial short-circuit current that is greater than zero. This current has a slightly nonlinear dependence on atomic oxygen fluence in comparison to opaque materials such as black Kapton as shown in the graph. For this graph figure, the total thickness of Kapton H was assumed to be 0.03 cm. The photodiode short-circuit current shown in the graph was generated on the basis of preliminary measurements-a total reflectance rho of 0.0424 and an optical absorption coefficient a of 146.5 cm(sup -1). In addition to obtaining on-orbit data, the advantage of this active erosion and erosion yield measurement technique is its simplicity and reliance upon well-characterized fluence witness materials as well as a nearly linear photodiode short-circuit current dependence upon atomic oxygen fluence. The optical technique is useful for measuring either atomic oxygen fluence or erosion, depending on the information desired. To measure the atomic oxygen erosion yield of a test material, one would need to have two photodiode sensors, one for the test material and one that uses a known erosion yield material (such as Kapton) to measure the atomic oxygen fluence.

  2. All-optical technique to correlate defect structure and carrier transport in transferred graphene films.

    PubMed

    Rochford, Caitlin; Kumar, Nardeep; Liu, Jianwei; Zhao, Hui; Wu, Judy

    2013-08-14

    Chemical vapor deposition of graphene on copper foil is an attractive method of producing large-area graphene films, but the electronic performance is limited by defects such as creases from the film transfer process, wrinkles due to the thermal expansion coefficient mismatch, and grain boundaries from the growth process. Here we present an all-optical technique to correlate defect structure with electronic properties using spatially resolved Raman spectroscopy and transient absorption microscopy. This technique is especially attractive since it does not require any lithographic steps to probe the electronic properties of the graphene film. As a first demonstration, we focus on the effects of both wrinkles and creases while averaging over many small grains. It was found that wrinkles and creases may decrease the charge carrier diffusion coefficient by over 50% due to increased defect scattering. This technique may easily be extended to large grain graphene films in order to study the effect of different types of grain boundaries. PMID:23855775

  3. Audio extraction from silent high-speed video using an optical technique

    NASA Astrophysics Data System (ADS)

    Wang, Zhaoyang; Nguyen, Hieu; Quisberth, Jason

    2014-11-01

    It is demonstrated that audio information can be extracted from silent high-speed video with a simple and fast optical technique. The basic principle is that the sound waves can stimulate objects encountered in the traveling path to vibrate. The vibrations, although usually with small amplitudes, can be detected by using an image matching process. The proposed technique applies a subset-based image correlation approach to detect the motions of points on the surface of an object. It employs the Gauss-Newton algorithm and a few other measures to achieve very fast and highly accurate image matching. Because the detected vibrations are directly related to the sound waves, a simple model is introduced to reconstruct the original audio information of the sound waves. The proposed technique is robust and easy to implement, and its effectiveness has been verified by experiments.

  4. Optical authentication technique based on interference image hiding system and phase-only correlation

    NASA Astrophysics Data System (ADS)

    Yuan, Sheng; Zhang, Tong; Zhou, Xin; Liu, Xuemei; Liu, Mingtang

    2013-09-01

    An optical authentication technique based on interference image hiding system and phase-only correlation is proposed. In this method, some predefined complex images with different amplitudes and the same phase are respectively encoded into two phase-only masks according to the interference principle. This technique can easily generate different verification keys for different users, so it brings convenience for multi-user application. In the verification stage, both a sharp correlation peak and a significant image represented the identity of a user are generated simultaneously. Therefore, in addition to simple verification, this method can also recognize the identity of the user. Moreover, this technique can effectively avoid the verification key being forged by other person. All the performances and the feasibility of our proposed method are tested by numerical simulations.

  5. A Test of Three Optical Flow Techniques-LCT, DAVE, and NAVE

    NASA Astrophysics Data System (ADS)

