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1

Optical Alignment Technique.  

National Technical Information Service (NTIS)

An optical technique was developed to assure proper alignment of a missile warhead section assembly stand. The initial alignment of an assembly stand was successfully performed at Sierra Army Depot. The required radial tolerance of 0.002 inch at the assem...

A. Davidoff J. Rayner

1971-01-01

2

Large-Telescope Alignment Utilizing Optical Tooling Techniques.  

National Technical Information Service (NTIS)

The report describes the alignment of a large astronomical telescope by the use of optical tooling techniques which are primarily based on the use of a standard-focusing aligning telescope, flat mirrors, and autocollimating procedures inside a closed dome...

G. Rogers

1969-01-01

3

Passive alignment and soldering technique for optical components  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

4

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

NASA Technical Reports Server (NTRS)

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.

Hagopian, John G.

2010-01-01

5

Development of a vision-based optical fiber alignment platform based on the multirate technique  

Microsoft Academic Search

Automatic optical fiber alignment is the key to reduce the cost of the packaging process for the manufacture of fiber-optic devices. This study develops a vision-based active optical fiber alignment technique using a piezo-actuated moving platform which is controlled to reduce the alignment difference to a certain degree. In the proposed approach, the centroid of the optical fibers to be

H. S. Chuang; C. H. Chiu; M. Y. Cheng; Y. C. Chuang

2008-01-01

6

Optical Alignment (Basic).  

National Technical Information Service (NTIS)

Continued developments in optical measurement systems (optical tooling) carried out by aerospace and related industries have resulted in practical techniques for effecting precise physical alignment of large structural elements. Contents: Optical principl...

1969-01-01

7

PDV Probe Alignment Technique  

SciTech Connect

This alignment technique was developed while performing heterodyne velocimetry measurements at LLNL. There are a few minor items needed, such as a white card with aperture in center, visible alignment laser, IR back reflection meter, and a microscope to view the bridge surface. The work was performed on KCP flyers that were 6 and 8 mils wide. The probes used were Oz Optics manufactured with focal distances of 42mm and 26mm. Both probes provide a spot size of approximately 80?m at 1550nm. The 42mm probes were specified to provide an internal back reflection of -35 to -40dB, and the probe back reflections were measured to be -37dB and -33dB. The 26mm probes were specified as -30dB and both measured -30.5dB. The probe is initially aligned normal to the flyer/bridge surface. This provides a very high return signal, up to -2dB, due to the bridge reflectivity. A white card with a hole in the center as an aperture can be used to check the reflected beam position relative to the probe and launch beam, and the alignment laser spot centered on the bridge, see Figure 1 and Figure 2. The IR back reflection meter is used to measure the dB return from the probe and surface, and a white card or similar object is inserted between the probe and surface to block surface reflection. It may take several iterations between the visible alignment laser and the IR back reflection meter to complete this alignment procedure. Once aligned normal to the surface, the probe should be tilted to position the visible alignment beam as shown in Figure 3, and the flyer should be translated in the X and Y axis to reposition the alignment beam onto the flyer as shown in Figure 4. This tilting of the probe minimizes the amount of light from the bridge reflection into the fiber within the probe while maintaining the alignment as near normal to the flyer surface as possible. When the back reflection is measured after the tilt adjustment, the level should be about -3dB to -6dB higher than the probes specified back reflection. This 3 to 6dB increase in back reflection from the surface relative to the probes specified back reflection is the optimal level for acquiring data from the flyer. Data obtained with the LLNL system is shown in Figure 5.

Whitworth, T L; May, C M; Strand, O T

2007-10-26

8

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

PubMed

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. PMID:23822375

Gerasimova, N; Dziarzhytski, S; Weigelt, H; Chalupský, J; Hájková, V; Vyšín, L; Juha, L

2013-06-01

9

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

NASA Astrophysics Data System (ADS)

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.

Gerasimova, N.; Dziarzhytski, S.; Weigelt, H.; Chalupský, J.; Hájková, V.; Vyšín, L.; Juha, L.

2013-06-01

10

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

SciTech Connect

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.

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

11

Characterization and bioactivity study of nanohydroxyapatite on superhydrophilic vertically aligned carbon nanotubes using optical techniques  

NASA Astrophysics Data System (ADS)

Vertically-aligned multi-walled carbon nanotubes (VACNT) is of particular interest in regenerative medicine. Templateinduced hydroxyapatite (HA) has broad prospects in applied fields of bone regenerative medicine. Thus, it becomes very attractive a combination these two excellent materials to bone tissue engineering applications. In this study the HA/VACNT nanocomposites were used as scaffolds to Human osteoblast cells culture. Superhydrophilic VACNT films were obtained by CVD method and funcionalized by oxygen plasma. The fabrication of HA/VACNT nanocomposites was performed with a direct electrodeposition of the thin HA films on the VACNT films. The bioactivity and biomineralization in vitro process of superhydrophilic HA/VACNT nanocomposites were investigated using simulated body fluid (SBF) and optical techniques. The characterization of of HA/VACNT nanocomposites was performed before and after soaking 21 days in SBF and compared to superydrophilic VACNT films. Fourier transform infrared spectroscopy, micro X-ray fluorescence spectrometer by energy-dispersive and X-ray difractogram were employed to investigate the structural and chemical properties. The morphology was investigated by FEG-SEM analysis. After 21 days was identified that others biological apatites were formed only on HA/VACNT nanocomposites. Optical techniques showing a powerful tool to characterizated and investigated the bioactivity in vitro process. These findings were very atractive to application of this new nanocomposite to bone tissue regeneration.

Ferreira Irineu, Joao Anderson; Marsi, Teresa C.; Santos, Tiago G.; Santo, Ana Maria E.; Rangel, Joao L.; Mengui, Ursula A.; Martin, Airton A.; Corat, Evaldo J.; Marciano, Fernanda R.; Lobo, Anderson O.

2012-02-01

12

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

NASA Technical Reports Server (NTRS)

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.

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

1976-01-01

13

Optics Alignment Panel  

NASA Technical Reports Server (NTRS)

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

Schroeder, Daniel J.

1992-01-01

14

Optical alignment device  

NASA Technical Reports Server (NTRS)

A patent application was presented for an invention whose principal objective is the provision of an improved alignment device for observing the degree of coalignment of a pair of objects. The device includes a beamsplitter to be interposed between a pair of objects for observing the degree of coalignment. Light from one of the objects is reflected from the beamsplitter into a retroreflector which reflects the light back through the beamsplitter into an imaging system. Light from the other object is reflected from the beamsplitter into the same imaging system. The amount of displacement of the two images is inversely related to the degree of coalignment of the two objects. The optical alignment device is useful for aligning a mirror with an object, two objects or two mirrors.

Thomas, N. L. (inventor)

1976-01-01

15

Optical test alignment using computer generated holograms  

Microsoft Academic Search

Measurement systems for optical surfaces that lack axisymmetry are notoriously difficult to align and have limited accuracy. This paper describes a technique that uses a single CGH to act as null lens for measuring the aspheric surface, at the same time as it projects alignment marks into space that can be used for aligning the test. By providing reference features

Jim Burge; Peter Koudelka

16

120 Gb\\/s-level VCSEL array optical subassembly using passive alignment technique  

Microsoft Academic Search

Our suggested VCSEL array optical subassembly (OSA) for 120 Gb\\/s-level parallel optical interconnect modules was composed of a 12 channel VCSEL array chip, a SiOB, two silicon spacers, and a molded microlens with accurate guide pin holes. For high speed operation above 10 Gb\\/s per a channel, we carefully designed transmission lines on the SiOB. The results of the transmission

Sung Hwan Hwang; Jung Woon Lim; Byung Sup Rho

2008-01-01

17

Optical Alignment for Lithography.  

National Technical Information Service (NTIS)

The total overlay budget in semiconductor lithography has many components, including mask dimensional accuracy, tool-to-tool printing distortion, and process bias, but historically alignment registration has been the most critical. Yet progress in alignme...

N. Bobroff A. E. Rosenbluth

1992-01-01

18

Systematic Image Based Optical Alignment and Tensegrity  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

19

Optical alignments of the Cosmic Background Explorer (COBE) observatory  

NASA Technical Reports Server (NTRS)

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

Sampler, Henry P.

1990-01-01

20

High-speed optical beam alignment based on a motion control technique for three-dimensional microelectromechanical systems optical switch modules  

NASA Astrophysics Data System (ADS)

For optical axis alignment when light deflection control of a MEMS mirror is done at high speed, we propose a method based on identifying the quadratic surface shape. The method uses information about the optical power monitored when the mirror is inclined to a small angle. It is shown that the search for maximum optical power is possible by using this method. We also designed a control system with a band-stop filter for resonance frequency to decrease residual vibration generated when the mirror is moved at high speed. We confirm that the searchable level of optical power can be improved.

Mizukami, Masato; Yamaguchi, Joji; Nemoto, Naru

2011-07-01

21

Low-Cost 10-Gb/s Optical Receiver Module Using a Novel Plastic Package and a Passive Alignment Technique  

NASA Astrophysics Data System (ADS)

A new low-cost 10-Gb/s optical receiver module constructed using a novel plastic package is proposed. Passive alignment using a glass V-groove substrate and an edge-illuminated refracting-facet photodiode (RFPD) was employed to reduce cost. Instead of a conventional GaAs IC, a Si-bipolar preamplifier IC was mounted on the package to reduce power consumption. High-speed signal lines with a bandwidth of more than 10 GHz were realized using a three-dimensional electromagnetic-field analysis. For the fabricated module, a 3-dB detection bandwidth of 7.7 GHz and a sensitivity of less than -14 dBm at 10 Gb/s were achieved. To confirm the reliability of the fabricated module, a damp-heat test without bias voltage and a temperature-cycling test were performed. The results show that the optical receiver module, if covered with silicone resin, has the ability to withstand humidity and thermal stress.

Kur Ki, Takeshi; Shuto, Yoshito; Tadokoro, Takashi; Yokoyama, Kenji; Endo, Jun; Amano, Michiyuki; Nakamura, Makoto; Ishihara, Noboru; Suzuki, Yasuhiro

2005-12-01

22

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

SciTech Connect

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

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

2007-07-31

23

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

SciTech Connect

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.

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

24

Alignment-free optical modules using optical microconnectors  

Microsoft Academic Search

An alignment-free optical module based on a 2-f optical system with optical microconnectors is proposed for free-space optical interconnection. The alignment accuracy is evaluated theoretically from paraxial optics. The availability of this method is confirmed using experimental optical modules.

Daisuke Miyazaki; Shoji Masuda; Kenji Matsushita

1999-01-01

25

Self-Illuminating Optical Alignment Target  

NASA Technical Reports Server (NTRS)

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

Ashcraft, Carl D.; Trenn, David A.

1996-01-01

26

Optical analysis and alignment applications using the infrared Smartt interferometer  

SciTech Connect

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.

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

1981-01-01

27

Optical Alignment Device for Binocular Displays.  

National Technical Information Service (NTIS)

This invention relates generally to the field of optical alignment systems and more particaularly to a novel optical device for detecting misalignment in a binocular display by superimposition of the two binocular display images. The present invention pro...

H. L. Task

1982-01-01

28

Optical alignment of a pupil imaging spectrometer  

NASA Technical Reports Server (NTRS)

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

Horchem, Stephen D.; Kohrman, Richard J.

1989-01-01

29

Optical alignment of pixelated 4f optical system using multiplexed filter.  

PubMed

Novel optical alignment techniques to perform precise alignment of a typical pixelated 4f optical system are presented in this paper. These techniques use optical multiplexed matched filters, which were designed using a simple, efficient iterative optimization algorithm, known as direct binary search. Three alignment challenges are identified: positioning, focusing, and magnification. The first two alignments were performed using the optical multiplexed matched filtering technique, and the last one was performed using a new optical arrangement. Experimental results of the new alignment techniques and a simple optical pattern recognition problem to demonstrate the benefits of the new alignment techniques are also presented. Two pixelated, electrically addressed spatial light modulators (128 × 128 pixels and one pixel width is 80 ?m) were used to represent the input and filter planes. The results clearly show that the new alignment techniques allow the 4f system to be aligned to a precision of 80 ?m in the x-y direction and 0.716 mm in the z direction. PMID:24216742

Manivannan, N; Neil, M A A; Balachandran, W

2013-11-10

30

Training manual on optical alignment instruments  

NASA Technical Reports Server (NTRS)

Training Manual RQA/M5 provides a basic course of instruction in the use of optical instruments for precise dimensional control and alignment of structural elements and assemblies, such as associated with space vehicles, aircraft, ships, and buildings.

1968-01-01

31

Fiber optics welder having movable aligning mirror  

DOEpatents

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.

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

1981-01-01

32

Micro-Optical Bench for Alignment-Free Optical Coupling  

Microsoft Academic Search

We propose an optical coupling module, the micro-optical bench, designed for the purpose of completely passive alignment of optical components. The principle is for one to position a planar microlens array, semiconductor device submounts, and optical fibers by using reference planes and V grooves made on a Si substrate. A prototype was fabricated, and we achieved an optical coupling loss

Yasuhiko Aoki; Toshio Kato; Rogerio Jun Mizuno; Kenichi Iga

1999-01-01

33

Measuring Cell Mechanics By Optical Alignment Compression Cytometry  

PubMed Central

To address the need for a high throughput, non-destructive technique for measuring individual cell mechanical properties, we have developed optical alignment compression (OAC) cytometry. OAC combines hydrodynamic drag in an extensional flow microfluidic device with optical forces created with an inexpensive diode laser to induce measurable deformations between compressed cells. In this, a low-intensity linear optical trap aligns incoming cells with the flow stagnation point allowing hydrodynamic drag to induce deformation during cell-cell interaction. With this novel approach, we measure cell mechanical properties with a throughput that improves significantly on current non-destructive individual cell testing methods.

Roth, Kevin B.; Eggleton, Charles D.; Neeves, Keith B.; Marr, David W. M.

2013-01-01

34

HETDEX: Optical Alignment Of The Virus Spectrographs  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

35

Smart and precise alignment of optical systems  

NASA Astrophysics Data System (ADS)

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

Langehanenberg, Patrik; Heinisch, Josef; Stickler, Daniel

2013-09-01

36

Optical Alignment Device For Laser Communication  

NASA Technical Reports Server (NTRS)

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.

Casey, William L.

1988-01-01

37

Scalable cell alignment on optical media substrates.  

PubMed

Cell alignment by underlying topographical cues has been shown to affect important biological processes such as differentiation and functional maturation in vitro. However, the routine use of cell culture substrates with micro- or nano-topographies, such as grooves, is currently hampered by the high cost and specialized facilities required to produce these substrates. Here we present cost-effective commercially available optical media as substrates for aligning cells in culture. These optical media, including CD-R, DVD-R and optical grating, allow different cell types to attach and grow well on them. The physical dimension of the grooves in these optical media allowed cells to be aligned in confluent cell culture with maximal cell-cell interaction and these cell alignment affect the morphology and differentiation of cardiac (H9C2), skeletal muscle (C2C12) and neuronal (PC12) cell lines. The optical media is amenable to various chemical modifications with fibronectin, laminin and gelatin for culturing different cell types. These low-cost commercially available optical media can serve as scalable substrates for research or drug safety screening applications in industry scales. PMID:23601659

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

2013-07-01

38

Optical properties of aligned carbon nanotubes  

Microsoft Academic Search

By using a series expression of effective dielectric function ?eff, the optical properties of alpha aligned carbon nanotubes arranged in a square array are investigated. The frequency dependence of the effective dielectric function is studied for various ratios rho (ratio between internal and external radii of carbon nanotube) and x (ratio between the lattice constant and the external radii of

Xuhong Wu; Lunsheng Pan; Hua Li; Xijun Fan; Teng Yong Ng; Diao Xu; Chengxiang Zhang

2003-01-01

39

Computer vision applications for coronagraphic optical alignment and image processing  

NASA Astrophysics Data System (ADS)

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.

Savransky, Dmitry; Thomas, Sandrine J.; Poyneer, Lisa A.; Macintosh, Bruce A.

2013-05-01

40

Computer aided optical system alignment with CODE VTM.  

NASA Astrophysics Data System (ADS)

High accuracy optical alignment generally requires interferometric methods. A simple computer aided interferometric optical alignment procedure, for the visible, IR and other regions, utilizing the Interferogram Interface in CODE V, is described. A numerical alignment simulation and an actual system alignment are presented for an F/10, 8 inch diameter Cassegrain objective.

Leigh, D.; Freiman, D.

41

Effects of angular misalignments on fiber-optic alignment automation  

Microsoft Academic Search

Automation of fiber-to-optic alignment is critical to the development of cost effective fiber-optic component manufacturing technologies. Key to the alignment automation is the angular alignment automation, which is now unavailable. But angular misalignments are unavoidable in practical fiber-optic aligning process. This work evaluates the effects of pitch, yaw, and roll angular misalignments for a butt coupling scheme involving the optical

Z. Tang; R. Zhang; F. G. Shi

2001-01-01

42

Alignment of an optical axis to a rotating mechanical axis using grating phase modulation  

NASA Astrophysics Data System (ADS)

We describe a technique for aligning the axis of an optical system to the axis of a rotating mechanical system. The optical system is focused onto a linear grating that rotates in conjunction with the mechanical system. Light reflected from the grating produces an interference pattern in the pupil of the optical system. Temporal modulation of the fringes in the interference pattern is observed as the mechanical system rotates of the optical and mechanical axes are misaligned. Our application for this technique is in aligning an optical and mechanical system for writing circularly symmetric computer generated holograms. Experimentally we demonstrate alignments to accuracies of 0.1 micrometers.

Vernold, Cynthia L.; Milster, Tom D.

1996-02-01

43

Alignment-insensitive technique for wideband tuning of an unmodified semiconductor laser  

SciTech Connect

Using simple optical components and an unmodified commercial semiconductor laser, a frequency-selective self-aligning optical-feedback technique has been devised that allows a semiconductor laser to be tuned to and scanned about any optical frequency within the laser gain curve. This technique employs a graded-index rod lens cat's eye and an intracavity etalon.

Bernacki, B.E.; Hemmer, P.R.; Smith, S.P.; Ezekiel, S.

1988-09-01

44

A novel algorithm for fiber-optic alignment automation  

Microsoft Academic Search

An efficient and robust fiber-optic active alignment algorithm for locating the optimal fiber-optic coupling position is critical to the fiber-optic packaging automation, and thus to the cost effective manufacturing of fiber optic components and modules. A robust and speedy fiber-optic alignment algorithm must be capable of avoiding local power peak trapping and simultaneous multidegree of freedom alignment. The currently most

Rong Zhang; Frank G. Shi

2004-01-01

45

AGORA: Assembly Guided by Optical Restriction Alignment  

PubMed Central

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.

2012-01-01

46

Optical alignment method for Indian Remote Sensing Satellite  

NASA Astrophysics Data System (ADS)

An alignment procedure was developed and used to align elements on the Indian Remote Sensing Satellite. The method uses an optical boundary around the spacecraft to generate the alignment directions. The details of the alignment procedure, the instruments are described and ground data are compared with orbital data.

Thyagaraj, M. R.; Badagandi, Rajeev R.; Venkata Rao, B.; Pattabhiraman, K.

1993-07-01

47

Passive alignment of optical elements in a printed circuit board  

Microsoft Academic Search

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

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

2006-01-01

48

Automatic Optical Fiber Alignment System Using Genetic Algorithms  

Microsoft Academic Search

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

Masahiro Murakawa; Hirokazu Nosato; Tetsuya Higuchi

2003-01-01

49

Optical-precision alignment of diffraction grating mold in moire interferometry  

NASA Technical Reports Server (NTRS)

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

Joh, D.

1992-01-01

50

Multilevel anisotropic diffractive optical elements fabricated by means of stepping photo-alignment technique using photo-cross-linkable polymer liquid crystals.  

PubMed

Multilevel anisotropic diffractive optical elements (DOEs), in which digitized spatial patterns of optical birefringence are fabricated by means of stepping photoalignment technique, has been demonstrated using photo-cross-linkable polymer liquid crystals (PCLCs). The polarization state of incident light is converted into a different polarization state by diffracting light in the practical, i.e., transparent in visible region and thermally stable, multilevel anisotropic DOEs, and both polarization azimuth and ellipticity can be widely controlled by their birefringence patterns. Theoretical considerations for such polarization conversion were also performed using the Jones calculus and diffraction theory and well-explained experimental observations. PMID:24787581

Noda, Kohei; Kawai, Kotaro; Sasaki, Tomoyuki; Kawatsuki, Nobuhiro; Ono, Hiroshi

2014-04-20

51

Real-time sensing of optical alignment  

NASA Technical Reports Server (NTRS)

The Large Deployable Reflector and other future segmented optical systems may require autonomous, real-time alignment of their optical surfaces. Researchers have developed gratings located directly on a mirror surface to provide interferometric sensing of the location and figure of the mirror. The grating diffracts a small portion of the incident beam to a diffractive focus where the designed diagnostics can be performed. Mirrors with diffraction gratings were fabricated in two separate ways. The formation of a holographic grating over the entire surface of a mirror, thereby forming a Zone Plate Mirror (ZPM) is described. Researchers have also used computer-generated hologram (CGH) patches for alignment and figure sensing of mirrors. When appropriately illuminated, a grid of patches spread over a mirror segment will yield a grid of point images at a wavefront sensor, with the relative location of the points providing information on the figure and location of the mirror. A particular advantage of using the CGH approach is that the holographic patches can be computed, fabricated, and replicated on a mirror segment in a mass production 1-g clean room environment.

Stier, Mark T.; Wissinger, Alan B.

1988-01-01

52

Corrective optics space telescope axial replacement alignment system  

NASA Astrophysics Data System (ADS)

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

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

1993-10-01

53

Alignment techniques used to improve emittance of the Los Alamos free-electron laser  

NASA Astrophysics Data System (ADS)

The presentation describes the optical alignment technique, the calculations that lead to the tolerances necessary for the alignment accuracy, and novel methods developed to locate the magnetic axis and center of the solenoids. Background measurements on the emittance before realignment are compared with the final emittance measurements taken after the accelerator was realigned.

Sollid, Jon E.; Carlsten, Bruce E.; Feldman, Donald W.; Warren, Roger W.

1987-06-01

54

The Sardinia Radio Telescope (SRT) optical alignment  

NASA Astrophysics Data System (ADS)

The Sardinia Radio Telescope (SRT) is the largest radio telescope recently built in Europe - a 64m Radio Telescope designed to operate in a wavelength regime down to 1mm. The SRT is designed in a classical Gregorian configuration, allowing access to the primary mirror focus (F1), the Gregorian focus (F2) as well as a further translation to different F3 using a beam waveguide system and an automated change between different F3 receiver positions. The primary mirror M1, 64m in diameter, is composed by 1008 individual panels. The surface can be actively controlled. It’s surface, as well as the one of the 8 m Gregorian subreflector, needed to be adjusted after panel mounting at the Sardinia site. The measurement technique used is photogrammetry. In case of the large scale M1 a dedicated combination of a large scale and a small scale approach was developed to achieve extremely high accuracy on the large scale dimension. The measurement/ alignment efforts were carried out in 2010 and 2011, with a final completion in spring 2012. The results obtained are presented and discussed. The overall alignment approach also included the absolute adjustments of M2 to M1 and the alignments of M3, M4 and M5. M3 is a rotating mirror guiding the RF beam to M4 or M5, depending on the operational scenario. These adjustments are based on Lasertracker measurements and have been carried out in an integrated approach.

Süss, Martin; Koch, Dietmar; Paluszek, Heiko

2012-09-01

55

A novel algorithm for fiber-optic alignment automation  

Microsoft Academic Search

An cfficicnt and robust fiber-optic active alignmcnl algoritluii for locating the optiiiial fiber-optic coupliiig position is critical lo the fibcr-optic packaging autoinition and tlius to the cost cffcctive manufacturing of fibcr optic components and modules. A robust and speedy fiber-optic alignment algorithm must be capable of avoiding local power peak trapping and siinultancous multidegree of freedom alignment. The currently most

Rong Zhang; F. G. Shi

2003-01-01

56

Optical alignment of high resolution Fourier transform spectrometers  

NASA Technical Reports Server (NTRS)

Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

1980-01-01

57

Interferometric optical synchro for alignment transfer  

Microsoft Academic Search

Two 50 nanoradian resolution angle transducers were built employing laser interferometric techniques. Each encoder was provided with a reference or zero marker which employed a white light Michelson interferometer. The encoders were operated and the performance of one was evaluated in terms of the performance of the other to evaluate the suitability of the encoders for use in an optical

Herman Deweerd

1989-01-01

58

An automatic alignment technique for multiple rangefinders  

NASA Astrophysics Data System (ADS)

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.

Fujiwara, Kenta; Yamauchi, Koichiro; Sato, Yukio

2008-03-01

59

Alignment technology of large telescope main optical system  

NASA Astrophysics Data System (ADS)

Optical alignment is very important in the commitment of a telescope. In this paper, the 2 meter class telescope of the Institute of Optics and Electronics, the Chinese Academy of Sciences is taken for example. The common alignment procedure and method of large telescopes are described, and the project method of getting better image quality in all the field of view is also included. The alignment procedure mainly includes the coarse alignment and the accurate adjustment. The method can be applied to the optical systems such as Cassegrain and R-C.

Xu, Qi-rui; Wu, Fan; Zhang, Ming; Wang, Bin

60

Free space optical interconnect at 1.25 Gb\\/s\\/channel using adaptive alignment  

Microsoft Academic Search

Free space optical backplanes have previously required precision mechanics or moving parts. An adaptive alignment technique is described, using redundant VCSEL and detector arrays for real-time mapping of parallel 1.25 Gb\\/s data channels to aligned links

Dominic J. Goodwill; David Kabal; Paparao Palacharla

1999-01-01

61

Optical techniques for industrial inspection  

SciTech Connect

This book contains papers divided among the following sections: Surface inspection; Optical techniques for quality control; 3D vision; Spectroscopic techniques; and Optical techniques for process control.

Cielo, P.G.

1986-01-01

62

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

PubMed Central

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

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

2009-01-01

63

Alignment of the NRC watt balance: considerations, uncertainties and techniques  

NASA Astrophysics Data System (ADS)

This paper presents a comprehensive analysis of the alignment uncertainties in the NRC watt balance. We show that, due to the use of a beam balance in both phases of the experiment, some of the alignment errors of the weighing phase are correlated with errors in the moving phase, which makes our watt balance insensitive to some forms of misalignment. These correlations become inexact in the presence of parasitic forces acting on the coil former. We present evidence of such forces and estimate their effect and contribution to the various uncertainty components. Finally we describe the techniques used to align the apparatus and we give an estimate of all relevant alignment uncertainty components.

Sanchez, C. A.; Wood, B. M.

2014-04-01

64

Optoelectromechanical switch array with passively aligned free-space optical components  

Microsoft Academic Search

An all-optical switch array with micro mirrors driven by electrostatic micro motors has been developed in a LIGA-technique. The system has been designed for single mode application at the telecommunication wavelength of 1.55 ?m. All fixed optical components are passively aligned inside a LIGA-structured micro optical bench. The signals are detoured inside the optical bench by means of micro mirrors,

Antonio C. M. Ruzzu; Dirk Haller; Jürgen A. Mohr; Ulrike Wallrabe

2003-01-01

65

Scalable opto-electromechanical switch array with passively aligned free-space optical components  

Microsoft Academic Search

An all-optical switch array with micro mirrors driven by electrostatic micro motors has been developed in LIGA-technique. The system has been designed for single mode application at the telecommunication wavelength 1.55 µm. All fixed optical components are passively aligned inside a LIGA- structured micro optical bench. The signals are detoured inside the optical bench by means of micro mirrors, which

Antonio C. M. Ruzzu; Dirk Haller; Jürgen Mohr; Ulrike Wallrabe

66

The optical alignment of the Gemini planet imager adaptive optics bench  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

67

Optical alignment system for the ZEUS micro vertex detector  

Microsoft Academic Search

The electron–proton scattering experiment ZEUS will be equipped with a silicon vertex detector in preparation for the upgrade of the HERA collider. An optical alignment system for the vertex detector is being developed. The alignment system measures the position of the vertex detector with respect to the outer tracking detector as well as the shape of the vertex detector using

Takashi Matsushita; Stewart Boogert; Robin Devenish; Roman Walczak

2001-01-01

68

Electrical read-out from optical alignment devices  

Microsoft Academic Search

It is often desirable or essential to obtain from an optical alignment device an electrical output which represents, in sense and magnitude, the error of alignment. This can be used to operate a recording meter, in order to give a permanent record over a period, or an indicating meter for convenience or if the measuring head is in an inaccessible

J. Dyson; P. J. W. Noble

1964-01-01

69

Micro-machined XY stage for fiber optics module alignment  

Microsoft Academic Search

A novel silicon micro-machined XY stage with a hybrid micro-lens for fiber optics module alignment is presented. A MEMS micro-alignment method and silicon chip design are described. Finally the micro-fabricated device performance is discussed.

