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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

Innovative optical alignment technique for CMP wafers  

Microsoft Academic Search

Detecting position of the wafers such as after CMP process is critical theme of current and forthcoming IC manufacturing. The alignment system must be with high accuracy for any process. To satisfy such requirements, we have studied and analyzed factors that have made alignment difficult. From the result of the studies, we have developed new optical alignment techniques which improve

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

2002-01-01

3

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

4

A technique for aligning sextupole systems using beam optics  

SciTech Connect

A technique for beam based alignment of sextupole system is developed exploiting the enhancement effect of orbit differences by the sextupoles. This technique can in principle be applied to sextupole or sextupole strings with controlled orbit pattern and BPM configurations. This paper will discuss the theoretical basis, special optimization considerations and expected accuracy. Application to the SLC final focus is also discussed.

Chao, Yu-Chiu

1992-03-01

5

Alignment-free optical modules using solder-bump-bonding technique for free-space optical interconnections  

NASA Astrophysics Data System (ADS)

We propose alignment-free optical modules using a solder-bump-bonding technique for constructing free-space optical interconnection systems without a special alignment procedure. Bonding pads for mounting an optoelectronic device chip are fabricated by exposing a photosensitive resin film to light traveling through the optical system of the module so that the image positions of the bonding pads on both image planes of the optical interconnection system are aligned with each other. A device chip is mounted by solder-bump bonding and is set at a proper position by the surface tension of molten solder. The effectiveness of the technique is verified by constructing alignment-free optical modules.

Miyazaki, Daisuke; Ohno, Yuji; Matsushita, Kenji

2008-01-01

6

NICMOS Fine Optical Alignment  

NASA Astrophysics Data System (ADS)

# The purpose of this activity is to perform a series of iterative adjustments of the NICMOS pupil alignment mechanism to establish the optical alignment in focus for cameras all 3 cameras and tilt for camera 1. Specifically, this activity will use established focus monitoring techniques to accomplish the establishment {or reconfirmation} of PAM focus and X/Y tilt. Cameras 1, 2, and 3 will be calibrated in this program. #

Noll, Keith

2001-07-01

7

NICMOS Coarse Optical Alignment  

NASA Astrophysics Data System (ADS)

# The purpose of this activity is to perform a series of iterative adjustments of the NICMOS pupil alignment mechanism to establish the initial optical alignment in focus and tilt for all three cameras. This proposal has been broken down into 4 sub-proposals to make implementation easier. The four phases of the NICMOS Focus/Alignment activity are: # 1} Pre-Alignment Check-out {prop 7134} 2} Coarse Optical Alignment {Initial Focus Sweep} {prop 7041} 3} Intermediate Focus/Alignment {prop 7135} 4} Fine Optical Alignment {prop 7042} # This is proposal 7041; Coarse Optical Alignment ------------------------ Objectives: a} Establish PAM focus starting points for each camera b} Establish coarse pupil alignment vector {PAM X/Y tilt} c} Cover sufficient region of PAM focus space to insure the optimal locations are included d} Allow sufficient time {7-10 days} to analyze data and uplink changes before the next activity {7135}

Schneider, Glenn

1997-12-01

8

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

9

NICMOS Fine Optical Alignment  

NASA Astrophysics Data System (ADS)

# The purpose of this activity is to perform a series of iterative adjustments of the NICMOS pupil alignment mechanism to establish the initial optical alignment in focus and tilt for all three cameras. This proposal has been broken down into 4 sub-proposals to make implementation easier. The four phases of the NICMOS Focus/Alignment activity are: # 1} Pre-Alignment Check-out {prop 7134} 2} Coarse Optical Alignment {Initial Focus Sweep} {prop 7041} 3} Intermediate Focus/Alignment {prop 7135} 4} Fine Optical Alignment {prop 7042} # This is proposal 7042; Fine Optical Alignment -------------------------- Objectives: a} Establish PAM focus and X/Y tilt for each camera b} Check performance over various filters {filter parfocality check} #

Calzetti, Daniela

1997-12-01

10

Microgroove fabrication with excimer laser ablation techniques for optical fiber array alignment purposes  

NASA Astrophysics Data System (ADS)

Currently, an ever increasing need for bandwidth, compactness and efficiency characterizes the world of interconnect and data communication. This tendency has already led to serial links being gradually replaced by parallel optical interconnect solutions. However, as the maximum capacity for the latter will be reached in the near future, new approaches are required to meet demand. One possible option is to switch to 2D parallel implementations of fiber arrays. In this paper we present the fabrication of a 2D connector for coupling a 4x8 array of plastic optical fibers to RCLED or VCSEL arrays. The connector consists primarily of dedicated PMMA plates in which arrays of 8 precisely dimensioned grooves at a pitch of 250 micrometers are introduced. The trenches are each 127 micrometers deep and their width is optimized to allow fixation of plastic optical fibers. We used excimer laser ablation for prototype fabrication of these alignment microstructures. In a later stage, the plates can be replicated using standard molding techniques. The laser ablation technique is extremely well suited for rapid prototyping and proves to be a versatile process yielding high accuracy dimensioning and repeatability of features in a wide diversity of materials. The dependency of the performance in terms of quality of the trenches (bottom roughness) and wall angle on various parameters (wavelength, energy density, pulse frequency and substrate material) is discussed. The fabricated polymer sheets with grooves are used to hold optical fibers by means of a UV-curable adhesive. In a final phase, the plates are stacked and glued in order to realize the 2D-connector of plastic optical fibers for short distance optical interconnects.

Naessens, Kris; Van Hove, An; Coosemans, Thierry; Verstuyft, Steven; Vanwassenhove, Luc; Van Daele, Peter; Baets, Roel G.

2000-11-01

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

MUSE optical alignment procedure  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

13

Adaptive optical alignment in microgravity environments  

Microsoft Academic Search

Microgravity researchers use optical measurement techniques to study fluid samples undergoing crystallization, solidification, separation, mixing, and other processes. However, optical systems are often environmentally sensitive, and can be difficult to keep aligned in space. We have developed a system that autonomously maintains alignment with a software controller and electronic feedback loops that adjust optical components. The project goal was to

Robert B. Owen

1997-01-01

14

Fast DNA sequence alignment using optical computing  

SciTech Connect

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

Yee, M.L.; Craft, D.C. [Sandia National Labs., Albuquerque, NM (United States). Exploratory Image Processing Systems II Dept.

1996-11-01

15

Adaptive optical alignment in microgravity environments  

NASA Astrophysics Data System (ADS)

Microgravity researchers use optical measurement techniques to study fluid samples undergoing crystallization, solidification, separation, mixing, and other processes. However, optical systems are often environmentally sensitive, and can be difficult to keep aligned in space. We have developed a system that autonomously maintains alignment with a software controller and electronic feedback loops that adjust optical components. The project goal was to develop mechanisms to stabilize optical beams under vibrationally noisy microgravity conditions. We constructed a testbed Mach-Zehnder interferometer system with automated systems that compensate for alignment shifts. We tested the system on the NASA KC-135 low-gravity simulation aircraft. We developed electronics to monitor and buffer high frequency vibrations, as well as mechanical systems to damp vibration and software systems to recalibrate alignment. We delivered a prototype adaptive self-aligning optical system capable of performing interferometric measurements under vibrational conditions of microgravity on KC-135 and space shuttle flights. This included design, construction and testing of a useful optical testbed, mechanical damping systems, specialized monitoring, feedback and controller electronics, and software realignment tools. We found that these systems could maintain alignment more quickly and efficiently than originally expected. We plan to apply these techniques to phase-shifting interferometry tailored to protein crystal growth studies.

Owen, Robert B.

1997-01-01

16

NICMOS NIC3 Fine Optical Alignment  

NASA Astrophysics Data System (ADS)

The purpose of this activity is to perform a series of iterative adjustments of the NICMOS pupil alignment mechanism to establish the optical alignment in focus and tilt for camera 3. Specifically, this activity will use established focus monitoring techniques to accomplish the establishment {or reconfirmation} of PAM focus and X/Y tilt for each camera. Camera 3 will be calibrated in this program; cameras 1 and 2 will be done in a contemporaneous program.

Noll, Keith

2001-07-01

17

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

18

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

19

Optical analysis and alignment applications using the infrared Smartt interferometer  

NASA Astrophysics Data System (ADS)

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.

20

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

Microsoft Academic Search

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

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

1995-01-01

21

Application for surveying technology for the alignment of large optical systems  

NASA Astrophysics Data System (ADS)

Precise alignment of optical elements in large optical systems in difficult if many elements are positioned such that direct alignment or boresighting becomes impossible. A practical approach is to identify discrete optical path segments and align these using standard surveying or optical-tooling instrumentation. An alignment theory must be developed in which the alignment optical path duplicates or closely approximates the optical path of the operational device. The surveying instruments are then used to simulate the optical input beams to the system segments to be aligned. Auxiliary targets and reflectors are added, and the alignment procedure is augmented by standard optical test instrumentation and techniques. Examples are given using theodolies, transits, and levels with autocollimating capability and micrometer adaptors to perform boresighting and autocollimation techniques on segments of the optical train of the Antares Laser Fusion System at Los Alamos National Laboratory.

Bauke, W.

1984-03-01

22

Application for surveying technology for the alignment of large optical systems  

SciTech Connect

Precise alignment of optical elements in large optical systems is difficult if many elements are positioned such that direct alignment or boresighting becomes impossible. A practical approach is to identify discrete optical path segments and align these using standard surveying or optical-tooling instrumentation. One simply has to develop an alignment theory in which the alignment optical path duplicates or closely approximates the optical path of the operational device. The surveying instruments can then be used to simulate the optical input beams to the system segments to be aligned. Auxiliary targets and reflectors may be added, and the alignment procedure may be augmented by standard optical test instrumentation and techniques. Examples are given using theodolites, transits, and levels with autocollimating capability and micrometer adaptors to perform boresighting and autocollimation techniques on segments of the optical train of the Antares Laser Fusion System at Los Alamos National Laboratory.

Bauke, W.

1984-01-01

23

Measuring cell mechanics by optical alignment compression cytometry.  

PubMed

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. PMID:23440063

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

2013-04-21

24

Laser beam shaper alignment and analysis techniques  

Microsoft Academic Search

Laser beam shapers challenge our sanity in new ways on a daily basis. From an industrial perspective; we design, analyze and then fabricate what is believed to be a simple solution to the complex problem of creating a uniform beam profile. Once the laser beam shaping optics are received and mounted, the task of alignment, fine tuning and measuring begins.

Todd E. Lizotte; Orest Ohar; Tracie Tuttle

2008-01-01

25

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

26

Optical combing to align photoreceptors in detached retinas  

NASA Astrophysics Data System (ADS)

In this paper, we presented a novel micro-manipulating method, called 'optical combing', that could improve the retina reattachment surgery results. Optical combing adopts the working principle of optical tweezers (i.e., focused Gaussian beam produces a trapping force when it incidents onto a micro-object. The trapping force can pull the micro-object to the central point of focused laser beam. Optical combing is implemented by scanning a focused laser beam on the misaligned micro objects (such as misaligned photoreceptors). In our preliminary experiment, a set of misaligned micro glass rods was re-aligned by applying this optical combing technology, which verified our theory. In the future, this technique will be used to re-align misaligned photoreceptors in real retina.