    Chae, Jongchul; Sakurai, Takashi

    2008-12-01

    A time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space may be utilized to determine the transverse flow field on the plane of the sky with the help of optical flow techniques. We have examined the performance of three different methods-a well-known technique called local correlation tracking (LCT), a recently developed technique called the differential affine velocity estimator (DAVE), and a new technique called the nonlinear affine velocity estimator (NAVE)-using three kinds of image data: mapping-based synthetic images, a set of MHD simulation data, and real images (magnetograms) taken by the Solar Optical Telescope on board Hinode. We have generalized the model equation of image evolution by adding to the continuity equation a source term that is proportional to the image value. Synthetic images were constructed based on the analytical solution of this equation with different velocity profiles: uniform, affine, or nonaffine. The tests with the synthetic data indicated that NAVE is very good at detecting subpixel motions, superpixel motions, and nonuniform motions, while LCT is not good at detecting nonuniform motions, especially around critical points, and the performance of DAVE is degraded in the presence of superpixel motions. In all the methods, the performance became worse as the velocity field deviated more from an affine one. We also found that the MHD simulation data we used are not quite suited for discriminating between the three methods, maybe because the data do not contain enough structural information to be used for tracing. In contrast, the determination of velocity fields from the real image data was somewhat sensitive to the technique adopted. The technique of NAVE with the source term produced velocity fields that are the most consistent with the data.

  6. A comparison of four pair-wise sequence alignment methods

    Microsoft Academic Search

    Nadia Essoussi; Sondes Fayech

    Protein sequence alignment has become an essential task in modern molecular biology research. A number of alignment techniques have been documented in literature and their corresponding tools are made available as freeware and commercial software. The choice and use of these tools for sequence alignment through the complete interpretation of alignment results is often considered non-trivial by end-users with limited

  7. Directed 3D cell alignment and elongation in microengineered hydrogels

    Microsoft Academic Search

    Hug Aubin; Jason W. Nichol; Ché B. Hutson; Hojae Bae; Alisha L. Sieminski; Donald M. Cropek; Paryam Akhyari; Ali Khademhosseini

    2010-01-01

    Organized cellular alignment is critical to controlling tissue microarchitecture and biological function. Although a multitude of techniques have been described to control cellular alignment in 2D, recapitulating the cellular alignment of highly organized native tissues in 3D engineered tissues remains a challenge. While cellular alignment in engineered tissues can be induced through the use of external physical stimuli, there are

  8. Comparison of Beam-Based Alignment Algorithms for the ILC

    SciTech Connect

    Smith, J.C.; Gibbons, L.; Patterson, J.R.; Rubin, D.L.; /Cornell U., LEPP; Sagan, D.; /Cornell U., Phys. Dept.; Tenenbaum, P.; /SLAC

    2006-03-15

    The main linac of the International Linear Collider (ILC) requires more sophisticated alignment techniques than those provided by survey alone. Various Beam-Based Alignment (BBA) algorithms have been proposed to achieve the desired low emittance preservation. Dispersion Free Steering, Ballistic Alignment and the Kubo method are compared. Alignment algorithms are also tested in the presence of an Earth-like stray field.

  9. Characterization of static and dynamic optical actuation of Al microbeams by microscopic interferometry techniques

    NASA Astrophysics Data System (ADS)

    Petitgrand, Sylvain; Courbet, Bérenger; Bosseboeuf, Alain

    2003-07-01

    Out-of-plane optical actuation of thin Al cantilever microbeams was investigated as a function of laser beam power, spot size, modulation frequency and location on the beam. Several microscopic interferometry techniques including quantitative time-averaged interferometry and phase shifting stroboscopic interferometry were used to determine the resonant frequencies, vibration mode shapes and optically induced mean deflection of the microbeams. Transient response measurements by stroboscopic interferometry are also demonstrated. Experimental results show that on-wafer, non-contact, full-field dynamic measurements can be performed up to at least several hundred kHz although a large light power is necessary to actuate Al microbeams. It is demonstrated that dynamical optical actuation tends to saturate as a function of laser beam power and is maximum when the laser spot is located below 1/3 of the beam length. It is also evidenced that fundamental resonant frequencies measured with optical actuation are lower than that measured with piezoelectric actuation. Results are discussed by considering that actuation is dominated by photothermal effects.

  10. Sub-wavelength terahertz beam profiling of a THz source via an all-optical knife-edge technique

    E-print Network

    Ho, Sze Phing; Shalaby, Mostafa; Peccianti, Marco; Clerici, Matteo; Pasquazi, Alessia; Ozturk, Yavuz; Ali, Jalil; Morandotti, Roberto

    2015-01-01

    We propose an all-optical Knife Edge characterization technique and we demonstrate its working principle by characterizing the sub-{\\lambda} features of a spatially modulated Terahertz source directly on the nonlinear crystal employed for the Terahertz generation.