Marc Epitaux; Jean-Marc Verdeil; Y. Petremand; Wilifried Noell; Nicoolas F. De Rooij

2005-01-01

70

Optically Controlled Alignment of Liquid Crystals: Devices and Applications  

Microsoft Academic Search

Optically controlled homogeneous-to-homogeneous alignment of liquid crystal molecules using polarized light is discussed. Applications of this technology and experimental results that support these applications are presented.

Wayne M. Gibbons; Paul J. Shannon; Shao-Tang Sun

1994-01-01

71

Oil-damped mercury pool makes precise optical alignment tool  

NASA Technical Reports Server (NTRS)

Mercury pool with a cover layer of high viscosity oil provides a reference reflector for precise alignment of optical instruments. The cover layer effectively damps any ripples in the mercury from support structure vibrations.

Thekaekara, M. P.

1965-01-01

72

Optical Rheometry of Nematic Liquid Crystals with Uniform Molecular Alignment.  

NASA Astrophysics Data System (ADS)

We have developed a modular rheo-optical apparatus to study the flow properties of liquid crystals. Its main components are shearing device, strong magnetic field, and optical microscope. We performed experiments on well defined initial morphologies with uniform molecular alignment. The monodomains were achieved with strong magnetic fields (4.7T). Time resolved conoscopy is the primary optical technique in our investigation. We propose a simple relation between the distribution of alignment angles over the sample thickness and the conoscopically measured angle, to quantitatively measure the alignment angle in shear flow. We followed the relaxation of a shear induced splay deformation in small molecule model systems (N-(p -methoxybenzylidene)-p-butyl aniline (MBBA), pentyl-cyano -biphenyl (5CB) and a commercially available mixture OMI4244, and devised a model, based on the diffusion equation, to determine the rotational diffusivity from the relaxation process. The director alignment behavior of the SMLC's in shear flow is well described by the two dimensional Leslie-Ericksen model. The effect of director elasticity can clearly be seen in our experiments, resulting in a decrease of the steady state alignment angle at smaller Ericksen numbers. We found that there is no strain rate dependence of the director vorticity from 0.002/s to 2/s for poly -(gamma-benzyl-D/L-glutamate) (PBG). We determined {alpha_2/alpha _3} = 44 for a 20% solution of 280.000 molecular weight PBG in m-cresol at 20^ circC. The conoscopic interference pattern vanished after 8 strain units from an initially planar alignment and shearing could be reversed up to 10 strain units to completely recover the initial monodomain. Liquid crystalline polymers (LCP) are known to arrange into periodic director patterns during flow. We studied this for shear flow of lyotropic poly gamma-(benzyl-glutamate) as a model system, which is a well characterized synthetic poly ( alpha amino acid) with rigid chain architecture and well defined conformations. The molecules were are aligned uniformly as the starting condition. This so called monodomain morphology was obtained by use of strong magnetic fields. The shear apparatus is placed in an optical microscope, which is set up for conoscopy to allow direct observation of the shear induced rotation of the molecules. After a small strain during which the molecules rotate around the vorticity axis, they 'break out' sideways and form a three dimensional spatially periodic pattern. The shear induced instabilities have been observed under crossed polars as spatially periodic patterns (bands), some researchers observing them during flow and and others after cessation of shearing^{(27, 42, 58, 59)}. Bands, which develop during shear flow of poly (benzyl glutamate) (PBG) have been reported in 1980^{(36)}. However, later workers have failed to reproduce their findings and periodic pattern are believed to occur only after cessation of flow. Our findings solve a long standing controversy in the literature about the formation of periodic director pattern during flow. By varying the initial molecular orientation with respect to the flow direction we could show that the periodic pattern does not depend on the shear direction; it is governed by the director of the initial monodomain.

Muller, Jorg Andreas

73

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

74

Optical transmission techniques  

NASA Astrophysics Data System (ADS)

An optical transmission system is a method of transferring information in the shape of bits or symbols for the case of digital systems, and of analogue waves for the case of analogue systems, between fixed points located on a fiber optics cable. Today and in the near future there are numerous such transmission techniques available. The increase of demands for data transfer from phone subscribers can be met only by means of digital techniques applied in the local network, in addition to the use of digital telephone exchange and of the digital transmission systems in the trees network. In order to increase the quantity of information transferred through one fiber, optical multiplexing techniques have been conceived and tested. The optical multiplexing is additional to the electrical signal multiplexing. The requests for the access network will become more and more complex, a larger flexibility and a wider band being needed. For the purpose of complying with these requests, the coherent simultaneous or alternative transmission towards the optical amplifiers represents a factor of technical progress. The multiplexing with wave length division allows for more channels to be transported through the same fiber with different wave lengths, in one or both directions.

Vasile, Irina B.; Filip, Luminita E.; Vasile, Alexandru

2005-08-01

75

New technique for reducing the angle random walk at the output of fiber optic gyroscopes during alignment processes of inertial navigation systems  

Microsoft Academic Search

Angle random walk (ARW) is the noise component at the output of a fiber optic gyroscope (FOG) and it affects the FOG short-term accuracy. Practical applications of FOGs inside an inertial navigation system necessitate monitoring the Earth's rotation rate component along the FOG sensitive axis to determine the initial attitude of the moving object. The ARW increases the measurement uncertainty,

Aboelmagd Noureldin; Dave Irvine-Halliday; Herb Tabler; Martin P. Mintchev

2001-01-01

76

Optical assembly and alignment for the National Ignition Facility project  

NASA Astrophysics Data System (ADS)

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.

Hurst, Patricia A.; Grasz, Erna L.; Wong, Henry; Schmitt, Ed H.; Simmons, Matt R.

1998-06-01

77

Precision Positioner for Aligning Optical Fibers.  

National Technical Information Service (NTIS)

The invention is a precision optical fiber positioner that manipulates optical fibers by means of a variable magnetic field. Iron particles are applied to the optical fiber by impregnating an epoxy with the iron particles and coating a section of the fibe...

S. A. Siegel

1981-01-01

78

Radio-Optical Alignments in a Low Radio Luminosity Sample  

NASA Technical Reports Server (NTRS)

We present an optically-based study of the alignment between the radio axes and the optical major axes of eight z approximately 0.7 radio galaxies in a 7C sample. The radio galaxies in this sample are approximately 20-times less radio luminous than 3C galaxies at the same redshift, and are significantly less radio-luminous than any other well-defined samples studied to date. Using Nordic Optical Telescope images taken in good seeing conditions at rest-frame wavelengths just longward of the 4000A break, we find a statistically significant alignment effect in the 7C sample. Furthermore, in two cases where the aligned components are well separated from the host we have been able to confirm spectroscopically that they are indeed at the same redshift as the radio galaxy. However, a quantitative analysis of the alignment in this sample and in a corresponding 3C sample from HST (Hubble Space Telescope) archival data indicates that the percentage of aligned flux may be lower and of smaller spatial scale in the 7C sample. Our study suggests that alignments on the 50-kpc scale are probably closely related to the radio luminosity, whereas those on the 15 kpc scale are not. We discuss these results in the context of popular models for the alignment effect.

Lacy, Mark; Ridgway, Susan E.; Wold, Margrethe; Lilje, Per B.; Rawlings, Steve

1999-01-01

79

Electro-optic properties of aligned polysiloxane dispersed ferroelectric liquid crystal composite thin films  

Microsoft Academic Search

Thin polymer dispersed ferroelectric liquid crystal (PDFLC) composite films were prepared using polydimethyl siloxanes of different viscosity grades and ferroelectric liquid crystal mixture (ZLI-3654) using solvent induced phase separation (SIPS) and polymer induced phase separation (PIPS) techniques simultaneously.The electro-optic properties of these films in aligned and unaligned configurations were measured. A comparison indicates that the performance of aligned PDFLCs is

G. Sumana; K. K. Raina

2005-01-01

80

Video based surface alignment technique for 3D patient positioning  

Microsoft Academic Search

Presents a technique to align a 3D surface model of a patient to video images of the patient on the treatment table. The technique can be used to quantify patient positioning errors in 3D. Three video cameras were mounted to the ceiling of the treatment room and geometrically calibrated in linear accelerator beam coordinate system. The calibration essentially determines how

S. W. Hadley; L. S. Johnson; C. A. Pelizzari

2000-01-01

81

KMOS pick-off arm optical alignment, calibration, and testing  

NASA Astrophysics Data System (ADS)

The pick-off arm is the part of the KMOS instrument which re-images a sub-field of the VLT focal plane to a position outside of the main field where it can be used for integral field spectroscopy. In this paper we describe the optical alignment and test procedure developed to meet the challenging alignment requirements of the instrument. It is important to note that although the alignment is done at ambient temperature, the alignment of the optical components must be maintained at the instruments cryogenic operational temperature. This paper describes the methods used to achieve the absolute positioning accuracy and the test results obtained and discussed some of the practical difficulties that were encountered.

Rees, Philip; Bennett, Richard J.; Davidson, George H.; Todd, Stephen P.

2010-07-01

82

Linear Stark Effect of Electro-Optically Aligned FA Centers  

Microsoft Academic Search

Using selective optical excitation under high dc fields, FA centers were aligned with respect to their optical-absorption tensors and microscopic inversion asymmetry. This ordering process removes the macroscopic inversion symmetry of the crystal, allowing the measurement of first-order electro-optical effects in the FA absorption. The analysis of the linear Stark effect provides information about size and sign of the dipolemoment

Franz Rosenberger; Fritz Lüty

1968-01-01

83

Focal Plane Alignment Utilizing Optical CMM  

NASA Technical Reports Server (NTRS)

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..

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

84

Misalignment effects of cross-phase grating lateral shearing interferometer and its alignment technique  

NASA Astrophysics Data System (ADS)

To realize in-situ wavefront aberration measurement of hypernumerical aperture projection optics, a hypernumerical aperture cross-phase grating lateral shearing interferometer (HNA-CPGLSI) is proposed. To achieve high-wavefront measurement accuracy, accurate alignment of HNA-CPGLSI is essential. Misalignments of HNA-CPGLSI include collimation optics, cross-phase grating, and CCD. Misalignment of collimation optics mainly produces defocus aberration. After the CPGLSI formed by cross-phase grating and CCD is accurately aligned, the alignment of collimation optics is easy to achieve by measuring and controlling the defocus aberration. So the misalignments effects analysis and alignment of CPGLSI formed by cross-phase grating and CCD are focused. Using wave interference theory and wavefront reconstruction technique, a method to analyze the sensitivity relationship between cross-phase grating or CCD and measured aberrations is built. Misalignment effects of CPGLSI on wavefront measurement accuracy are evaluated. An experimental study on CPGLSI is also carried out. The results show that the measurement accuracy of CPGLSI after accurate alignment can reach to 3.0 m? (1.9 nm, ?=632.8 nm) root mean square (RMS) and repeatability can reach to 0.20 m? (0.13 nm, ?=632.8 nm) RMS.

Wang, Hai; Li, Yanqiu; Liu, Ke

2014-05-01

85

Optical alignment of a cylindrical object  

NASA Astrophysics Data System (ADS)

This paper reports the use of theory of geometrical optics to analyze how an optical field interacts with a cylindrical object. Of great interest is the mechanism with which a laser beam with a special profile manipulates a particle which has a similar shape as the beam profile. The present paper investigates the interaction between a cylinder-shape fiber and a laser beam with a line-shape profile. Based on the Fresnel equation, a numerical model was formulated to describe the optical torque generated by a projected line-shape optical image. The drag force was also considered in the model to accurately describe the fiber's movement in a liquid. A differential equation is established to describe this damped movement of the cylinder. Parametric analysis was carried out to investigate the influence of the beam power and the liquid viscosity as well as the density, the length, and the diameter of the cylindrical object. The movement of a carbon fiber was measured with a CCD camera. The observed experimental results agree well with the theoretical results.

Song, Chaolong; Nguyen, Nam-Trung; Krishna Asundi, Anand

2009-03-01

86

Techniques to Synchronize and Align Driving Simulator Data  

Microsoft Academic Search

We describe techniques used to overcome issues encountered in collecting and aligning driving simulation data recorded from multiple devices. Driving simulators offer the ability to monitor the driver, vehicle, and environment in situations and in detail that are impractical for roadway vehicles, but the data is often collected from various independent asynchronous data recording devices. Even when all subsystems properly

Kari Torkkola; Bob Leivian; Noel Massey; Chris Schreiner; Mike Gardner

87

Optical Alignment Optimizations for Reducing Wafer-Induced Shift  

NASA Astrophysics Data System (ADS)

Detecting the position of wafers after chemical mechanical polishing (CMP) is a critical issue in current and forthcoming IC manufacturing. A wafer alignment system must be highly accurate for all processes. To satisfy such requirements, we have studied and analyzed factors that have made alignment difficult. From the results of the studies, we have developed new optical alignment optimizations that improve the accuracy of FIA (wafer alignment sensor of Nikon’s exposure system) and examined them. The approaches are optimizing the focus position based on new classification of measurement errors, developing an advanced algorithm for position determination, and selecting a suitable mark design. The new classification method classifies measurement errors into errors caused by light amplitude errors and errors caused by phase errors. In the experiment, we have fabricated special wafers that make it possible to evaluate the influence of CMP processes on the alignment accuracy. The simulation and experimental results show that overlay error decreases markedly with the new alignment optimizations. FIA with these new optimizations will be highly accurate and suitable alignment sensor for CMP and other processes of future-generation LSI production.

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

2004-11-01

88

Radio-optical alignments in a low radio luminosity sample  

Microsoft Academic Search

We present an optically based study of the alignment between the radio axes and the optical major axes of eight z~0.7 radio galaxies in a 7C sample. The radio galaxies in this sample are ~20 times less radio-luminous than 3C galaxies at the same redshift, and are significantly less radio-luminous than any other well-defined samples studied to date. Using Nordic

Mark Lacy; Susan E. Ridgway; Margrethe Wold; Per B. Lilje; Steve Rawlings

1999-01-01

89

Automated Two-Axes Optical Fiber Alignment Using Grayscale Technology  

Microsoft Academic Search

In this paper, we report a new method for actuating an optical fiber in two axes. This device enables in package active alignment of an optical fiber towards reducing the time and cost of optoelectronic packaging by eliminating the need for expensive and slow macroalignment machines. Opposing comb-drive actuators with integrated three-dimensional (3-D) wedges (fabricated using grayscale technology) create a

Brian Morgan; Jonathan McGee; Reza Ghodssi

2007-01-01

90

Interferometric Optical Synchro for Alignment Transfer.  

National Technical Information Service (NTIS)

Two 50 nanoradian resolution angle transducers were built employing laser interferometric techniques. Each encoder was provided with a reference or zero marker which employed a white light Michelson interferometer. The encoders were operated and the perfo...

H. DeWeerd

1989-01-01

91

The development of an optical fiber alignment and fusion machine  

Microsoft Academic Search

This paper introduces the development of an optical fiber alignment and fusion machine that has sub-micrometer precision. The system structure, resolution of machine components, and operation procedure are illustrated in this article. Experiments are conducted to test the function of this machine. The results are satisfactory and some of them are reported in this article.

Chih-Liang Chu; Shyng-Her Lin; Zu-Yu Fu; Kung-Kun Yen

2005-01-01

92

XY-stage for alignment of optical elements in MOEMS  

NASA Astrophysics Data System (ADS)

The alignment of optical elements in a Micro-Opto-Electro- Mechanical System, is of prime importance in order to realize a reliable and low loss system. Fabrication errors or temperature changes deteriorate the alignment accuracy. These errors can be compensated with the aid of an active alignment system. The aim of the paper is to investigate an active system in order to align microlenses and fibers. A high lateral precision is required for single mode fiber injection, typically better than 1 micrometers . The alignment along the optical axis is less critical. Our system consists of a microlens placed between one input fiber and one output fiber. The fibers are held in V-grooves and the microlens is mounted on an XY-stage. The lens is fabricated by melting resist technology and subsequent etching in quartz. The mechanical parts are realized by wire electro-discharge machining (wire-EDM). Two piezo-electrical actuators move the flexible bearings of the stage in the X and Y direction. We will present the results obtained with this system and we will discuss its potential.

Peter, Yves-Alain; Herzig, Hans P.; Bottinelli, Stefano

1998-09-01

93

Hydrodynamic optical alignment for microflow cytometry†  

PubMed Central

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

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

2013-01-01

94

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

95

Application of the Brewster angle illumination technique to eliminate resist-induced alignment errors  

NASA Astrophysics Data System (ADS)

Resist coating on alignment marks can be asymmetrical due to the spinning motion. Alignment errors may result from this asymmetrical coating because the alignment signal can contain asymmetry when the optics detects the mark through the resist. The amount of signal asymmetry depends on the mark topography, resist thickness, spin speed, location on the wafer and the alignment technique. We have proposed a Brewster angle illumination technique (BAIT) as an effective means to greatly reduce the resist-induced alignment error by reducing alignment signal reflections from the surface of the resist. In this paper, we present the experimental results. We built an interferometric alignment system to implement BAIT. By scanning a resist-coated mark in close proximity to an exposed reference mark, drift and other system offsets are minimized, allowing an offset detectability of 6 nm. Resist-induced alignment errors with a radial dependence on mark position and magnitudes up to 25 nm have been measured when BAIT is not used. However, when BAIT is employed the resist-induced errors at all positions on the wafer are reduced to less than 10 nm and are close to the resolution limit of the alignment setup. The validity of the data was established by changing the polarization of the light from TM to TE, thereby destroying the BAIT condition while holding all other parameters constant. A study of the dependence of resist-induced alignment error on spin speed reveals that the amount of asymmetry in the resist profile increases monotonically as the spin speed increases. This effect is due to two factors: that the resist is thinner and that the spin speed is also faster. Further study using a thinner to dilute the resist isolated these factors and showed that the resist-induced alignment errors depend more sensitively on spin speed than the resist thickness. In most of the cases, the BAIT alignment system is immune to resist coating asymmetry and the error magnitude stays below 10 nm. However, the BAIT cannot work effectively when resist thickness becomes thinner than 0.6 micrometer. This limitation of BAIT technique was attributed to the ripples in the resist profile causing local impinging angles to deviate significantly from the Brewster angle.

Chen, Xun; Ghazanfarian, Amir Aalam; McCord, Mark A.; Pease, Roger Fabian W.

1998-06-01

96

Aligning Optical Fibers by Means of Actuated MEMS Wedges  

NASA Technical Reports Server (NTRS)

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

Morgan, Brian; Ghodssi, Reza

2007-01-01

97

Optical alignment measurements at Goddard Space Flight Center  

NASA Technical Reports Server (NTRS)

The significant changes that have been made in the Optical Alignment Facility at the Goddard Space Flight Center since it was last described (Appler and Howell, 1968) are discussed. The changes are reflected in both the hardware and the software involved in making alignment measurements. The data analysis procedures can now be done on a desktop computer with turn-around times of approximately 4 h. Arbitrary coordinate transformations and corrections for facility errors are also feasible while retaining absolute accuracies of less than 6 sec of arc.

Eichhorn, W. L.

1982-01-01

98

Aligning Arrays of Lenses and Single-Mode Optical Fibers  

NASA Technical Reports Server (NTRS)

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

Liu, Duncan

2004-01-01

99

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

PubMed

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. PMID:21934900

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

2011-08-01

100

A new multimode optical fiber splicing technique  

NASA Astrophysics Data System (ADS)

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

Ruello, Y.; Malavieille, F. L.

1986-11-01

101

Optical alignment of electrodes on electrical discharge machines  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

102

Optical alignment verification of the Herschel-SPIRE instrument  

Microsoft Academic Search

The SPectral and Photometric Imaging REceiver (SPIRE) will be launched in 2007 as one of three instruments on ESA's sub-millimetric space telescope Herschel. It covers the 200-670 micron spectral range with a three-band, 4'x8' field-of-view (FOV) photometer and a dual-band, 2.6' diameter FOV imaging Fourier transform spectrometer. Alignment verification of the instrument is accomplished optically by means of OGSE based

Kjetil Dohlen; Alain Origne; Marc Ferlet

2004-01-01

103

Survey techniques developed to align stacked beamlines at CEBAF  

SciTech Connect

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

Curtis, C.J.; Oren, W.; Tremblay, K.J. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

1994-04-01

104

New technique for aberration diagnostics and alignment of an extreme ultraviolet Schwarzschild objective  

NASA Astrophysics Data System (ADS)

Schwarzschild objectives are widely used in the extreme ultraviolet (EUV)/soft X-ray spectral region both as reduction and magnification optics, e.g. for small-field projection lithography and microscopy, respectively. When using a Schwarzschild objective as a micro-exposure tool (MET) at high spatial resolution (half-pitch?0.1 ?m), in addition to the tight requirements on the design and surface figure for the single optics, also an accurate alignment between the two mirrors is needed to reach the planned spatial imaging detail. Ideally, at-wavelength alignment should be done in order to overcome limitations due to diffractive effects. While this can be easily performed on synchrotron beam lines, it becomes time expensive (and components consuming) on low-power laboratory plasma sources. In this work we propose and test a new technique to align a EUV Schwarzschild objective by means of ultraviolet light. The aligned objective allowed the attainment of lithographic patterning with edge response of 90 nm, as part of the laboratory-scale MET for EUV projection lithography realized at the ENEA Frascati Research Centre.

Bollanti, S.; Di Lazzaro, P.; Flora, F.; Mezi, L.; Murra, D.; Torre, A.

2013-08-01

105

Inverting Image Data For Optical Testing And Alignment  

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

106

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

NASA Astrophysics Data System (ADS)

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.

Malevich, Y. V.; Adomavi?ius, R.; Krotkus, A.; Malevich, V. L.

2014-02-01

107

Optical polarizer made of mechanically aligned carbon nanotubes  

NASA Astrophysics Data System (ADS)

We report optical polarizer made of single-wall carbon nanotubes/poly(vinyl alcohol) composite. The film of the composite was mechanically stretched to form uniaxial alignment of carbon nanotubes in the polymer matrix. In order to obtain well-aligned carbon nanotubes efficiently, we used single-wall carbon nanotubes shortened into the length of less than 200 nm. Thanks to ? plasmon-originated broad absorption spectrum and strong anisotropy of single-wall carbon nanotubes, the film exhibits the degree of polarization of ~ 95 % with keeping flat transmittance through spectral region from 350 nm to 800 nm. We also observed enhancement of the degree of polarization at the wavelengths of van Hove singularities.

Shoji, Satoru; Suzuki, Hidemasa; Zaccaria, Remo P.; Sekkat, Zouheir; Kawata, Satoshi

2007-09-01

108

Automatic optical axis alignment for active free space optics  

Microsoft Academic Search

This paper proposes an active FSO system that enables a mobile terminal to be tracked for unilateral and short-range telecommunications. The central idea is to incorporate a mechanism that controls the transmittal beam direction. This provides the system with a highspeed and ubiquitous optical communication capability over a conventional wireless network with a lower bitrate for control signal transmission. A

Koichi Yoshida; T. Yano; Takeshi Tsujimura

2004-01-01

109

Coherent optical adaptive techniques.  

PubMed

The theory of multidither adaptive optical radar phased arrays is briefly reviewed as an introduction to the experimental results obtained with seven-element linear and three-element triangular array systems operating at 0.6328 microm. Atmospheric turbulence compensation and adaptive tracking capabilities are demonstrated. PMID:20125977

Bridges, W B; Brunner, P T; Lazzara, S P; Nussmeier, T A; O'Meara, T R; Sanguinet, J A; Brown, W P

1974-02-01

110

Automated alignment of microstructured optical fibers and conventional single-mode fibers  

NASA Astrophysics Data System (ADS)

Aligning two optical fibers is a crucial step in designing good optical fiber-based systems and networks. Good alignment optimizes the power transmitted between the fibers, especially when a microstructured optical fiber (MOF) is interfaced with a single-mode fiber (SMF). In this paper, we present a self-alignment algorithm based on particle swarm optimization (PSO). The PSO algorithm is used to locate the optimal coupling position with the highest optical power for alignments with multiple degrees of freedom. The proposed algorithm is validated by applying it for two different sources and checking the achieved alignment of SMF and MOF and that of two SMFs.

Landry, Marc; Kaddouri, Azeddine; Bouslimani, Yassine; Ghribi, Mohsen

2013-06-01

111

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

NASA Astrophysics Data System (ADS)

The dielectric anisotropy of a highly dispersive dual-frequency nematic liquid crystal (MDA-00-3969 (Merck KGa)) has been determined using the optical fully-leaky guided-mode technique. A 4Vrms sinusoidal voltage was applied across a 5µm hybrid aligned nematic (HAN) cell at various frequencies in both the positive and negative dielectric anisotropy regime. Optical data was collected at each frequency enabling the director profile in each case to be determined using a multi-layer optics model in combination with a liquid crystal free-energy minimization routine. The thresholdless response of the HAN cell combined with the extreme sensitivity of the optical characterization technique has allowed subtle changes in dielectric permittivity with frequency to be observed. The resulting measured dispersion shows excellent agreement with a single Debye-type relaxation model.

Jewell, S. A.; Sambles, J. R.

2005-04-01

112

Elevation angle alignment of quasi optical receiver mirrors of collective Thomson scattering diagnostic by sawtooth measurements  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

113

Elevation angle alignment of quasi optical receiver mirrors of collective Thomson scattering diagnostic by sawtooth measurements  

SciTech Connect

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

Moseev, D. [FOM DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Nieuwegein (Netherlands); Max-Planck-Institut fuer Plasmaphysik, Euratom Association-IPP, 85748 Garching (Germany); Meo, F.; Korsholm, S. B.; Leipold, F.; Michelsen, P. K.; Nielsen, S. K.; Salewski, M.; Stejner, M. [Association EURATOM - DTU, Department of Physics, Technical University of Denmark, Riso Campus, 4000 Roskilde (Denmark); Bindslev, H. [Faculty of Science and Technology, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Furtula, V. [Chalmers University of Technology, SE-412 96 Gothenburg (Sweden); Kantor, M. [FOM DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, Nieuwegein (Netherlands); FZ Juelich GmbH, EURATOM, Trilateral Euregio Cluster, D-52425 Juelich (Germany); Ioffe Institute, RAS, Saint Petersburg 194021 (Russian Federation)

2012-10-15

114

Automation of multi-degree-of-freedom fiber-optic alignment using a modified simplex method  

Microsoft Academic Search

Automation of fiber-to-optic alignment is the key to reduce the cost of the packaging process for the manufacturing of fiber-optic devices. Due to its fast convergence and easy of implementation, the King's modified simplex method (MSM) seems suitable for the fiber-optic alignment automation. This paper presents the use of this method on automatic three-dimensional (3D) fiber-to-optic alignment. A series of

Chyuan-Yow Tseng; Jun-Ping Wang

2005-01-01

115

Optical digital techniques  

NASA Technical Reports Server (NTRS)

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

1979-01-01

116

Two-Dimensional Alignment-Free Optical Interconnect Using Micro Optical Bench Scheme  

Microsoft Academic Search

In this paper, we have proposed and demonstrated a novel packaging method involving a vertical cavity-surface emitting laser (VCSEL) array. The concept is based on micro optical bench (MOB) placing a laser sub-mount and two-dimensional optical fiber array to match the reference plane of MOB to provide an alignment free optical interconnect. No degradation of I-V and I-L characteristics of

Yasuhiko Aoki; Yuji Shimada; Rogerio Jun Mizuno; Kenichi Iga

2000-01-01

117

Alignment strategy for mixed e-beam and optical lithography  

NASA Astrophysics Data System (ADS)

Although maskless electron beam lithography is viewed as an alternative lithographic technology by the mainstream semiconductor industry, it has long been a key lithographic tool of the compound semiconductor devices. It combines very high resolution with a high depth of field, but its wide acceptance in semiconductor production has been hindered by lower throughput when compared to optical lithography. Several new approaches to parallel e-beam lithography are currently being developed. These technologies, however, have not yet demonstrated the throughput per dollar invested that the current optical tools achieve. Given the cost and high throughput requirements set by most semiconductor manufacturers, the new parallel e-beam lithography tools are likely to be used for processing only a few critical layers, similar to the way the older electron beam tools are used by compound semiconductor manufacturers. Overlay accuracy is another big challenge when mixing optical and E-beam lithography tools. An alignment mark strategy is needed which will results in optimum registration accuracy between E-beam and optically defined layers on the chip.