Yin, Shizhuo; Gardner, Thomas W.; Wu, Fei; Cholker, Milind S.

2004-07-01

27

Three wavelength optical alignment of the Nova laser  

SciTech Connect

The Nova laser, presently under construction at Lawrence Livermore National Laboratory, will be capable of delivering more than 100 kJ of focused energy to an Inertial Confinement Fusion (ICF) target. Operation at the fundamental wavelength of the laser (1.05 ..mu..m) and at the second and third harmonic will be possible. This paper will discuss the optical alignment systems and techniques being implemented to align the laser output to the target at these wavelengths prior to each target irradiation. When experiments require conversion of the laser light to wavelengths of 0.53 ..mu..m and 0.35 ..mu..m prior to target irradiation, this will be accomplished in harmonic conversion crystals located at the beam entrances to the target chamber. The harmonic alignment system will be capable of introducing colinear alignment beams of all three wavelengths into the laser chains at the final spatial filter. The alignment beam at 1.05 ..mu..m will be about three cm in diameter and intense enough to align the conversion crystals. Beams at 0.53 ..mu..m and 0.35 ..mu..m will be expanded by the spatial filter to full aperture (74 cm) and used to illuminate the target and other alignment aids at the target chamber focus. This harmonic illumination system will include viewing capability as well. A final alignment sensor will be located at the target chamber. It will view images of the chamber focal plane at all three wavelengths. In this way, each beam can be aligned at the desired wavelength to produce the focal pattern required for each target irradiation. The design of the major components in the harmonic alignment system will be described, and a typical alignment sequence for alignment to a target will be presented.

Swift, C.D.; Bliss, E.S.; Jones, W.A.; Seppala, L.G.

1983-11-16

28

Computer vision applications for coronagraphic optical alignment and image processing.  

PubMed

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. PMID:23669856

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

2013-05-10

29

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

30

Alignment tolerance as a figure of merit for optical design  

NASA Astrophysics Data System (ADS)

Real world optical systems have optical components which are not perfectly aligned. The alignment errors degrade image quality (Wetherell, 1974, 1980). The effects of expected alignment errors must be analyzed for each potential optical design to objectively evaluate its anticipated 'as built' performance. The value of using optical alignment tolerancing as a figure of merit in the optical design phase of a catadioptric lens is demonstrated. The result is a high performance optical system which can be sized for hand held airborne reconnaissance or long range spaceborne reconnaissance. The effects of sizing on alignment tolerance are presented.

Cross, E. W.; Woodfin, G. L.

1983-01-01

31

Optical aligning and measuring methods for large aperture optical system  

NASA Astrophysics Data System (ADS)

How to implement high accuracy measurement of large-aperture coaxial optical system is crucial to the optical alignment and optical property evaluation. The methods of image quality measurement including interferometer-collimating testing, wave front testing by using Hartmann, image processing and analysis of out-of-focus image were introduced. Both the advantages and disadvantages of the three methods were compared, which showed that the alignment method based on interferometer-collimating testing is the one with the highest accuracy. The method of computer-aided alignment (CAA) based on interferometer-collimating was discussed in detail. By using a ZYGO interferometer, interferograms with different field of views and a series of Zernike coefficients were obtained to express the disalignment of the system, and then these incorrect parameters were calculated by CAA algorithms. An alignment experiment of coaxial three-mirror system with 4m focal length and 500mm aperture was carried out. The RMS value of the system is lower than 0.07? after iterations, which is close to the optical diffraction limit, proving the effectiveness of CAA method in alignment guidance.

Zhang, Xue-min; Wei, Ru-yi; Duan, Jia-you; Yang, Jian-feng; Li, Hua; Hou, Xiaohua

2012-10-01

32

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

33

A phase angle tracking method used for optical collimator alignment  

Microsoft Academic Search

Optical collimators are very important components in the construction of practical fiber network. But unfortunately, the problem of low-efficiency alignment is always a bottleneck of optical collimators assembly. Currently, most fiber alignment algorithms are only suitable for lateral axes, and for angular alignment, manual coupling is still widely used in product line. In recent years, engineers have tried to apply

Xin Wang; Hao Shen; Wenyi Qiang

2008-01-01

34

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

35

Alignment of vacuum feed stations on the Navy Prototype Optical Interferometer  

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

36

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

37

Wavefront sensor alignment and calibration techniques for laser communication systems  

NASA Astrophysics Data System (ADS)

Laser communication systems operate in the presence of strong atmospheric turbulence, affecting communication platform by broadening of the laser footprint, random jitter of the laser beam, and high spatial frequency intensity fluctuations referred to as scintillation. The prediction of the effects induced by the atmospheric turbulence is a crucial task for reliable data transmission. Equipping the lasercom platform with adaptive optics system capable of probing the atmospheric turbulence and generating the data on wave front errors in real time improves performance and extends the range of optical communications systems. Most adaptive optics systems implement wavefront sensors to measure the errors induced by the atmospheric turbulence. Real time analysis of the data received from the wavefront sensor is used for outgoing laser beam compensation significantly improves the lasercom performance. To obtain reliable data, the wavefront sensor needs to be accurately aligned and calibrated. To model the performance of a laser communication system operating in the real world we have developed an outdoor 3.2 km, partially over water, turbulence measurement and monitoring communication link. The developed techniques of wavefront sensor alignment and calibration led to the successful data collection and analysis are discussed in this paper.

Sergeyev, Aleksandr V.; Levin, Eugene; Roggemann, Michael C.

2012-05-01

38

Application for surveying technology for the alignment of large optical systems  

Microsoft Academic Search

Precise alignment of optical elements in large optical systems in difficult if many elements are positioned such that direct alignment or boresighting becomes impossible. A practical approach is to identify discrete optical path segments and align these using standard surveying or optical-tooling instrumentation. An alignment theory must be developed in which the alignment optical path duplicates or closely approximates the

W. Bauke

1984-01-01

39

Functional Alignments and Self-Tests for Tilted and Decentered Optics.  

National Technical Information Service (NTIS)

The alignment of tilted and decentered optics is ordinarily difficult, because such optics have neither simple alignment points amenable to ordinary boresight methods, nor a simple alignment theory. Several different alignment examples which provide insig...

W. Bauke E. W. Cross

1983-01-01

40

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

41

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

42

Application for Surveying Technology for the Alignment of Large Optical Systems.  

National Technical Information Service (NTIS)

Precise alignment of optical elements in large optical systems is difficult if many elements are positioned such that direct alignment or boresighting becomes impossible. A practical approach is to identify discrete optical path segments and align these u...

W. Bauke

1984-01-01

43

Coherent Optical Mapping Techniques.  

National Technical Information Service (NTIS)

Coherent optical data processing techniques were investigated for automatic matching and parallax measurement. The study included image plane correlators with amplitude spatial filters and frequency plane correlators with complex spatial filters, i.e., Fo...

S. J. Krulikoski J. C. Dawson D. C. Kowalski

1970-01-01

44

The Coital Alignment Technique (CAT): An Overview of Studies  

Microsoft Academic Search

The Coital Alignment Technique (CAT), a basic physiological alignment that provides consistent and effective stimulation for female coital orgasm, has been evaluated in a series of controlled studies. An overview of the CAT is discussed as well as related studies including replication studies, and subsequent studies of Orgasm Consistency Training (OCT), which incorporates the CAT technique. Classic sex problems like

Aaron Paul Pierce

2000-01-01

45

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

PubMed

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

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

2013-01-10

46

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

47

Computer-guided alignment I : Phase and amplitude modulation of alignment-influenced optical wavefront  

NASA Astrophysics Data System (ADS)

As the first part of a development programme on computer-guided alignment (CGA), we model the alignment influence on the optical wavefront in terms of the phase and amplitude modulation. This modulation is derived from the interaction between alignment parameters and influence functions, both expressed in complex form. The alignment influence model is used to approximate the ray-traced target wavefront of a randomly mis-aligned multi-element system. The approximated wavefront shows a factor of ~ 100 improvement in predicting the target, when coupled non-linear influences among elements are included. This demonstrates the significance of the inter-element effect. We discuss the possibility of adopting the model for rectifying mis-alignment of multi-element systems.

Lee, Hanshin; Dalton, Gavin B.; Tosh, Ian A.; Kim, Sug-Whan

2007-03-01

48

Auto-aligning stimulated emission depletion microscope using adaptive optics  

PubMed Central

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

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

2013-01-01

49

Polarization metrology: Alignment of polarizing prisms in optical polarization systems  

NASA Astrophysics Data System (ADS)

A new simple and precise method for the alignment of polarizing prisms in optical polarization systems is presented. The Poincaré sphere representation is used to explain the alignment procedure. The method considers the case of an imperfect polarizer and is applicable to both transmission and reflection polarization systems.

Nagib, N. N.; Bahrawi, M. S.; Ismail, L. Z.; Othman, M. H.; Abdallah, A. W.

2013-12-01

50

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

51

New techniques for initial alignment of strapdown inertial navigation system  

Microsoft Academic Search

Some new techniques for initial alignment of strapdown inertial navigation system are proposed in this paper. A new solution for the precise azimuth alignment is given in detail. A new prefilter, which consists of an IIR filter and a Kalman filter using hidden Markov model, is designed to attenuate the influence of sensor noise and outer disturbance. Navigation algorithm in

Shaolin Lü; Ling Xie; Jiabin Chen

2009-01-01

52

Electro-optic thin films of organic nonlinear optic molecules aligned through vacuum deposition.  

PubMed

Nonlinear optical molecules can be vacuum deposited into uniform thin films using thermal evaporation. Alignment order can be achieved during thin film deposition by an in-plane electrical field poling using electrodes patterned on the substrate. Electro-optic (EO) coefficients, r33 and r13 are independently measured using Young's interferometry technique. Thin-films of N-benzyl-2-methyl-4-nitroaniline (BNA) can exhibit an EO coefficient, r33, comparable to that of BNA single crystals. EO coefficients of BNA at different poling fields, wavelengths, and frequencies are investigated. PMID:21716347

Sun, Weiwei; Wang, Zhaohong; Chen, Antao; Kosilkin, Ilya; Bale, Denise; Dalton, Larry R

2011-06-01

53

Optical assembly and alignment for the National Ignition Facility project  

SciTech Connect

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

1997-12-23

54

Optical Alignment of the Spherical Antenna Measurement System.  

National Technical Information Service (NTIS)

Precise range and positioner alignment are required for the accurate measurement of the radiation characteristics of microwave antennas using a spherical antenna measurement range. This report presents a custom designed system and novel techniques develop...