  11. Monitoring natural regeneration using optical remote sensing techniques1 Dr Tim J Malthus and David T Shaw

    E-print Network

    Monitoring natural regeneration using optical remote sensing techniques1 Dr Tim J Malthus and David). An increasingly available and well- used research tool for this purpose is the field spectroradiometer (Malthus

  12. Amplitude spectrum modulation technique for analog data processing in fiber optic sensing system with temporal separation of channels

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory

    1988-01-01

    A novel technique to analyze analog data in fiber optic sensing systems with temporal separation of channels is proposed. A theoretical explanation of the process is presented and an experimental setup that was used to obtain data is described.

  13. Comparison of thermal and optical techniques for describing light interaction with vascular grafts, sutures, and thrombus

    NASA Astrophysics Data System (ADS)

    Obremski, Susan M.; LaMuraglia, Glenn M.; Bruggemann, Ulrich H.; Anderson, R. Rox

    1991-06-01

    Pulsed photothermal radiometry (PPTR) and integrating sphere spectrophotometry analyzed by the theory of Kubelka and Munk (KM) were used to determine optical absorption coefficients of prosthetic grafts and sutures and arterial thrombus. The KM method, a purely optical theory and technique, resulted in higher absorption coefficients than those found using PPTR, a primarily thermal technique. This difference was statistically significant (t.025) for the prosthetic materials. With the KM method, other properties such as scattering can also be quantified and the experiment can be performed over a range of wavelengths at one time. The PPTR technique is limited to a single wavelength but it has the advantage that most materials can be tested without any special preparation. In addition, with PPTR the measured quantity is the temporal temperature response of an object to a laser pulse, which is itself of interest. Clinically, the high absorption coefficient of thrombus as compared to that of the graft and sutures (t.025 for the PPTR measurements) suggests that laser thrombectomy may be safe in polyethylene terephthalate (Dacron) grafts.

  14. Accurate high reflectivity measurement based on a novel optical feedback cavity ring-down technique

    NASA Astrophysics Data System (ADS)

    Gong, Yuan; Li, Bincheng; Han, Yanling; Liu, Mingqiang

    2008-10-01

    Highly reflective mirrors have been widely used in high power lasers, laser gyros, and gravitational-wave detection, etc. However, reliable measurement of high reflectivity (R>99.99%) is difficult. In this paper a novel optical feedback cavity ring-down technique (OF-CRD) by re-injecting the strong optical feedback from the ring-down cavity (RDC) into the oscillator cavity of a Fabry-Perot diode laser is developed for the ultra-high reflectivity measurement. The laser line is narrowed and occasionally in resonance with one or more ring-down cavity modes. The amplitude of the RDC output signal is enhanced by a factor of over two orders of magnitude, compared with the conventional phase-shift CRD technique. Four pairs of cavity mirrors with different reflectivity are used to investigate the sensitivity and reproducibility of the OF-CRD technique. The accuracy is greatly enhanced from about 0.003% to 0.00003% as the reflectivity of cavity mirrors increases from about 99.8% to 99.996%. A folded RDC with cavity length of 70cm is constructed by inserting a planar test mirror into the linear RDC and the reflectivity of the test mirror is statistically determined to be 99.9526+/-0.0004%. The OF-CRD is simple, reliable, highly-sensitive and cost efficient.

  15. Frequency-resolved optical gating technique for retrieving the amplitude of a vibrational wavepacket

    PubMed Central

    Nabekawa, Yasuo; Furukawa, Yusuke; Okino, Tomoya; Amani Eilanlou, A.; Takahashi, Eiji J.; Yamanouchi, Kaoru; Midorikawa, Katsumi

    2015-01-01

    We propose a novel method to determine the complex amplitude of each eigenfunction composing a vibrational wavepacket of / molecular ions evolving with a ~10?fs time scale. We find that the two-dimensional spectrogram of the kinetic energy release (KER) of H+/D+ fragments plotted against the time delay of the probe pulse is equivalent to the spectrogram used in the frequency-resolved optical gating (FROG) technique to retrieve the complex amplitude of an ultrashort optical pulse. By adapting the FROG algorithm to the delay-KER spectrogram of the vibrational wavepacket, we have successfully reconstructed the complex amplitude. The deterioration in retrieval accuracy caused by the bandpass filter required to process actual experimental data is also discussed. PMID:26068640

  16. Analog fiber optic multiplexing techniques and results from the Hunters Trophy Experiment

    SciTech Connect

    Hansen, G.J.