Duval, Paul; Tabatabaie-Alavi, Kamal; Shaw, Dale; St. Germain, Alan

2013-03-01

118

Optically driven angular alignment of microcomponents made of in-plane birefringent polyimide film based on optical angular momentum transfer  

Microsoft Academic Search

The optically driven angular alignment of micromachined components (microlenses and microprisms) within a single-beam optical trap using a linearly-polarized laser is presented. This optically induced angular alignment around the laser beam axis results from the spin angular momentum of the laser beam produced by the birefringence of the trapped microcomponents. The microcomponents are fabricated by reactive ion etching of an

E. Higurashi; R. Sawada; T. Ito

2001-01-01

119

Fiber optic active alignment method based on a pattern search algorithm  

Microsoft Academic Search

Automation of fiber optic alignment is critical to reduce the cost of fiber optic devices packaging and ensure the quality of the products. The conventional fiber optic alignment method based on a hill-climbing algorithm is usually time consuming and it often fails to search the optimal alignment position. The reason is that the hill-climbing algorithm is a 1-D method, while

Jing Chun; Yulie Wu; Yi-Fan Dai; Shengyi Li

2006-01-01

120

Rigorous method for compensation selection and alignment of microlithographic optical systems  

SciTech Connect

The assembly of an optical system requires the correction of aberrations in the entire imaging field by making selected rigid-body motions of the optical elements. We present a rigorous method for determining which adjustment motions, called compensators, to use for alignment. These compensators are found by employing techniques from linear algebra that choose the most independent vectors from a set which are interdependent. The method finds the smallest number of compensators to correct for misalignments of a given magnitude. As an example the method is applied to a four-mirror scanning ring-field EUV lithography system. It is shown that out of 32 degrees of freedom in the configuration of the optical elements, only eight compensators are required on the optics. By adjusting these compensators a misaligned configuration giving a 30 {lambda} wavefront error can be assembled to {lambda}/50 in the absence of measurement noise.

Chapman, H.N.; Sweeney, D.W.

1998-03-25

121

First results from the ATLAS muon spectrometer optical alignment system  

NASA Astrophysics Data System (ADS)

The muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) at CERN consists of 1182 muon chambers for precision track measurements, arranged in three concentric cylinders of up to 25 m length in the central (barrel) region, and in four wheels of up to 25 m diameter in each of the two endcaps. They are located between 5 and 22 m from the interaction point, and each muon track is detected in three equally spaced chambers. The muon chambers are equipped with a complex high-precision optical alignment system to monitor their positions and deformations during ATLAS data-taking to an accuracy of 30-40?m, which is ultimately required for reconstructing high-momentum final-state muons with the desired momentum resolution of 10% at 1 TeV. The alignment system, the sensors, and the readout and reconstruction software are described. The installation and commissioning of the more than 12 000 sensors in the ATLAS cavern were completed in 2008, and first data from the full system are presented.

Amelung, C.; Atlas Collaboration

2010-11-01

122

Design of Two-Dimensional Optical Alignment Signals Robust to Diffractive Effects  

Microsoft Academic Search

Mask alignment is one of the most critical processes in photolithography. Prior to the shadow projection, the alignment between the lithographic mask and the silicon wafer is needed. In contact and proximity photolithography, a method to achieve the alignment with submicron or even nanometer resolution consists of superimposing two identical 2-D zero reference codes and registering the optical output signal.

José Saez-Landete; Sancho Salcedo-Sanz; Fernando Cruz-Roldan; Pedro Amo-Lopez; Manuel Blanco-Velasco

2008-01-01

123

Focused, Single Strand, Optical Fiber Rotational Alignment Image-Sensing and Comparing System.  

National Technical Information Service (NTIS)

This system permits the detection of rotational mis-alignment (i.e., twist) of two initially aligned, but separated, members. The two aligned members are linked by a single strand of focused optical fiber which, in combination with other co-acting compone...

L. S. Gresko

1980-01-01

124

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

NASA Astrophysics Data System (ADS)

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.

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

2010-08-01

125

Uniaxial alignment of triisopropylsilylethynyl pentacene via zone-casting technique.  

PubMed

Uniaxially aligned triisopropylsilylethynyl pentacene (TIPS-pentacene) crystals over a large area were fabricated using zone-casting technique. The array of TIPS-pentacene displayed a high orientation degree with a dichroic ratio (DR) of 0.80. The crystals were arranged with c axis perpendicular to the substrate and the long axis of the ribbon corresponded to the a axis of TIPS-pentacene. The properties of the solutions and the processing parameters were shown to influence the formation of the oriented TIPS-pentacene crystalline array. Solvent with a low boiling point (such as chloroform) favoured the orientation of the ribbon-like crystals. The concentration of the solution should be appropriate, ensuring the crystallization velocity of TIPS-pentacene matching with the receding of the meniscus. Besides, we proved that the casting speed should be large enough to induce a sufficient concentration gradient. The orientation mechanism of TIPS-pentacene was attributed to a synergy of the ordered nuclei and a match between the crystallization velocity and the casting speed. Field effect transistors (FETs) based on the oriented TIPS-pentacene crystalline array showed a mobility of 0.67 cm(2) V(-1) s(-1). PMID:23884009

Su, Yajun; Gao, Xiang; Liu, Jiangang; Xing, Rubo; Han, Yanchun

2013-09-14

126

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

NASA Technical Reports Server (NTRS)

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.

Taylor, Jaime; Rakoczy, John; Steincamp, James

2003-01-01

127

Novel techniques for optical performance monitoring in optical systems  

NASA Astrophysics Data System (ADS)

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.

Ku, Yuen Ching

128

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

NASA Technical Reports Server (NTRS)

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

Jennings, Donald

2013-01-01

129

Some effects of optical alignment errors in a differential laser Doppler velocimeter  

Microsoft Academic Search

A formulation has been developed to treat the effects of alignment errors of the optical system used in a differential laser Doppler velocimeter. It is then applied to analyse the properties of output beat signals obtained by the velocimeter. The effects of optical alignment errors on the spectral width and signal-to-noise ratio of the output beat signals and on the

Hiromichi Mishina; Toshimitsu Asakura

1973-01-01

130

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

NASA Technical Reports Server (NTRS)

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.

Decker, Arthur J.; Krasowski, Michael J.

1991-01-01

131

Alignment and integration of ASSIST: a test bench for VLT adaptive optics facility  

NASA Astrophysics Data System (ADS)

ASSIST, The Adaptive Secondary Setup and Instrument STimulator, is being developed to provide a testing facility for the ESO Adaptive Optics Facility (AOF). It will allow the off-telescope testing of three elements of the VLT AOF; the Deformable Secondary Mirror (DSM) and the AO systems for MUSE and HAWK-I (GALACSI and GRAAL). The core of ASSIST consists of a 2-mirror setup (AM1-AM2) allowing the on-axis test of the DSM in interferometric mode. However, during the initial stages of ASSIST integration, DSM would not be present. This makes the task of aligning AM1-AM2 to within an accuracy of 0.05mm/1 arcmin rather challenging. A novel technique known as Shack-Hartmann method has been developed and tested in the lab for this purpose. A Shack Hartmann wavefront sensor will be used to measure the mis-alignment between AM1-AM2 by recording the coma and astigmatism in the presence of large spherical aberration introduced because of tilt/decenter of AM2 with respect to AM1. Thereafter, 20 optical components including lenses, flat mirrors and beam-splitter cubes divided into five sub-assemblies should be aligned to AM1-AM2- DSM axis which ultimately passes through the mechanical axis of large AMOS rotator.

Deep, Atul; Arsenault, Robin; Boland, Wilfried; Delabre, Bernard; Hubin, Norbert; La Penna, Paolo; Madec, Pierre-Yves; Molster, Frank; Stuik, Remko; Tordo, Sebastien; Wiegers, Emiel

2010-08-01

132

Enhancement of optical nonlinearity of LCs with gold-nanoparticle-doped alignment layers  

NASA Astrophysics Data System (ADS)

In this study, the optical nonlinearity of LCs with cell substrates coated with gold-nanoparticle (AuNP) -doped PVA alignment layers were examined using the Z-scan technique. The results show that the nonlinear refractive index n2 of the sample is enhanced by the gold nanoparticles doped in the alignment layers, because of the thermal effect of the absorption by the surface of the sample through the localized surface plasmon resonance (LSPR) of the gold nanoparticles. As the concentration of AuNPs in the alignment layers of the LC sample increases, the thermal effect of the LSPR increases, and |n2| observably increases. Furthermore, the self-defocusing effect (n2<0) of the sample can be modulated by the application of an external voltage, and a self-focusing effect (n2<0) can be observed when samples are illuminated by a high-intensity laser with the application of a high voltage. Therefore, the magnitude and the sign of n2 of the sample can be modulated by combining the applied electric field and the optical field.

Lin, Hui-Chi; Fuh, Andy Y. G.; Lin, Ci-Yong; Li, Ming-Shian

2013-05-01

133

A rapid protein structure alignment algorithm based on a text modeling technique  

PubMed Central

Structural alignment of proteins is widely used in various fields of structural biology. In order to further improve the quality of alignment, we describe an algorithm for structural alignment based on text modelling techniques. The technique firstly superimposes secondary structure elements of two proteins and then, models the 3D-structure of the protein in a sequence of alphabets. These sequences are utilized by a step-by-step sequence alignment procedure to align two protein structures. A benchmark test was organized on a set of 200 non-homologous proteins to evaluate the program and compare it to state of the art programs, e.g. CE, SAL, TM-align and 3D-BLAST. On average, the results of all-against-all structure comparison by the program have a competitive accuracy with CE and TM-align where the algorithm has a high running speed like 3D-BLAST.

Razmara, Jafar; Deris, Safaai; Parvizpour, Sepideh

2011-01-01

134

A rapid protein structure alignment algorithm based on a text modeling technique.  

PubMed

Structural alignment of proteins is widely used in various fields of structural biology. In order to further improve the quality of alignment, we describe an algorithm for structural alignment based on text modelling techniques. The technique firstly superimposes secondary structure elements of two proteins and then, models the 3D-structure of the protein in a sequence of alphabets. These sequences are utilized by a step-by-step sequence alignment procedure to align two protein structures. A benchmark test was organized on a set of 200 non-homologous proteins to evaluate the program and compare it to state of the art programs, e.g. CE, SAL, TM-align and 3D-BLAST. On average, the results of all-against-all structure comparison by the program have a competitive accuracy with CE and TM-align where the algorithm has a high running speed like 3D-BLAST. PMID:21814392

Razmara, Jafar; Deris, Safaai; Parvizpour, Sepideh

2011-01-01

135

A micromachined 2 × 2 optical switch aligned with bevel-ended fibers for low return loss  

Microsoft Academic Search

This paper presents the design and optical performance characteristics of a micromachined 2 × 2 optical switch with low return loss for an optical add-drop application. The switch is equipped with four optical fibers beveled at 8°. An intentional lateral offset was introduced to align the refracted light at the input fiber-air interface with output fibers. A micromirror was actuated

Ho Nam Kwon; Jong-Hyun Lee

2004-01-01

136

Holographic Weapons Sight as Crew Optical Alignment Sight  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

137

Molecular alignment and orientation with a hybrid Raman scattering technique  

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

138

Enzyme activity assays within microstructured optical fibers enabled by automated alignment  

PubMed Central

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.

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

2012-01-01

139

Alignment control study for the solar optical telescope  

NASA Technical Reports Server (NTRS)

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

1976-01-01

140

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

141

Electronic implementation of optical burst switching techniques  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

142

Reliability by Robust Design for optical alignment in a CD pickup  

Microsoft Academic Search

Micron-level alignment of optical components in the laser pickup of a compact disc (CD) system is critical for its performance. The robustness of the rotational alignment of the laser\\/diffraction grating unit (LDGU) is studied in detail using finite element analysis and Robust Design tools. Robust design simulations were constructed in terms of the process capability indices Cp, Cpk, and yield

T. Y. Lin; A. S. Yak

2000-01-01

143

Performance of semitransparent silicon strip sensors for high precision optical alignment monitoring systems  

Microsoft Academic Search

Novel semitransparent optical position sensors (“ALMY sensors”) have been developed for the alignment monitoring systems of modern large-area tracking detectors. The high transmittance of up to 90% allows to align more than 10 sensors along a collimated laser beam. A position resolution of 1 ?m and an uncertainty in the deflection of the traversing laser beam of less than 3

Florian Bauer; Marcos Fernandez Garcia; Sandra Horvat; Hubert Kroha; Andrei Ostapchuk; Stefan Schael

2001-01-01

144

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

DOEpatents

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

Naulleau, Patrick (5239 Miles Ave., Apt. A, Oakland, CA 94618); Goldberg, Kenneth Alan (1622 Oxford St., #5t, Berkeley, CA 94709)

2000-01-01

145

Automated Optical Extraction from Line Arrays of the Alignment Between Microfabricated Layers  

NASA Technical Reports Server (NTRS)

Machine reading of layer alignment from line arrays in fully fabricated wafers is demonstrated. Misalignment is calculated from the correlation funcation of optical intensity scans through arrays in the two layers.

Lieneweg, Udo

1997-01-01

146

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

NASA Technical Reports Server (NTRS)

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

Taylor, Jaime R.

2003-01-01

147

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

NASA Astrophysics Data System (ADS)

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.

Dawkins, Samuel T.; Luiten, André N.

2008-03-01

148

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

PubMed

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

Dawkins, Samuel T; Luiten, André N

2008-03-20

149

Closed Loop RZ-DPSK Alignment for Optical Communications.  

National Technical Information Service (NTIS)

A method and system are provided for using a power spectral density of an output of a modulator to facilitate closed loop feedback for controlling alignment of a pulse with respect to information formed upon the pulse.

G. Yu J. R. Dupont L. C. Wah P. Y. Cheung

2004-01-01

150

New Adaptive Optics Technique Demonstrated  

NASA Astrophysics Data System (ADS)

First ever Multi-Conjugate Adaptive Optics at the VLT Achieves First Light On the evening of 25 March 2007, the Multi-Conjugate Adaptive Optics Demonstrator (MAD) achieved First Light at the Visitor Focus of Melipal, the third Unit Telescope of the Very Large Telescope (VLT). MAD allowed the scientists to obtain images corrected for the blurring effect of atmospheric turbulence over the full 2x2 arcminute field of view. This world premiere shows the promises of a crucial technology for Extremely Large Telescopes. ESO PR Photo 19a/07 ESO PR Photo 19a/07 The MCAO Demonstrator Telescopes on the ground suffer from the blurring effect induced by atmospheric turbulence. This turbulence causes the stars to twinkle in a way which delights the poets but frustrates the astronomers, since it blurs the fine details of the images. However, with Adaptive Optics (AO) techniques, this major drawback can be overcome so that the telescope produces images that are as sharp as theoretically possible, i.e., approaching space conditions. Adaptive Optics systems work by means of a computer-controlled deformable mirror (DM) that counteracts the image distortion induced by atmospheric turbulence. It is based on real-time optical corrections computed from image data obtained by a 'wavefront sensor' (a special camera) at very high speed, many hundreds of times each second. The concept is not new. Already in 1989, the first Adaptive Optics system ever built for Astronomy (aptly named "COME-ON") was installed on the 3.6-m telescope at the ESO La Silla Observatory, as the early fruit of a highly successful continuing collaboration between ESO and French research institutes (ONERA and Observatoire de Paris). Ten years ago, ESO initiated an Adaptive Optics program to serve the needs for its frontline VLT project. Today, the Paranal Observatory is without any doubt one of the most advanced of its kind with respect to AO with no less than 7 systems currently installed (NACO, SINFONI, CRIRES and four AO systems for the interferometric mode of the VLT). ESO PR Photo 19b/07 ESO PR Photo 19b/07 The Globular Cluster Omega Centauri (MAD/VLT) Present AO systems can only correct the effect of atmospheric turbulence in a relative small region of the sky - typically 15 arcseconds, the correction degrading very quickly when moving away from the central axis. Engineers have therefore developed new techniques to overcome this limitation, one of which is multi-conjugate adaptive optics (MCAO). At the end of 2003, ESO, together with partners in Italy and Portugal, started the development of a MCAO Demonstrator, named MAD. "The aim of MAD is to prove the feasibility and performances of new adaptive optics techniques, such as MCAO, meant to work on large fields of view and to serve as a very powerful test tool in understanding some of the critical issues that will determine the development of future instruments, for both the VLT and the Extremely Large Telescopes," said Norbert Hubin, head of the AO group at ESO. MAD is an advanced generation adaptive optics system, capable of compensating for the atmospheric turbulence disturbance on a large field of view (FoV) on the sky. It can successfully correct a 1-2 arcmin FoV, much larger than the ~15 arcsec typically provided by the existing adaptive optics facilities. MAD was fully developed and extensively characterized by ESO using a dedicated turbulence generator (MAPS, Multi Atmospheric Phase screens and Stars) able to reproduce in the laboratory the temporal evolution and the vertical structure of the turbulence observed at the Observatory. ESO PR Photo 19c/07 ESO PR Photo 19c/07 The MCAO Concept MAD was then disassembled and shipped to Paranal for re-integration at the Nasmyth Visitor focus of UT3. The integration took about 1 month, after which the system was ready for daylight testing and further characterization. "On the night of 25 March, we could successfully close the first MCAO loop on the open cluster NGC 3293," said Enrico Marchetti, the MAD Project Manager. "The system behavio

2007-03-01

151

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

152

Optical on line techniques for nuclear applications  

SciTech Connect

Optical on line techniques enable non intrusive physical measurements in harsh environments (high temperature, high pressure, radioactivity, ...). Optical absorption spectrometries such as UV-Visible, FTIR, CRDS have been successfully used to study gas phase speciation in different nuclear applications. LIBS which relies on laser matter interactions is a on line optical technique for solids and liquids elementary analysis. (authors)

Doizi, D. [CEA, Nuclear Energy Div. DEN, DANS/DPC/SECR/LSRM (France); Pailloux, A.; Maury, C.; Sirven, J. B.; Dauvois, V.; Roujou, J. L.; Rosset, C. D. [CEA, Nuclear Energy Div. DEN, DANS/DPC (France); Hartmann, J. M. [CNRS., UMR 7583, LISA, Creteil (France)

2011-07-01

153

Optically guided mode study of nematic liquid crystal alignment on a zero-order grating  

NASA Astrophysics Data System (ADS)

The characterization of a liquid crystal cell, which comprises one zero-order (that is, at the wavelength of study it is nondiffractive) diffraction grating and one rubbed polyimide-coated substrate, has been performed using an optically guided mode technique. The cell is filled with nematic liquid crystal E7 (manufactured and sold by Merck, Poole, U.K.). The excitation of fully leaky guided modes within the liquid crystal layer has allowed the optical director profile to be quantified under the application of weak in-plane electric fields. The fitting of angle-dependent optical data to multilayer optical theory yields the accurate twist profile of the liquid crystal for different field strengths. Comparisons with profiles predicted from elastic continuum theory, assuming a Rapini-Papoular-type anchoring at the surfaces, allow both the azimuthal anchoring strength at each surface and the twist elastic constant of the bulk to be accurately determined. Repeating these measurements as a function of temperature allows the surface and bulk order parameters of the grating-aligned liquid crystal to be deduced.

Hallam, B. T.; Sambles, J. R.

2000-06-01

154

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

NASA Astrophysics Data System (ADS)

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.

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

2007-10-01

155

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

NASA Technical Reports Server (NTRS)

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.

Rakoczy, John; Steincamp, James; Taylor, Jaime

2003-01-01

156

Steerable optical flow based image registration: application to aligning human torso images  

NASA Astrophysics Data System (ADS)

The aim of image registration is to align two or more images taken from different viewpoints, at different time instances, or by different modalities. Image registration methods are divided into two main categories, feature based and intensity based methods. Recently intensity based methods have gained popularity since they aim at finding a dense correspondence between the images needed to be aligned without calculating correspondence between salient features. In this work, a new intensity based image registration method has been proposed and tested. This method models the source and target image as a single image displaced over time and calculates the optical flow fields in a multiresolution framework. In order to have the ability to represent complex fields, the deformation has been modelled as locally affine but globally smooth. Multiresolution image representation by steerable pyramid decomposition is integrated with the differential image registration technique in order to find accurate image deformations. The usage of steerable pyramid overcomes traditional problems in other pyramidal methods namely aliasing across different bands, lack of translation and rotation invariance. The new algorithm was validated using torso images for volunteers at the University of Alberta in addition to images captured of a cast model of the human torso. Experiments have demonstrated promising results in terms of root mean square error and average pixel error.

Elsafi, Ahmed; Zewail, Rami; Durdle, Nelson

2009-05-01

157

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

NASA Astrophysics Data System (ADS)

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

Schiffner, Sebastian; Sure, Thomas

2013-09-01

158

Optical manipulation of self-aligned graphene flakes in liquid crystals.  

PubMed

Graphene recently emerged as a new two-dimensional material platform with unique optical, thermal and electronic properties. Single- or few-atom-thick graphene flakes can potentially be utilized to form structured bulk composites that further enrich these properties and enable a broad range of new applications. Here we describe optical manipulation of self-aligned colloidal graphene flakes in thermotropic liquid crystals of nematic and cholesteric types. Three-dimensional rotational and translational manipulation of graphene flakes by means of holographic optical tweezers allows for non-contact spatial patterning of graphene, control of liquid crystal defects, and low-power optical realignment of the liquid crystal director using these flakes. Potential applications include optically- and electrically-controlled reconfigurable liquid crystalline dispersions of spontaneously aligning colloidal graphene flakes and new electro-optic devices with graphene-based interconnected transparent electrodes at surfaces and in the bulk of liquid crystals. PMID:23389026

Twombly, Christopher W; Evans, Julian S; Smalyukh, Ivan I

2013-01-14

159

Optical modeling activities for NASA's James Webb Space Telescope (JWST): Part V. Operational alignment updates  

NASA Astrophysics Data System (ADS)

This paper is part five of a series on the ongoing optical modeling activities for the James Webb Space Telescope (JWST). The first two papers discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients. The third paper investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory, and the fourth introduced the software toolkits used to perform much of the optical analysis for JWST. The work here models observatory operations by simulating line-of-sight image motion and alignment drifts over a two-week period. Alignment updates are then simulated using wavefront sensing and control processes to calculate and perform the corrections. A single model environment in Matlab is used for evaluating the predicted performance of the observatory during these operations.

Howard, Joseph M.; Ha, Kong Q.; Shiri, Ron; Smith, J. Scott; Mosier, Gary; Muheim, Danniella

2008-07-01

160

Electro-optical properties of aligned polymer dispersed liquid crystal films  

Microsoft Academic Search

We study the electro-optical properties of polymer dispersed liquid crystal (PDLC) films with various kinds of alignment. These films are transparent in the electric field-on state and opaque in the field-off state. Experimental data show that the contrast ratio of these aligned films can be higher than that of a usual type PDLC film. The relationship between the field-off state

Jin-Jei Wu; Chih-Ming Wang

1997-01-01

161

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

Microsoft Academic Search

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

W. Blum; H. Kroha; P. Widmann

1996-01-01

162

Optical alignment of axial Fe centers in KTaO3  

Microsoft Academic Search

Axial Fe3+-OI centers in KTaO3 can be aligned using linearly polarized Ar+-ion laser light with lambda=456 nm. The alignment is observed directly via the change of the characteristic line pattern of the optically detected magnetic resonance (ODMR) of these centers. The ODMR is monitored by the magnetic circular dichroism (MCD) of absorption and is unambiguously attributed to Fe3+-OI, because the

H.-J. Reyher; B. Faust; M. Käding; H. Hesse; E. Ruza; M. Wöhlecke

1995-01-01

163

Evidence for Polarized Synchrotron Components in Radio-Optical Aligned Quasars  

Microsoft Academic Search

A tendency for the axes of double-lobed radio quasars to be aligned with the\\u000aelectric vectors of optical polarization in the active galactic nuclei is\\u000awell-known. However, the origin of the polarization and reason behind its\\u000acorrelation with radio morphology is not yet established. From accurate\\u000aspectropolarimetry of 7 quasars which show this alignment effect, we find that\\u000athe polarization

Gary D. Schmidt; Paul S. Smith

2000-01-01

164

WFC3 Optical Alignment Characterization in Thermal-Vacuum Test #3  

Microsoft Academic Search

We have performed an assessment of the optical alignment of the WFC3 instrument in its final flight configuration, including the UVIS-1' and IR-4 detectors, during the 3 rd thermal-vac test in March 2008. Both detectors are found to be aligned to well within tolerance in all degrees of freedom. The corrector settings, after adjustment to optimize image quality, are within

G. F. Hartig

2008-01-01

165

Adaptive alignment packaging for 2-D arrays of free-space optical-interconnected optoelectronic systems  

Microsoft Academic Search

An adaptive alignment scheme for packaging two-dimensional (2D) arrays of optoelectronic systems interconnected by free-space optics is presented. A method of using three quadrant detectors to detect alignment errors in six degrees of freedom is described. However, the complexity of this system increases due to the interactions among the detected error signals. A novel control algorithm is presented to eliminate

Tsung-Yi Yang; James Gourlay; Andrew C. Walker

2002-01-01

166

TwoAxis MEMS Lens Alignment System for Free-Space Optical Interconnect  

Microsoft Academic Search

We present a two-axis microelectromechanical sys- tems (MEMS) lens aligner with a 260 ?m × 220 ?m transla- tion range that positions a 6.35 mm lens with focal length f = 12.1 mm for alignment compensation of free-space optical inter- connects (FSOIs) between computer servers separated by 50 mm spacing. Efficient ultrasonic linear piezoelectric motors (PMs) pro- vide actuation with

Brian E. Yoxall; Robert Walmsley; Huei-Pei Kuo; Shih-Yuan Wang; Mike Tan; David A. Horsley

2011-01-01

167

Thermomechanically Driven Polymer Actuator for High-Precision Optical Alignment  

Microsoft Academic Search

Precise thermomechanical positioning has been demonstrated in an actuator device based on a silicone elastomer with a high thermal expansion coefficient. The actuator performance has been characterized using optical microscopy, and the actuator has been deployed in an optical coupling experiment to demonstrate the precise positioning of a ball lens between two single-mode fibers. Tuning of the coupling efficiency has

G. Jordan; A. M. Lyons

2007-01-01

168

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

169

Assembly, alignment, and testing of the DECam wide field corrector optics  

NASA Astrophysics Data System (ADS)

The DES project is a 5 year imaging survey of the southern sky using the 4m Blanco Telescope at the Cerro Tololo International Observatory in Chile. A new wide field camera with a 2.2 degree diameter field of view has been built to undertake this survey. The alignment of the large lenses for this camera poses a significant challenge as they have to be aligned to a tolerance of ±50 micrometers. This paper presents the assembly and alignment process of the full optical system along with the test results. Also included is the predicted imaging performance from the as-built system.

Doel, Peter; Brooks, David; Antonik, Michelle L.; Flaugher, Brenna L.; Stefanik, Andrew; Kent, Stephen M.; Gutierrez, Gaston; Cease, Herman P.; Abbott, Timothy M.; Walker, Alistair R.; DePoy, Darren L.; Bernstein, Rebecca A.; Worswick, Sue

2012-09-01

170

Linearized optical transmitter with modified feedback technique  

NASA Astrophysics Data System (ADS)

A linearized laser diode transmitter is proposed with combination of feedback and feedforward techniques. Compared to the conventional feedback method, the proposed linearized transmitter offers an advantage of higher differential gain. Only one optical source is needed in the new configuration compared to the optical feedforward techniques. The proposed method is theoretically analyzed and simulated for an optical transmitter using a large signal model for the laser diode.

Liu, Qing Z.