C. J. Brochu J. W. Moffat G. A. Morin

1997-01-01

55

Luminosity Dependence of Optical Activity and Alignments Into Radio Galaxies  

NASA Astrophysics Data System (ADS)

We present the results of deep infrared imaging of matched samples of 3CR and fainter Parkes radio galaxies in a redshift band around z ~ 1. The difference in radio power of a factor ~10 between these galaxies has a marked effect upon their optical/infrared properties. The 3CR galaxies, despite beIng more nucleated at K than at optical wavelengths, nevertheless display a clear infrared-radio `alignment effect'. In contrast, the Parkes galaxies are rounder and show no statistical tendency for their radio and optical/infrared axes to be aligned. The Parkes galaxies are also redder than most of the 3CR galaxies, consistent with the absence or reduced amplitude of an aligned blue component associated with the radio activity. The amplitude of this blue component displays a strong correlation with a combination of radio power and spectral index. We show that this is analogous to the correlation between radio-jet power and L_NLR_ found by Rawlings & Saunders, but propose that both correlations arise from a underlying correlation with environment. Considering also (i) the universal shape of the UV continuum; (ii) the common detection of significant optical/UV polarization; (iii) the inaccuracy of the optical-radio alignments; (iv) the close spatial correspondence between the extended UV continuum and line emission; and (v) the correlation between radio-lobe depolarization and extended optical emission, we conclude that a scattering model is preferred. A large fraction of the optical/UV activity and the optical alignment effect in the 3CR sample probably results from Thomson scattering of a `flat' (f_v_ is proportional to V^-0.2^) quasar continuum emitted within a broad cone centred on the radio axis. At least part of the aligned infrared light may have a separate if related origin: when infrared alignments occur, they are tightly aligned with the radio axis. Possible mechanisms include inverse Compton scattering of microwave background photons, or Thomson scattering of a much steeper v^-1.5^ blazar continuum, emitted within a narrower cone of opening angle <~ 10^deg^. Finally we argue that the small dispersion in colour displayed by the Parkes galaxies indicates that the significant AGN contamination of optical/infrared light seen in the 3CR galaxies is largely confined to the top decade of radio power. Less extreme radio galaxies may still be useful as probes of elliptical galaxy evolution - and indicate a low degree of star-forming activity at z = 1.

Dunlop, J. S.; Peacock, J. A.

1993-08-01

56

Functional alignments and self-tests for tilted and decentered optics (A)  

Microsoft Academic Search

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

Walter Bauke; Eugene W. Cross

1983-01-01

57

Functional alignments and self-tests for tilted and decentered optics  

SciTech Connect

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

Bauke, W.; Cross, E.W.

1983-01-01

58

Commercialization of alignment of an optical correlator: architectures and alignment procedures  

Microsoft Academic Search

In this paper we describe the basic characteristics of an optical correlator and draw attention to the specific joint transform design currently being marked by SORL. This system incorporates liquid crystal TVs as input devices providing a high degree of feature discrimination. We address two issues here: The first is a detailed explanation of an alignment procedure which can be

Damon P. Manettas; Mark L'Antigua; Michael A. Fiddy

1993-01-01

59

The Stonehenge technique. A method for aligning coherent bremsstrahlung radiators  

NASA Astrophysics Data System (ADS)

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

Livingston, Ken

2009-05-01

60

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

61

Passive alignment optical subassemblies for military\\/aerospace fiber-optic transmitter\\/receiver modules  

Microsoft Academic Search

Under the DARPA sponsored Avionics Optoelectronic Module Technology program, new passive alignment carrier (PAC) optical subassemblies (LED-PAC and PIN-PAC) ruggedized for military\\/aerospace avionics fiber-optic transmitter and receiver applications have been developed, LED-PAC and PIN-PAC silicon micro-optical bench substrates were fabricated together on a 5 in diameter silicon wafer via multistage photolithography, thin-film, and substrate processing. Alignment v-grooves designed for passive

Mark W. Beranek; Eric Y. Chan; Chiu-Chao Chen; Kenneth W. Davido; Harold E. Hager; Chi-Shain Hong; Dennis G. Koshinz; Mostafa Rassaian; Harold P. Soares; R. L. St. Pierre; Philip J. Anthony; Mark A. Cappuzzo; John V. Gates; Louis T. Gomez; Gerard E. Henein; Joseph Shmulovich; Mark A. Occhionero; Kevin P. Fennessy

2000-01-01

62

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

63

The coital alignment technique (CAT): an overview of studies.  

PubMed

The Coital Alignment Technique (CAT), a basic physiological alignment that provides consistent and effective stimulation for female coital orgasm, has been evaluated in a series of controlled studies. An overview of the CAT is discussed as well as related studies including replication studies, and subsequent studies of Orgasm Consistency Training (OCT), which incorporates the CAT technique. Classic sex problems like female coital anorgasmia and premature ejaculation and modern day epidemic-level sex problems such as hypoactive sexual desire are analyzed in relation to a syndrome of sexual dysfunction symptoms devolving from failed intercourse. Studies indicate that some symptoms of sexual dysfunction considered to have their etiological foundations in pathology are the result of ineffective intercourse techniques. PMID:10929574

Pierce, A P

64

Improved assessment of lower extremity alignment using new roentgenographic techniques  

SciTech Connect

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

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

1987-06-01

65

Progress in linear optics, non-linear optics and surface alignment of liquid crystals  

SciTech Connect

We first discuss the progress in linear optics, in particular, the formulation and application of geometrical-optics approximation and its generalization. We then discuss the progress in non-linear optics, in particular, the enhancement of a first-order Freedericksz transition and intrinsic optical bistability in homeotropic and parallel oriented nematic liquid crystal cells. Finally, we discuss the liquid crystal alignment and surface effects on field-induced Freedericksz transition. 50 refs.

Ong, H.L.; Meyer, R.B.; Hurd, A.J.; Karn, A.J.; Arakelian, S.M.; Shen, Y.R.; Sanda, P.N.; Dove, D.B.; Jansen, S.A.; Hoffmann, R.

1989-01-01

66

Optical Kerr constant of liquid crystals with gold-nanoparticle-doped alignment films  

NASA Astrophysics Data System (ADS)

This investigation studies the optical Kerr constant (n2) of liquid crystals with cell substrates being treated with gold-nanoparticle-doped alignment films using the Z-scan technique. The results indicate that the doping of gold nanoparticles into polyvinyl-alcohol alignment films in a liquid crystal cell enhances the optical Kerr constant, n2, of the liquid crystals. This enhancement is caused by the thermal effect of the absorption of light due to the localized surface plasmon resonance of gold nanoparticles. The magnitude and the sign of n2 of a sample can be modulated by a combination of the applied external electric and optical fields. Furthermore, the variation of n2 of the sample with ambient temperature is studied.

Ying-Guey Fuh, Andy; Lin, Ci-Yong; Li, Ming-Shian; Lin, Hui-Chi

2012-11-01

67

Performance of Optical Flow Techniques  

Microsoft Academic Search

While different optical flow techniques continue to appear, there has been a lack of quantitative evaluation of existing methods. For a common set of real and synthetic image sequences, we report the results of a number of regularly cited optical flow techniques, including instances of differential, matching, energy-based and phase-based methods. Our comparisons are primarily empirical, and concentrate on the

John L. Barron; David J. Fleet; Steven S. Beauchemin

1994-01-01

68

Practical implementation of the complex wavefront modulation model for optical alignment  

NASA Astrophysics Data System (ADS)

We discuss the implementation of the complex wavefront modulation model in practical optical alignment procedures and present its interim results. This modulation model describes the relation between the alignment state and the wavefront of a system, both are expressed in mathematical complex quantities. It addresses the importance of the coupled inter-element alignment effect to the resultant system wavefront. We utilise this effect in order to extract the alignment state of a system from measured optical wavefronts. We demonstrate the method's practical applicability to the real optical alignment procedure by showing alignment simulations of a centered three-mirror system.

Lee, Hanshin; Dalton, Gavin B.; Tosh, Ian A. J.; Kim, Sug-Whan

2007-06-01

69

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

70

A Concept for Zero-Alignment Micro Optical Systems  

SciTech Connect

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

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

1999-09-16

71

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

72

Passive alignment optical subassemblies for military\\/aerospace fiber-optic transmitter\\/receiver applications  

Microsoft Academic Search

Under the DARPA sponsored Avionics Optoelectronic Module Technology program, Boeing, Lucent Technologies, and Ceramics Process Systems have collaboratively developed new passive alignment carrier (PAC) optical subassemblies (LED-PAC and PIN-PAC) ruggedized for military\\/aerospace avionics fiber-optic transmitter and receiver applications. LED-PAC and PIN-PAC silicon micro-optical bench substrates were fabricated together on a 5 inch diameter silicon wafer via multi-stage photolithography, thin-film, and

M. W. Beranek; E. Y. Chan; C. C. Chen; K. W. Davido; H. E. Hager; C. S. Hong; D. G. Koshinz; M. Rassaian; R. L. St. Pierre; P. J. Anthony; M. A. Cappuzzo; J. V. Gates; L. T. Gomez; G. E. Henein; J. Shmulovich; M. A. Occhionero; K. P. Fennessy

1999-01-01

73

Optical transceiver on silicon with self-aligned laser diode  

NASA Astrophysics Data System (ADS)

An optical transceiver is presented consisting of a polarization insensitive directional coupler, a hybrid integrated self-aligned laser diode and a hybrid integrated photodiode. In order to increase waveguide-fiber coupling, the fiber is connected to a tapered waveguide. The polarization insensitive directional coupler is designed for separation of the transmitting ((lambda) equals1.3 micrometers ) and the receiving ((lambda) equals1.55 micrometers ) wavelengths. The coupler is based on Al2O3 waveguides realized by MOPECVD processes. These waveguides show attenuation below 0.3 dB/cm at the wavelengths of interest after annealing at ~700 degree(s)C. The hybrid integration of the laser diode is realized by a self-aligned soldering process. Electroplated tin/gold is used as the solder, while the pre-positioning of the laser diode is achieved by a fine-placer. After self-alignment, the misalignment of the laser has to be smaller than +/- 0.5 micrometers vertical and +/- 1.5 micrometers lateral to achieve coupling losses below 3 dB. Vertical mirrors are used for guiding the signal on the chip to reduce optical losses and chip size. The waveguide-fiber coupling is optimized by a tapered waveguide during the deposition of the Al2O3 layer by a KOH-etched silicon mask. The lateral positioning of the fiber is guaranteed by the vertically etched walls of the waveguide improving the properties of the coupling facet. The depth of the fiber groove is machined by an isotropic silicon plasma etch process.

Heider, Hans J.; Wiechmann, Stefan; Mahnke, Matthias; Mueller, Joerg

2002-06-01

74

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

NASA Astrophysics Data System (ADS)

The sensitivity of a GW interferometric antenna depends critically on the alignment of the Fabry-Perot (F-P) resonators placed in the two atms of a Michelson interferometer. To this end a servo system can be used for controlling the position and the orientation of the end mirrors by using error signals obtained by analyzing the transverse distribution of the beams reflected by the interferometers. This is tantamount to using an inverse scattering technique for gaining informations about the F-P resonators geometry. In this communication, an analytic expression of the components of the scattering matrix of a misaligned resonator excited by a mismatched and misaligned laser beam in presence of mirror aberrations and for finite mirror sizes is derived by representing the beams as superpositions of Gauss-Laguerre modes.