    1993-11-01

    Due to the growth in the use of analog fiber optic data transmission systems at the Nevada Test Site and other locations, Sandia National Laboratories (SNL) has recognized the need to be able to multiplex several data channels per fiber. Wavelength-division, frequency-division, and time-division multiplex techniques have been investigated. A time-division system using optically-multiplexed laser transmitters driving a common receiver was fielded on the HUNTERS TROPHY event at the NTS. Stability, noise, and dynamic range compared favorably with that seen on nonmultiplexed links. Amplitude, width, and rise time of data transmitted via the multiplexed links was consistent with that recorded from non-multiplexed links.

  17. [Techniques of on-line monitoring volatile organic compounds in ambient air with optical spectroscopy].

    PubMed

    Du, Zhen-Hui; Zhai, Ya-Qiong; Li, Jin-Yi; Hu, Bo

    2009-12-01

    Volatile organic compounds (VOCs) are harmful gaseous pollutants in the ambient air. The techniques of on-line monitoring VOCs are very significant for environment protection. Until now, there is no single technology that can meet all the needs of monitoring various VOCs. The characteristics and present situation of several optical methods, which can be applied to on-line monitoring VOCs, including non dispersive infrared (NDIR), Fourier transform infrared (FTIR) spectroscopy, differential optical absorption spectroscopy (DOAS), and laser spectroscopy were reviewed. Comparison was completed between the national standard methods and spectroscopic method for measuring VOCs. The main analysis was focused on the status and trends of tuning diode laser absorption spectroscopy (TDLAS) technology. PMID:20210131

  18. Optical asymmetric cryptography based on elliptical polarized light linear truncation and a numerical reconstruction technique.

    PubMed

    Lin, Chao; Shen, Xueju; Wang, Zhisong; Zhao, Cheng

    2014-06-20

    We demonstrate a novel optical asymmetric cryptosystem based on the principle of elliptical polarized light linear truncation and a numerical reconstruction technique. The device of an array of linear polarizers is introduced to achieve linear truncation on the spatially resolved elliptical polarization distribution during image encryption. This encoding process can be characterized as confusion-based optical cryptography that involves no Fourier lens and diffusion operation. Based on the Jones matrix formalism, the intensity transmittance for this truncation is deduced to perform elliptical polarized light reconstruction based on two intensity measurements. Use of a quick response code makes the proposed cryptosystem practical, with versatile key sensitivity and fault tolerance. Both simulation and preliminary experimental results that support theoretical analysis are presented. An analysis of the resistance of the proposed method on a known public key attack is also provided. PMID:24979424

  19. Structural and optical properties of CdO thin films deposited by RF magnetron sputtering technique

    SciTech Connect

    Kumar, G. Anil, E-mail: anilhcu@gmail.com; Reddy, M. V. Ramana, E-mail: anilhcu@gmail.com [Department of Physics, Osmania University, Hyderabad-500007 (India); Reddy, Katta Narasimha, E-mail: anilhcu@gmail.com [Department of Physics, Mahatma Gandhi University, Nalgonda-508003 (India)

    2014-04-24

    Cadmium oxide (CdO) thin films were deposited on glass substrate by r.f. magnetron sputtering technique using a high purity (99.99%) Cd target of 2-inch diameter and 3 mm thickness in an Argon and oxygen mixed atmosphere with sputtering power of 50W and sputtering pressure of 2×10{sup ?2} mbar. The prepared films were characterized by X-ray diffraction (XRD), optical spectroscopy and scanning electron microscopy (SEM). The XRD analysis reveals that the films were polycrystalline with cubic structure. The visible range transmittance was found to be over 70%. The optical band gap increased from 2.7 eV to2.84 eV with decrease of film thickness.