1997-01-01

171

Real-time Optical Alignment and Diagnostic System (ROADS)  

NASA Technical Reports Server (NTRS)

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.

1972-01-01

172

Optical coupling and alignment tolerances in optoelectronic array interface assemblies  

Microsoft Academic Search

A novel analytic beam propagation approach to multimode coupling modeling is presented which models mode power and phase distributions from first principles (unlike ray-tracing.) Coupling between axially misaligned multimode fibers has been simulated and compared with measurements. The relationships between optical coupling and fabrication and assembly tolerances have been studied for a generic laser diode array-to-optical fiber array coupler. Sources

J. Sutherland; G. George; J. P. Krusius

1995-01-01

173

Aero-Optics Experimental Techniques.  

National Technical Information Service (NTIS)

This report summarizes results of a study to determine the most appropriate aerodynamic experimental techniques for gathering data in aircraft boundary layer and shear layer turbulent flow, flow fields. It focuses on two primary techniques: hot-wire anemo...

W. C. Rose

1984-01-01

174

Optical metrology and alignment of the James Webb Space Telescope Integrated Science Instrument Module  

NASA Astrophysics Data System (ADS)

The James Webb Space Telescope (JWST) is an infrared space telescope scheduled for launch in 2013. JWST has a 6.5 meter diameter deployable and segmented primary mirror, a deployable secondary mirror, and a deployable sun-shade. The optical train of JWST consists of the Optical Telescope Element (OTE), and the Integrated Science Instrument Module (ISIM), which contains four science instruments. When the four science instruments are integrated to ISIM at NASA Goddard Space Flight Center, the structure becomes the ISIM Element. The ISIM Element is assembled at ambient cleanroom conditions using theodolite, photogrammetry, and laser tracker metrology, but it operates at cryogenic temperature, and temperature-induced mechanical and alignment changes are measured using photogrammetry. The OTE simulator (OSIM) is a high-fidelity, cryogenic, telescope simulator that features a ~1.5 meter diameter powered mirror. OSIM is used to test the optical performance of the science instruments in the ISIM Element, including focus, pupil shear, and wavefront error. OSIM is aligned to the flight coordinate system in six degrees of freedom via OSIM-internal cryogenic mechanisms and feedback from alignment sensors. We highlight optical metrology methods, introduce the ISIM and the Science Instruments, describe the ambient alignment and test plan, the cryogenic test plan, and verification of optical performance of the ISIM Element in cryo-vacuum environment.

Connelly, Joseph A.; Bos, Brent J.; Davila, Pamela S.; Eichhorn, William L.; Frey, Bradley J.; Hagopian, John G.; Hylan, Jason E.; Marsh, James M.; McGuffey, Douglas B.; McMann, Joseph; Nowak, Maria D.; Ohl, Raymond G., IV; Redman, Kevin W.; Sabatke, Derek; Sampler, Henry P.; Stock, Joseph; Sullivan, Joseph; Wenzel, Gregory W.; Wright, Geraldine A.; Young, Philip

2008-08-01

175

A concept for the assembly and alignment of arrayed microelectronic and micro-optical systems for optical multi-gigabit communication  

NASA Astrophysics Data System (ADS)

In the first part of this contribution we present a concept for the fabrication, assembly and alignment of a multichannel micro optical-coupler and arrayed microelectronic devices placed on a PCB. This concept is based on a micro opticalcoupler that integrates several optical sub-systems in a monolithic substrate in order to simplify adjustment processes. The optical-coupler is fabricated by plastic replication of a metal master with the negative shape of the coupler. For the fabrication on the PCB, only one alignment step is necessary. By placing markers on the PCB it is possible to position the coupler over the VCSEL or photodiode array. The placement and connections between the electronic devices on the PCB are taken into account in the design of the coupler. The mechanical assemblies for populating PCBs with electronic devices have an accuracy of a few micrometers. Using these techniques an optimal position of the coupler relative to the VCSEL or photodiode array can be found. In the second part we examine with the help of simulations the effect of misalignment and tilt of the optical surfaces and possible differences between the optical fibers like decentering. Bitrates of 120 Gbps in a 12-channel system can be reached using this coupler with commercial electronic devices. Applications for this system are active optical cables and ultra wide-band board to board communication systems. A FPGA-board for the test of this concept is in the design phase and will be reported.

Merchán, Fernando; Brenner, Karl-Heinz

2011-02-01

176

A Novel Fiber Alignment Shift Measurement and Correction Technique in Laser-Welded Laser Module Packaging  

NASA Astrophysics Data System (ADS)

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 parameters: the lateral position (r), the position angle (alpha), the swing angle (theta), and the tilt angle (psi). Further studies show that the deformation of the lateral shift and the position angle are the dominant mechanisms that determine the fiber alignment shifts induced by the PWS. This clearly indicates that the PWS can be quantitatively corrected timely by applying a single weld spot on the negative lateral shift and the position angle to compensate for the fiber alignment shifts. In comparison with previous studies of the PWS correction by a qualitatively estimated technique, this LDM technique has significantly provided an important tool for quantitative measurement and correction to the effect of the PWS on the fiber alignment shifts in laser-welded laser module packaging. Therefore, the reliable laser modules with high yield and high performance used in low-cost lightwave transmission systems may be developed and fabricated.

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

2005-02-01

177

Optical alignment and spinning of laser-trapped microscopic particles  

Microsoft Academic Search

Light-induced rotation of absorbing microscopic particles by transfer of angular momentum from light to the material raises the possibility of optically driven micromachines. The phenomenon has been observed using elliptically polarized laser beams (1) or beams with helical phase structure (2, 3). But it is difficult to develop high power in such experiments because of overheating and unwanted axial forces,

M. E. J. Friese; T. A. Nieminen; N. R. Heckenberg; H. Rubinsztein-Dunlop

1998-01-01

178

Optical tweezers technique and its applications  

NASA Astrophysics Data System (ADS)

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

Guo, HongLian; Li, ZhiYuan

2013-12-01

179

High Speed Optical Transmission Technique.  

National Technical Information Service (NTIS)

High speed transmitters with DFB-LDs and a broadband APD/FET receiver have been developed in order to realize high-bit-rate long span optical fiber transmission systems. Receiver sensitivities of -37.4 dBm at 2 Gbps, and -32.4 dBm at 4 Gbps have been obta...

K. Minemura I. Takano M. Shikada I. Mito K. Taguchi

1986-01-01

180

Alignment solutions for the optical development system lab for the ATLAS instrument  

NASA Astrophysics Data System (ADS)

The ATLAS Instrument for the ICESat-2 mission at NASA's Goddard Space Flight Center requires a test-bed to prove out new concepts before the mission launches in 2016. The Optical Development System (ODS) laboratory was created to use breadboard, prototype, and engineering-model levels of hardware and software to model and evaluate the ATLAS alignment system. A one meter parabolic mirror was used to create a collimated light beam to align prototype and engineering model transmitter and receiver optics and test closed-loop alignment algorithms. To achieve an error of less than two micro-radians, an active deformable mirror was used to correct the wave front to subtract out the collimator mount error.

Evans, Tyler; Lehan, John; Chavez, Hector

2012-10-01

181

Integration and alignment of ATLAS instrument engineering model components in Optical Development System Lab  

NASA Astrophysics Data System (ADS)

The ATLAS Instrument for the ICESat-2 mission at NASA's Goddard Space Flight Center required a test-bed to prove out new concepts before the mission launches in 2016. The Optical Development System (ODS) laboratory was created to use breadboard, prototype, and engineering-model levels of hardware and software to model and evaluate the ATLAS alignment system. A one meter parabolic mirror was used to create a collimated light beam to align prototype and engineering model transmitter and receiver optics and test closed-loop alignment algorithms. To achieve an error of less than two micro-radians, an active deformable mirror was used to correct the wave front to subtract out the collimator mount error.

Evans, Tyler

2013-09-01

182

A method for star vector determination from alignment optical telescope sighting  

NASA Technical Reports Server (NTRS)

A method is described for determining the measured star vector in LM body coordinates when the measurement data consist of a spiral measurement, a cusor measurement, and a time associated with each measurement. The method is defined from alignment optical telescope (AOT) sightings from the LM on the lunar surface. This formulation will be coded into the real-time computer complex off-line AOT and gravity (AOT+G) bench program, the Gravity-Optics LM Attitude and Position (GOLAP) program.

Crigler, S. W.; Blucker, T. J.

1971-01-01

183

Optomechanical integration and alignment verification of the James Webb Space Telescope (JWST) optical telescope element  

Microsoft Academic Search

The Optical Telescope Element (OTE) consists of a 6.6 m, all-reflective, three-mirror anastigmat. The 18-segment primary mirror (PM) presents unique and challenging assembly, integration and alignment requirements. To integrate and verify each of the Primary Mirror Segment Assemblies (PMSAs), an integrated network of laser trackers will be used in the Ambient Optical Assembly Stand (AOAS). The AOAS consists of an

Conrad Wells; Matthew Coon

2009-01-01

184

Optical alignment and spinning of laser-trapped microscopic particles  

Microsoft Academic Search

Light-induced rotation of absorbing microscopic particles by transfer of\\u000aangular momentum from light to the material raises the possibility of optically\\u000adriven micromachines. The phenomenon has been observed using elliptically\\u000apolarized laser beams or beams with helical phase structure. But it is\\u000adifficult to develop high power in such experiments because of overheating and\\u000aunwanted axial forces, limiting the achievable

M. E. J. Friese; T. A. Nieminen; N. R. Heckenberg; H. Rubinsztein-Dunlop

1998-01-01

185

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

NASA Astrophysics Data System (ADS)

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

Antonik, Michelle L.; Bacon, David J.; Bridle, Sarah; Doel, Peter; Brooks, David; Worswick, Sue; Bernstein, Gary; Bernstein, Rebecca; DePoy, Darren; Flaugher, Brenna; Frieman, Joshua A.; Gladders, Michael; Gutierrez, Gaston; Jain, Bhuvnesh; Jarvis, Michael; Kent, Stephen M.; Lahav, Ofer; Parker, S.-J.; Roodman, Aaron; Walker, Alistair R.

2013-06-01

186

An Integrated Parallel Micromanipulator with Flexure Hinges for Optical Fiber Alignment  

Microsoft Academic Search

A novel six degree-of-freedom (DOF) parallel micromanipulator with flexure hinges driven by piezoelectric actuators is presented for optical fiber alignment. The micromanipulator is designed based on integration of mechanism, driver and measurement. The 6-SPS mechanism is used to develop the parallel robot, the mechanical parameters of the structure are optimized, and the working space and stiffness analysis is given. Then

Zhenhua Wang; Liguo Chen; Lining Sun

2007-01-01

187

Active Optical Fiber Alignment with a Piezoelectric Ultrasonic Motor Integrated Into Low Temperature Cofired Ceramics  

Microsoft Academic Search

The major goal of this research was to integrate an ultrasonic motor into a ceramic package for an active optical fiber alignment. Two degrees of freedom ultrasonic motor was successfully cofired with commercial low temperature cofired ceramic green tapes as well as with silver electrodes without encountering serious delamination, camber, and inter diffusion issues. High-power piezoelectric ceramics that can be

Seung-Ho Park; Amanda Baker; Richard E. Eitel; Clive A. Randall; Kenji Uchino

2010-01-01

188

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

Microsoft Academic Search

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

H. John Wood

1989-01-01

189

Alignment and tracking of a free-space optical communications link to a UAV  

Microsoft Academic Search

This paper investigates the ability of a mechanical gimbal to perform alignment and tracking of a free-space optical communications link between a ground station and an unmanned aerial vehicle. The repeatability and accuracy of a mechanical gimbal are experimentally analyzed in order to generate probability distribution functions for the gimbal's performance. A simulation portion investigates the amount of divergence present

Alan Harris; James J. Sluss Jr; Hazem H. Refai; Peter G. LoPresti

2005-01-01

190

Spectral-Domain Optical Processing Techniques.  

National Technical Information Service (NTIS)

Optical techniques for spectral domain processing (SDP) have been investigated. A computer model for the design of nonlinear devices for frequency mixing in multiquantum well (MQW) materials has been developed. The model has been used to calculate nonline...

H. F. Taylor

1993-01-01

191

Control techniques for optical image stabilizing system  

Microsoft Academic Search

A novel optical image stabilizer was implemented on a consumer video camera. Novel feedback servo techniques were developed in order to control the nonlinear, unstable, variable fluid prism. As a result better frequency response was achieved. The system has the following features: (1) maintenance of picture resolution and (2) compensation for the fluctuation in optically zoomed pictures. When the new

K. Sato; S. Ishizuka; A. Nikami; M. Sato

1993-01-01

192

Towards Precise Simulation of Optical Elastography Technique  

Microsoft Academic Search

Optical elastography is a promising new imaging technique which utilizes optical frequency radiation to produce images of elastic modulus distribution of compliant tissue. Elastography practice is generally accomplished under the assumption of a linear stress-strain relationship in biological tissue. This assumption is not valid for most biological tissues even for small applied compressions. The nonlinear stress-strain relationship of different tissue

Maryam Mehdizadeh Dastjerdi; Ali Mahloojifar

2009-01-01

193

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

NASA Astrophysics Data System (ADS)

A method for real-time alignment of a Gaussian beam to an optical resonator is discussed. While the frequency of a source laser is stabilized to a fundamental cavity mode resonance, phase modulation sidebands are applied at the off-axis mode frequencies. The active laser beam position stabilization technique, as described by Grafstrom et al. (1988), directly monitors the presence of cavity off-axis modes, indicative of misalignments, by a heterodyne method that measures the light transmitted by the reference cavity. System performance measurements include: (1) measurement of the quadrant detector noise; (2) calibration measurements of error signals; and (3) open and closed loop error signal noise measurements. The feasibility of using active control of beam alignment to suppress the coupling of an input beam has been demonstrated. Performance within a factor of 2 of the shot noise limitation of the error signal measurement was obtained for a detected power of 160 microwatts.

Sampas, Nicholas M.; Anderson, Dana Z.

1990-01-01

194

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

Microsoft Academic Search

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

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

195

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

SciTech Connect

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

Borkar, Tushar [Department of Materials Science and Engineering and Center for Advanced Research and Technology, University of North Texas, Denton 76203 (United States)] [Department of Materials Science and Engineering and Center for Advanced Research and Technology, University of North Texas, Denton 76203 (United States); Chang, Won Seok [Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu, Daejeon 305-343 (Korea, Republic of)] [Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu, Daejeon 305-343 (Korea, Republic of); Hwang, Jun Yeon, E-mail: Junyeon.Hwang@kist.re.kr [Department of Materials Science and Engineering and Center for Advanced Research and Technology, University of North Texas, Denton 76203 (United States); Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-902 (Korea, Republic of); Shepherd, Nigel D.; Banerjee, Rajarshi [Department of Materials Science and Engineering and Center for Advanced Research and Technology, University of North Texas, Denton 76203 (United States)] [Department of Materials Science and Engineering and Center for Advanced Research and Technology, University of North Texas, Denton 76203 (United States)

2012-10-15

196

Enzyme-etching technique to fabricate micropatterns of aligned collagen fibrils  

PubMed Central

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

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

2014-01-01

197

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

198

Alignment off-axis optical system using Nodal Aberration Theory  

NASA Astrophysics Data System (ADS)

We present the Fringe Zernike coefficients of the parent system pupil can be converted into coefficients of off-axis system, it is show that the coefficients of the Fringe Zernike polynomials in the off-axis pupil only contain orders equal to or lower than the Fringe Zernike polynomials originally placed on the parent pupil, and for the 3rd aberration the pupil transformation matrix has been finding. Using nodal aberration, we get the misaligned matrix of rotational symmetry parent optical system. Then with the pupil transformation matrix, the misaligned matrix of off-axis two-mirror system was found, the amounts of the misalignments are calculated by the off-axis misaligned matrix.

Jiang, Bo; Zhou, Si-zhong; Jiang, Kai; Fu, Huai-yang; Mei, Chao

2013-08-01

199

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

NASA Technical Reports Server (NTRS)

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.

Anderson, Richard

1994-01-01

200

Optical multiple object tracking techniques  

NASA Technical Reports Server (NTRS)

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

Liu, Hua-Kuang; Chao, Tien-Hsin

1989-01-01

201

Introduction to high-resolution accelerator alignment using x-ray optics.  

SciTech Connect

A novel alignment technique utilizing the x-ray beam of a dedicated alignment undulator in conjunction with pinholes and position-sensitive detectors for positioning accelerator components in an x-ray free-electron laser will be presented. In this concept two retractable pinholes at each end of the main undulator line define a stable and reproducible x-ray beam axis (XBA). Targets are precisely positioned on the XBA using a pinhole camera technique. Position-sensitive detectors responding to both x-ray and electron beams enable the direct transfer of the position setting from the XBA to the electron beam. This system has the potential to deliver superior alignment accuracy in the micron range for target pinholes in the transverse directions over long distances. It defines the beam axis for the electron-beam-based alignment with high reproducibility. This concept complements the electron-beam-based alignment and the existing survey methods advancing the alignment accuracy of long accelerators to an unprecedented level. Further improvements of the transverse accuracy using x-ray zone plates and a concurrent measurement scheme during accelerator operation, providing real-time feedback for transverse position corrections, will be discussed.

Yang, B. X.; Friedsam, H.

2006-01-01

202

Techniques for Solution- Assisted Optical Contacting  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

203

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

DOEpatents

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.

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

1985-01-18

204

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

DOEpatents

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.

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

1987-01-01

205

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

SciTech Connect

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

Oh, Byeong-Yun; Lee, Kang-Min; Kim, Byoung-Yong; Kim, Young-Hwan; Han, Jin-Woo; Han, Jeong-Min; Lee, Sang-Keuk; Seo, Dae-Shik [Information Display Device Laboratory, Department of Electrical and Electronic Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

2008-09-15

206

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

PubMed

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

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

2014-06-16

207

Compact Optical Technique for Streak Camera Calibration  

SciTech Connect

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

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

2004-04-01

208

Applying Harmonic Optical Microscopy for Spatial Alignment of Atrial Collagen Fibers  

PubMed Central

Background Atrial fibrosis creates a vulnerable tissue for atrial fibrillation (AF), but the spatial disarray of collagen fibers underlying atrial fibrosis is not fully elucidated. Objective This study hypothesizes that harmonics optical microscopy can illuminate the spatial mal-alignment of collagen fibers in AF via a layer-by-layer approach. Patients and Methods Atrial tissues taken from patients who underwent open-heart surgery were examined by harmonics optical microscopy. Using the two-dimensional Fourier transformation method, a spectral-energy description of image texture was constituted and its entropy was used to quantify the mal-alignment of collagen fibers. The amount of collagen fiber was derived from its area ratio to total atrial tissue in each image. Serum C-terminal pro-collagen pro-peptide (CICP), pro-matrix metalloproteinase-1 (pro-MMP-1), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) were also evaluated. Results 46 patients were evaluated, including 20 with normal sinus rhythm and 26 with AF. The entropy of spectral-energy distribution of collagen alignment was significantly higher in AF than that in sinus rhythm (3.97±0.33 vs. 2.80±0.18, p<0.005). This difference was more significant in the permanent AF group. The amount of collagen was also significantly higher in AF patients (0.39±0.13 vs. 0.18±0.06, p<0.005) but serum markers of cardiac fibrosis were not significantly different between the two groups. Conclusions Harmonics optical microscopy can quantify the spatial mal-alignment of collagen fibers in AF. The entropy of spectral-energy distribution of collagen alignment is a potential tool for research in atrial remodeling.

Tsai, Ming-Rung; Chang, Yi-Chung; Hsu, Rong-Bin; Yu, Hsu-Yu; Sun, Chi-Kuang; Ho, Yi-Lwun

2010-01-01

209

Optically induced angular alignment of trapped birefringent micro-objects by linearly polarized light  

Microsoft Academic Search

Optically induced mechanical angular alignment of trapped birefringent micrometer-sized objects resulting from the transfer of angular momentum produced by birefringence using linearly polarized light has been experimentally demonstrated. Fluorinated polyimide (PMDA\\/TFDB) micro-objects having a large birefringence of Deltan=nslow-nfast=0.13 (refractive indices nslow=1.62, nfast=1.49), which were fabricated by micromachining (reactive ion etching) and suspended in water (n=1.33), were trapped and manipulated by

E. Higurashi; R. Sawada; T. Ito

1999-01-01

210

Piezoelectric thin-film unimorph actuator for optical fibre alignment applications  

Microsoft Academic Search

Feasibility of a piezoelectric unimorph thin-film actuator for optical fibre alignment was investigated. The main interest was focused on the fabrication, and electrical and mechanical characterization of a low-voltage driven component which was small-sized, efficient and suitable for integration into the low-temperature co-fired ceramic (LTCC) environment. Lead zirconate titanate (PZT) was chosen as ferroelectric thin-film material due to its excellent

Jarkko Tuominen; Jyrki Lappalainen; Jussi Hiltunen; Jyrki Ollila; Vilho Lantto

2006-01-01

211

Transient optical alignment and relaxation of excitons in GaAs\\/AlGaAs quantum wells  

Microsoft Academic Search

The dynamical behaviour of excitons in quantum well structures is studied by picosecond time-resolved resonance fluorescence. Transient optical alignment of 2d-excitons is observed which is destroyed by fast depolarization scattering in some ten picoseconds. The analysis of the time-dependent spectra within the density matrix formalism allows to determine the energy and cross relaxation times between degenerate exciton levels separately. To

H. Stolz; D. Schwarze; W. von der Osten; G. Weimann

1989-01-01

212

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

NASA Technical Reports Server (NTRS)

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.

Chrisp, Michael P.; Macenka, Steven A.

1991-01-01

213

Self-assembled microactuated XYZ stages for optical scanning and alignment  

Microsoft Academic Search

A novel self-assembled, surface-micromachined micro-XYZ stage with large displacements and fine positioning accuracy has been demonstrated on a Si microoptical bench for optical scanning\\/alignment applications. Continuous lateral scanning up to 120 ?m and vertical scanning up to 250 ?m have been achieved with integrated scratch drive actuators (SDA), which have step resolutions of 27 nm. The XYZ stage can be

Li Fan; Ming C. Wu; Kent D. Choquette; Mary H. Crawford

1997-01-01

214

Electro-optical response of ferroelectric liquid crystal cells with photo-dimerization alignment layer  

Microsoft Academic Search

The electro-optical characteristics of ferroelectric liquid crystal (FLC) cells were investigated with a surface-stabilized alignment layer by a photo-dimerization method. The photo-dimerization was performed using a polarized UV light (PUVL) irradiation and monitored with an UV\\/Vis spectrophotometer. It was found that the photo-dimerization method required the lower energy in PUVL exposure energy consumption than a photo-degradation method did. The highest

Kyung-Soo Choi; Hyun-Wuk Kim; Jin-Yool Kim; Tae-Min Kim; Yong-Bae Kim; Jong-Duk Kim

2003-01-01

215

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

NASA Astrophysics Data System (ADS)

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

Gubarev, Mikhail; Alexander, Cheryl; Ramsey, Brian

2005-08-01

216

A user"s guide of optical mounts and alignment fixtures: example from a Mersenne reflecting afocal Gregory form telescope  

NASA Astrophysics Data System (ADS)

Good wavefront quality, easy to align, and stable mounts are desired requirements for any optical system. Small variations in design parameters of mounts can radically diminish these qualities and performance of an optical system if tolerances of mounts don"t match optical requirements. We present design considerations required to create a stable ball knuckle mount with 5 degrees of freedom for a secondary mirror. Our system also required a rigid hub-mounted primary mirror with minimal optical deformation. Wavefront figure will be traced during design development of each mount. Overall final optical alignment was stable in 2 gravity vectors.

Ryder, Leigh A.; Houston, Joe B., Jr.; Bruner, Rich

2004-10-01

217

Combining calcium imaging with other optical techniques.  

PubMed

Ca(2+) imaging is a commonly used approach for measuring Ca(2+) signals at high spatial resolution. The method is often combined with electrode recordings to correlate electrical and chemical signals or to investigate Ca(2+) signals following an electrical stimulation. To obtain information on electrical activity at the same spatial resolution, Ca(2+) imaging must be combined with membrane potential imaging. Similarly, stimulation of subcellular compartments requires photostimulation. Thus, combining Ca(2+) imaging with an additional optical technique facilitates the study of a number of physiological questions. The aim of this article is to introduce some basic principles regarding the combination of Ca(2+) imaging with other optical techniques. We discuss the design of the optics, the design of experimental protocols, the optical characteristics of Ca(2+) indicators used in combination with an optical probe, and the affinity of the Ca(2+) indicator in relation to the type of measurement. This information will enable the reader to devise an optimal strategy for combined optical experiments. PMID:24298025

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

2013-12-01

218

Optical and structural properties of amorphous SexTe100-x aligned nanorods  

PubMed Central

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.

2013-01-01

219

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

NASA Astrophysics Data System (ADS)

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.

Al-Agel, Faisal A.

2013-12-01

220

Nonlinear optical techniques for surface studies. [Monolayers  

SciTech Connect

Recent effort in developing nonlinear optical techniques for surface studies is reviewed. Emphasis is on monolayer detection of adsorbed molecules on surfaces. It is shown that surface coherent antiStokes Raman scattering (CARS) with picosecond pulses has the sensitivity of detecting submonolayer of molecules. On the other hand, second harmonic or sum-frequency generation is also sensitive enough to detect molecular monolayers. Surface-enhanced nonlinear optical effects on some rough metal surfaces have been observed. This facilitates the detection of molecular monolayers on such surfaces, and makes the study of molecular adsorption at a liquid-metal interface feasible. Advantages and disadvantages of the nonlinear optical techniques for surface studies are discussed.

Shen, Y.R.

1981-09-01

221

Eye investigation with optical microradar techniques  

Microsoft Academic Search

Many problems exist in ophthalmology, where accurate measurements of eye structure and its parameters can be provided using optical radar concept is of remote sensing. Coherent and non-coherent approaches are reviewed aiming cornea shape measurement and measurement of aberration distribution in the elements and media of an eye. Coherent radar techniques are analyzed taking into account non- reciprocity of eye

Vasyl V. Molebny; Ioannis G. Pallikaris; Leonidas P. Naoumidis; Vitalij N. Kurashov; Igor H. Chyzh

1997-01-01

222

Optical Measurement Technique for Space Column Characterization  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

223

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

PubMed

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

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

2014-02-24

224

Optical/ultraviolet morphology and alignment of low-redshift radio galaxies  

NASA Astrophysics Data System (ADS)

Fifteen of the lower redshift (0.0optical structure is closely (within 12°) aligned with the radio axis. Three of these, which are the most radio-luminous galaxies in our sample, show an alignment of their optical long axis. The other three <12° alignments appear to be produced by merging companion galaxies at position angles close to the radio axes. In five galaxies, the radio axes and the projected position angles of the interacting pairs coincide within 21°, and there is evidence that the radio jet interacts with the companion. As we estimate that only one such alignment would occur by chance in our sample, this may be evidence for a second type of alignment effect produced by companion galaxies. For the cluster cD galaxy 3C 348, we find some evidence that the distribution of cluster galaxies is aligned with the radio axis. Most (10 out of 15) of the radio galaxies have optical half-light radii consistent with the size-luminosity relation of local radio-quiet early-type galaxies, the exceptions being three known cluster cDs, which have larger radii than normal ellipticals, and the two galaxies at the highest redshifts, which are ~0.8mag more luminous than expected for their size. Most (13 out of 15) have radial profiles best fitted by a bulge [exp(-rre)0.25] model, but two are closer in a ?2 test to an exponential profile. One of these, 3C 285, appears sufficiently well-imaged to be classified as a disc galaxy and shows evidence of a previous merger on a polar axis.

Roche, Nathan; Eales, Stephen A.