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

75

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

76

Environmental monitoring using optical techniques  

Microsoft Academic Search

An overview of optical techniques for environmental monitoring is presented. Range-resolved measurements of atmospheric pollutants can be performed using the differential absorption lidar technique. Fluorescence lidar allows assessment of vegetation status and also the conditions of the facades of historical buildings. Diode lasers provide particularly realistic schemes for atmospheric gas analysis, where certain wavelength ranges, which are not easily directly

Sune Svanberg

2003-01-01

77

Automatic alignment system for optical lithography based on machine vision  

NASA Astrophysics Data System (ADS)

This paper presents an automatic alignment system based on machine vision method. A high-speed gray pattern match algorithms is proposed based on the combination of sequential similarity detection algorithm (SSDA) and multiresolution pagoda structure algorithm (MPSA). A dynamic system calibration model suitable for the algorithm automatic alignment system is established to relate the pixel coordinate in CCD to the physical coordinate, which is based on Tsai's two-step algorithm but with the help of precise positioning of the wafer stage in X-Y directions. A lot of experiments conducted on a machine vision experimental platform confirm that the proposed technique is feasible and effective. The pattern match algorithm is demonstrated to achieve an error less than one-twentieth pixels, while the computation time is shorter than 200ms when using a large pattern image with 320×320 pixels. The absolute alignment error is illustrated to be lower than 200nm within a large field of view of 1mm×1mm after the platform is calibrated using the proposed dynamic calibration method.

Huang, Tao; Liu, Shiyuan; Yi, Pengxing; Shi, Tielin

2009-05-01

78

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

79

Nanophotonics of vertically aligned carbon nanotubes: Two-dimensional photonic crystals and optical dipole antennas  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) and related nanostructures represent a novel class of condensed matters with intriguing properties due to their unique atomic structures and nanoscale morphologies. It is of particular interest to examine the interaction behavior and mechanism between the free electron gas within carbon nanotubes and the external electromagnetic wave, which may greatly facilitate the understanding of the physics of nanophotonics at the fundamental level. This dissertation is committed to investigate the optical responses of arrays of vertically aligned CNTs in different configurations, based on their fabrication by Plasma-Enhanced Chemical Vapor Deposition (PECVD) and other techniques involved therein. The mechanisms of the photonic results are categorized into inter-CNT and intra-CNT contributions through data analysis on periodic and random CNT arrays, which then give rise to practical applications in photonic crystals and optical antennas. The growth and fabrication procedure of vertically aligned CNTs with optimized morphology and well-defined arrangement is first elaborated in this dissertation, owing to the tremendous difficulties encountered and efforts paid during the sample fabrication and optimization process, and the dominant effect of sample quality on the final results at the optical characterization stage. To fabricate periodic CNT arrays, a microsphere self-assembly technique is first adopted for catalyst patterning and a parametric study is carried out systematically for CNT growth by PECVD method. For random CNT arrays, the growth conditions are also modified so that small diameter CNTs can be grown and an IC industry-compatible procedure can be developed for practical application purposes. The inter-scatterer optical responses are studied by using hexagonal lattices of vertically aligned CNTs with various lattice constants and CNT morphologies. The diffraction patterns of theses CNT arrays are recorded and compared to theoretical calculations based on Bragg diffraction principles for two-dimensional photonic crystals where good consistencies are obtained. The intra-scatterer optical responses are investigated using random CNT arrays with various CNT spacing and lengths. The reflection spectra revealed optical antenna effects of individual vertically aligned CNTs including polarization effect, length-matching effect and multilobe radiation pattern. The results indicate that photocurrents are generated on the CNTs upon illumination. Challenges are identified and potential solutions are proposed to utilize CNT optical antennas for optoelectronic applications.

Wang, Yang

80

On liquid crystal diffractive optical elements utilizing inhomogeneous alignment.  

PubMed

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

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

2012-07-01

81

Simulation study of four-mirror alignment of advanced Kirkpatrick-Baez optics  

NASA Astrophysics Data System (ADS)

We have studied four-mirror alignment for an advanced Kirkpatrick-Baez optics system that consists of two sets of mirrors made up of an elliptical mirror and a hyperbolic mirror. To develop an achromatic hard X-ray imaging system, the tolerance limits for alignment errors to form an image without degrading the resolution were calculated using a wave-optics simulation. A four-mirror alignment procedure is proposed based on the results obtained.

Matsuyama, S.; Fujii, M.; Yamauchi, K.

2010-05-01

82

Post delivery test report for light duty utility arm optical alignment system (OAS)  

SciTech Connect

This report documents the post delivery testing of the Optical Alignment System (OAS) LDUA system, designed for use by the Light Duty Utility Arm (LDUA) project. The post delivery test shows by demonstration that the optical alignment system is fully operational to perform the task of aligning the LDUA arm and mast with the entry riser during deployment operations within a Hanford Site waste tank.

Pardini, A.F.

1996-04-18

83

Bit parallel time-aligned WDM optical communications systems  

NASA Astrophysics Data System (ADS)

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

Ruiz, Everardo David

84

Passive alignment method of polymer PLC devices by using a hot embossing technique  

Microsoft Academic Search

A novel fabrication process using a hot embossing technique has been developed for micromechanical passive alignment of polymer planar lightwave circuit (PLC) devices. With only one step of embossing, single-mode waveguide straight channels and micropedestals for passive aligning are simultaneously defined on a polymer thin film with an accuracy of ±0.5 ?m. This process reduces the steps for fabricating alignment

Jin Tae Kim; Keun Byoung Yoon; Choon-Gi Choi

2004-01-01

85

Fabrication of a side aligned optical fibre interferometer by focused ion beam machining  

NASA Astrophysics Data System (ADS)

Focused ion beam (FIB) machining is a promising technique for the fabrication of micro-optical components with high quality surface finishes. In this work, a prototype of a side aligned optical fibre interferometer was successfully fabricated by the three-dimensional deterministic FIB machining technique. A highly accurate 45° reflective mirror with surface roughness (Ra) of 10 nm has been successfully fabricated at the centre of the fibre to direct the core guided light to the side of the fibre. A surface topography simulation method was developed to simulate the ion beam polishing process. According to the simulation result, a 0.5° offset on the ion beam polishing direction is necessary to maintain the machining accuracy. In the fabrication process, it was also found that for structures requiring a high aspect ratio the existence of an open edge can mitigate against the material redeposition on the sidewalls and therefore increase the overall material removal rate. The fibre has been tested optically and the interference signals have been successfully observed, demonstrating the alignment accuracy of the fabrication method.

Sun, J.; Li, J.; Maier, R. R. J.; Hand, D. P.; MacPherson, W. N.; Miller, M. K.; Ritchie, J. M.; Luo, X.

2013-10-01

86

Optical determination of flexoelectric coefficients and surface polarization in a hybrid aligned nematic cell.  

PubMed

We present an optical study of the influence of both the flexoelectric effect and surface polarization on a hybrid-aligned nematic cell using the half-leaky guided mode technique. Tilt angle profiles, obtained from fits of experimental data (reflectivity curves) taken under applied voltages, are compared with the ones derived by a complete theoretical model. Measurements with an applied alternating voltage allow the evaluation of the anchoring energy by solving the torque balance equation at the planar surface. From measurements with static fields, the sum of flexoelectric coefficients and the surface polarization are determined by numerical solution of Euler-Lagrange equations. PMID:11497609

Mazzulla, A; Ciuchi, F; Sambles, J R

2001-07-24

87

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

88

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

PubMed

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

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

2011-02-28

89

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

2013-07-25

90

Active alignment for interferometric techniques onboard the International Space Station  

NASA Astrophysics Data System (ADS)

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

Kebbel, Volker; Becker, Joachim; Jueptner, Werner

2004-08-01

91

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

Microsoft Academic Search

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

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

1988-01-01

92

Holographic weapons sight as a crew optical alignment sight  

NASA Astrophysics Data System (ADS)

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.

2011-05-01

93

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

NASA Astrophysics Data System (ADS)

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

Winrow, Edward G.; Chavez, Victor H.

2011-09-01

94

Lessons learned from the optics and focal plane alignment of a wide field of view RC telescope  

NASA Astrophysics Data System (ADS)

Medium-sized Aperture Camera (MAC) is the main payload for Earth observation satellite RazakSAT to be launched at the end of 2005. The flight model has been recently assembled and tested. The 300 mm diameter Cassegrain telescope optics and the focal plane assembly for a space camera have been aligned. Topics discussed in this paper include the lessons learned from the optics alignment and assembly of the telescope and the focal plane. A computer-aided alignment method was used for the alignment of the relatively wide field of view (+/-1 deg) telescope. RMS wavefront error measurement environment was found to be more critical than previously experienced, and the importance of the initial alignment is discussed. System modulation transfer function (MTF) was used as the figure-of-merit for the alignment of the focal plane assembly with linear CCD detectors. MTF was measured by a knife-edge scanning technique using a dedicated 450 mm diameter collimator with diffraction-limited performance.

Kim, Eugene D.; Choi, Young-Wan; Kang, Myung-Seok; Kim, Ee-Eul; Yang, Ho-Soon; Bin Ismail, Ad. Mohd. Afiq; Sabirin Arshad, Ahmad

2005-08-01

95

Daytime Polar Alignment of Telescope Mountings Using GPS and Internal Reference Optics  

NASA Astrophysics Data System (ADS)

A technique is presented for performing polar alignment of astronomical telescope mountings to high precision during daylight hours. This work originated in the requirement to erect a truck mounted astronomical telescope at multiple locations during the day in order to measure the atmospheric convective turbulence Fried Parameter r0 by tracking stars at various zenith angles. The custom equatorial mounting built for this project incorporates a surveyor's theodolite, which is used to establish an optical line of sight to the North Celestial Pole (NCP). The elevation angle of this line of sight is set directly by adjusting the theodolite tube elevation angle to that of the local geographic latitude obtained from a Global Positioning System (GPS) receiver. The theodolite is set into the azimuth of the Pole by observing an object on the horizon of known bearing angle or by observing the Sun=92s known azimuth at a specified time. Once the theodolite line of sight to the NCP is established, an optical target projector contained within and aligned with the polar axis provides an illuminated pattern, which is viewed by the theodolite. Subsequent adjustments of the elevation and azimuth of the polar axis bring the projected pattern onto the intersection of the crosshairs in the theodolite reticule, thereby bringing the polar axis into close coincidence with the NCP. Denver University astronomers are interested in this application for their proposed Fully Adaptive Segmented Telescope (FAST) instrument, a meter-class instrument which can be transported among high altitude sites (see www. adaptive-optics.com). Equinox Interscience (303-843-0313) can provide this daytime polar alignment capability to interested users for equatorial mountings.

Mellon, R. R.; Scheld, D.; Stencel, R. E.

1998-12-01

96

Omnium-G parabolic dish optical efficiency: A comparison of two independent measurement techniques  

NASA Astrophysics Data System (ADS)

Measurements made at SERI of the optical efficiency of the Omnium-G parabolic dish concentrator are described. Two independent techniques are emphasized: the cold water calorimeter method; and the heat of fusion method. Results from both techniques indicate that the optical efficiency for a 10 cm receiver aperture is 25 percent. An optical alignment procedure is described that resulted in the increase in optical efficiency from 21 percent to the current value of 25 percent.