  20. Noninvasive optical polarimetric glucose sensing using a true phase measurement technique.

    PubMed

    Coté, G L; Fox, M D; Northrop, R B

    1992-07-01

    The focus of this paper was to describe the development and testing of a noninvasive true phase optical polarimetry sensing system to monitor in vivo glucose concentrations. To demonstrate the applicability of this optical sensor for glucose measurement, we first calibrated the system and then tested it in vitro using both a glass test cell filled with glucose solution in the physiologic range, with a path length of 0.9 cm to approximate one centimeter path length present in the anterior chamber of the eye, and then on an excised human eye. Our technique used helium neon laser light which was coupled through a rotating linear polarizer along with two stationary linear polarizers and two detectors to produce reference and signal outputs whose amplitudes varied sinusoidally with a frequency of twice the angular velocity of the rotating polarizer, and whose phase was proportional to the rotation of the linear polarization vector passing through the glucose solution. PMID:1516942

  1. Frequency-resolved optical gating technique for retrieving the amplitude of a vibrational wavepacket.

    PubMed

    Nabekawa, Yasuo; Furukawa, Yusuke; Okino, Tomoya; Amani Eilanlou, A; Takahashi, Eiji J; Yamanouchi, Kaoru; Midorikawa, Katsumi

    2015-01-01

    We propose a novel method to determine the complex amplitude of each eigenfunction composing a vibrational wavepacket of / molecular ions evolving with a ~10?fs time scale. We find that the two-dimensional spectrogram of the kinetic energy release (KER) of H(+)/D(+) fragments plotted against the time delay of the probe pulse is equivalent to the spectrogram used in the frequency-resolved optical gating (FROG) technique to retrieve the complex amplitude of an ultrashort optical pulse. By adapting the FROG algorithm to the delay-KER spectrogram of the vibrational wavepacket, we have successfully reconstructed the complex amplitude. The deterioration in retrieval accuracy caused by the bandpass filter required to process actual experimental data is also discussed. PMID:26068640

  2. Design tools and modeling techniques for integrated optics devices: requirements and applications

    NASA Astrophysics Data System (ADS)

    Waechter, Christoph A.

    2004-08-01

    The paper presents a short review of the theoretical basics of modeling techniques in integrated optics, essentially mode solving and field propagation, and some of the underlying numerical approaches in short. To meet the requirements of an effective design process of a potentially complex waveguide circuitry different levels of abstraction are used preferably. Thus, the application of tools adequate for the individual problem and the confirmation of results is of special importance. If the waveguide device is to be regarded as a real multi-physics microsystem-as in the case of the simple thermo-optical switch-the use of parametric models is a prevalent procedure to speed up the design process. For different applications, ranging from sensor devices to standard telecom components, specific requirements of the design and the use of standard and individual design tools are discussed.

  3. 1000 V/ m pulsed poling technique for photolime-gel electro-optic polymer with room-temperature repoling feature

    E-print Network

    Chen, Ray

    , ranging from 50 to 100 ms, very little current is injected through the polymer film under the poling1000 V/ m pulsed poling technique for photolime-gel electro-optic polymer with room is developed for achieving high-performance electro-optic polymers. A high poling field of 1 kV/ m can

  4. Analysis of the AO-FDPC optical heterodyne technique for microwave time delay and phased array beamsteering applications

    Microsoft Academic Search

    William D. Jemison

    2002-01-01

    This paper presents a theoretical analysis of the application of the acousto-optic frequency-dependent phase compensated (AO-FDPC) optical heterodyne technique for microwave time delay applications and phased array beamsteering. A primary goal of the paper is to resolve open questions that have been associated with this interesting and highly referenced technique. The work presented here quantifies, for the first time, the

  5. Automated alignment and on-sky performance of the Gemini planet imager coronagraph

    NASA Astrophysics Data System (ADS)

    Savransky, Dmitry; Thomas, Sandrine J.; Poyneer, Lisa A.; Dunn, Jennifer; Macintosh, Bruce A.; Sadakuni, Naru; Dillon, Daren; Goodsell, Stephen J.; Hartung, Markus; Hibon, Pascale; Rantakyrö, Fredrik; Cardwell, Andrew; Serio, Andrew

    2014-07-01

    The Gemini Planet Imager (GPI) is a next-generation, facility instrument currently being commissioned at the Gemini South observatory. GPI combines an extreme adaptive optics system and integral field spectrograph (IFS) with an apodized-pupil Lyot coronagraph (APLC) producing an unprecedented capability for directly imaging and spectroscopically characterizing extrasolar planets. GPI's operating goal of 10-7 contrast requires very precise alignments between the various elements of the coronagraph (two pupil masks and one focal plane mask) and active control of the beam path throughout the instrument. Here, we describe the techniques used to automatically align GPI and maintain the alignment throughout the course of science observations. We discuss the particular challenges of maintaining precision alignments on a Cassegrain mounted instrument and strategies that we have developed that allow GPI to achieve high contrast even in poor seeing conditions.