2000-09-01

225

Optical-Radio Alignment in Compact Steep-Spectrum Radio Sources  

NASA Astrophysics Data System (ADS)

We discuss Hubble Space Telescope (HST) WFPC2 observations through the broad red filter F702Wof 30 3CR sources from the Compact Steep Spectrum (CSS) radio source sample, and present 11 new HST/WFPC2 images through linear ramp filters (LRF), isolating either rest-frame [O II] 3727 Å or[O III] 5007 Å radiation. In nearly all the CSS galaxies, we find high surface brightness emission that is aligned with the radio axis. The strong nuclear PSF prevents us from detecting such aligned light at similar levels in most of the CSS quasars. However, a comparison between CSS galaxies and quasars with PSF signatures removed reveals no inconsistency with the viewing angle unification scheme. The alignment effect in CSS sources is not a strong function of redshift, and is seen over the entire redshift range of the sample (0.2<~z<~1.5). Our analysis of the LRF images and complementary KPNO spectroscopy reveals that the aligned light is predominantly emission-line gas. These observations demonstrate the existence of dense gas in the host galaxies of CSS sources, strongly interacting with the expanding radio sources. Assuming such a shock interaction, cooling-time arguments suggest that lobe expansion speeds of >~1000 km s-1 and ambient densities of ~1 cm-3 are consistent with the observed offset between the leading edge of the radio lobe and the optical line emission.

de Vries, W. H.; O'Dea, C. P.; Baum, S. A.; Barthel, P. D.

1999-11-01

226

A Precise Pointing Technique for Free Space Optical Networking  

Microsoft Academic Search

In free space optical communication networks, pointing, acquisition, and tracking (PAT) techniques are needed to establish and maintain optical links among the static or mobile nodes in the network. This paper describes a precise pointing technique to steer the local directional laser beam of an optical transceiver to a target optical transceiver at a remote transceiver node. The pointing technique

Yohan Shim; Stuart D. Milner; Christopher C. Davis

2007-01-01

227

An Approach to Ontology Alignment Problems based on Category Matching Technique  

NASA Astrophysics Data System (ADS)

When ontology description data by different authors would become widespread in the world, we will be faced with the difficulties of the ontology alignment (OA) problem required for integration and interoperability of ontologies. The OA problem is the problem to find couples of semantically same classes / properties between two ontologies, and includes points of different naming of classes / properties, polysemous naming of classes / properties, different granularity of classes / properties, different hierarchical structures, and so on. We applied our semantic category matching (SCM) tool to the ontology alignment problems. Our approach found pairs of semantically corresponding categories from two different classification hierarchies such as Yahoo directory or library classification as UDC or NDC, based on natural language processing, similarity searching of huge vector spaces, and structural consistency analysis. We tackled problems of the EON2004 Ontology Alignment Contest. For examples, the Contest's random name problems (#201, #202) could not be solved using conventional character string resemblance techniques. However, when we applied SCM to these problems, the results showed that SCM had improved the accuracy as compared to the conventional method (F-measure: 0.021=>0.949, 0.021=>0.580), and exceeded the accuracy average in all problem areas by over 10 % as compared to conventional methods. Our team participated as a competitor in EON OA Contest and could obtain satisfactory results.

Hoshiai, Tadashi; Yamane, Yasuo; Tsuda, Hiroshi

228

Study on computer-aided alignment method of a three-mirror off-axis aspherical optical system  

NASA Astrophysics Data System (ADS)

The precise alignment of multiple element off-axis optical system is a challenging task. In order to increase the alignment process efficiency, computer-aided alignment methods utilizing Zernike polynomial coefficients have been developed. In this paper, the misalignment state of three-mirror off-axis optical system is simulated in CODEV and computer-aided alignment software. The corresponding relationship between the misalignment and Zernike polynomial coefficients is analyzed, Finally, the alignment scheme is determined by the above analysis. In order to verify the feasibility, by using inverse optimization method to join the different disorders analysis of come up with the ways of solving the optimization variables, based on the established computer-aided alignment model to calculate misalignment. The off-axis three-mirror telescope was aligned by measuring the wave-front error (WFE) in several fields, namely, obtain Zernike polynomial, then using the self-compiled computer-aided alignment software to calculate the value and direction of misalignment, this method is realized by optimizing adjustment to compensate for the other variables misalignment-related variables. It can meet the precision requirement and accelerate the convergence of misalignment variables. With variables deduced, the time of alignment is saved. At a wavelength of 632.8nm, the results of 0°field wave-front error of 0.060? rms, +3°field of 0.076? rms and -3°field of 0.073; rms are obtained. The quality factor is better than 0.85.

Zhao, Xi-Ting; Jiao, Wen-Chun; Liao, Zhi-Bo; Wang, Yun; Chen, Jia-Yi

2010-05-01

229

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

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

M. Winter; R. Hauffe; A. Kilian

2005-01-01

230

Technique for precision optical timing measurements  

Microsoft Academic Search

High-accuracy absolute timing of optical pulses is usually performed by PMTs, in conjunction with advanced discriminator and time-measurement electronics. This paper presents a new technique that is capable of less than 1.0 psec absolute timing measurements, using Si APDs, with significantly relaxed requirements for the discriminator and timing electronics. An EO modulator is used to modulate the polarization of the

Kent L. Anderson

1993-01-01

231

A rapid topographic mapping and eye alignment method using optical imaging in Macaque visual cortex  

PubMed Central

In optical imaging experiments, it is often advantageous to map the field of view and to converge the eyes without electrophysiological recording. This occurs when limited space precludes placement of an electrode or in chronic optical chambers in which one may not want to introduce an electrode each session or for determining eye position in studies of ocular disparity response in visual cortex of anesthetized animals. For these purposes, we have developed a spot imaging method that can be conducted rapidly and repeatedly throughout an experiment. Using small 0.2° – 0.5° spots, the extent of the imaged field of view is mapped by imaging cortical response to single spots, placed at different positions (0.2° steps) in either the horizontal or vertical axes. By shifting the relative positions of two spots, one presented to each eye, eye convergence can be assessed to within 0.1° resolution. Once appropriate eye alignment is determined, stimuli for further optical imaging procedures (e.g. imaging random dot stimuli for study of disparity responses) can then be confidently placed. This procedure can be quickly repeated throughout the experiment to ensure maintained eye alignment.

HD, Lu; G, Chen; DY, Ts'o; AW, Roe

2009-01-01

232

Imaging techniques with refractive beam shaping optics  

NASA Astrophysics Data System (ADS)

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

Laskin, Alexander; Laskin, Vadim

2012-10-01

233

Variable bandwidth optical filters with vertical micromirrors and silicon optical bench alignment technology  

Microsoft Academic Search

This paper reports on a variable-bandwidth optical filter employing a free-space grating as a dispersive element, and a variable-aperture MEMS reflector that selects the passband. This design introduces negligible dispersion across the passband, and provides individual control of the center wavelength and the optical bandwidth, as required for optimization of high-speed optical communication systems. The variable-aperture MEMS reflectors are defined

Kyoungsik Yu; Daesung Lee; Olav Solgaard

2004-01-01

234

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

PubMed

A two-in-one Faraday rotator mirror was presented, which functions as two independent Faraday rotation mirrors with a single device. With the introduction of a reflection lens as substitution of the mirror in traditional structure, this device is characterized by exemption of active optical alignment for the designers and manufacturers of Faraday rotator mirrors. A sample was fabricated by passive mechanical assembly. The insertion loss was measured as 0.46 dB/0.50 dB for the two independent ports, respectively. PMID:24663645

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

2014-02-10

235

Rethinking Program Assessment through the Use of Program Alignment Mapping Technique  

ERIC Educational Resources Information Center

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

Liu, Min; Wrobbel, Duff; Blankson, Isaac

2010-01-01

236

Self-assembled coronene nanofibers: optical waveguide effect and magnetic alignment  

NASA Astrophysics Data System (ADS)

To fabricate organic nanofibers that function as active optical waveguides with semiconductor properties, a facile procedure was developed to grow single crystalline nanofibers via ?-? stacking of the polycyclic aromatic molecule, coronene, through solution evaporation on a substrate. The fabricated nanofibers with millimeter-scale lengths have well-defined shapes, smooth surfaces, and low-defect structures. The nanofibers are demonstrated to function as efficient active waveguides that propagate their fluorescence (FL) along the fiber axis over their entire length. We further demonstrate that the nanofibers can be highly aligned on the substrate when solution evaporation is conducted in a magnetic field of 12 T. The mechanism of the magnetic alignment can be elucidated by considering the anisotropy of the diamagnetic susceptibility of a single coronene molecule and the crystal structure of a nanofiber. Owing to the high degree of alignment, the nanofibers rarely cross each other, allowing for measurement of the waveguiding properties of single isolated nanofibers. The nanofibers propagate their FL of ? > 500 nm with a low propagation loss of 0-3 dB per 100 ?m, indicating that the nanofibers function as sub-wavelength scale, low-loss waveguides. Thus, they are promising building blocks for miniaturized optoelectronic circuits.

Takazawa, Ken; Inoue, Jun-Ichi; Mitsuishi, Kazutaka

2014-03-01

237

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

238

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

NASA Technical Reports Server (NTRS)

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

Katow, M. S.

1986-01-01

239

High-resolution measurement of the fiber diameter variations using whispering gallery modes and no optical alignment  

Microsoft Academic Search

Light is coupled from the guided mode along one tapered optical fiber into the whispering gallery modes around the circumference of another. Small diameter variations in the second fiber are measured by tracking, at different points along it, the wavelengths at which these modes exist. The measurement does not require any optical alignment, and its resolution can be 1 part

T. A. Birks; J. C. Knight; T. E. Dimmick

2000-01-01

240

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

NASA Astrophysics Data System (ADS)

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.

Zhou, Dayong

241

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

PubMed

In this Letter, we describe the realization of a tracked line-of-sight optical wireless communication system for indoor data distribution. We built a laser-based transmitter with adaptive focus and ray steering by a microelectromechanical systems mirror. To execute the alignment procedure, we used a CMOS image sensor at the transmitter side and developed an algorithm for image recognition to localize the receiver's position. The receiver is based on a self-developed optoelectronic integrated chip with low requirements on the receiver optics to make the system economically attractive. With this system, we were able to set up the communication link automatically without any back channel and to perform error-free (bit error rate <10-9) data transmission over a distance of 3.5 m with a data rate of 3 Gbit/s. PMID:24978803

Brandl, Paul; Weiss, Alexander; Zimmermann, Horst

2014-07-01

242

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

243

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

244

Imaging techniques utilizing optical fibers and tomography  

SciTech Connect

Two-dimensional, time-dependent images generated by neutrons, gamma rays, and x-rays incident on fast scintillators are relayed to streak and video cameras over optical fibers. Three dimensions, two spatial and one temporal, have been reduced to two, one in space and time utilizing sampling methods permitting reconstruction of a time-dependent, two-dimensional image subsequent to data recording. The manner in which the sampling is done optimized the ability to reconstruct the image via a maximization of entropy algorithm. This method uses four linear fiber optic arrays typically 30 meters long and up to 35 elements each. A further refinement of this technique collapses the linear array information into four single fibers by wavelength multiplexing. This permits economical transmission of the data over kilometer distances to the recording equipment.

Wilke, M.; King, N.S.P.; Gray, N.; Johnson, D.; Esquibel, D.; Nedrow, P.; Ishiwata, S.

1985-01-01

245

Technique for precision optical timing measurements  

NASA Astrophysics Data System (ADS)

High-accuracy absolute timing of optical pulses is usually performed by PMTs, in conjunction with advanced discriminator and time-measurement electronics. This paper presents a new technique that is capable of less than 1.0 psec absolute timing measurements, using Si APDs, with significantly relaxed requirements for the discriminator and timing electronics. An EO modulator is used to modulate the polarization of the optical pulse at a microwave frequency (e.g., 8 GHz), and the two resulting polarization components are detected by the APDs. Relative signal levels at the two polarizations provide a vernier timing measurement with respect to the phase of the microwave modulating signal, and the time ambiguity is resolved by a relatively coarse timing measurement of the detected signals. This technique offers the potential for simpler, lower-cost implementations than PMT and/or streak camera systems, and it is applicable to a wider range of wavelengths, particularly near-IR systems. This paper discusses the general principles and design issues of the technique, and describes a particular design implementation applicable to 2-color lidar ranging.

Anderson, Kent L.

1993-01-01

246

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

NASA Astrophysics Data System (ADS)

Thermal annealing effects of the aligned thiophene-based polymer films were studied. Aligned poly{2,5-bis(3-alkylthiophene-2-yl)thieno[3,2-b]thiophene} (pBTTT) and poly{2,5-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.

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

2012-02-01

247

Compressive moving objects localization techniques based on optical Radon projections  

NASA Astrophysics Data System (ADS)

We overview two optical compressive motion detection technique we have developed. First technique detects changes in a sequence of frames reconstructed from a compressive imager that captures optically Radon projections. The second technique uses a specially designed optical motion detector. Compressive motion tracking with compression ratio of 2-3 orders of magnitude is achieved.

Stern, Adrian; Kashter, Yuval; Levi, Ofer

2013-05-01

248

Through-etched silicon carriers for passive alignment of optical fibers to surface-active optoelectronic components  

Microsoft Academic Search

Silicon carriers for passive alignment of optical fibers to surface-active optoelectronic components with micrometer precision are presented. The carriers are through-etched by deep reactive ion etching (DRIE) to make vertical fiber alignment holes that go through the chip. On the top surface of the carrier, high-precision electrodes and eutectic AuSn-solder bumps are deposited by evaporation and electroplating. Surface active opto-components,

Johan Holm; Henrik Åhlfeldt; Magnus Svensson; Christian Vieider

2000-01-01

249

Self-Calibration Techniques for 3-point Intrinsic Alignment Correlations in Weak Gravitational Lensing Surveys  

NASA Astrophysics Data System (ADS)

Weak gravitational lensing due to large scale structure (cosmic shear) has been shown to be contaminated by the intrinsic alignment (IA) of galaxies, which poses a barrier to precision weak lensing measurements in planned surveys. To address this contamination, we have extended the 2-point self-calibration techniques to the cosmic shear bispectrum, using information already measured in a weak lensing survey to self-calibrate the IA contamination. The 3-point self-calibration techniques use the redshift separation dependencies of the IA bispectra and the non-linear galaxy bias in order to isolate and remove the impact of the IA correlations on the cosmic shear signal. Using conservative estimates of photo-z accuracy, we find that planned surveys will be able to measure the IA redshift separation dependence over ranges in photo-z of 0.2 in the 3-point ellipticity auto-correlation. For the 3-point cross-correlations, we find that the self-calibration technique allows for reductions in the IA contamination by a factor of 10 or more over most scales and redshift bin choices and in all cases by a factor of 3-5 or more. The 3-point self-calibration techniques thus provide a means to greatly reduce the impact of IA contamination of the bispectrum in future measurements of cosmic shear.

Troxel, Michael A.; Ishak-Boushaki, M. B.

2013-01-01

250

Alignment of palatally impacted canine with open window technique and modified K-9 spring  

PubMed Central

The patient was an 18-year-old female who had an Angle Class I malocclusion with a left palatally impacted maxillary canine. The orthodontic treatment of a palatally impacted canine is aimed at bringing the tooth into its correct position in the dental arch without causing any periodontal damage. To achieve this goal, a variety of surgical and orthodontic techniques have been proposed in relation to the position of the impacted tooth and there are various treatment methods used for traction. The duration of the traction was 3 months and alignment duration was 12 months the total treatment time was 15 months. In the following case, we presented that maxillary palatally impacted canine was brought into the arch with open window method for canine exposure and modified K-9 spring for traction, that is simple spring for orthodontic traction of the palatally impacted canines.

Shastri, Dipti; Nagar, Amit; Tandon, Pradeep

2014-01-01

251

Spontaneous induction of the uniform lying helix alignment in bimesogenic liquid crystals for the flexoelectro-optic effect  

NASA Astrophysics Data System (ADS)

Using in-plane electric fields, the electrical induction of the uniform lying helix (ULH) alignment in chiral nematic liquid crystals is reported. This process permits spontaneous induction of the ULH alignment to give an in-plane optic axis, without the need for complex processing. Flexoelectro-optic switching is subsequently obtained by holding the in-plane electrodes at a common voltage and addressing via a third, plane-parallel electrode on a second, or upper, substrate to give a field across the device in the viewing direction. For this device, in optimized bimesogenic materials, we demonstrate full intensity modulation and sub-millisecond response times at typical device temperatures.

Gardiner, Damian J.; Morris, Stephen M.; Hands, Philip J. W.; Castles, Flynn; Qasim, Malik M.; Kim, Wook-Sung; Seok Choi, Su; Wilkinson, Timothy D.; Coles, Harry J.

2012-02-01

252

The optical properties of vertically aligned ZnO nanowires deposited using a dimethylzinc adduct.  

PubMed

The optical properties of zinc oxide nanowires are critically influenced by the growth process. Herein, we describe a metal-organic chemical vapour deposition (MOCVD) process for the growth of ZnO nanowires with improved optical properties. A tetrahydrofuran adduct is used to control the reactivity of dimethylzinc to enable this. Vertically aligned zinc oxide nanowires have been grown on Si(111) substrates by liquid injection MOCVD, using a solution of [Me(2)Zn(tetrahydrofuran)] in the presence of oxygen. The ZnO morphology becomes nanowire-like in a narrow temperature range centred about 500 degrees C. Above and below this temperature range, the ZnO is deposited in the form of polycrystalline films. The ZnO nanowires grow from a polycrystalline nucleation layer, with the (0002) c-axis parallel to the Si[111] substrate orientation. High-resolution electron microscopy reveals a highly crystalline nanowire microstructure. Resonance enhanced ultraviolet Raman spectroscopy shows that the ratio of first- and second-order longitudinal optic modes is commensurate with electron-phonon coupling effects observed previously in ZnO nanostructures. Photoluminescence exhibits intense near band-edge emission with a full width at half-maximum of 110 meV at room temperature and shows negligible defect-related visible emission. PMID:20009167

Black, K; Jones, A C; Alexandrou, I; Heys, P N; Chalker, P R

2010-01-29

253

The optical properties of vertically aligned ZnO nanowires deposited using a dimethylzinc adduct  

NASA Astrophysics Data System (ADS)

The optical properties of zinc oxide nanowires are critically influenced by the growth process. Herein, we describe a metal-organic chemical vapour deposition (MOCVD) process for the growth of ZnO nanowires with improved optical properties. A tetrahydrofuran adduct is used to control the reactivity of dimethylzinc to enable this. Vertically aligned zinc oxide nanowires have been grown on Si(111) substrates by liquid injection MOCVD, using a solution of [Me2Zn(tetrahydrofuran)] in the presence of oxygen. The ZnO morphology becomes nanowire-like in a narrow temperature range centred about 500 °C. Above and below this temperature range, the ZnO is deposited in the form of polycrystalline films. The ZnO nanowires grow from a polycrystalline nucleation layer, with the (0002) c-axis parallel to the Silang111rang substrate orientation. High-resolution electron microscopy reveals a highly crystalline nanowire microstructure. Resonance enhanced ultraviolet Raman spectroscopy shows that the ratio of first- and second-order longitudinal optic modes is commensurate with electron-phonon coupling effects observed previously in ZnO nanostructures. Photoluminescence exhibits intense near band-edge emission with a full width at half-maximum of 110 meV at room temperature and shows negligible defect-related visible emission.

Black, K.; Jones, A. C.; Alexandrou, I.; Heys, P. N.; Chalker, P. R.

2010-01-01

254

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

PubMed

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

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

2014-06-01

255

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

PubMed Central

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.

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

2014-01-01

256

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

NASA Astrophysics Data System (ADS)

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 sensors, based on crystalline and on amorphous silicon as active material, have been studied. The sensors are optimized for the typical diameters of collimated laser beams of 3-5 mm over distances of 10-20 m. They provide very high position resolution, on the order of 1 ?m, uniformly over a wide measurement range of several centimeters. The preparation of the sensor surfaces requires special attention in order to achieve high light transmittance and minimum distortion of the traversing laser beams. At selected wavelengths, produced by laser diodes, transmission rates above 90% have been achieved. This allows to position more than 30 sensors along one laser beam. The sensors will be equipped with custom designed integrated readout electronics.

Blum, W.; Kroha, H.; Widmann, P.

1996-02-01

257

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

NASA Astrophysics Data System (ADS)

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

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

1996-08-01

258

Inter-channel crosstalk in densely aligned multimode polymer parallel optical waveguides  

NASA Astrophysics Data System (ADS)

We theoretically estimate the inter-channel crosstalk in densely aligned multimode polymer parallel optical waveguides using a beam propagation method, and compare the results of graded-index (GI)-core waveguides with those of conventional step-index (SI)-core counterpart. In particular, we simulate the crosstalk in bridged core waveguides. Here, the bridged core is sometimes observed in the waveguides fabricated using the imprinting method. The inter-channel crosstalk in SI-core waveguide increases from -25 dB to -4 dB with increasing the bridge thickness. Contrastingly, the worst crosstalk in a GI-core is as low as -15 dB despite the bridged structure as long as the bridge of the core is not included in the index distribution of the GI-core core, namely SI bridged core. In addition, the crosstalk in the GI-core decreases when the multiple cores aligned in parallel have a different structure (core size, refractive index, etc.), because the difference in the core structure makes changes in the distribution of propagation constants, resulting in decreasing the mode coupling efficiency between the two cores. Hence, the worst crosstalk in the GI-core waveguide with a slightly different core structure is as low as -19 dB despite the bridged structure. Thus, the imprinting method should be utilized for GI-core waveguides: the inter-channel crosstalk is un-problematic even if a residual layer remains.

Kudo, Takuya; Ishigure, Takaaki

2014-03-01

259

Aligned growth of ZnO nanowires by NAPLD and their optical characterizations  

NASA Astrophysics Data System (ADS)

Not only vertically aligned ZnO nanowires but also horizontally aligned ZnO nanowires have been successfully grown on the annealed (0 0 0 1) c-cut and (1 1 2 0) a-cut sapphire substrates, respectively using catalyst-free nanoparticle-assisted pulsed-laser ablation deposition (NAPLD). The as-synthesized ZnO nanowires exhibit an ultraviolet emission at around 390 nm and the absent green emission under room temperature. The single ZnO nanowire was collected in the electrode gap by dielectrophoresis (DEP). Under the optical pumping, the single ZnO nanowire exhibited UV emission at around 390 nm with several sharp peaks whose energy spacings are almost constant, which greatly differs from the broad UV emission of the film with many nanowires, suggesting ZnO nanowires as candidates for laser media. The single ZnO nanowire showed polarized photoluminescence (PL). The as-synthesized ZnO nanowires could find many interesting applications in short-wavelength light-emitting diode (LED), laser diode and gas sensor.

Guo, Ruiqian; Matsumoto, Masato; Matsumoto, Takafumi; Higashihata, Mitsuhiro; Nakamura, Daisuke; Okada, Tatsuo

2009-09-01

260

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

NASA Technical Reports Server (NTRS)

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.

Wood, H. John

1989-01-01

261

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

NASA Astrophysics Data System (ADS)

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.

Wood, H. John

262

Fiber probes based optical techniques for biomedical diagnosis  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

263

Simple Measurement Technique of the Cross Phase Modulation in Optical Fibers Using Heterodyne Detection Technique  

Microsoft Academic Search

We present a simple measurement technique of the cross phase modulation in optical fibers. A pump laser generates a new optical component (Stokes wave) in a probe optical wave with the modulation frequency of a pump laser. We investigated optical heterodyning between the probe optical wave and the Stokes wave, which allows one to generate and evaluate a beat signal

Hyunjae Lee; Sang Soo Lee; Hyung Joo Kim; Yool Kwon; Chang-Bong Kim

2002-01-01

264

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

NASA Technical Reports Server (NTRS)

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

Howard, Joseph

2007-01-01

265

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)

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.

Hagopian, John G.

1996-10-01

266

Optical replication techniques for image slicers  

NASA Astrophysics Data System (ADS)

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.

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

2006-06-01

267

Design of microlens illuminated aperture array fabricated by aligned ultraviolet imprinting process for optical read only memory card system  

Microsoft Academic Search

A microlens illuminated aperture array (MLIAA) was designed for the multiprobe optical read only memory card system. As a method to integrate the microlens array (MLA) with the aperture array containing 1000×1000 apertures, an aligned ultraviolet imprinting process was used to satisfy the system objectives of reduced focal length and reduced spot size. An analysis using diffraction theory was performed

Hongmin Kim; Jeeseung Lee; Jiseok Lim; Seok-Min Kim; Shinill Kang; Young-Joo Kim; Christopher Busch

2006-01-01

268

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

NASA Astrophysics Data System (ADS)

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

Ohl, R.

2009-08-01

269

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

Microsoft Academic Search

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

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

1999-01-01

270

Merging and alignment of Dirac points in a shaken honeycomb optical lattice  

NASA Astrophysics Data System (ADS)

Inspired by the recent creation of a honeycomb optical lattice and the realization of a Mott-insulating state in a square lattice by shaking, we study here the shaken honeycomb optical lattice. For a periodic shaking of the lattice, Floquet theory may be applied to derive a time-independent Hamiltonian. In this effective description, the hopping parameters are renormalized by a Bessel function, which depends on the shaking direction, amplitude, and frequency. Consequently, the hopping parameters can vanish and even change sign, in an anisotropic manner, thus yielding different band structures. Here, we study the merging and the alignment of Dirac points and dimensional crossovers from the two-dimensional system to one-dimensional chains and zero-dimensional dimers. We also consider next-nearest-neighbor hopping, which breaks the particle-hole symmetry and leads to a metallic phase when it becomes dominant over the nearest-neighbor hopping. Furthermore, we include weak repulsive on-site interactions and find the density profiles for different values of the hopping parameters and interactions, both in a homogeneous system and in the presence of a trapping potential. Our results may be experimentally observed by use of momentum-resolved Raman spectroscopy.

Koghee, Selma; Lim, Lih-King; Goerbig, M. O.; Smith, C. Morais

2012-02-01

271

An optical leveling technique for parallel near-field photolithography system  

NASA Astrophysics Data System (ADS)

An optical leveling technique is reported for a compact parallel (multi-cantilever) scanning near-field photolithography (SNP) prototype. This instrument operates in liquid and was designed to overcome the challenge of low sample throughput of previous serial scanning SNPs. A combination of zone plate lens array, probe array, and standard atomic force microscope feedback technique are employed to deliver parallel probe operation in the current SNP. Compared to the commonly used two-end or multi-end ``force feedback'' alignment techniques, the optical levelling technique applied provides a simple solution to maintaining all levers in an array within the near-field region. As a proof-of-principle experiment, the operation of the prototype was demonstrated by producing nano-scale patterns in parallel using scanning near-field photolithography.

Liu, Zhuming; Chen, Xinyong; Zhang, Yuan; Weaver, John; Roberts, Clive J.

2012-10-01

272

New scanning technique for the optical vortex microscope.  

PubMed

In the optical vortex microscopy the focused Gaussian beam with optical vortex scans a sample. An optical vortex can be introduced into a laser beam with the use of a special optical element--a vortex lens. When moving the vortex lens, the optical vortex changes its position inside the spot formed by a focused laser beam. This effect can be used as a new precise scanning technique. In this paper, we study the optical vortex behavior at the sample plane. We also estimate if the new scanning technique results in observable effects that could be used for a phase object detection. PMID:22505087

Augustyniak, Ireneusz; Popio?ek-Masajada, Agnieszka; Masajada, Jan; Drobczy?ski, S?awomir

2012-04-01

273

Alignment layerless flexible liquid crystal display fabricated by an imprinting technique at ambient temperature  

Microsoft Academic Search

The authors report on an alignment layerless (AL) flexible liquid crystal (LC) display fabricated at ambient temperature through an imprinting process. One-dimensional microgrooves and two-dimensional arrays of microstructures embossed on plastic substrates provide the spontaneous alignment of the LC molecules and spacers for the uniform cell gap in a flexible LC display, respectively. It is found that the azimuthal anchoring

Yeun-Tae Kim; Seongmo Hwang; Jong-Ho Hong; Sin-Doo Lee

2006-01-01

274

MEMS Integrated Submount Alignment for Optoelectronics  

NASA Astrophysics Data System (ADS)

One of the most expensive and time-consuming production processes for single-mode fiber-optic components is the alignment of the photonic chip or waveguide to the fiber. The alignment equipment is capital intensive and usually requires trained technicians to achieve desired results. Current technology requires active alignment since tolerances are only ~0.2 ? m or less for a typical laser diode. This is accomplished using piezoelectric actuated stages and active optical feedback. Joining technologies such as soldering, epoxy bonding, or laser welding may contribute significant postbond shift, and final coupling efficiencies are often less than 80%. This paper presents a method of adaptive optical alignment to freeze in place directly on an optical submount using a microelectromechanical system (MEMS) shape memory alloy (SMA) actuation technology. Postbond shift is eliminated since the phase change is the alignment actuation. This technology is not limited to optical alignment but can be applied to a variety of MEMS actuations, including nano-actuation and nano-alignment for biomedical applications. Experimental proof-of-concept results are discussed, and a simple analytical model is proposed to predict the stress strain behavior of the optical submount. Optical coupling efficiencies and alignment times are compared with traditional processes. The feasibility of this technique in high-volume production is discussed.