Bohn, M.; Gaul, H. W.

1980-10-01

97

Medical image processing with optical Fourier techniques  

Microsoft Academic Search

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

Pengfei Wu

2003-01-01

98

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

NASA Astrophysics Data System (ADS)

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 optical bench (OB) to support the JWST Optical Telescope Element (OTE), a personnel access platform structure (PAPS), an optics integration gantry system (OIGS), and a PMSA alignment and integration fixture (PAIF). The PAIF and OIGS are used to deliver; offload and precision align each PMSA segment and the aft optical subsystem (AOS) to their integration locations. This paper will introduce the functional design of this ground support equipment (GSE), illustrate the coordinate systems used for integration, and detail the integration processes.

Wells, Conrad; Coon, Matthew

2009-08-01

99

Implementation of differential wavefront sampling in optical alignment of pupil-segmented telescope systems  

NASA Astrophysics Data System (ADS)

We describe the implementation of differential wavefront sampling(DWS) in optical alignment of a pupil-segmented telescope system. As a wavefront-based optical alignment method, DWS can efficiently provide estimations of misalignments present in an optical system by deliberately perturbing optical elements in a systematic manner. This has been demonstrated in our previous numerical studies with realistic uncertainties in wavefront measurements, motion control, and optical surface deformations, suggesting that the method has potential in optical alignment and phasing of pupil-segmented systems such as the future Extremely Large Telescopes (ELTs). The basic idea and procedures of DWS are first described. We then present and discuss preliminary simulations using the currently proposed European Extremely Large Telescope (E-ELT) as an example system.

Lee, Hanshin; Dalton, Gavin B.; Tosh, Ian A. J.; Kim, Sug-Whan

2008-07-01

100

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

101

An auxiliary visible imaging method for alignment of x-ray Kirkpatrick-Baez optics  

Microsoft Academic Search

An auxiliary visible imaging method was introduced to solve the axial and pointing alignment of x-ray Kirkpatrick-Baez optics. Through ZEMAX simulation and x-ray imaging experiments, the axial and pointing alignment accuracy were determined to be +\\/-300mum and +\\/-20mum respectively. The numerical aperture of x-ray Kirkpatrick-Baez optics is rather small, so it's impossible to adjust Kirkpatrick-Baez system by visible imaging directly.

Baozhong Mu; Shengzhen Yi; Jingtao Zhu; Jing Xu; Xin Wang; Shengling Huang; Moyan Tan; Qiushi Huang; Liang Bai; Xiaoqiang Wang; Yi Huang; Li Jiang; Hongying Liu; Zhanshan Wang; Lingyan Chen; Yongkun Ding; Wenyong Miao; Jianjun Dong

2009-01-01

102

Substrate patterning for liquid crystal alignment by optical interference  

SciTech Connect

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

Lu Xuemin; Lee, Fuk Kay; Sheng, Ping; Kwok, H.S.; Chigrinov, V.; Tsui, Ophelia K.C. [Department of Physics, Hong Kong University of Science and Technology, Hong Kong (China); Department of Electrical and Electronic Engineering, Hong Kong University of Science and Technology, Hong Kong (China); Department of Physics, Hong Kong University of Science and Technology, Hong Kong (China)

2006-06-12

103

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

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

104

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

105

Role of dopants on the electro-optic effect in nematic liquid crystals aligned with doped polypyrrole  

Microsoft Academic Search

In order to estimate electro-optical response times, measurements of the transmitted light intensity through positive uniaxial nematic thin films in planar alignment have been performed. Very fast relaxation times were experimentally found for nematic samples aligned with conductive polymers, namely, polypyrrole doped with 5 types of anions having different molecular sizes and geometries. Using undoped polypyrrole alignment layers, slower electro-optical

Matei Raicopol; Constanta Dascalu; Ruxandra Atasiei; Andrei Th Ionescu

2011-01-01

106

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

107

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

108

Recent progress in optical current sensing techniques  

Microsoft Academic Search

This paper reviews recent developments in the field of current measurement which employ a wide range of optical and fiber optic techniques. Depending on the current sensing mechanisms involved and the sensing materials used, optical current sensors (OCSs) may be categorized into four main groups: (i) OCSs employing optical fiber as their sensing elements, (ii) OCSs using bulk glass to

Y. N. Ning; Z. P. Wang; A. W. Palmer; K. T. V. Grattan; D. A. Jackson

1995-01-01

109

German Encyclopedia Alignment Based on Information Retrieval Techniques  

Microsoft Academic Search

\\u000a Collaboratively created online encyclopedias have become increasingly popular. Especially in terms of completeness they have\\u000a begun to surpass their printed counterparts. Two German publishers of traditional encyclopedias have reacted to this challenge\\u000a and decided to merge their corpora to create a single more complete encyclopedia. The crucial step in this merge process is\\u000a the alignment of articles. We have developed

Roman Kern; Michael Granitzer

2010-01-01

110

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

PubMed

To enhance male-female sexual compatibility, principles of physical alignment were formulated to make clitoral contact possible in coitus. The Coital Alignment technique combines (a) the "riding high" variation of the "missionary" coital posture, with (b) genitally focused pressure-counterpressure stimulus applied in the coordination of sexual movement. It was hypothesized that the Alignment technique would correlate with high frequency of female orgasm and partner simultaneity. A questionnaire was given to a group of males and females (n = 43) who had learned the Alignment technique, and to a volunteer group (n = 43) who had no knowledge of the Alignment concept. The mean age for the experimental females (n = 22) was 39.7, and for the control females (n = 22) was 38.7. Analysis of variance and post-hoc LSD procedures conducted on the key dependent variables showed significant differences (p less than .05, two-tailed) between experimental and control females, favoring experimental females on the orgasmic attainment criteria of coital orgasm, simultaneous orgasm, and orgasm experienced as "complete and satisfying." Pearson Product Correlations were conducted across all four groups, experimental and control males and females combined (N = 86). Greater adherence to behaviors associated with the Coital Alignment technique--learned and incidental--had a significant positive correlation with the above and additional sexual satisfaction variables (p less than .01). The Alignment technique may be an important option for a majority of women that have difficulty in attaining orgasm in coitus. PMID:3204637

Eichel, E W; Eichel, J D; Kule, S

1988-01-01

111

Optical response of magnetically aligned nematic soft matter by transverse nemato-magnetic waves  

Microsoft Academic Search

Based on the method of molecular field dominated by magnetic component, it is shown that a homogeneous magnetically aligned nematic liquid crystal can respond to a circularly polarized optical field by transverse nemato-magnetic wave in which velocity of incompressible flow and director undergo coupled oscillations slowly traveling along the axis of magneto-optical anisotropy. The effect may be of practical interest

Sergey Bastrukov; Pik-Yin Lai; Dima Podgainy; Irina Molodtsova

2006-01-01

112

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

Microsoft Academic Search

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

Richard Anderson

1994-01-01

113

A novel optical vector spectrum analysis technique  

Microsoft Academic Search

- Abstract: A novel technique for measuring frequencydependent magnitude and phase information across an optical channel is presented using tunable, integrated ring-resonator-based optical filters and a detector with a small bandwidth relative to the full channel width. 02003 Optical Society of America OCIS codes: 130.3120 (Integrated optics devices), 230.7390 (Waveguides, planar) 1. Jntmduction A novel optical vector spectral analysis (OVSA)

C. K. Madsen; M. Cappuzzo; E. Chen; L. Gomez; A. Griffin; E. J. Laskowski; Wong-Foy; C. Rolle

2004-01-01

114

An auxiliary visible imaging method for alignment of x-ray Kirkpatrick-Baez optics  

NASA Astrophysics Data System (ADS)

An auxiliary visible imaging method was introduced to solve the axial and pointing alignment of x-ray Kirkpatrick-Baez optics. Through ZEMAX simulation and x-ray imaging experiments, the axial and pointing alignment accuracy were determined to be +/-300?m and +/-20?m respectively. The numerical aperture of x-ray Kirkpatrick-Baez optics is rather small, so it's impossible to adjust Kirkpatrick-Baez system by visible imaging directly. An auxiliary visible lens was designed, which was equivalent to x-ray Kirkpatrick-Baez optics on conjugate relationship and accuracy control. The comparative experiments of visible imaging and x-ray imaging indicate that this auxiliary system could meet the alignment accuracy of Kirkpatrick-Baez optics.

Mu, Baozhong; Yi, Shengzhen; Zhu, Jingtao; Xu, Jing; Wang, Xin; Huang, Shengling; Tan, Moyan; Huang, Qiushi; Bai, Liang; Wang, Xiaoqiang; Huang, Yi; Jiang, Li; Liu, Hongying; Wang, Zhanshan; Chen, Lingyan; Ding, Yongkun; Miao, Wenyong; Dong, Jianjun

2009-05-01

115

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

116

Multimodal vessel mapping for precise large area alignment of functional optical imaging data to neuroanatomical preparations in marmosets.  

PubMed

Imaging technologies, such as intrinsic optical imaging (IOI), functional magnetic resonance imaging (fMRI) or multiphoton microscopy provide excellent opportunities to study the relationship between functional signals recorded from a cortical area and the underlying anatomical structure. This, in turn, requires accurate alignment of the recorded functional imaging data with histological datasets from the imaged tissue obtained after the functional experiment. This alignment is complicated by distortions of the tissue which naturally occur during histological treatment, and is particularly difficult to achieve over large cortical areas, such as primate visual areas. We present here a method that uses IOI vessel maps revealed in the time course of the intrinsic signal, in combination with vascular casts and vascular lumen labeling techniques together with a pseudo three dimensional (p3D) reconstruction of the tissue architecture in order to facilitate alignment of IOI data with posthoc histological datasets. We demonstrate that by such a multimodal vessel mapping approach, we are able to constitute a hook in anatomical-functional data alignment that enables the accurate assignment of functional signals over large cortical regions. As an example, we present precise alignments of IOI responses showing orientation selectivity of primate V1 with anatomical sections stained for cytochrome-oxidase-reactivity. PMID:21843550

Valverde Salzmann, Matthias F; Wallace, Damian J; Logothetis, Nikos K; Schüz, Almut

2011-08-06

117

Advanced Techniques for Improving Laser Optical Surfaces.  

National Technical Information Service (NTIS)

This program is a study of surface-finishing techniques considered to be capable of improving the surface quality of laser optical materials. A variety of conventional and superpolishing techniques will be developed for single-crystal and polycrystalline ...

C. B. Willingham

1974-01-01

118

Concept for Zero-Alignment Micro Optical Systems.  

National Technical Information Service (NTIS)

We are developing a method of constructing compact, three-dimensional photonics systems consisting of optical elements, e.g., lenses and mirrors, photo-detectors, and light sources, e.g., VCSELS or circular-grating lasers. These optical components, both a...