  6. Holograms for laser diode: Single mode optical fiber coupling

    NASA Technical Reports Server (NTRS)

    Fuhr, P. L.

    1982-01-01

    The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

  7. Spot Scanning Proton Beam Therapy for Prostate Cancer: Treatment Planning Technique and Analysis of Consequences of Rotational and Translational Alignment Errors

    SciTech Connect

    Meyer, Jeff, E-mail: jmeye3@utsouthwestern.ed [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States); Bluett, Jaques; Amos, Richard [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States)

    2010-10-01

    Purpose: Conventional proton therapy with passively scattered beams is used to treat a number of tumor sites, including prostate cancer. Spot scanning proton therapy is a treatment delivery means that improves conformal coverage of the clinical target volume (CTV). Placement of individual spots within a target is dependent on traversed tissue density. Errors in patient alignment perturb dose distributions. Moreover, there is a need for a rational planning approach that can mitigate the dosimetric effect of random alignment errors. We propose a treatment planning approach and then analyze the consequences of various simulated alignment errors on prostate treatments. Methods and Materials: Ten control patients with localized prostate cancer underwent treatment planning for spot scanning proton therapy. After delineation of the clinical target volume, a scanning target volume (STV) was created to guide dose coverage. Errors in patient alignment in two axes (rotational and yaw) as well as translational errors in the anteroposterior direction were then simulated, and dose to the CTV and normal tissues were reanalyzed. Results: Coverage of the CTV remained high even in the setting of extreme rotational and yaw misalignments. Changes in the rectum and bladder V45 and V70 were similarly minimal, except in the case of translational errors, where, as a result of opposed lateral beam arrangements, much larger dosimetric perturbations were observed. Conclusions: The concept of the STV as applied to spot scanning radiation therapy and as presented in this report leads to robust coverage of the CTV even in the setting of extreme patient misalignments.

  8. Coordinate measurement machines as an alignment tool

    SciTech Connect

    Wand, B.T.

    1991-03-01

    In February of 1990 the Stanford Linear Accelerator Center (SLAC) purchased a LEITZ PM 12-10-6 CMM (Coordinate measurement machine). The machine is shared by the Quality Control Team and the Alignment Team. One of the alignment tasks in positioning beamline components in a particle accelerator is to define the component's magnetic centerline relative to external fiducials. This procedure, called fiducialization, is critical to the overall positioning tolerance of a magnet. It involves the definition of the magnetic center line with respect to the mechanical centerline and the transfer of the mechanical centerline to the external fiducials. To perform the latter a magnet coordinate system has to be established. This means defining an origin and the three rotation angles of the magnet. The datum definition can be done by either optical tooling techniques or with a CMM. As optical tooling measurements are very time consuming, not automated and are prone to errors, it is desirable to use the CMM fiducialization method instead. The establishment of a magnet coordinate system based on the mechanical center and the transfer to external fiducials will be discussed and presented with 2 examples from the Stanford Linear Collider (SLC). 7 figs.

  9. Nanomaterials-Based Optical Techniques for the Detection of Acetylcholinesterase and Pesticides

    PubMed Central

    Xia, Ning; Wang, Qinglong; Liu, Lin

    2015-01-01

    The large amount of pesticide residues in the environment is a threat to global health by inhibition of acetylcholinesterase (AChE). Biosensors for inhibition of AChE have been thus developed for the detection of pesticides. In line with the rapid development of nanotechnology, nanomaterials have attracted great attention and have been intensively studied in biological analysis due to their unique chemical, physical and size properties. The aim of this review is to provide insight into nanomaterial-based optical techniques for the determination of AChE and pesticides, including colorimetric and fluorescent assays and surface plasmon resonance. PMID:25558991

  10. Classification of remotely sensed data using OCR-inspired neural network techniques. [Optical Character Recognition

    NASA Technical Reports Server (NTRS)

    Kiang, Richard K.

    1992-01-01

    Neural networks have been applied to classifications of remotely sensed data with some success. To improve the performance of this approach, an examination was made of how neural networks are applied to the optical character recognition (OCR) of handwritten digits and letters. A three-layer, feedforward network, along with techniques adopted from OCR, was used to classify Landsat-4 Thematic Mapper data. Good results were obtained. To overcome the difficulties that are characteristic of remote sensing applications and to attain significant improvements in classification accuracy, a special network architecture may be required.