Shakespeare, W. Jeffrey; Pearson, Raymond A.; Grenestedt, Joachim L.; Hutapea, Parsaoran; Gupta, Vikas

2005-02-01

275

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

NASA Astrophysics Data System (ADS)

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.

Mills, J. P.; Moeller, C. E.

1980-01-01

276

Optical wavelength converters: techniques and system aspects  

NASA Astrophysics Data System (ADS)

Optical wavelength conversion will be a key function in photonic networks. Therefore the development of effective and practical all-optical wavelength converters is subject to considerable attention. Here, the application is outlined and the performance of wavelength conversion by semiconductor optical amplifiers reviewed.

Joergensen, Carsten; Danielsen, Soren L.; Mikkelsen, Benny; Stubkjaer, Kristian E.; Vodjdani, Nakita; Ratovelomanana, F.; Enard, Alain; Glastre, Genevieve; Rondi, D.; Blondeau, Robert R.; Doussiere, P.; Garabedian, G.; Graver, C.; Jourdan, Amaury; Schilling, Michael; Idler, Wilfried; Wunstel, K.

1996-03-01

277

Antares beam-alignment-system performance  

SciTech Connect

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

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

1983-01-01

278

Novel method for the production of spin-aligned RI beams in projectile fragmentation reaction with the dispersion matching technique  

NASA Astrophysics Data System (ADS)

A novel method to produce spin-aligned rare-isotope (RI) beam has been developed, that is the two-step projectile fragmentation method with a technique of dispersion matching. The present method was verified in an experiment at the RIKEN RIBF, where an RI beam of 32Al with spin alignment of 8(1) % was successfully produced from a primary beam of 48Ca, with 33Al as an intermediate nucleus. Figure of merit of the present method was found to be improved by a factor larger than 50 compared with a conventional method employing single-step projectile fragmentation.

Ichikawa, Y.; Ueno, H.; Ishii, Y.; Furukawa, T.; Yoshimi, A.; Kameda, D.; Watanabe, H.; Aoi, N.; Asahi, K.; Balabanski, D. L.; Chevrier, R.; Daugas, J. M.; Fukuda, N.; Georgiev, G.; Hayashi, H.; Iijima, H.; Inabe, N.; Inoue, T.; Ishihara, M.; Kubo, T.; Nanao, T.; Ohnishi, T.; Suzuki, K.; Tsuchiya, M.; Takeda, H.; Rajabali, M. M.

2013-05-01

279

Eye investigation with optical microradar techniques  

NASA Astrophysics Data System (ADS)

Many problems exist in ophthalmology, where accurate measurements of eye structure and its parameters can be provided using optical radar concept is of remote sensing. Coherent and non-coherent approaches are reviewed aiming cornea shape measurement and measurement of aberration distribution in the elements and media of an eye. Coherent radar techniques are analyzed taking into account non- reciprocity of eye media and anisoplanatism of the fovea, that results in an exiting image being not an auto- correlation of the point-spread function of a single pass, even in the approximation of spatial invariance of the system. It is found, that aberrations of the cornea and lens are not additive, and may not be brought to summary aberrations on the entrance aperture of the lens. Anisoplanatism of the fovea and its roughness lead to low degree of coherence in scattered light. To estimate the result of measurements, methodology has been developed using Zernike polynomials expansions. Aberration distributions were gotten from measurements in 16 points of an eye situated on two concentric circles. Wave aberration functions have been approximated using least-square criterion. Thus, all data were provided necessary for cornea ablation with PRK procedure.

Molebny, Vasyl V.; Pallikaris, Ioannis G.; Naoumidis, Leonidas P.; Kurashov, Vitalij N.; Chyzh, Igor H.

1997-08-01

280

Optical techniques for determining dynamic material properties  

SciTech Connect

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

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

1996-12-31

281

Optical polarizer made of uniaxially aligned short single-wall carbon nanotubes embedded in a polymer film  

NASA Astrophysics Data System (ADS)

An intrinsic characteristic of carbon nanotubes (CNTs), which are allotropes of carbon, is one-dimensional anisotropy. It is derived from the peculiar geometrical shape of the molecules and is manifested in their electrical, thermal, mechanical, and optical properties. Here, we report an optical polarizer that makes effective use of such anisotropy of CNTs. The polarizer we fabricated is made of uniaxially aligned CNTs embedded in a polymer film. Thanks to the ? plasmon-originated broad absorption spectrum and strong optical anisotropy of single-wall CNTs (SWCNTs), the film exhibits a degree of polarization of ˜90% with keeping flat transmittance through the spectral region from 350 to 800 nm. In order to efficiently obtain well-aligned CNTs, we used SWCNTs shortened into a length of less than 200 nm. We also observed enhancement of the degree of polarization at the wavelengths of Van Hove singularities.

Shoji, Satoru; Suzuki, Hidemasa; Zaccaria, Remo Proietti; Sekkat, Zouheir; Kawata, Satoshi

2008-04-01

282

Aberration evaluation of alignment optics in lithographic tools by use of a step-height structure highly sensitive to the asymmetry of an optical image  

SciTech Connect

To satisfy the increasing demand for extremely tight overlay accuracy in semiconductormanufacturing processes, all the measurement error factors in alignment systems andoverlay measurement tools need be identified and eliminated. The principle of mostalignment systems is based on image processing of target marks on the wafer under bright-fieldillumination. Although the phenomenon that the sensitivity to the alignment errorvaries with the step height (SH) of the mark has been known and used for evaluating theperformance of the alignment optics, no investigation has been made into the origin andthe physical mechanism of the phenomenon. We propose a simplified opticalmodel that can account for the origin of the asymmetric image and clarify its relation to theSHs. The model is validated with simulation and experimental results. Theimproved performance of an alignment system using marks with optimally designedSHs is demonstrated.

Ina, Hideki; Takeda, Mitsuo

2007-06-10

283

Alignment of an inexpensive paraboloidal concentrator for hybrid solar lighting applications  

NASA Astrophysics Data System (ADS)

We describe a practical method for precisely aligning the optical components of a low-cost solar concentrator developed for fiber optic solar lighting applications. A two-stage alignment process, involving both mechanical and optical alignment techniques, is described which allows the tilt, centering, and focal alignment of a large parabolic primary reflector relative to a segmented planar secondary mirror to be accurately determined. The alignment strategy is well suited to optical systems utilizing large reflectors with non-referenced optical axes and non-precision surface characteristics, as is typical of many inexpensive reflectors.

Earl, D. D.; Maxey, L. Curt

2004-01-01

284

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

285

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

SciTech Connect

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.

CASTILLO,JOSE E.; OTTO,JAMES S.

2000-02-11

286

Dimensional metrology of large refractive optical components using nonoptical techniques  

Microsoft Academic Search

Traditionally, the key component design parameters such as radius, lens thickness, size and shape of most types of optical components are measured using optical techniques. There are several reasons for this, but in particular: the form of the entire surface is generally revealed in one testing set up, the optical functionality of the component is almost always the performance defining

Graham Peggs

2002-01-01

287

Advanced technique in fiber optic sensors  

NASA Astrophysics Data System (ADS)

There are a lot of optical sensors for the selective determination of ion species. Some organic compounds also have been determined by optical sensors using the enzymatic and immunological reactions. On the other hand, calixarenes are well known as novel host molecules, and specific guest ions or molecules can be incorporated inside the cavity of calixarenes. This specific recognition function of calixarene has been applied to the development of electrochemical and optical ion sensors. However, an optical sensing of organic molecules using this host-guest system is a new approach at present. In this study, a sensing membrane containing a fluorescent probe and a calixarene derivative is prepared, and it is attached on a distal end of an optical fiber. An organic compound, which specially interacts with the calixarene derivative, is optically determined. The response mechanism of the sensor is discussed.

Kawabata, Yuji; Yamashiro, T.; Imasaka, Totaro

1993-04-01

288

Optical beam forming techniques for phased array antennas  

NASA Technical Reports Server (NTRS)

Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are 1) the fiber replacement of conventional RF phased array distribution and control components, 2) spatial beam forming, and 3) optical beam splitting techniques. Two novel optical beam forming approaches, i.e., the spatial beam forming with a 'smart pixel' spatial light modulator (SLM) and the optical beam splitting approaches are conceived with integrated quasi-optical components. Also presented are the transmit and receive array architectures with the new SLM.

Wu, Te-Kao; Chandler, Charles W.

1993-01-01

289

Compact optical technique for streak camera calibration  

NASA Astrophysics Data System (ADS)

To produce accurate data from optical streak cameras requires accurate temporal calibration sources. We have reproduced an older technology for generating optical timing marks that had been lost due to component availability. Many improvements have been made which allow the modern units to service a much larger need. Optical calibrators are now available that produce optical pulse trains of 780 nm wavelength light at frequencies ranging from 0.1 to 10 GHz, with individual pulse widths of approximately 25 ps full width half maximum. Future plans include the development of single units that produce multiple frequencies to cover a wide temporal range, and that are fully controllable via an RS232 interface.

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

2004-10-01

290

Optical addressing technique for a CMOS RAM  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

291

Predicting the accuracy of multiple sequence alignment algorithms by using computational intelligent techniques  

PubMed Central

Multiple sequence alignments (MSAs) have become one of the most studied approaches in bioinformatics to perform other outstanding tasks such as structure prediction, biological function analysis or next-generation sequencing. However, current MSA algorithms do not always provide consistent solutions, since alignments become increasingly difficult when dealing with low similarity sequences. As widely known, these algorithms directly depend on specific features of the sequences, causing relevant influence on the alignment accuracy. Many MSA tools have been recently designed but it is not possible to know in advance which one is the most suitable for a particular set of sequences. In this work, we analyze some of the most used algorithms presented in the bibliography and their dependences on several features. A novel intelligent algorithm based on least square support vector machine is then developed to predict how accurate each alignment could be, depending on its analyzed features. This algorithm is performed with a dataset of 2180 MSAs. The proposed system first estimates the accuracy of possible alignments. The most promising methodologies are then selected in order to align each set of sequences. Since only one selected algorithm is run, the computational time is not excessively increased.

Ortuno, Francisco M.; Valenzuela, Olga; Pomares, Hector; Rojas, Fernando; Florido, Javier P.; Urquiza, Jose M.

2013-01-01

292

A method of gravity release compensation in the optical alignment of orbiting meteorological sounding and imaging instruments  

NASA Technical Reports Server (NTRS)

This paper describes a method developed for precompensating the front-end (telescope) optical alignment of the Imager and Sounder radiometric instruments, which will be launched as components of the GOES I - M series of meteorological satellites. To satisfy the severe pointing accuracy requirements on these instruments, their alignments must be offset in the one - G field of the laboratory, in order that they will be correct in orbit. A method was developed to make the necessary alignment offset, using a counterweight mechanism; autocollimation returns from reference mirrors on the instrument structure and supporting fixturing provided feedback for adjusting the counterweight mechanism. A series of experiments was performed to verify that these autocollimation return measurements were a good predictor of telescope line-of-sight changes; these experiments are described and their results summarized.

Wetzel, James C.

1988-01-01

293

Optical link upgrade by DDMS technique with compensating fiber in optical cable closure  

NASA Astrophysics Data System (ADS)

A well-known dense dispersion management soliton (DDMS) technique is applied to increase bandwidth of metropolitan area network fiber optic links. This technique requires an installation of optical cables with dispersion compensating fibers (DCFs), which leads to high costs for upgrading of installed fiber optic links. To become the DDMS more applicable, we propose to place DCFs in optical fiber closures. Here results of numerical simulations of optical pulse propagation and following bit-error-ratio estimation in fiber optic link with DCFs in optical closures are represented.

Burdin, Vladimir A.; Dashkov, Michael V.; Bourdine, Anton V.; Volkov, Kirill A.

2010-01-01

294

Some Alignment Considerations for the Next Linear Collider  

SciTech Connect

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

Ruland, R

2004-06-08

295

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

Microsoft Academic Search

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

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

2006-01-01

296

Parallel optical interconnect between surface-mounted devices on FR4 printed wiring board using embedded waveguides and passive optical alignments  

NASA Astrophysics Data System (ADS)

Technologies to design and fabricate high-bit-rate chip-to-chip optical interconnects on printed wiring boards (PWB) are studied. The aim is to interconnect surface-mounted component packages or modules using board-embedded optical waveguides. In order to demonstrate the developed technologies, a parallel optical interconnect was integrated on a standard FR4-based PWB. It consists of 4-channel BGA-mounted transmitter and receiver modules as well as of four polymer multimode waveguides fabricated on top of the PWB using lithographic patterning. The transmitters and receivers built on low-temperature co-fired ceramic (LTCC) substrates include flip-chip mounted VCSEL or photodiode array and 4x10 Gb/s driver or receiver IC. Two microlens arrays and a surface-mounted micro-mirror enable optical coupling between the optoelectronic device and the waveguide array. The optical alignment is based on the marks and structures fabricated in both the LTCC and optical waveguide processes. The structures were optimized and studied by the use of optical tolerance analyses based on ray tracing. The characterized optical alignment tolerances are in the limits of the accuracy of the surface-mount technology.

Karppinen, Mikko; Alajoki, Teemu; Tanskanen, Antti; Kataja, Kari; Mäkinen, Jukka-Tapani; Karioja, Pentti; Immonen, Marika; Kivilahti, Jorma

2006-04-01

297

Optical modeling activities for NASA's James Webb Space Telescope (JWST): III. Wavefront aberrations due to alignment and figure compensation  

NASA Astrophysics Data System (ADS)

This paper is part three of a series describing the ongoing optical modeling activities for the James Webb Space Telescope (JWST). The first two papers discussed modeling JWST on-orbit performance using wavefront sensitivities to predict line of sight motion induced blur, and stability during thermal transients [1-2]. The work here investigates the aberrations resulting from alignment and figure compensation of the controllable degrees of freedom (i.e. the primary and secondary mirrors), which may be encountered during ground alignment and on-orbit commissioning of the observatory. The optical design of the telescope is a three-mirror anastigmat, with an active fold mirror at the exit pupil for fine guiding. The primary mirror is over 6.5 meters in diameter, and is composed of 18 hexagonal segments that can individually positioned on hexapods, as well as compensated for radius of curvature. This architecture effectively gives both alignment and figure control of the primary mirror. The secondary mirror can be moved in rigid body only, and the tertiary mirror is fixed. Simulations are performed of various combinations of alignment and figure errors corrected by the primary and secondary mirrors. Single field point knowledge is assumed in the corrections, and aberrations over the field are reported for the varying cases.

Howard, Joseph M.

2007-09-01

298

Optical and field emission properties of single-crystalline aligned ZnO nanorods grown on aluminium substrate  

NASA Astrophysics Data System (ADS)

Optical and field emission (FE) properties of aligned single-crystalline ZnO nanorods, grown on aluminium substrate at 530 °C by the non-catalytic thermal evaporation process, have been examined. Raman-scattering and room-temperature PL spectra exhibit a strong and sharp optical phonon E2 mode at 437 cm-1 and a strong ultraviolet emission at 381 nm, respectively. The FE characterization shows that a turn-on field for the vertically aligned nanorods was 5.8 V µm-1 and the emission current density reached to 0.061 mA cm-2 at an applied electrical field of 9.0 V µm-1 and shows no saturation. The field enhancement factor ? was estimated, from the F-N plot, to be about ~2.081 × 103.

Umar, Ahmad; Kim, S. H.; Lee, Hansung; Lee, Naesung; Hahn, Y. B.

2008-03-01

299

Optical Image Segmentation Using Wavelet Filtering Techniques.  

National Technical Information Service (NTIS)

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 visi...

C. P. Veronin

1990-01-01

300

Monolithically integrated laser\\/rear-facet monitor arrays with V-groove for passive optical fiber alignment  

Microsoft Academic Search

An InGaAsP\\/InP laser monolithically integrated with a rear facet monitor and a fiber V-groove has been demonstrated for the first time. The integrated device incorporates an etched-facet laser fabricated using an in situ, multistep, reactive ion etch process. The integrated V-groove, which is etched directly into the InP substrate, is designed to enable passive alignment of an optical fiber to

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

1993-01-01

301

Temperature-insensitive optical alignment of the exciton in nanowire-embedded GaN quantum dots  

NASA Astrophysics Data System (ADS)

We report on the exciton spin dynamics of nanowire-embedded GaN/AlN quantum dots (QDs) investigated by time-resolved photoluminescence spectroscopy. Under a linearly polarized quasiresonant excitation, we evidence the quenching of the exciton spin relaxation and a temperature-insensitive degree of the exciton linear polarization, demonstrating the robustness of the optical alignment of the exciton spin in these nanowire-embedded QDs. A detailed examination of the luminescence polarization angular dependence shows orthogonal linear exciton eigenstates.

Balocchi, A.; Renard, J.; Nguyen, C. T.; Gayral, B.; Amand, T.; Mariette, H.; Daudin, B.; Tourbot, G.; Marie, X.

2011-12-01

302

Optical fiber sensor technique for strain measurement  

DOEpatents

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

Butler, Michael A. (Albuquerque, NM); Ginley, David S. (Albuquerque, NM)

1989-01-01

303

A new optical fiber sensor with improved strain sensitivity based on distributed optical fiber sensing technique  

Microsoft Academic Search

In general, macro-strain is an effective index for health monitoring of civil infrastructures, which can reveal the unforeseen damage accumulation. However, it is difficult to acquire precise strain distribution with existing fully-distributed optical fiber sensing techniques. Based on the distributed optical fiber strain sensing technique of pulse-prepump Brillouin Optical Time Domain Analysis (PPP-BOTDA), a new optical fiber sensor with improved

Sheng Shen; Zhisheng Wu; Caiqian Yang; Yongsheng Tang; Gang Wu; Wan Hong

2009-01-01

304

The Virgo automatic alignment system  

Microsoft Academic Search

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

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

305

Techniques for optical packet switching and optical burst switching  

Microsoft Academic Search

Wavelength-division multiplexing appears to be the solution of choice for providing a faster networking infrastructure that can meet the explosive growth 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-ing and optical burst

Lisong Xu; H. G. Perros; G. Rouskas

2001-01-01

306

Optical and electrochemical measurements for optical fibre corrosion sensing techniques  

Microsoft Academic Search

The feasibility of an optical fibre corrosion sensor (OFCS) was studied. A multi-mode fibre was metallised by physical vacuum deposition and electroplating of a Fe–C alloy film on a 1–2cm uncladded section of an optical fibre. The shift of light power transmitted through the fibre was registered with corrosion. Microanalysis was carried out to show the formation of metallised film.

Saying Dong; Yanbiao Liao; Qian Tian; Yanan Luo; Zhigang Qiu; Shizhe Song

2006-01-01

307

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

308

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

PubMed

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

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

2013-01-01

309

Project valuation, capital investment and strategic alignment—tools and techniques at Anglo Platinum  

Microsoft Academic Search

Central to the success of any mining company is the ability to manage capital investment effectively so as to ensure acceptable stakeholder returns within an overall strategic context. Critical to this process is the effective selection and implementation of a strategically aligned project portfolio that enables optimal resource exploitation while operating within mandated bounds and identified constraints. Consideration is given

G. L. SMITH; J. PEARSON-TAYLOR; D. C. ANDERSEN; A. M. MARSH

310

Applications of optical techniques in smart structures: an overview  

NASA Astrophysics Data System (ADS)

In recent years many exciting developments have taken place in the area of smart structures which are designed to react to their environment by the use of integrated sensors and actuators. At the same time, important advances in lasers, fiber optics, semiconductor optoelectronics, optical and thermal imaging, and optical processing have made possible the application of optical methods in many novel ways. Optical techniques and technologies have thus a major role to play in the development of smart sensors and structures. The purpose of this paper is to present a review of some recent developments in this direction.

Selvarajan, Ananth

1998-04-01

311

Control of spatial polarization by use of a liquid crystal with an optically treated alignment layer and its application to beam apodization  

Microsoft Academic Search

We have investigated the alignment of a liquid crystal whose orientation is controlled by photoisomerization reaction for use in developing optical devices to improve beam quality. A glass window of a liquid-crystal cell that is coated with poly(vinyl alcohol) doped with azo dye was illuminated with a Hg lamp. We confirmed the dependence of the spatially controlled alignment direction of

Keiichi Sueda; Kouji Tsubakimoto; Noriaki Miyanaga; Masahiro Nakatsuka

2005-01-01

312

Registration of Neural Maps through Value-Dependent Learning: Modeling the Alignment of Auditory and Visual Maps in the Barn Owl's Optic Tectum  

Microsoft Academic Search

In the optic tectum (OT) of the barn owl, visual and auditory maps of space are found in close alignment with each other. Experiments in which such alignment has been disrupted have shown a considerable degree of plasticity in the auditory map. The external nucleus of the inferior colliculus (ICx), an auditory center that projects massively to the tectum, is

Michele Rucci; Giulio Tononi; Gerald M. Edelman

1997-01-01

313

Imaging Techniques Utilizing Optical Fibers and Tomography.  

National Technical Information Service (NTIS)

Two-dimensional, time-dependent images generated by neutrons, gamma rays, and x-rays incident on fast scintillators are relayed to streak and video cameras over optical fibers. Three dimensions, two spatial and one temporal, have been reduced to two, one ...

M. Wilke N. S. P. King N. Gray D. Johnson D. Esquibel

1985-01-01

314

Three-dimensional optical information processing techniques  

Microsoft Academic Search

Capturing and manipulating three-dimensional information of the object space make it possible to deal with the object information with more freedom and completeness. In this paper, we present various optical methods to process three-dimensional information of the object.

Nam Kim; Jae-Hyeung Park

2009-01-01

315

Optical system for Argus 355-nm 90-mm aperture target-illumination experiments  

SciTech Connect

The requirements of laser alignment, crystal tuning, target alignment, and laser beam diagnosis are provided by this optical system. Initial setup and preshot alignment techniques are discussed. Layout and operation are contrasted with the 532 nm target experiments.

Johnson, B.C.; Boyd, R.; Hermes, G.; Hildum, J.S.; Linford, G.; Martin, W.E.

1982-02-01

316

New developments in optical control techniques for phased array radar  

Microsoft Academic Search

Recent work on optical signal distribution and control techniques for phased-array radar is described. Experimental results for millimeter-wave reference signal generation by heterodyning the outputs of two semiconductor lasers are presented. Mixers in which the local oscillator input is an intensity-modulated optical signal are described. The use of these developments, together with other optically controlled devices, in phased-array element architectures

A. J. Seeds; I. D. Blanchflower; N. J. Gomes; G. King; S. J. Flynn

1988-01-01

317

Optical fiber hydrogen sensor based on photothermal reflectance detection technique  

NASA Astrophysics Data System (ADS)

This article proposes an optical fiber hydrogen (H2) sensor based on photothermal reflectance [hereinafter modulated optical reflectance (MOR)] technique. Our H2 sensor is based on a technique that detects the changes of MOR signals in palladium film, which is widely known to absorb H2 gas. The sensor element is a palladium film deposited on a 2.5-mm-diameter FC-ferrule made from zirconium to realize the optical fiber sensor. Our recently developed "laptop" MOR instrument assembled with optical fiber components is applied to this technique. Thus, an extremely compact photothermal H2 gas sensor system can be constructed. We certified that our technique has hypersensitive less than 1% with a concentration of H2 gas and also demonstrated that the response time is approximately 5 seconds when the sensor head is filled with H2 gas.

Yarai, A.; Nakanishi, T.

2010-03-01

318

Wavelength-Multiplexed Imaging Techniques Using Optical Fibers.  

National Technical Information Service (NTIS)

Wavelength multiplexing techniques provide the basis for many efficient image transmission schemes using optical fibers. A variety of examples is presented and important system characteristics and tradeoffs are considered. (ERA citation 11:051798)

C. E. Iverson M. A. Nelson B. R. Marshall T. J. Davies J. W. Ogle

1986-01-01

319

Wavelength-multiplexed imaging techniques using optical fibers  

SciTech Connect

Wavelength multiplexing techniques provide the basis for many efficient image transmission schemes using optical fibers. A variety of examples is presented and important system characteristics and tradeoffs are considered.

Iverson, C.E.; Nelson, M.A.; Marshall, B.R.; Davies, T.J.; Ogle, J.W.

1986-01-01

320

Sixport technique for phase measurement of guided optical fields  

NASA Astrophysics Data System (ADS)

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

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

2010-04-01

321

Optical Computing Techniques for Radar and Sonar Signal Processing.  

National Technical Information Service (NTIS)

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of...

D. Casasent

1977-01-01

322

Optical modulation techniques for underwater detection, ranging and imaging  

Microsoft Academic Search

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

Linda Mullen; Brandon Cochenour; Alan Laux; Derek Alley

2011-01-01

323

Optical alignment of a 0.5 meter ultra-violet spectrometer for Apollo 17  

NASA Technical Reports Server (NTRS)

Description of the design and performance of a 0.5 m Ebert spectrometer mounted on Apollo 17 for research on the ultraviolet spectrum of the lunar atmosphere. The instrument was designed for operation in the range 1175 to 1675 A. A method was developed for aligning subassemblies in such a way that the assembled instrument would be aligned in the ultraviolet to an accuracy of 2 A with maximum efficiency.

Schroader, I. H.; Holliday, C. T.; Bush, G. B.

1973-01-01

324

In-flight alignment\\/calibration techniques for unaided tactical guidance  

Microsoft Academic Search

An evaluation is conducted of various alignment\\/calibration procedures which permit the use of low-cost sensors in unaided navigation satisfying tactical mission requirements. The missile navigation system and its interface with the reference launch aircraft navigation system are illustrated in a figure. Strapdown gyros and accelerometers are included in the missile's inertial sensor subsystem. To provide the optimum cost-effective utilization of

J. W. Kraemer; N. J. Roessler; D. M. Brandin

1978-01-01

325

Optical correlator techniques applied to robotic vision  

Microsoft Academic Search

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

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

1991-01-01

326

(Optical characterization techniques applied to ceramic oxides)  

SciTech Connect

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

Abraham, M.M.

1990-10-15

327

Optical techniques for determining dynamic material properties  

Microsoft Academic Search

Miniature plates are laser-launched with a 10-Joule Nd:YAG for 1D impacts on to target materials much like gas gun experiments and explosive plane wave plate launch. By making the experiments small, flyer plates (3 mm diameter X 50 micron thick) and targets (10 mm diameter X 200 micron thick), 1D impact experiments can be performed in a standard laser-optical laboratory

Dennis L. Paisley; David B. Stahl

1997-01-01

328

Optical techniques for determining dynamic material properties  

Microsoft Academic Search

Miniature plates are laser-launched with a 10-Joule Nd:YAG for one-dimensional (1-D) impacts on to target materials much like gas gun experiments and explosive plane wave plate launch. By making the experiments small, flyer plates (3 mm diameter x 50 micron thick) and targets (10 mm diameter x 200 micron thick), 1-D impact experiments can be performed in a standard laser-optical

D. L. Paisley; D. B. Stahl

1996-01-01

329

Eigendecomposition-Based Clutter Filtering Technique for Optical Microangiography  

Microsoft Academic Search

In this paper, we propose eigendecposition (ED)- based clutter filtering technique for 3-D optical imaging of blood flow. Due to its best mean-square approximation of the clutter, eigenregression filters can theoretically provide maximum clutter suppression. Compared to the existing clutter rejection techniques in the literature used for optical imaging of blood flow, ED-based clutter filtering is less sensitive to tissue

Siavash Yousefi; Zhongwei Zhi; Ruikang K. Wang

2011-01-01

330

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

PubMed

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

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

2012-01-01

331

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

PubMed Central

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.

2012-01-01

332

A unified approach to real time audio-to-score and audio-to-audio alignment using sequential Montecarlo inference techniques  

Microsoft Academic Search

We present a methodology for the real time alignment of mu­ sic signals using sequential Montecarlo inference techniques. The alignment problem is formulated as the state tracking of a dynamical system, and differs from traditional Hidden Markov Model -Dynamic Time Warping based systems in that the hidden state is continuous rather than discrete. The major contribution of this paper is

Nicola Montecchio; Arshia Cont

2011-01-01

333

Interface Alignment System.  