Descour Kololuoma Levey Rantala Shul

1999-01-01

119

Omnium-G parabolic dish optical efficiency: a comparison of two independent measurement techniques  

SciTech Connect

Measurements made at SERI of the optical efficiency of the Omnium-G parabolic dish concentrator are described. Two independent techniques were used: the cold-water calorimeter method and the heat of fusion method. Results from both techniques agree quite well and indicate that the optical efficiency for a 10-cm receiver aperture is 25%. Optical efficiency measured in early 1979 was 37%, and in mid 1979 it had degraded to 21%. An optical alignment procedure is described that resulted in the increase in optical efficiency from 21% to the current value of 25%.

Bohn, M.; Gaul, H.

1980-10-01

120

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

SciTech Connect

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

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

1997-10-13

121

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

SciTech Connect

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

Hurst, P.; Grasz, E.

1998-05-12

122

The coital alignment technique and directed masturbation: A comparative study on female orgasm  

Microsoft Academic Search

To evaluate the effectiveness of two sexual therapy techniques, a nonclinical population of 36 married women were randomly assigned with their spouses to either a sexual enrichment workshop with instruction on the coital alignment technique (19 women) or directed masturbation (17 women). Both workshops yielded clinically significant improvements in orgasm consistency during sexual intercourse, orgasm strength, and the overall number

David Farley Hurlbert; Carol Apt

1995-01-01

123

Active alignment for interferometric techniques onboard the International Space Station  

Microsoft Academic Search

Different interferometric techniques are required to cover most of the scientific needs in the field of fluid dynamics science in microgravity research. The Fluid Science Laboratory (FSL), currently under upgrade for the Columbus Orbital Facility of the International Space Station (ISS), shall provide Holographic Interferometry, Digital Holography, Electronic Speckle Pattern Interferometry (ESPI) and Shearing Interferometry among other diagnostic tools. On

Volker Kebbel; Joachim Becker; Werner Jueptner

2004-01-01

124

Current status of the optic alignment of the 2m Rozhen telescope  

NASA Astrophysics Data System (ADS)

The two hyperbolic mirrors design of a Ritchey-Chretien (RC) optical system is characterized as a system free from coma, astigmatism and spheric aberrations. By definition, the RC telescopes offers high quality images over a large field of view. In order to optimally utilize the advantages of a RC telescope, its optic should be perfectly collimated with a checking of the mutual disposal of the optical elements. In this article we present the steps we followed to establish the current status of the 2-meter Ritchey-Chretien-Coude NAO Rozhen telescope optic alignment after the recoat of its mirrors. We consider the normal status of the telescope is restored.

Markov, Haralambi; Markishki, Pencho; Bonev, Tanyu

125

Chip-on-chip 3D optical interconnect with passive alignment  

Microsoft Academic Search

In this paper, a chip-on-chip 3D optical interconnect is introduced. The package consists of a SiOB and a flip chip mirror carrier. The light beam is deflected by two pairs of micro-mirrors on both the SiOB and the flip chip mirror carrier. The optical fibers are passively aligned with the pre-defined V-grooves on the SiOB. The mirror pairs on both

Jeffery C. C. Lo; S. W. Rick Lee; J. S. Wu; J. K. Kim; Matthew M. F. Yuen

2004-01-01

126

All grazing incidence interferometer for testing and in situ alignment of imaging X-ray optics  

Microsoft Academic Search

An interferometer is described which allows in situ assessment and alignment of any image forming grazing incidence optic. The fringes are localized in the exit pupil of the X-ray telescope or microscope (either under manufacture or during use) and mark out in units of one wavelength the departure of an actual convergent image forming wavefront from the Gaussian reference sphere.

R. J. Speer; M. Chrisp

1979-01-01

127

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

128

Selective Alignment of Gold Nanowires Synthesized With DNA as Template by Surface-Patterning Technique  

Microsoft Academic Search

The direct and selective assembly of deoxyribonucleic acid (DNA)-templated metal (e.g., Ag, Au, Cu, and Pd) nanowires (NWs) is a key technique for the application to electronic devices and nanowire-based biosensors. In this study, a new technique was developed to carefully control the interval of DNA-templated gold NWs (AuNWs) using surface-patterning techniques. The ??-DNA molecules were stretched and aligned along

Hyung Jin Kim; Yonghan Roh; Byungyou Hong

2010-01-01

129

Alignment techniques required by precise measurement of effective focal length  

NASA Astrophysics Data System (ADS)

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

Wise, T. D.

1980-01-01

130

Novel optical and ultrasound techniques for biomedicine  

NASA Astrophysics Data System (ADS)

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

Esenaliev, Rinat O.

2003-10-01

131

Surface diffusion studies by optical diffraction techniques.  

National Technical Information Service (NTIS)

The newly developed optical techniques have been combined with either second harmonic (SH) diffraction or linear diffraction off a monolayer adsorbate grating for surface diffusion measurement. Anisotropy of surface diffusion of CO on Ni(l10) was used as ...

X. D. Xiao

1992-01-01

132

Optical surface grinding of optical glasses with ELID grinding technique  

NASA Astrophysics Data System (ADS)

In this paper, the authors present a new technique which through electrolytic truing, could use metal bonded supermicro diamond wheel to machine optical glasses and obtain optical surfaces with best-quality finish. Using this technique to machine K9, F4 and zerodur, the surface roughness Ra could reach a value less than 10 nanometer and a planeness less than 1 micrometer. In addition, the authors have also studied some phenomena occurred in the grinding process.

Wang, Ping; Shi, Zhenfang; Xin, Qiming

2000-10-01

133

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

134

Carbon nanotubes in liquid suspension: Electric-field-induced alignment and optical anisotropy  

NASA Astrophysics Data System (ADS)

Nanofluids consisting of particles or tubes of nanoscale dimensions suspended in liquids have unusual and technologically important properties. They have been found to have enhanced thermal conductivities, which makes them attractive for heat-transfer applications (Eastman et al.2001, Choi et al.2001). As part of our investigation on the properties of nanofluids, we report on experiments on the optical detection of electric-field-induced alignment of carbon-nanotubes. Single-walled carbon nanotubes (SWNTs) are dispersed in nonconducting liquids and subject to electric fields. Under alternating electric fields, the nanotubes are found to align with the field, causing the nanofluid to act as a polarizer at visible wavelengths. The effects of the magnitude and frequency of the electric field on nanotube alignment are explored. The role of temperature on the relaxation of aligned nanotubes in liquid suspension is also investigated. Alignment of the suspended SWNTs, which have diameters and lengths on the order of 1 nanometer and 1 micron, respectively, is optically detected by state-of-polarization effects on light transmitted through the nanofluid.

Shan, Jerry W.; Brown, Matthew; Lin, Chen

2004-11-01

135

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

SciTech Connect

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

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

1987-01-01

136

The computer-aided alignment study of three-mirror off-axis field bias optical system  

NASA Astrophysics Data System (ADS)

Determine the misalignment of optical element quickly and exactly is the key to the technology of computer-aided alignment (CAA). For alignment a three-mirror off-axis field bias system, the sensitivity matrix method was used to simulate the alignment process. The results of simulation show that the sensitivity matrix method was not convergence. A new CAA method to get misalignment was put forward; the misalignment was obtained by programming the function of optical design software CODE V's auto-optimization option. The system's alignment characteristic was analysis and made use of this new method put up a computer simulation. The results of simulation show that the misalignment determined by only once auto-optimization and guidable to alignment of this system. After alignment, the optical system produced a measured wave front error across the all image plane less than 0.08 waves RMS at ?=0.6328?m.

Pang, Zhihai; Fan, Xue-wu; Ma, Zhen; Chen, Qinfang

2012-10-01

137

Polymer nanofibers embedded with aligned gold nanorods: a new platform for plasmonic studies and optical sensing.  

PubMed

This paper reports the fabrication and characterization of polymer nanofibers embedded with gold nanorods in uniaxial alignment for applications in optical waveguiding and sensing. Using a waveguiding approach, we demonstrated highly efficient excitation of localized surface plasmon resonance in the embedded gold nanorods with a photon-to-plasmon-conversion efficiency as high as 70% for a single nanorod at its longitudinal resonance wavelength. On the basis of waveguiding polymer nanofibers embedded with gold nanorods, we further demonstrated compact optical humidity sensors with a response time of 110 ms and an operation optical power as low as 500 pW. PMID:22582809

Wang, Pan; Zhang, Lei; Xia, Younan; Tong, Limin; Xu, Xia; Ying, Yibin

2012-05-17

138

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

NASA Astrophysics Data System (ADS)

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

Duffy, Alan; Yates, Brian; Hu, Yongfeng

2011-09-01

139

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

140

An Automatic Alignment Procedure for a 4Source Photometric Stereo Technique applied to Scanning Electron Microscopy  

Microsoft Academic Search

This paper presents an automatic alignment procedure for a 4-source photometric stereo technique to reconstruct the depth map in the scanning electron microscopy. PS, based on the so-called reflectance map, used several images of a surface to estimate the surface depth at each image point. Lambertian reflectivity function is the simplest one. In the SEM one of the most important

Ruggero Pintus; Simona Podda; Massimo Vanzi

2006-01-01

141

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

NASA Astrophysics Data System (ADS)

Weak gravitational lensing can be used to constrain cosmological parameters to high precision using the 2- and 3-point weak lensing shear correlations. The intrinsic alignment (IA) of galaxies has been shown to be a significant barrier to precision weak lensing measurements. We review a proposed self-calibration technique to calculate the induced gravitational lensing-galaxy intrinsic alignment correlation (GI) for the power spectrum in weak gravitational lensing surveys with photometric redshift measurements, which is expected to reduce the IA contamination by at least a factor of 10 for currently proposed surveys. We confirm this using an independent analysis and propose an expansion to the self-calibration technique for the weak lensing bispectrum in order to calculate the dominant lensing-lensing-intrinsic alignment correlation (GGI). We explore the performance of the GGI self-calibration technique and show that it can potentially reduce the IA contamination by up to a factor of 5-10 for most redshift bin choices. The self-calibration thus promises to be an efficient technique to remove both the 2-point and 3-point intrinsic alignment contamination from weak gravitational lensing measurements.

Troxel, Michael; Ishak, Mustapha

2011-10-01

142

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

143

Division Ix: Optical & Infrared Techniques  

NASA Astrophysics Data System (ADS)

Division IX provides a forum for astronomers engaged in the planning, development, construction, and calibration of optical and infrared telescopes and instrumentation, as well as observational procedures including data processing. A few years ago, discussions were started about changes in the structure of Division IX, with the aim of bringing it more in line with today's world of large coordinated projects and multi-national observatories. The course of this process, and further steps to be taken in the period from 2009 to 2012, were at the focus of the deliberations at the business meeting of Division IX at the IAU General Assembly in Rio de Janeiro.

Quirrenbach, Andreas; Silva, David R.; Kudritzki, Rolf-Peter; Burton, Michael G.; Cui, Xiangqun; McLean, Ian S.; Milone, Eugene F.; Murthy, Jayant; Ridgway, Stephen T.; Tautvaišiene, Gražina; Tokovinin, Andrei A.; Torres, Guillermo

2010-05-01

144

The coital alignment technique and directed masturbation: a comparative study on female orgasm.  