  11. Applications of Optical Image Processing Technique for Steel Mill Non-contacting Conveyance System Operations

    NASA Astrophysics Data System (ADS)

    Liu, Cheng-Tsung; Yang, Yung-Yi; Lin, Sheng-Yang

    This paper is aimed to present the design and feasibility investigations of adopting the available on-site optical inspection system, which is commonly used for steel plate dimension measurement, to supply on-line dynamic gap measurements of a non-contacting conveyance structure in a steel mill. Adequate software and hardware implementations based on digital image processing techniques have been adapted to the entire system formulations and estimations. Results show that the system can supply accurate and rapid gap measurements and thus can fulfill the design and operational objectives.

  12. Application of optical techniques for in situ analysis of plasma facing carbon tiles

    NASA Astrophysics Data System (ADS)

    Nakazato, H.; Yoshida, M.; Tanabe, T.; Masaki, K.; Miya, N.; Sato, M.

    2009-06-01

    Optical absorption/emission spectroscopy is considered to be used for in situ characterization of plasma facing carbon tiles and quantitative evaluation of tritium. In this paper we have applied ex situ laser Raman spectroscopy for carbon tiles used as first wall and divertor in JT-60 exposed to HH discharge plasma to verify the applicability of the technique. The analysis shows that the micro-structure of the carbon tile surfaces is modified in a similar way like damaging by energetic ion irradiation and that one can get information of how graphite structures are damaged by plasma exposure or what kind of structures the redeposited carbon obtains.

  13. The Direct Optical Transition Line Shape Function from the Equilibrium Density Projection Operator Technique

    NASA Astrophysics Data System (ADS)

    Sug, J. Y.; Jo, S. G.; Choi, S. D.

    1999-10-01

    Using the equilibrium density projection operator technique (EDPT), we calculate the lineshape function for the magneto-optical direct interband transition in an electron-phonon system. We present the calculation processes for obtaining the scattering factor using the EDPT. We introduce two useful identities necessary to expand the elements of the scattering factor. We derive a cancellation relation which simplifies the expansion of the scattering factor. We obtain the lineshape function in the case of a weak interaction and compared our results with those of other theories.

  14. Active cleaning techniques for removing contamination from optical surfaces in space

    NASA Technical Reports Server (NTRS)

    Shannon, R. L.; Gillette, R. B.

    1973-01-01

    Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

  15. Resonator micro optic gyro with double phase modulation technique using an FPGA-based digital processor

    NASA Astrophysics Data System (ADS)

    Ma, Huilian; Mao, Hui; Chen, Yan; Jin, Zhonghe

    2011-05-01

    A resonator micro optic gyro (RMOG) with the proposed FPGA-based digital processor is set up. The double phase modulation technique is applied to achieve high total carrier suppression. Rotation tests from +/-0.1 °/s to +/-5 °/s are tested, where the processing circuit of RMOG is implemented by the instruments. The rotation test over a range of +/-550 °/s has been successfully obtained with all the processing circuit implemented in FPGA. To the best of our knowledge, these results are the best results of RMOG ever demonstrated in silica resonator with the ring length as short as 7.9 cm.

  16. Multilevel Signal Processing Technique for a 30 Gbit/inch2 Phase-Change Optical Disk System

    NASA Astrophysics Data System (ADS)

    Hayashi, Hideki; Minagawa, Noboru

    2003-02-01

    We developed a multilevel recording technique and a Viterbi decoding technique for increasing the recording density of a phase-change optical disk. In this multilevel recording technique, each mark recorded on the disk changes its edge position in four steps according to four-level data. Since two consecutive mark edges are reproduced simultaneously, their reproduced signal takes seven levels. We devised a Viterbi decoder with reference matrices in order to improve data detection performance by compensating the nonlinearity of this multilevel signal. We evaluated the error rate performance of this optical disk system by computer simulation. The Viterbi decoder with the reference matrices showed superior performance, and had an improved noise margin which is 3.5 dB higher than that of a conventional Viterbi decoder. By employing the multilevel recording technique and the Viterbi decoding technique, we confirmed the feasibility of the phase-change optical disk system with a recording density of 30 Gbit/inch2.