National Technical Information Service (NTIS)

A novel optical alignment system and method is provided for detecting misalignment of the optical components of a high energy laser comprising a source of radiation, such as HeNe laser, for providing an alignment beam to intersect the optical path of the ...

P. J. Pomphrey

1983-01-01

334

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

PubMed

A technique is proposed to measure the high-resolution and wide-band characterization of amplitude, phase responses, and polarization property of optical components. This technique combines the optical spectrum stitching and optical channel estimation methods. Two kinds of fiber Bragg grating based Fabry-Perot cavities with ultrafine structures have been characterized based on this technique. By using 1024 point fast Fourier transform and a narrow linewidth, wavelength-tunable laser source, a frequency resolution of ~10 MHz is realized with an optical measurement range beyond 250 GHz. PMID:23811913

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

2013-07-01

335

Fabrication of Highly Scaled Silicon Nanowire Gate-All-Around MetalOxideSemiconductor Field Effect Transistors by Using Self-Aligned Local-Channel V-gate by Optical Lithography Process  

Microsoft Academic Search

The silicon nanowire gate-all-around (GAA) metal-oxide-semiconductor field effect transistors (MOSFETs) have been fabricated by using inverted sidewall spacers to scale the gate length. The patterning strategy of inverted sidewall spacers is based on the self-aligned local-channel V-shaped gate electrode (V-gate) by optical lithography (SALVO) process. Through this technique, we have obtained an aggressively scaled gate length down to 10 nm

Jae Hyun Park; Jae Young Song; Jong Pil Kim; Sang Wan Kim; Jang-Gn Yun; Byung-Gook Park

2010-01-01

336

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

PubMed

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

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

2014-01-21

337

Paraxial propagation of a partially coherent Hermite-Gaussian beam through aligned and misaligned ABCD optical systems.  

PubMed

Paraxial propagation of a partially coherent Hermite-Gaussian beam through aligned and misaligned ABCD optical systems is investigated based on the generalized Collins formula for treating the propagation of a partially coherent beam through such optical systems. Analytical formulas for the cross-spectral density of a partially coherent Hermite-Gaussian beam propagating through such optical systems are derived. As an application example, we derive the propagation formulas for a partially coherent flattened Gaussian beam by expressing it as a superposition of a series of partially coherent Hermite-Gaussian beams by using polynomial expansion. The focusing properties of a partially coherent Hermite-Gaussian beam focused by a thin lens are studied as a numerical example. PMID:17621342

Cai, Yangjian; Chen, Chiyi

2007-08-01

338

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

SciTech Connect

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 (GB) reflection coefficient and grain size. A resistivity based model was used as the complementary method to the thickness-dependent optical model to trace the change in GB reflection coefficient and grain size. After silicidation, the complex dielectric function of NiSi films exhibit non-Drude behavior due to superimposition of interband absorptions arising at lower frequencies. The Optical models of the complete film stack were refined using x-ray photoelectron spectroscopy, Rutherford backscattered spectroscopy, and x-ray reflectivity (XRR).

Kamineni, V. K.; Bersch, E. J.; Diebold, A. C. [College of Nanoscale Science and Engineering, University at Albany, 255 Fuller Rd., Albany, New York 12203 (United States); Raymond, M. [GLOBALFOUNDRIES, 255 Fuller Rd., Albany, New York 12203 (United States); Doris, B. B. [IBM, 255 Fuller Rd., Albany, New York 12203 (United States)

2010-05-15

339

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

PubMed

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

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

2013-05-15

340

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

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

341

Techniques for optically compressing light intensity ranges  

DOEpatents

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

Rushford, Michael C. (Livermore, CA) [Livermore, CA

1989-01-01

342

Techniques for optically compressing light intensity ranges  

DOEpatents

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

Rushford, M.C.

1989-03-28

343

Real-time optical image processing techniques  

NASA Technical Reports Server (NTRS)

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

Liu, Hua-Kuang

1988-01-01

344

Treatment outcome and efficacy of an aligner technique - regarding incisor torque, premolar derotation and molar distalization  

PubMed Central

Background The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. Methods We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. Results The overall mean efficacy was 59% (SD?=?0.2). The mean accuracy for upper incisor torque was 42% (SD?=?0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD?=?0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD?=?0.2). Conclusion Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy.

2014-01-01

345

RCS prediction comparison between physical optics and moment method techniques  

Microsoft Academic Search

The analysis of complex scattering objects can be accomplished using various numerical methods. Two complementary techniques that have found great success in many classes of electromagnetic applications are the moment method (MM) and the physical optics techniques. This paper will present results of RCS predictions using Riverside Research Institute modified moment method code `IBC3D' and Georgia Tech Research Institute developed

J. S. Sidhu; E. J. Kuster; P. G. Friederich; E. J. Hopkins

1997-01-01

346

Advanced Optical Techniques for Measurements of Atmospheric Constituents  

Microsoft Academic Search

Spectral models available for calculations of optical propagation conditions provide the research and development community valuable tools for design, simulation, and validation of remote sensing techniques. Examples of these techniques applied to lidar developments are described. A white light super continuum laser has been proposed as a new tool for measurements of minor species concentrations on long paths in the

David M. Brown; Adam Willitsford; Kebin Shi; Zhiwen Liu; C. Russell Philbrick

347

Physical optics of the laser-schlieren shock tube technique  

Microsoft Academic Search

The physical optics of the laser-schlieren technique for the measurement of rate processes in shock waves is examined in detail. The method utilized the Kirchhoff-Hyggens integral with the usual thin lens, paraxial, and Fresnel approximations, all of which are appropriate for the typical laser schlieren experiment. The resolution and sensitivity of the technique are defined for all detector separations, and

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

1981-01-01

348

New optical techniques for crystal growth from fluids  

Microsoft Academic Search

Electronic speckle interferometry (ESPI) is a non-contact optical technique commonly devoted to the observation of microscopic deformation of materials due to stress or applied loads in real time with an accuracy of the order of a wavelength of light. This interferometric technique may also be applied to the observation of physical phenomena in transparent fluids, such as density and concentration

E Piano; G. A Dall’Aglio; S Crivello; R Chittofrati; F Puppo

2000-01-01

349

Self-alignment and instability of waveguides induced by optical forces  

SciTech Connect

We introduce a fundamental property of waveguides induced by the forces of the guided light, namely, the ability to self-align or be in instability. A nanoscale waveguide broken by an offset and a gap may tend to self-align to form a continuous waveguide. Conversely, depending on the geometry and light polarization, the two parts of the waveguide may be deflected away from each other, thus, being in an unstable state. These effects are unique as they rely on the presence of both the guided mode and the scattered light. Strong self-alignment forces, in both the transverse and longitudinal directions, may be facilitated by near field interaction with polarization surface charges.

Mizrahi, Amit; Ikeda, Kazuhiro; Bonomelli, Fabio; Lomakin, Vitaliy; Fainman, Yeshaiahu [Department of Electrical and Computer Engineering, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093-0407 (United States)

2009-10-15

350

Phase retrieval techniques for adaptive optics  

SciTech Connect

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

Carrano, C. J., LLNL

1998-03-01

351

Flip-chip packaging using micromachined conductive polymer bumps and alignment pedestals for MOEMS  

Microsoft Academic Search

Using flip-chip bonding techniques with micromachined conductive polymer bumps and passive alignment techniques with electroplated side alignment pedestal bumps, a prototype microoptoelectromechanical systems (MOEMS) structure for optical input\\/output (I\\/O) couplers has been designed, fabricated and characterized. A top MOEMS substrate has through holes, contact metal pads, and side alignment pedestals with electroplated NiFe to align GaAs metal-semiconductor-metals (MSMs). Conductive polymer

Kwang W. Oh; Chong H. Ahn; Kenneth P. Roenker

1999-01-01

352

Optical technique to characterize heavy rain  

NASA Technical Reports Server (NTRS)

A technique to measure the size and velocity of raindrops is presented and experimental and numerical results discussed. The technique bases the droplet size on the absolute intensity of the light scattered when the droplets cross a laser-based probe volume. The velocity is obtained from the Doppler frequency. A size range of 0.1 mm to 9 mm was covered with overlapping ranges. Experiments were conducted with simulated rain sprays except that the local LWC was much larger than the values encountered in natural rain. The accuracy of the size measurement was not strongly affected by spray interference, but it showed a clear dependence with the droplet shape. A simple numerical model based on the light reflected from ellipsoids attempts to explain the relationship between droplet shape and absolute scattered light.

Hess, C. F.; Li, F.

1986-01-01

353

Polarimetry of the aligned optical continuua in high redshift radio galaxies  

NASA Astrophysics Data System (ADS)

Replace these paragraphs with your abstract. We encourage you to include a sentence acknowledging your funding agency. Milky Way and SMC dust grain models are used to model the quasar-illuminated dust reflection nebulae that contribute to the alignment effect in high redshift radio galaxies. The model explains why QSRs have little or no extinction while allowing for the alignment effect in HZRGs to be dominated by dust scattering and still preserving the unification of radio galaxies and quasars. Model images, spectra, and polarization images will be compared with observations of high redshift radio galaxies and quasars.

Chambers, K. C.

2002-05-01

354

Optical link upgrade by dispersion and nonlinearity management technique realized by compensating optical cable coiled around of fiber optic closure  

NASA Astrophysics Data System (ADS)

We represent results of numerical simulations for upgrade of optical link with SMF by using the DDMS technique based on application of compensating optical cable coiled around of optical closure. We propose this technique for minimization land cost. Nonlinearity management for decreasing of quasi-solitons interaction is considered. Based on NLSE the model of optical link regeneration section with dispersion and nonlinearity management is described. The NLSE was solved numerically. Estimated values for optical system performance were derived by taking into account the amplified spontaneous emission noise, parameters of dispersion map deviations, and the interaction of quasi-solitons.

Burdin, Vladimir A.; Bourdine, Anton V.; Volkov, Kirill A.

2012-01-01

355

Compact and passive-alignment 4-channel x 2.5-Gbps optical interconnect modules based on silicon optical benches with 45 degrees micro-reflectors.  

PubMed

Compact and passive-alignment 4-channel x 2.5-Gbps optical interconnect modules are developed based on the silicon optical benches (SiOBs) of 5 x 5 mm2. A silicon-based 45 degrees micro-reflector and V-groove arrays are fabricated on the SiOB using anisotropic wet etching. Moreover, high-frequency transmission lines of 4 channel x 2.5 Gbps, and bonding pads with Au/Sn eutectic solder are also deposited on the SiOB. The vertical-cavity surface-emitting laser (VCSEL) array and photo-detector (PD) array are flip-chip assembled on the intended positions. The multi-mode fiber (MMF) ribbons are passively aligned and mounted onto the V-groove arrays. Without the assistance of additional optics, the coupling efficiencies of VCSEL-to-MMF in the transmitting part and MMF-to-PD in the receiving part can be as high as -5.65 and -1.98 dB, respectively, under an optical path of 180 microm. The 1-dB coupling tolerance of greater than +/- 20 microm is achieved for both transmitting and receiving parts. Eye patterns of both parts are demonstrated using 15-bit PRBS at 2.5 Gbps. PMID:20052136

Hsiao, Hsu-Liang; Lan, Hsiao-Chin; Chang, Chia-Chi; Lee, Chia-Yu; Chen, Siou-Ping; Hsu, Chih-Hung; Chang, Shuo-Fu; Lin, Yo-Shen; Kuo, Feng-Ming; Shi, Jin-Wei; Wu, Mount-Learn

2009-12-21

356

Advanced optical characterization techniques for borophosphosilicate films  

NASA Astrophysics Data System (ADS)

FTIR spectra of borophosphosilicate (BPSG) films which are obtained by metal backed configurations are compared to those obtained by the conventional normal incidence transmission geometry. Sensitivity advantages are demonstrated for both hydrogen incorporation and dopant analyses. P-polarized measurements are explored for preferential excitation of vibrational modes. Reflectance measurements of BPSG films on silicon by FTIR and by the emerging techniques of spectroscopic ellipsometry (SE) both in the UV-visible and mid-IR spectral ranges are reviewed. The use of differential and derivative spectral data anlysis is illustrated for investigating structural and compositional changes which occur from film densification and in the course of film storage.

Carpio, Ronald A.; Taylor, Jon

1995-09-01

357

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)

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.

Wilkerson, Gary W.; Huegele, Vinson

1998-01-01

358

Liquidus temperature and optical properties measurement by containerless techniques  

NASA Technical Reports Server (NTRS)

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

Anderson, Collin D.

1993-01-01

359

Preliminary studies on a magneto-optical procedure for aligning RHIC magnets  

Microsoft Academic Search

Colloid dispersions of magnetite were used at SLAC and KEK to locate multipole magnet centers. We study here possible adaption of this method, to align RHIC magnets. A procedure for locating magnetic centers with respect to external fiducial markers, using electronic coordinate determination and digital TV image processing is described

M. A. Goldman; R. E. Sikora; T. J. Shea

1993-01-01

360

Steerable optical flow based image registration: application to aligning human torso images  

Microsoft Academic Search

The aim of image registration is to align two or more images taken from different viewpoints, at different time instances, or by different modalities. Image registration methods are divided into two main categories, feature based and intensity based methods. Recently intensity based methods have gained popularity since they aim at finding a dense correspondence between the images needed to be

Ahmed Elsafi; Rami Zewail; Nelson G. Durdle

2009-01-01

361

Optical alignment equipment and methods for visible and IR imaging meteorological radiometer  

NASA Technical Reports Server (NTRS)

This paper describes the test equipment required for precise IR and visible channel microradian alignments for geosynchronous orbiting meteorological instruments. The test equipment design criteria, design, function and use are explained in detail. Wave front error measurements, vibration isolation, thermal compensation and stress free mounting configurations are described.

Herendeen, R.; Kreigh, N.; Wetzel, J.

1989-01-01

362

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

SciTech Connect

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

Pardini, A.F., Westinghouse Hanford

1996-07-16

363

Tumor margin detection using optical biopsy techniques  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

364

Optical beam forming techniques for phased array antennas  

NASA Technical Reports Server (NTRS)

Conventional phased array antennas using waveguide or coax for signal distribution are impractical for large scale implementation on satellites or spacecraft because they exhibit prohibitively large system size, heavy weight, high attenuation loss, limited bandwidth, sensitivity to electromagnetic interference (EMI) temperature drifts and phase instability. However, optical beam forming systems are smaller, lighter, and more flexible. Three optical beam forming techniques are identified as applicable to large spaceborne phased array antennas. They are (1) the optical fiber replacement of conventional RF phased array distribution and control components, (2) spatial beam forming, and (3) optical beam splitting with integrated quasi-optical components. The optical fiber replacement and the spatial beam forming approaches were pursued by many organizations. Two new optical beam forming architectures are presented. Both architectures involve monolithic integration of the antenna radiating elements with quasi-optical grid detector arrays. The advantages of the grid detector array in the optical process are the higher power handling capability and the dynamic range. One architecture involves a modified version of the original spatial beam forming approach. The basic difference is the spatial light modulator (SLM) device for controlling the aperture field distribution. The original liquid crystal light valve SLM is replaced by an optical shuffling SLM, which was demonstrated for the 'smart pixel' technology. The advantages are the capability of generating the agile beams of a phased array antenna and to provide simultaneous transmit and receive functions. The second architecture considered is the optical beam splitting approach. This architecture involves an alternative amplitude control for each antenna element with an optical beam power divider comprised of mirrors and beam splitters. It also implements the quasi-optical grid phase shifter for phase control and grid amplifier for RF power. The advantages are no SLM is required for this approach, and the complete antenna system is capable of full monolithic integration.

Wu, Te-Kao; Chandler, C.

1993-01-01

365

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

366

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

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

367

Optical techniques for time and frequency transfer  

NASA Technical Reports Server (NTRS)

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.

Baumont, Francoise; Gaignebet, Jean

1994-01-01

368

Simple technique for optical flow estimation  

NASA Technical Reports Server (NTRS)

The theoretical principles, design, and implementation of an image-motion detection system with possible robotics and autonomous-navigation applications are discussed. The operation of a simple one-dimensional second-derivative edge-motion detector is explained; its extension to a two-dimensional motion sensor based on the Laplacian of a Gaussian (Marr and Hildreth, 1980) is outlined; a center-surround array of 13 of these sensors (12 in a circle around a central sensor) is proposed; and processing techniques to overcome the aperture problem are examined. Simple video images involving unidirectional motion are then analyzed using a prototype version of this design; the sensors employed are based on a 15 x 15-pixel mask made up of 13 7 x 7-pixel kernels. Accurate measurements of image velocity are obtained, as required for navigation through complex environments. It is pointed out that the procedure is noniterative and well suited to implementation as a parallel network.

Perrone, John A.

1990-01-01

369

Evaluation of Protein Immobilisation Techniques on Optical Fibre Tirf Sensor  

NASA Astrophysics Data System (ADS)

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

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

2000-12-01

370

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

371

Optical analysis of AlGaInP laser diodes with real refractive index guided self-aligned structure  

NASA Astrophysics Data System (ADS)

Optical modes of AlGaInP laser diodes with real refractive index guided self-aligned (RISA) structure were analyzed theoretically on the basis of two-dimension semivectorial finite-difference methods (SV-FDMs) and the computed simulation results were presented. The eigenvalue and eigenfunction of this two-dimension waveguide were obtained and the dependence of the confinement factor and beam divergence angles in the direction of parallel and perpendicular to the pn junction on the structure parameters such as the number of quantum wells, the Al composition of the cladding layers, the ridge width, the waveguide thickness and the residual thickness of the upper P-cladding layer were investigated. The results can provide optimized structure parameters and help us design and fabricate high performance AlGaInP laser diodes with a low beam aspect ratio required for optical storage applications.

Xu, Yun; Zhu, Xiaopeng; Ye, Xiaojun; Kang, Xiangning; Cao, Qing; Guo, Liang; Chen, Lianghui

2004-05-01

372

Neurovascular coupling: in vivo optical techniques for functional brain imaging  

PubMed Central

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.

2013-01-01

373

Optical measurement techniques applied to solar selective coatings  

Microsoft Academic Search

Optical measurement techniques have been developed for determining the solar absorptance, ..cap alpha..\\/sub s\\/, and emittance, epsilon, of solar coatings. The optical equipment includes a Beckman DK-2 Spectroreflectometer and a Gier Dunkle Solar Reflectometer (Model MS-251) for ..cap alpha..\\/sub s\\/ measurements and a Gier Dunkle Infrared Reflectometer (Model DB-100) for epsilon measurements. Because all this equipment is designed to accommodate

Pettit

1977-01-01

374

Thermal-vacuum testing and in-situ optical alignment measurements of the HALOE telescope/sun sensor assembly  

NASA Technical Reports Server (NTRS)

Design features, test data and projected performance levels of the telescope/sun sensor assembly for the Halogen Occultation Experiment (HALOE) on board the Upper Atmosphere Research Satellite are described. HALOE will gather data on stratospheric chemical species with an IR telescope pointed through the atmosphere at the sun during occultation periods. The pointing accuracy will need to be 1 arcmin elevation and 1.6 arcmin azimuthal. Adjustments of the gimbaled instrument are guided by a sun sensor and its associated electronics. The components were subjected to thermal-vacuum, optical boresight stability tests and the data generated were compared with a finite element model of the telescope and sun sensor. The tests consisted of exposure to various thermal gradients while the telescope and sun sensor alignments were tracked by optical deflectometry. The thermal behavior was compared with predictions made with a finite difference model. Alignments were within tolerable ranges and the thermal behavior model was concluded valid for predicting the thermal behavior of orbiting instruments.

Foss, R. A.; Smith, D. M.; Faison, R. W.; Spiers, R. B.

1985-01-01

375

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

PubMed

Aligned ZnO nanorods were grown on ZnO/Si substrate via simple aqueous solution process at low-temperature of - 65 degrees C by using zinc nitrate and hexamethylenetetramine (HMTA). The detailed morphological and structural properties measured by FESEM, XRD, EDS and TEM confirmed that the as-grown nanorods are vertically aligned, well-crystalline possessing wurtzite hexagonal phase and grown along the [0001] direction. The room-temperature photoluminescence spectrum of the grown nanorods exhibited a strong and broad green emission and small ultraviolet emission. The as-prepared ZnO nanorods were post-annealed in nitrogen (N2) and oxygen (O2) environments and further characterized in terms of their morphological, structural and optical properties. After annealing the nanorods exhibit well-crystallinity and wurtzite hexagonal phase. Moreover, by annealing the PL spectra show the enhancement in the UV emission and suppression in the green emission. The presented results demonstrate that simply by post-annealing process, the optical properties of ZnO nanostructures can be controlled. PMID:24738429

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

2014-06-01

376

Synthesis and optical properties of well-aligned ZnS nanowires on Si substrate  

NASA Astrophysics Data System (ADS)

An organic-assistant chemical vapor transport and condensation method is introduced to synthesize well-aligned ZnS nanowires. By means of decomposition of organics, a risen flow is generated that drives the ZnS nanowires growth direction upwards. From SEM images, the diameters of nanowires are uniform and nanowires are well-aligned and vertical to the surface of the silicon substrate. XRD pattern, TEM image and SAED suggest that the structure of ZnS nanowires is hexagonal and single crystalline. The growth orientation of nanowires is toward <0 0 2>. In RAMAN spectrum, the E1 (LO) mode resulting from the lateral morphology of ZnS nanowires is also observed in our sample. It restricts the phonon propagation direction to parallel the c-axis. A blue-light emission band is revealed in the PL spectrum which can be attributed to vacancies and surface states.

Lu, Hao-Ying; Chu, Sheng-Yuan; Chang, Chi-Chian

2005-06-01

377

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

NASA Astrophysics Data System (ADS)

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.

Jin, Yuanhao; Li, Qunqing; Li, Guanhong; Chen, Mo; Liu, Junku; Zou, Yuan; Jiang, Kaili; Fan, Shoushan

2014-01-01

378

Physical optics of the laser-schlieren shock tube technique  

SciTech Connect

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

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

1981-01-15

379

Effective Medium Theory of the Optical Properties of Aligned Carbon Nanotubes  

Microsoft Academic Search

We present an effective medium theory in order to analyze the reported\\u000aoptical properties of aligned carbon nanotube films (W.A. de Heer et al.,\\u000aScience 268, 845 (1995)). This methodology is based on photonic band structure\\u000acalculations and allows treatment of complex media consisting of particles\\u000athat interact strongly. We also develop a simple Maxwell-Garnett type approach\\u000afor studying this

F. J. Garc ´ õa-Vidal; J. M. Pitarke

1997-01-01

380

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

NASA Astrophysics Data System (ADS)

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.

Owkes, Jeanmarie Kathleen

381

Optical phase imaging using a synthetic aperture phase retrieval technique.  

PubMed

Optical phase imaging enables visualization of transparent samples, numerical refocusing, and other computational processing. Typically phase is measured quantitatively using interferometric techniques such as digital holography. Researchers have demonstrated image enhancement by synthetic aperture imaging based on digital holography. In this work we introduce a novel imaging technique that implements synthetic aperture imaging using phase retrieval, a non-interferometric technique. Unlike digital holography, phase retrieval obviates the need for a reference arm and provides a more compact, less expensive, and more stable experimental setup. We call this technique synthetic aperture phase retrieval. PMID:24787826

Lee, Dennis J; Weiner, Andrew M

2014-04-21

382

An optically controlled microwave phase stabilizer based on polarization interference technique using semiconductor optical amplifier  

NASA Astrophysics Data System (ADS)

We introduce an optically controlled microwave phase stabilizer based on polarization interference technique using single semiconductor optical amplifier (SOA). A prototype with a frequency of 10 GHz is experimentally demonstrated. It provides a stable phase drift that can be linearly compensated over 10 km single-mode fiber by controlling the SOA injection current.

Chen, Han; Sun, Mingming; Sun, Xiaohan

2014-03-01

383

High speed EUV using post processing and self-aligned double patterning as a speed enhancement technique  

NASA Astrophysics Data System (ADS)

EUV is an ongoing industry challenge to adopt due to its current throughput limitations. The approach to improve throughput has primarily been through a significant focus on source power which has been a continuing challenge for the industry. The subject of this paper is to review and investigate the application of SADP (Self aligned double patterning) as a speed enhancing technique for EUV processing. A process with the potential of running a 16 nm self-aligned final etched pattern in less than 10mJ exposure range is proposed. Many of the current challenges with shot noise and resolution change significantly when SADP is used in conjunction with EUV. In particular, the resolution challenge for a 16nm HP final pattern type image changes to 32nm as an initial pattern requirement for the patterned CD. With this larger CD starting point, the burden of shot noise changes significantly and the ability for higher speed resist formulations to be used is enabled. Further resist candidates that may have not met the resolution requirements for EUV can also be evaluated. This implies a completely different operational set-point for EUV resist chemistry where the relaxation of both LER and CD together combined, give the resist formulation space a new target when EUV is used as a SADP tool. Post processing mitigation of LWR is needed to attain the performance of the final 16nm half pitch target pattern to align with the industry needs. If the original process flow at an 85W projected source power would run in the 50WPH range, then the flow proposed here would run in the <120WPH range. Although it is a double patterning technology, the proposed process still only requires a single pass through the EUV tool, This speed benefit can be used to offset the added costs associated with the double patterning process. This flow can then be shown to be an enabling approach for many EUV applications.

Wandell, Jerome; deVilliers, Anton; Huli, Lior; Biesemans, Serge; Nafus, Kathleen; Carcasi, Mike; Smith, Jeff; Hetzer, Dave; Higgins, Craig; Rastogi, Vinayak; Verduijn, Erik

2014-04-01

384

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

PubMed

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

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

2014-01-01

385

Using the x-ray region of the electromagnetic spectrum for alignment. Overview, geometric optics and design considerations.  

National Technical Information Service (NTIS)

Traditional alignment systems based on the use of visible light are not practical when opaque materials obstruct the alignment axis. X-ray Alignment Systems (XRA) have been designed specifically to overcome this limitation. XRA systems are analogous to vi...

R. B. Addis

1990-01-01

386

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)  

NASA Astrophysics Data System (ADS)

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 ISIM level using an element in the MIRI Filter Wheel, the pupil alignment reference (PAR), developed by NASA GSFC and provided to MIRI. It is a ~2.3g aluminum piece that has a flat, specularly reflective, 3mm diameter surface in its center, with laser-etched fiducials within its aperture. The PAR is illuminated via an optical stimulus (ground support equipment) and imaged using a pupil imaging camera, during the ISIM test program in order to determine absolute and relative changes in the alignment that impact pupil shear and roll. Here we describe the MIRI PAR; its physical properties and challenges during its design, manufacturing, and testing.

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

2009-08-01

387

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

NASA Technical Reports Server (NTRS)

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.

Lee, George

1992-01-01

388

Active particle control through silicon using conventional optical trapping techniques.  

PubMed

Functional integration of optical trapping techniques with silicon surfaces and environments can be realized with minimal modification of conventional optical trapping instruments offering a method to manipulate, track and position cells or non-biological particles over silicon substrates. This technique supports control and measurement advances including the optical control of silicon-based microfluidic devices and precision single molecule measurement of biological interactions at the semiconductor interface. Using a trapping laser in the near infra-red and a reflective imaging arrangement enables object control and measurement capabilities comparable to trapping through a classical glass substrate. The transmission efficiency of the silicon substrate affords the only reduction in trap stiffness. We implement conventional trap calibration, positioning, and object tracking over silicon surfaces. We demonstrate control of multiple objects including cells and complex non-spherical objects on silicon wafers and fabricated surfaces. PMID:18030409

Appleyard, David C; Lang, Matthew J

2007-12-01

389

Efficient Molecular Imaging Techniques Using Optically Active Molecules  

Microsoft Academic Search

Efficient imaging techniques aimed at the increasing of the image contrast of a structure, surrounded by a scattering medium, using optically active and high index of refraction molecules as molecular contrast agents, are presented. Specifically, an enhanced degree of linear polarization (DOLP) target detection and imaging is obtained by doping the surrounding medium with molecular contrast agents consisting of aqueous

George C. Giakos; S. Atreya Paturi; Keerthisrivatsav Valluru; P. Bathini; V. Adya; Srinivas Sukumar; K. Ambadipudi; B. Mandadi; M. Becker; S. Athawale; P. Farajipour; S. Marotta; D. Sheffer; G. Livanos; M. Zervakis

2010-01-01

390

Feasibility of Techniques for a Doppler Optical Navigator.  