PubMed

To evaluate the effectiveness of two sexual therapy techniques, a non-clinical population of 36 married women were randomly assigned with their spouses to either a sexual enrichment workshop with instruction on the coital alignment technique (19 women) or directed masturbation (17 women). Both workshops yielded clinically significant improvements in orgasm consistency during sexual intercourse, orgasm strength, and the overall number of orgasms experienced in partner-related activities. In instances where differences in the workshop were discovered (increases in orgasm consistency during sexual intercourse), the coital alignment technique yielded a somewhat more positive outcome than did directed masturbation. Treatment approaches that combine the two techniques, such as orgasm consistency training, may prove more beneficial than a treatment model that depends on either one or the other. PMID:7608994

Hurlbert, D F; Apt, C

1995-01-01

145

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

146

Daytime Polar Alignment of Telescope Mountings Using GPS and Internal Reference Optics  

Microsoft Academic Search

A technique is presented for performing polar alignment of astronomical telescope mountings to high precision during daylight hours. This work originated in the requirement to erect a truck mounted astronomical telescope at multiple locations during the day in order to measure the atmospheric convective turbulence Fried Parameter r0 by tracking stars at various zenith angles. The custom equatorial mounting built

R. R. Mellon; D. Scheld; R. E. Stencel

1998-01-01

147

Optical pupil relay design for SILEX - Optimising wavefront error and transmit/receive beams co-alignment  

NASA Astrophysics Data System (ADS)

This paper describes some of the key parameters that have been considered for the European Satellite Interorbital Link EXperiment (SILEX) optical relay lens design. Particular attention has been given to the specific requirement of transmit/receive beams co-alignment. The method of evaluating co-alignment errors is described and the effect of manufacturing tolerances and environmental long term stability on the co-alignment error investigated.

Jonas, Reginald P.

1992-06-01

148

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

NASA Astrophysics Data System (ADS)

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

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

2007-06-01

149

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

PubMed Central

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

Fusti-Molnar, Laszlo; Merz, Kenneth M.

2008-01-01

150

The weight-bearing scanogram technique provides better coronal limb alignment than the navigation technique in open high tibial osteotomy.  

PubMed

BACKGROUND: Successful outcomes following high tibial osteotomy (HTO) require precise realignment of the mechanical axis of the lower extremity. The present study investigated whether the weight-bearing limb scanogram (WBS) technique provided a more accurate mechanical axis realignment than the navigation technique in open high tibial osteotomy (OHTO). METHODS: This prospective study involved 80 knees (78 patients) undergoing OHTO. The WBS technique was used in 40 knees and the navigation technique in 40 knees. Each technique was performed by a different surgeon in a different hospital. Postoperative coronal limb alignment was assessed using the weight-bearing line (WBL) ratio on full-length standing hip-to-ankle radiographs. RESULTS: We found that the mean postoperative WBL ratio was greater in the WBS compared to the navigation group (p=0.001), and hence the ratio for the WBS group was closer to the ratio target of 62%. There was a greater proportion of WBL ratio outliers in the navigation group than the WBS group (25% vs. 10%, p=0.034). CONCLUSION: We conclude that the WBS technique was more accurate than the navigation technique for restoration of coronal leg alignment in OHTO. LEVEL OF EVIDENCE: Level II. PMID:23041300

Lee, Dae-Hee; Han, Seoung-Bum; Oh, Kwang-Jun; Lee, Jun Seop; Kwon, Jae-Ho; Kim, Jong-In; Patnaik, Smarajit; Shetty, Gautam M; Nha, Kyung-Wook

2012-10-01

151

Study of optical destruction techniques for optical discs  

NASA Astrophysics Data System (ADS)

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

Choi, Taeyoung

152

Construction of a numerically controlled device for aligning optical and mechanical axis of a microscope lens on a lathe  

NASA Astrophysics Data System (ADS)

In microscope manufacturing lenses are normally cemented in special mounts. The optical axis is aligned to the mechanical axis by a turning operation on a special lathe. Solutions to automate this process are presented.

Juranek, H. J.

1981-02-01

153

A Study of Observing Optical Waveform Applying All Optical Signal Sampling Technique Using a High Nonlinear Fiber  

NASA Astrophysics Data System (ADS)

All optical signal sampling technique using a high nonlinear fiber is experimentally investigated in order to observing a waveform of a high symbol-rate optical signal. Optical sampling pulses having time width of 2.8 ps are generated from an output of a semiconductor mode lock laser module by reducing the pulses using optical gates. Envelope of the optical signal is sliced to the slow rate signal by the sampling pulses through the effect of four wave mixing caused in the high nonlinear fiber. Applying this manner, simple and less alignment system is realized. In order to confirm the basic operation of the scheme, signal conversion efficiencies to idler light are evaluated by using two types of fiber. Moreover, optical signal sampling experiments are carried out by using a 160 Gb/s On-Off-Keying signal.

Yamashita, Ikuo; Kagawa, Masatoshi; Inafune, Koji; Murai, Hitoshi

154

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

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

155

Alignment of 3-D Optical Coherence Tomography Scans to Correct Eye Movement Using a Particle Filtering  

PubMed Central

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

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

2012-01-01

156

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

157

A simple accurate method of alignment of beamline optics with the use of EUV multilayer polarizers.  

PubMed

A simple alignment method is proposed, which enables the alignment of beamline optics of a bending section accurately, relying on the linear state of polarization of synchrotron orbital radiation rather than the beam intensity. The method utilizes extreme UV (EUV) multilayers as a compact polarization monitor detecting unwanted vertical polarization components. The proposed method was found to be far more sensitive than that relying on the maximum intensity. Another advantage is the insensitivity to surface contamination, such as an irradiation mark on the mirror degrading reflectance. A design example is presented for use around a photon energy of 370 eV along with an experimental example at a photon energy of 97 eV. PMID:15263623

Yamamoto, M; Furudate, M; Yanagihara, M; Kimura, H

1998-05-01

158

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

159

Simple fabrication of a double-layer multi-channel optical waveguide using passive alignment.  

PubMed

This study proposes a simple and cost-effective method of fabricating a double-layer polymeric optical waveguide, using two hot-embossing processes with a single stamp and template for passive alignment between the top and bottom layers. The two hot-embossing processes were conducted sequentially on the top layer and the bottom layer of the polymer layer. The second hot-embossing process was conducted after fabricating the buffer layer on the surface of the polymeric channel structure to control deformation and destruction of the previously fabricated polymeric channel structure. Passive alignment of the channel structure for the top layer and the bottom layer was automatically performed by simple insertion of the stamp and polymer layer using a metal template with the same dimensions (width x length) as the stamp. Regarding the polymer layer, the buffer layer on the side with the channel structure was coated, whereas the layer contacting the stamp did not have a buffer layer. For the purposes of this study, a 2 x 50 channel polymeric multimode optical waveguide was fabricated using a stamp with 50 straight ribs, without any coupling between the layers. The fabricated optical waveguide was controlled within positional tolerances of less than ± 5 ?m between layers; propagation loss of below 0.2 dB/cm at 850 nm; and channel uniformity of below 0.5 dB. PMID:21263659

Ryu, Jin Hwa; Lee, Tea Ho; Cho, In-Kui; Kim, Chang-Seok; Jeong, Myung Yung

2011-01-17

160

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

161

Hollow ARROW waveguides on self-aligned pedestals for high-sensitivity optical sensing  

NASA Astrophysics Data System (ADS)

Antiresonant reflecting optical waveguides (ARROWs) provide a promising approach to realizing high-sensitivity sensing platforms on planar substrates. We have previously developed ARROW platforms that guide light in hollow cores filled with liquid and gas media. These platforms include integrated traditional solid waveguides to direct light into and out of sensing media. To improve the sensitivity of these platforms for optical sensing, hollow waveguide loss must be reduced. We are working towards this by using anisotropic plasma etching to create near-ideal hollow ARROW geometries. These structures rely on an etching mask that also serves as the sacrificial core for the waveguide. This self-aligned process creates a hollow waveguide on a pedestal which is surrounded by a terminal layer of air in three directions. We previously produced ARROWs by pre-etching the silicon substrate and aligning the sacrificial core to the pedestal. However, this necessitates using a pedestal which is wider than the core, leading to higher loss and poor reproducibility. We have also increased the hollow to solid waveguide transmission efficiency by using a design that coats the sides and top of the hollow core with a single layer of silicon dioxide. Using this design, we have demonstrated an interface transmission improvement of more than two times. A much improved optical sensor platform will incorporate both of these features, using the self-aligned pedestal process for most of the length of the hollow waveguides to decrease loss, and employing the single layer design only at the interfaces to improve hollow-solid waveguide coupling.

Lunt, Evan J.; Phillips, Brian S.; Keeley, Jared M.; Hawkins, Aaron R.; Measor, Philip; Wu, Bin; Schmidt, Holger

2010-02-01

162

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

163

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

Microsoft Academic Search

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

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

2009-01-01

164

Techniques for Recovering Optical Spectral Features Using a CHirped Optical Field.  

National Technical Information Service (NTIS)

Techniques for recovering optical spectral features include receiving a detected time series that represents a temporally varying intensity of an optical signal. The optical signal is formed in response to an interaction between a target optical spectrum ...

K. Merkel M. Tian T. Chang W. R. Babbitt

2005-01-01

165

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

PubMed

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

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

166

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

NASA Astrophysics Data System (ADS)

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

Livingston, Kenneth

2005-08-01

167

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

NASA Astrophysics Data System (ADS)

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

Enoch, Jay M.

2009-08-01

168

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

169

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

170

Optical multichannel analyzer techniques for high resolution optical spectroscopy  

SciTech Connect

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

Chao, J.L.

1980-06-01

171

Transport and optical gaps and energy band alignment at organic-inorganic interfaces  

NASA Astrophysics Data System (ADS)

The transport and optical band gaps for the organic semiconductor tin (II) phthalocyanine (SnPc) and the complete energy band profiles have been determined for organic-inorganic interfaces between SnPc and III-V semiconductors. High throughput measurement of interface energetics over timescales comparable to the growth rates was enabled using in situ and real-time photoelectron spectroscopy combined with Organic Molecular Beam Deposition. Energy band alignment at SnPc interfaces with GaAs, GaP, and InP yields interface dipoles varying from -0.08 (GaP) to -0.83 eV (GaAs). Optical and transport gaps for SnPc and CuPc were determined from photoelectron spectroscopy and from optical absorption using spectroscopic ellipsometry to complete the energy band profiles. For SnPc, the difference in energy between the optical and transport gaps indicates an exciton binding energy of (0.6 +/- 0.3) eV.

Evans, D. A.; Vearey-Roberts, A. R.; Roberts, O. R.; Williams, G. T.; Cooil, S. P.; Langstaff, D. P.; Cabailh, G.; McGovern, I. T.; Goss, J. P.