  17. Apodization of coupled resonator optical waveguide devices through a longitudinal offset technique

    NASA Astrophysics Data System (ADS)

    Doménech, J. D.; Muñoz, P.; Capmany, J.

    2010-05-01

    In this paper, a novel technique to set the coupling constant between cells of a coupled resonator optical waveguide (CROW) device, in order to tailor the filter response, is presented. It is known that using the same K value for all the couplers produces filtering responses with significant side-lobes for the side-coupled integrated spaced sequence of resonators (SCISSOR) or significant ripples in the pass-band for the direct coupled microrings (CROW). It is also known that the side-lobes/ripples can be reduced, and the pass/reject bands can be made wider, by apodizing the K value of each individual coupler in the structure, starting from a nominal K value (either increasing or decreasing it). This technique consists on changing the effective length of the coupling section by applying a longitudinal offset between the resonators. On the contrary, the conventional techniques are based in the transversal change of the distance between the ring resonators, in steps that are commonly below the current fabrication resolution step (nm scale), leading to strong restrictions in the designs. The technique has been experimentally demonstrated employing a racetrack ring resonator geometry. The proposed longitudinal offset technique allows a more precise control of the coupling and presents an increased robustness against the fabrication limitations, since the needed resolution step is two orders of magnitude higher. Both techniques are compared in terms of the transmission response of CROW devices, under finite fabrication resolution steps. The offset technique presented is sufficient by itself for apodization, and optimized CROW's can be produced with a fixed distance between the rings, solely by changing the offsets.

  18. Global alignment: Finding rearrangements during alignment

    SciTech Connect

    Brudno, Michael; Malde, Sanket; Poliakov, Alexander; Do, Chuong B.; Couronne, Olivier; Dubchak, Inna; Batzoglou, Serafim

    2003-01-06

    Motivation: To compare entire genomes from different species, biologists increasingly need alignment methods that are efficient enough to handle long sequences, and accurate enough to correctly align the conserved biological features between distant species. The two main classes of pairwise alignments are global alignment, where one string is transformed into the other, and local alignment, where all locations of similarity between the two strings are returned. Global alignments are less prone to demonstrating false homology as each letter of one sequence is constrained to being aligned to only one letter of the other. Local alignments, on the other hand, can cope with rearrangements between non-syntenic, orthologous sequences by identifying similar regions in sequences; this, however, comes at the expense of a higher false positive rate due to the inability of local aligners to take into account overall conservation maps.

  19. Development of a simplified optical technique for the simultaneous measurement of particle size distribution and velocity

    NASA Technical Reports Server (NTRS)

    Smith, J. L.

    1983-01-01

    Existing techniques were surveyed, an experimental procedure was developed, a laboratory test model was fabricated, limited data were recovered for proof of principle, and the relationship between particle size distribution and amplitude measurements was illustrated in an effort to develop a low cost, simplified optical technique for measuring particle size distributions and velocities in fluidized bed combustors and gasifiers. A He-Ne laser illuminated Rochi Rulings (range 10 to 500 lines per inch). Various samples of known particle size distributions were passed through the fringe pattern produced by the rulings. A photomultiplier tube converted light from the fringe volume to an electrical signal which was recorded using an oscilloscope and camera. The signal amplitudes were correlated against the known particle size distributions. The correlation holds true for various samples.

  20. Measurement of Temperature Change in Nonlinear Optical Materials by Using the Z-Scan Technique

    NASA Astrophysics Data System (ADS)

    Dong, Shu-Guang; Yang, Jun-Yi; Shui, Min; Yi, Chuan-Xiang; Li, Zhong-Guo; Song, Ying-Lin

    2011-08-01

    Spatial and temporal changes of temperature in a novel polymer are investigated by using the Z-scan technique under ns laser pulse excitation. According to the open aperture Z-scan experimental results, the nonlinear absorption coefficient of the polymer is determined. By solving the diffusion equation of heat conduction induced by optical absorption, the spatial and temporal changes in temperature are obtained. This change in temperature drives the photo-acoustic and electromagnetic wave propagating in the polymer and induces the change in refractive index, which serves as a negative lens, and the closed aperture Z-scan shows a peak and valley profile. Based on the numerical calculation, we achieve a good fit to the closed-aperture Z-scan curve with an optimized nonlinear refractive index. This consistency attests the existence of temperature change in the solution, and the Z-scan technique is suitable to investigate this change in temperature.