National Technical Information Service (NTIS)

The objective of this program was to determine the feasibility of novel laser techniques for Doppler optical navigation. The ultimate performance goal is the measurement of ground speed of a satellite, traveling at a velocity of 10,000 meters per second a...

W. J. Hannan L. J. Nicastro T. E. Penn J. Vollmer

1964-01-01

391

Computational modeling techniques in charged-particle optics  

Microsoft Academic Search

In this paper, some of the key techniques used in the computer modelling of charged particle optical systems are reviewed and illustrated. The topics covered include: Magnetic electron lens design using the finite element method; electrostatic lens design by finite element and finite difference methods; analysis of matrix lenses and multipole lenses, using a fully three- dimensional (3D) finite difference

Eric Munro

1993-01-01

392

Novel optical techniques for remote water column temperature measurement  

NASA Astrophysics Data System (ADS)

This paper assesses novel optical techniques for the remote mastermind of water column temperatures, using non-linear effects such as stimulated Raman scattering. Results are presented from a modeling program to predict water flow patterns produced by an underwater heat source.

Cresswell, Brian; Hodgson, Elizabeth M.; Wakefield, Clare

1997-04-01

393

Novel optical techniques for remote water column temperature measurement  

Microsoft Academic Search

This paper assesses novel optical techniques for the remote mastermind of water column temperatures, using non-linear effects such as stimulated Raman scattering. Results are presented from a modeling program to predict water flow patterns produced by an underwater heat source. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text

Brian Cresswell; Elizabeth M. Hodgson; Clare Wakefield

1997-01-01

394

Optical computing techniques for radar and sonar signal processing  

Microsoft Academic Search

New applications of the use of coherent optical processing techniques, especially matched spatial filtering and input format control, in radar and sonar signal processing are reviewed. Emphasis is given to specific problems such as long coded waveforms of thousands of bits, processing of coded phased array and pulse burst radar waveforms, generation of the ambiguity function for use in radar

D. Casasent

1977-01-01

395

Optical Holography: Principles, Techniques and Applications (2nd edn)  

Microsoft Academic Search

The first edition of the book was published in 1983. One of the stated purposes of the new edition is to add new material which includes two new chapters on holographic optical elements and advanced techniques in interferometry. Also, an attempt is made to make the book self-contained. The book may be a good illustration that the field of holography

James D Trolinger

1997-01-01

396

Path Radiance Technique for Retrieving Aerosol Optical Thickness over Land  

NASA Technical Reports Server (NTRS)

The key issue in retrieving aerosol optical thickness over land from short-wave satellite radiances is to identify and separate the signal due to scattering by a largely transparent aerosol layer from the noise due to reflection by the background surface, where the signal is relatively uniform compared to the highly inhomogeneous surface contribution. Sensitivity studies in aerosol optical thickness retrievals reveal that the apparent reflectance at the top of the atmosphere is very susceptible to the surface reflectance, especially when aerosol optical thickness is small. Uncertainties associated with surface reflectance estimation can greatly amplify the error of the aerosol optical thickness retrieval. To reduce these uncertainties, we have developed a "path radiance" method to retrieve aerosol optical thickness over land by extending the traditional technique that uses the "dark object" approach to extract the aerosol signal. This method uses the signature of the correlation of visible and mid-IR reflectance at the surface, and couples the correlation with the atmospheric effect. We have applied this method to a Landsat TM (Thematic Mapper) image acquired over the Oklahoma Southern Great Plains (SGP) site of DoE's ARM (Department of Energy's Atmospheric Radiation Measurement) program on September 27, 1997, a very clear day (aerosol optical thickness of 0.07 at 0.5 pm) during the first Landsat IOP (Intensive Observation Period). The retrieved mean aerosol optical thickness for TM band 1 at 0.49 pm and band 3 at 0.66 pm agree very well with the ground-based sun-photometer measurements at the ARM site. The ability to retrieve small aerosol optical thickness makes this path radiance technique promising. More importantly, the path radiance is relatively insensitive to surface inhomogeneity. The retrieved mean path radiances in reflectance units have very small standard deviations for both TM blue and red bands. This small variability of path radiance further supports the current aerosol retrieval method.

Tsay, S.-C.; Wen, G.; Cahalan, R. F.; Oreopoulos, L.

1999-01-01

397

Path Radiance Technique for Retrieving Aerosol Optical Thickness Over Land  

NASA Technical Reports Server (NTRS)

The key issue in retrieving aerosol optical thickness over land from shortwave satellite radiances is to identify and separate the signal due to scattering by a largely transparent aerosol layer from the noise due to reflection by the background surface, where the signal is relatively uniform compared to the highly inhomogeneous surface contribution. Sensitivity studies in aerosol optical thickness retrievals reveal that the apparent reflectance at the top of the atmosphere is very susceptible to the surface reflectance, especially when aerosol optical thickness is small. Uncertainties associated with surface reflectance estimation can greatly amplify the error of the aerosol optical thickness retrieval. To reduce these uncertainties, we have developed a "path radiance" method to retrieve aerosol optical thickness over land by extending the traditional technique that uses the "dark object" approach to extract the aerosol signal. This method uses the signature of the correlation of visible and mid-IR reflectance at the surface, and couples the correlation with the atmospheric effect. We have applied this method to a Landsat TM (Thematic Mapper) image acquired over the Oklahoma Southern Great Plains (SGP) site of DoE's ARM (Department of Energy's Atmospheric Radiation Measurement) program on September 27,1997, a very clear day (aerosol optical thickness of 0.07 at 0.5 microns) during the first Landsat Intensive Observation Period (IOP). The retrieved mean aerosol optical thickness for TM band 1 at 0.49 micron and band 3 at 0.66 micron agree very well with the ground-based sun-photometer measurements at the ARM site. The ability to retrieve small aerosol optical thickness makes this path radiance technique promising. More importantly, the path radiance is relatively insensitive to surface inhomogeneity. The retrieved mean path radiances in reflectance units have very small standard deviations for both TM blue and red bands. This small variability of path radiance further supports the current aerosol retrieval method.

Tsay, S.-C.; Wen, G.; Cahalan, R. F.; Oreopoulos, L.

1999-01-01

398

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

SciTech Connect

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.

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

399

Constellation-X Soft X-Ray Telescope Segmented Optic Assembly and Alignment Implementation  

Microsoft Academic Search

The Constellation-X mission will perform X-Ray science with improvements in resolution and effective area over its predecessor missions. The primary instrument on the Constellation-X spacecraft is the Soft X-Ray Telescope (SXT). The SXT is a 1.6m diameter grazing incidence mirror assembly comprised of approximately 4000 optic elements. In order for the optic elements to work together to achieve the required

Jason H. Hair; Jeffery Stewart; Robert Petre; William W. Zhang; Timo T. Saha; William A. Podgorski; Paul Glenn; Mark L. Schattenburg; Ralf Heilmann

400

A Probabilistic Analysis of False Positives in Optical Map Alignment and Validation 1  

Microsoft Academic Search

In the recent years, genome-wide shot-gun optical mapping of several microorganisms (Lai99, Lin99) have led to sequence-ready high-resolution restriction maps that directly fa- cilitated sequence assembly avoiding gaps and compressions or validated shotgun sequence assembly (AMS99). The simplicity and scalability of shot-gun optical mapping suggests obvious extensions to bigger and more complex genomes, and in fact, its applications to human

Thomas Anantharaman

2001-01-01

401

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

Microsoft Academic Search

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

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

2000-01-01

402

Self-assembled micro-XYZ stages for optical scanning and alignment  

Microsoft Academic Search

Summary form only given. In summary, a fully actuated micro-XYZ stage with bi-directional scratch drive actuator array has been demonstrated for the first time. This fabrication process of this micro-XYZ is fully compatible with the free-space micro-optical bench technology. This allows high performance free-space optical systems to be monolithically integrated on a chip

Li Fan; Shi-Sheng Lee; Ming C. Wu

1997-01-01

403

Spatial Heterodyning Optical Code Division Multiple Access Technique for Near-Field Free-Space Optical Communication Systems  

Microsoft Academic Search

We present a novel optical code division multiple access (OCDMA) scheme based on spatial optical heterodyning for free-space optical communication systems. In this technique, in particular, the decoding process is established by means of a spatial optical heterodyne receiver. The spatial heterodyning OCDMA introduced can be considered to be in the class of spread-space techniques, which implies that there is

Ali Salehiomran; Jawad A. Salehi

2009-01-01

404

Optical measurement techniques for high Reynolds number train investigations  

NASA Astrophysics Data System (ADS)

This article reports on experimental aerodynamic investigations on a generic high-speed train configuration performed within two different wind tunnels. Both wind tunnels are specialized facilities for high Reynolds number investigations and offer low turbulence levels. The wind tunnels are the cryogenic wind tunnel located in Cologne (KKK) and in the high-pressure wind tunnel located in Göttingen (HDG). Both facilities are part of the German Dutch wind tunnel association (DNW). The adaptation and application of three optical measurement techniques for such high Reynolds number investigations is described in the article. The optical methods are: Particle Image Velocimetry for the measurement of velocity fields, Background Oriented Schlieren technique for density gradient measurements, and a white light Digital Speckle Photography technique for model deformation monitoring.

Loose, S.; Richard, H.; Bosbach, J.; Thimm, M.; Becker, W.; Raffel, M.

2006-04-01

405

Electro-optic techniques in electron beam diagnostics  

SciTech Connect

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

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

2011-06-17

406

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

NASA Technical Reports Server (NTRS)

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

Nguyen, Hung D.

1999-01-01

407

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

PubMed

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

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

2012-08-01

408

Substantial progress in optical monitoring by intermittent measurement technique  

NASA Astrophysics Data System (ADS)

The production capabilities for optical multilayer coatings were improved significantly in the last decade. So called "shift free" coatings have become a standard in the coating production. Direct optical monitoring plays a key role to improve the layer thickness accuracy and takes advantage of error compensation effects. For the production of DWDM filters direct monitoring was introduced in the last decade. Continuous measurement is applied on relatively small substrate areas. (Ø < 200 mm). The paper reports substantial progress which has been achieved for coating systems with large area substrate holders (up to Ø 1050 mm). The stationary light spot of a single wavelength optical monitor is far out of centre of the rotating substrate holder. Intermittent monitoring on a substrate or a witness is applied. This technique enables rapid prototyping with tight specifications and high yields in large area batch coaters. Application results of challenging optical multilayer systems are demonstrating clearly the potential of this powerful monitoring technique. The monitoring capability was investigated for a lot of different layer systems such as dielectric mirrors, anti-reflection coatings, sophisticated edge filters, polarizer coatings, beam splitters and multiple cavity band-pass filters. Strong coincidence of theory with experiment was achieved with PIAD and magnetron sputtering. Reproducibility experiments have clearly shown the benefits of this monitoring technique.

Zoeller, A.; Boos, M.; Goetzelmann, R.; Hagedorn, H.; Klug, W.

2005-09-01

409

Path Radiance Techniques for Retrieving Aerosol Optical Thickness over Land  

NASA Technical Reports Server (NTRS)

The key issue in retrieving aerosol optical thickness over land from shortwave satellite radiances is to identify and separate the signal due to scattering by a largely transparent aerosol layer from the noise due to reflection by the background surface, where the signal is relatively uniform compared to the highly inhomogeneous surface contribution. Sensitivity studies in aerosol optical thickness retrievals reveal that the apparent reflectance at the top of the atmosphere is very susceptible to the surface reflectance, especially when aerosol optical thickness is small. Uncertainties associated with surface reflectance estimation can greatly amplify the error of the aerosol optical thickness retrieval. To reduce these uncertainties, we have developed a "path radiance" method to retrieve aerosol optical thickness over land by extending the traditional technique that uses the "dark object" approach to extract the aerosol signal. This method uses the signature of the correlation of visible and mid-IR reflectance at the surface, and couples the correlation with the atmospheric effect. We have applied this method to a TM (Landsat Thematic Mapper) image acquired over the Oklahoma Southern Great Plains (SGP) site of DoE's ARM (Atmospheric Radiation Measurement) program on September 27, 1997, a very clear day during the first Landsat IOP (Intensive Observation Period). The retrieved mean aerosol optical thickness for TM band 1 at 0.49 micrometers and band 3 at 0.66 micrometers agree very well with the ground-based sun-photometer measurements at the ARM site. The ability to retrieve small aerosol optical thickness (such as 0.07 at 0.5 micrometers as in the example considered here) makes this path radiance technique promising. More importantly, the path radiance is relatively insensitive to surface inhomogeneity. The retrieved mean path radiances in reflectance units have very small standard deviations for both TM blue and red bands. This small variability of path radiance further supports the current aerosol retrieval method.

Wen, Guoyong; Tsay, Si-Chee; Cahalan, Robert F.; Oreopoulos, Lazaros

1999-01-01

410

Evaluation of limb alignment, component positioning, and function in primary total knee arthroplasty using a pinless navigation technique compared with conventional methods.  

PubMed

The purpose of this study was to examine component positioning, limb alignment, and the early functional range of motion of a pinless image-free computer-assisted navigation system, and compare it to conventional intramedullary component alignment methods. A total of 72 patients underwent cemented total knee arthroplasty. The pinless navigation group consisted of 40 knees in 39 patients, while the conventional group comprised 33 knees in 33 patients. Preoperative and postoperative radiographs were evaluated for coronal and sagittal alignment. Functional assessment was evaluated by early postoperative range of motion. There was no statistical significance when examining individual component alignment or early functional range of motion. When evaluating ability to achieve overall anatomic tibiofemoral alignment within a range of 4 to 7 degrees valgus, the conventional group was able to accomplish this 39% of the time, whereas the pinless navigation group succeeded in 65% of cases (p < 0.03). The tourniquet time was mean 59.5 minutes (range: 48 to 77 minutes) for the conventional group, compared with mean 71.9 minutes (range: 54 to 97 minutes) for the navigation group (p < 0.0001, 95% CI). The pinless navigation technique improved coronal anatomic alignment without complications that have been cited with use of femoral or tibial reference tracker pins or intramedullary alignment guides. PMID:23288760

Keyes, Brian J; Markel, David C; Meneghini, Robert Michael

2013-04-01

411

Broadband, polarization-sensitive photodetector based on optically-thick films of macroscopically long, dense, and aligned carbon nanotubes.  

PubMed

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

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

2013-01-01

412

Optical and digital microscopic imaging techniques and applications in pathology  

PubMed Central

The conventional optical microscope has been the primary tool in assisting pathological examinations. The modern digital pathology combines the power of microscopy, electronic detection, and computerized analysis. It enables cellular-, molecular-, and genetic-imaging at high efficiency and accuracy to facilitate clinical screening and diagnosis. This paper first reviews the fundamental concepts of microscopic imaging and introduces the technical features and associated clinical applications of optical microscopes, electron microscopes, scanning tunnel microscopes, and fluorescence microscopes. The interface of microscopy with digital image acquisition methods is discussed. The recent developments and future perspectives of contemporary microscopic imaging techniques such as three-dimensional and in vivo imaging are analyzed for their clinical potentials.

Chen, Xiaodong; Zheng, Bin; Liu, Hong

2012-01-01

413

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)

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.

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

2012-01-01

414

A rheo-optical apparatus for real time kinetic studies on shear-induced alignment of self-assembled soft matter with small sample volumes  

NASA Astrophysics Data System (ADS)

In soft materials, self-assembled nanoscale structures can allow new functionalities but a general problem is to align such local structures aiming at monodomain overall order. In order to achieve shear alignment in a controlled manner, a novel type of rheo-optical apparatus has here been developed that allows small sample volumes and in situ monitoring of the alignment process during the shear. Both the amplitude and orientation angles of low level linear birefringence and dichroism are measured while the sample is subjected to large amplitude oscillatory shear flow. The apparatus is based on a commercial rheometer where we have constructed a flow cell that consists of two quartz teeth. The lower tooth can be set in oscillatory motion whereas the upper one is connected to the force transducers of the rheometer. A custom made cylindrical oven allows the operation of the flow cell at elevated temperatures up to 200 °C. Only a small sample volume is needed (from 9 to 25 mm3), which makes the apparatus suitable especially for studying new materials which are usually obtainable only in small quantities. Using this apparatus the flow alignment kinetics of a lamellar polystyrene-b-polyisoprene diblock copolymer is studied during shear under two different conditions which lead to parallel and perpendicular alignment of the lamellae. The open device geometry allows even combined optical/x-ray in situ characterization of the alignment process by combining small-angle x-ray scattering using concepts shown by Polushkin et al. [Macromolecules 36, 1421 (2003)].

Laiho, Ari; Ikkala, Olli

2007-01-01

415

Optical properties of aligned carbon nanotube systems studied by the effective-medium approximation method  

Microsoft Academic Search

Using the effective-medium approximation (EMA), which is valid for densely and randomly distributed particle composites, we have investigated optical properties of a dense carbon nanotube system, in which the nanotubes are parallel in orientation but random in position. The morphologies of both the Maxwell-Garnett theory (MGT) and the array model are not consistent with the dense and random character of

Wengang Lü; Jinming Dong; Zhen-Ya Li

2001-01-01

416

Optical properties of silicon-silicon dioxide interfaces by linear and nonlinear optical techniques  

Microsoft Academic Search

The objective of this research is to understand the physics of (001)Si-SiO 2 interfaces by noninvasive, nondestructive optical techniques, that is, linear reflectance difference spectroscopy (RDS) and nonlinear second harmonic generation (SHG). The approach is to apply RDS and SHG to study optical anisotropy and interfacial bonding properties at the vicinal (001)Si-SiO 2 interfaces respectively. Miscutting (001)Si samples introduces atomic

Jih-Fu Trevor Wang

2002-01-01

417

Probing Molecular Dynamics with Non-linear Optical Techniques  

NASA Astrophysics Data System (ADS)

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.

Lausten, Rune

418

Optical fiber technique for in-reactor mechanical properties measurement  

SciTech Connect

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.

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

419

Optical fiber modulation techniques for single mode fiber sensors  

Microsoft Academic Search

\\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

R. P. Tatam

420

Intracoronary optical coherence tomography, basic theory and image acquisition techniques  

PubMed Central

Optical coherence tomography (OCT) imaging is showing great potential as an alternative or complementary tool to intravascular ultrasound (IVUS) for aiding in stent procedures and future diagnosis/treatment of atherosclerosis. Here, we describe the basic theory behind OCT imaging and explain important parameters such as axial resolution, lateral resolution and sensitivity. Also, we describe several image acquisition techniques that have been adopted for OCT imaging.

Prati, F.; Jenkins, M. W.; Di Giorgio, A.; Rollins, A. M.

2013-01-01

421

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

Microsoft Academic Search

The purpose of this paper is to investigate an integrated X\\/Y motion system, compatible with silicon process that will allow the positioning of micro-optical devices. The basic actuator, used for this system is referred as scratch drive actuator (SDA). SDA is able to produce a 1-D displacement, so, by combining several SDA, multi-degree of freedom motion is obtained. First, the

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

1996-01-01

422

DOUBLE-LAMBDA SENSOR PROTOTYPE FOR OPTICAL ALIGNMENT IN INHOMOGENEOUS ENVIRONMENT  

Microsoft Academic Search

The last decade has been marked by an intensive development of the optical systems for a high-precision monitoring of the geometry of the large-scale detectors built and being constructed for the high-energy experiments. In these systems, the light\\/laser beams serve as reference frames for the measurement of the detector movements at a few microns accuracy. One can mention three-point RASNIK

Hrant Azizbekyan; Ara A. Grigoryan; Natella Grigoryan; Hrant Gulkanyan; Henrik Vardanyan

2004-01-01

423

Optical Microscopy Techniques to Inspect for Metallic Whiskers  

NASA Technical Reports Server (NTRS)

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

Brusse, Jay A.

2006-01-01

424

New room-temperature deposition technique for optical coatings  

NASA Astrophysics Data System (ADS)

We describe a new coating method `laminar flow coating' (LFC) technique developed to obtain highly reflective (HR) laser damage resistant sol-gel multidielectric coatings. Such coatings are used in high-power lasers for inertial confinement fusion experiments (ICF). This technique uses substrates in an upside-down position and a travelling wave of coating solution is laminary transported under the substrate surface with a tubular dispense unit. This creates a thin-film coating by the solvent evaporation. Satisfactory results have been obtained onto 20 cm square glass substrates regarding the optical performances, the thickness uniformity, the edge-effects and the laser damage resistance. This deposition technique combines the advantages of both classical techniques: the substrate non-exclusive geometry such as in dip- coating and the small solution consumption such as in spin-coating. The association of sol-gel colloidal suspensions and LFC coating process has been demonstrated as a promising way to produce cheap specific optical coatings.

Belleville, Phillippe F.; Floch, Herve G.

1993-06-01

425

Unified calibration technique and its applications in optical triangular profilometry.  

PubMed

A unified calibration technique based on ray tracing for optical triangular profilometry is presented. The proposed technique based on the inherent geometric relation between depth and a distorted signal is capable of speedy and accurate measurement without the determination of geometric parameters. The technique can also reduce calibration error caused by the lens distortion of the projector and the camera owing to the reasonable assumption that mapping in a small local area is a linear transformation and the coefficients of the linear transformation may be varied in different local areas. Three classical systems of triangular profilometry, spot inspection, a single-line system, and a projection-grating system, are discussed and demonstrated by experiment. PMID:18319957

Asundi, A; Wensen, Z

1999-06-01

426

Liquid sound speeds at pressure from the optical analyzer technique  

SciTech Connect

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

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

1993-08-01

427

Application of optical correlation techniques to particle imaging  

NASA Technical Reports Server (NTRS)

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

Wernet, Mark P.; Edwards, Robert V.

1988-01-01

428

Application of optical correlation techniques to particle imaging velocimetry  

NASA Technical Reports Server (NTRS)

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

Wernet, Mark P.; Edwards, Robert V.

1988-01-01

429

Visual attitude orientation and alignment system  

NASA Technical Reports Server (NTRS)

Active vehicle optical alignment aid and a passive vehicle three-dimensional alignment target ensure proper orientation and alignment plus control of the closure range and rate between two bodies, one in controlled motion and one at rest.

Beam, R. A.; Morris, D. B.

1967-01-01

430

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

Microsoft Academic Search

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

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

2008-01-01

431

New optical tomographic & topographic techniques for biomedical applications  

NASA Astrophysics Data System (ADS)

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

Buytaert, Jan

432

Development of Optical Diagnostic Techniques for Microgravity Materials Processing  

NASA Technical Reports Server (NTRS)

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

Cha, Soyoung Stephen

1999-01-01

433

Fiber optic diagnostic techniques applied to electrical discharge machining sparks  

NASA Astrophysics Data System (ADS)

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

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

2002-02-01

434

Effect of polymer viscosity on morphological and electro-optic properties of aligned polymer dispersed ferroelectric liquid crystal composite films  

Microsoft Academic Search

A room temperature ferroelectric liquid crystal mixture was dispersed in UV curable polymers of different viscosity in 30:70 wt\\/wt ratio. These polymer dispersed ferroelectric liquid crystal (PDFLC) composite films were prepared by polymerization induced phase separation technique. It was found that the polymer viscosity influences the droplet size and the electro-optic properties. The spontaneous polarization of PDFLC decreases with an

Praveen Malik; Jasjit K. Ahuja; K. K. Raina

2003-01-01

435

Simple technique for integrating compact silicon devices within optical fibers.  

PubMed

In this work, we present a simple fabrication process enabling the integration of a subwavelength amorphous silicon layer inside optical fibers by means of the arc discharge technique. To assess our method, we have fabricated a compact in-line Fabry-Perot interferometer consisting of a thin (<1???m) a-Si:H layer completely embedded within a standard single-mode optical fiber. The device exhibits low loss (1.3 dB) and high interference fringe visibility (~80%) both in reflection and transmission, due to the high refractive index contrast between silica and a-Si:H. A high linear temperature sensitivity up to 106??pm/°C is demonstrated in the range 120°C-400°C. The proposed interferometer is attractive for point monitoring applications as well as for ultrahigh-temperature sensing in harsh environments. PMID:24562226

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

2014-02-15

436

Optical Fiber Technique for Remote Stabilization of RF Phase  

NASA Astrophysics Data System (ADS)

We demonstrate an optical-fiber-based technique to deliver a radio-frequency reference phase to a remote location. Using a reflected portion of the RF amplitude-modulated optical signal from the remote location in a feedback loop, we show that the remote phase can be kept within ± 0.3° of the desired value, independent of temperature variations along a fiber length of 2 km or more. The instrument is designed to operate at 416 MHz, and works satisfactorily over a ± 10% RF bandwidth. In addition, an automatic phase ranging circuit allows the device to maintain phase stabilization over an infinite number of phase cycles. The system is presently being installed at the Molonglo Observatory Synthesis Telescope near Canberra, Australia.

Krug, Peter A.; Large, Michael I.; Davison, Ralph G.

1999-04-01

437

Optical multiple access techniques for on-board routing  

NASA Technical Reports Server (NTRS)

The purpose of this research contract was to design and analyze an optical multiple access system, based on Code Division Multiple Access (CDMA) techniques, for on board routing applications on a future communication satellite. The optical multiple access system was to effect the functions of a circuit switch under the control of an autonomous network controller and to serve eight (8) concurrent users at a point to point (port to port) data rate of 180 Mb/s. (At the start of this program, the bit error rate requirement (BER) was undefined, so it was treated as a design variable during the contract effort.) CDMA was selected over other multiple access techniques because it lends itself to bursty, asynchronous, concurrent communication and potentially can be implemented with off the shelf, reliable optical transceivers compatible with long term unattended operations. Temporal, temporal/spatial hybrids and single pulse per row (SPR, sometimes termed 'sonar matrices') matrix types of CDMA designs were considered. The design, analysis, and trade offs required by the statement of work selected a temporal/spatial CDMA scheme which has SPR properties as the preferred solution. This selected design can be implemented for feasibility demonstration with off the shelf components (which are identified in the bill of materials of the contract Final Report). The photonic network architecture of the selected design is based on M(8,4,4) matrix codes. The network requires eight multimode laser transmitters with laser pulses of 0.93 ns operating at 180 Mb/s and 9-13 dBm peak power, and 8 PIN diode receivers with sensitivity of -27 dBm for the 0.93 ns pulses. The wavelength is not critical, but 830 nm technology readily meets the requirements. The passive optical components of the photonic network are all multimode and off the shelf. Bit error rate (BER) computations, based on both electronic noise and intercode crosstalk, predict a raw BER of (10 exp -3) when all eight users are communicating concurrently. If better BER performance is required, then error correction codes (ECC) using near term electronic technology can be used. For example, the M(8,4,4) optical code together with Reed-Solomon (54,38,8) encoding provides a BER of better than (10 exp -11). The optical transceiver must then operate at 256 Mb/s with pulses of 0.65 ns because the 'bits' are now channel symbols.

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

1992-01-01

438

Inertial Navigation Systems: Prelaunch Alignment  

Microsoft Academic Search

A conventional inertial navigation system navigates by sensing components of the acceleration vector along three mutually perpendicular axes held stable after some initial alignment. This paper discusses the need for initial alignment, followed by a review of the effects of alignment errors on navigation in order to establish the order of accuracies desired. Several alignment techniques are described and compared

Richard H. Parvin

1962-01-01

439

Accelerating diffractive optics design with GPU-based parallel technique  

NASA Astrophysics Data System (ADS)

In this paper GPU based data parallel technique is used to reduce calculating time in diffractive optics elements (DOE) design. By using compute unified device architecture (CUDA) framework, comparison of acceleration radio of some major methods using in DOE design, including Gerchberg Saxton algorithm for global optimization in conjunction with Rayleigh-Sommerfeld diffractive integrating transformation, genetic algorithm with a finite-difference time-domain method and simulated annealing algorithm, is made with demonstrational DOE-lens design, whose focal spot size is 0.5 ?m, incident light wavelength is 650 nm, focal length is 3mm, DOE aperture size is 2mm.

Liu, Kan; Li, Hui; Zhang, Xinyu; Li, Dehua; Wei, Mingyue; Li, Bin; Xie, Changsheng; Zhang, Tianxu

2010-08-01

440

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

NASA Astrophysics Data System (ADS)

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 ap