2013-09-01

172

Anisotropy of the optical conductivity and infrared-active optical phonons in magnetically aligned single wall carbon nanotubes  

NASA Astrophysics Data System (ADS)

We investigated effective dielectric function of the samples with aligned single wall carbon nanotubes (SWNT) in the far infrared frequency range between 50 and 4000 cm-1. A combination of the Fourier-transform infrared (FT-IR) ellipsometry and synchrotron radiation of the U10A and U2B beamlines at the National Synchrotron Light Source, Brookhaven National Laboratory, has been utilized. Anisotropy of the both real and imaginary parts of the effective dielectric function of the SWNT has been observed. In the far infrared spectral range, the optical conductivity along the direction of the nanotubes is about 5 times higher than that for the perpendicular direction. The investigated samples revealed metallic behavior at room temperature, while at low temperatures the samples became more insulating. A formation of an infrared optical gap in the optical conductivity in the region between 200 and 300 cm-1 have been detected at low temperature. Spectral features related to the IR-active optical phonons have been measured at about 1630 cm-1.

Sirenko, A. A.; Eklund, P. C.; Bernhard, C.; Holden, Todd; Homes, C.; Marinkovic, N.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2001-03-01

173

Optical stimulation of the prostate nerves: A potential diagnostic technique  

NASA Astrophysics Data System (ADS)

There is wide variability in sexual potency rates (9--86%) after nerve-sparing prostate cancer surgery due to limited knowledge of the location of the cavernous nerves (CN's) on the prostate surface, which are responsible for erectile function. Thus, preservation of the CN's is critical in preserving a man's ability to have spontaneous erections following surgery. Nerve-mapping devices, utilizing conventional Electrical Nerve Stimulation (ENS) techniques, have been used as intra-operative diagnostic tools to assist in preservation of the CN. However, these technologies have proven inconsistent and unreliable in identifying the CN's due to the need for physical contact, the lack of spatial selectivity, and the presence of electrical artifacts in measurements. Optical Nerve Stimulation (ONS), using pulsed infrared laser radiation, is studied as an alternative to ENS. The objective of this study is sevenfold: (1) to develop a laparoscopic laser probe for ONS of the CN's in a rat model, in vivo; (2) to demonstrate faster ONS using continuous-wave infrared laser radiation; (3) to describe and characterize the mechanism of successful ONS using alternative laser wavelengths; (4) to test a compact, inexpensive all-single-mode fiber configuration for optical stimulation of the rat CN studies; (5) to implement fiber optic beam shaping methods for comparison of Gaussian and flat-top spatial beam profiles during ONS; (6) to demonstrate successful ONS of CN's through a thin layer of fascia placed over the nerve and prostate gland; and (7) to verify the experimentally determined therapeutic window for safe and reliable ONS without thermal damage to the CN's by comparison with a computational model for thermal damage. A 5.5-Watt Thulium fiber laser operated at 1870 nm and two pigtailed, single mode, near-IR diode lasers (150-mW, 1455-nm laser and 500-mW, 1550-nm laser) were used for non-contact stimulation of the rat CN's. Successful laser stimulation, as measured by an intracavernous pressure (ICP) response in the penis, was achieved with the laser operating in CW mode. CW optical nerve stimulation provides a significantly faster ICP response time using a lower laser power laser than conventional pulsed stimulation. An all-single-mode fiber design was successfully tested in a rat model. The CN reached a threshold temperature of ˜ 42 °C, with response times as short as 3 s, and ICP responses in the rat penis of up to 50 mmHg compared to a baseline of 5--10 mmHg. Chemical etching of the distal single-mode-fiber tip produced a concave shape and transformed the Gaussian to a flat-top spatial beam profile, resulting in simplified alignment of the laser beam with the nerve. This novel, all-single-mode-fiber laser nerve stimulation system introduces several advantages including: (1) a less expensive and more compact ONS configuration; (2) elimination of alignment and cleaning bulk optical components; and (3) improved spatial beam profile for simplified alignment. For the fascia layers over the CN's (240--600 microm), the 1550 nm laser with an optical penetration depth of ˜ 930 microm in water was substituted for the 1455 nm laser. Successful ONS was achieved, for the first time, in fascia layers up to 450 microm thick which is critical for future clinical translation of this method for intra-operative identification and preservation of CN's during prostate cancer surgery. In order to define the upper limit of the therapeutic window for ONS of CN in a rat model, in vivo, identification of the thermal damage threshold for the CN after laser irradiation was investigated by direct comparison of the visible thermal damage data with a theoretical thermal damage calculation utilizing a standard Arrhenius integral model.

Tozburun, Serhat

174

A diffraction technique to investigate the orientational alignment of anisotropic particles: studies of clay under flow  

NASA Astrophysics Data System (ADS)

Measurement of the orientation distribution of anisotropic particles is of considerable interest. The free energy of such materials depends strongly on the relative orientation of the particles and will effect the order-to-disorder transitions associated with liquid-crystal phases and alignment under the influence of external fields. This paper illustrates the use of a diffraction technique that measures the full orientation distribution of anisotropic crystalline particles in a fluid. Neutron diffraction data for dispersions of plate-like particles in pipe flow are presented and the changes in orientational order with flow and shape are described. This technique gives data about orientation which is decoupled from effects of both inter-particle order and the shape of the particles. Wider applications of this method, which provides order parameters for liquid crystals to arbitrary high order, are discussed.

Clarke, S. M.; Rennie, A. R.; Convert, P.

1996-07-01

175

Redesign of the image processing techniques used for the alignment of the LMJ amplifier section  

NASA Astrophysics Data System (ADS)

The laser Megajoule (LMJ) project was launched in 1995 by the French Atomic Energy Commission and is aimed at developing a facility to achieve inertial confinement fusion. The LMJ architecture is based on 176 laser beamlines. To provide these 176 high-powered beams when required for subsequent operations, one of the main issues consists in reliably aligning the laser amplifier sections. This paper provides an overview of the image processing techniques developed to identify and measure the beam centering and pointing directions. These techniques have been developed and tested thoroughly against sets of up to 450 images representing both nominal and extreme conditions acquired during the initiation and power rising of the Laser Integration Line (LIL). This facility is fully consistent with the LMJ requirements, a complete laser chain with 4 beamlines. After presenting the basic design principles, we focus on the demonstrated performances measured.

Hilsz, Laurent; Challois, Sylvain; Nicaise, Frédéric; Luttmann, Michel; Adolf, Alain

2010-08-01

176

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

NASA Astrophysics Data System (ADS)

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

Troxel, Michael A.; Ishak, M.

2012-01-01

177

Self-calibration technique for three-point intrinsic alignment correlations in weak lensing surveys  

NASA Astrophysics Data System (ADS)

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

Troxel, M. A.; Ishak, M.

2012-01-01

178

Passive alignment of second generation optoelectronic devices  

Microsoft Academic Search

This paper details how expanded-mode semiconductor devices and passive alignment techniques can be used to realize low-cost high-performance fiber grating laser and laser amplifier packages for future generations of optical telecommunication systems

John V. Collins; I. F. Lealman; A. Kelly; C. W. Ford

1997-01-01

179

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

180

Operational performance of the Antares alignment system  

SciTech Connect

A review of the operational performance of the alignment system for the large Antares optical system is presented. The alignment of twenty-four optical channels consisting of two hundred optical elements is verified and established as required prior to each target shot for this CO/sub 2/ laser fusion test facility. The overall system design included features such as automatic operation, data base driven controls, self calibration, provisions for initial optical alignment set up, and system aided fault location. The system approach employed two alignment stations which sequentially viewed the 24 optical channels (sectors) and could be used for prealignments and calibrations. Closed-loop operations via the computer permit rapid mirror alignments. The performance of the applied techniques and devices is evaluated and compared to the required performance specifically from the standpoint of accuracy and shot rate. Overall system performance with verification by actual target shots is presented.

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

1984-01-01

181

Probe alignment and design issues of microelectromechanical system based optical coherence tomography endoscopic imaging.  

PubMed

Endoscopic optical coherence tomography (OCT) imaging has been demonstrated using microelectromechanical system (MEMS) technology by several research groups. The focus of this work is to study how the OCT imaging performance is affected by the radius of curvature of MEMS mirrors as well as the optical alignment accuracy inside small imaging probes. The goal of this study is to provide guidance for assembly tolerance and design optimization of OCT endoscopic probes. Gaussian beam propagation is used for theoretical analysis which is confirmed by optical simulation and verified experimentally with a time-domain OCT system as well. It has been found that the OCT imaging is very sensitive to the distance from the fiber end to the gradient-index (GRIN) lens, which needs to be controlled within 0.1 mm to achieve working distance (WD) longer than 3.5 mm and lateral resolution around 25 ?m. The impact on image quality of the MEMS mirror is negligible if the radius of curvature of the mirror surface is greater than 200 mm. In addition, we studied the astigmatism introduced by cylindrical plastic tubing; the maximum astigmatism ratio is 1.1 when the WD is around 2.5 mm. PMID:24085137

Duan, Can; Sun, Jingjing; Samuelson, Sean; Xie, Huikai

2013-09-10

182

Method providing optimum optical trains alignment in a passive multi-channel fiber optic rotary joint  

NASA Astrophysics Data System (ADS)

A method is disclosed for use in the fabrication of a passive multichannel optical fiber rotary joint having an axis of rotation and of the type in which optical fiber communication channels are coupled via bilaterally symmetrically disposed miniature collimation lenses as collimated beams to one and the other sides of an image derotation prism and prism rotational drive assembly prism which rotates at a predetermined ratio of the relative rotation of the sides of the rotary joint to derotate optical propagation paths across the transverse rotary interface associated with the respective ones of the miniature collimation lenses. Each channel at each side of the rotary joint includes a fiber and lens junction at which a ferrule encased fiber termination couples to the axially outwardly disposed face of the miniature collimation lens. A lens array holding piece serves as the mount for this junction. Each array piece is provided with a locality of axial engagement at the adjacent side of the image derotation prism of the image derotation prism and prism rotational drive subassembly.

Ames, Gregory H.

1993-12-01

183

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

NASA Astrophysics Data System (ADS)

The weak lensing signal (cosmic shear) has been shown to be contaminated by correlations between the intrinsic alignment (IA) of galaxies, which poses a barrier to precision weak lensing measurements in planned surveys. We review recent work to extend the self-calibration approach to the cosmic shear bispectrum. The 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. We outline the proposed self-calibration techniques for the 3-point cosmic shear auto- and cross-correlations and summarize their performance. Using conservative estimates of photo-z accuracy, we find that planned surveys will be able to measure the IA redshift separation dependence over ranges of |?z^P|<=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 on the cosmic shear signal.

Troxel, Michael; Ishak, Mustapha

2012-10-01

184

Use of the Abbe sine condition to quantify alignment aberrations in optical imaging systems  

NASA Astrophysics Data System (ADS)

Violation of Abbe's sine condition is well-known to cause coma in axisymmetric imaging systems, and generally any offense against the sine condition (OSC) will cause aberrations that have linear dependence on the field angle. A well-corrected imaging system must obey the Abbe sine condition. A misaligned optical system can have particular forms of the OSC which are evaluated here. The lowest order non-trivial effects of misalignment have quadratic pupil dependence which causes a combination of astigmatism and focus that have linear field dependence. Higher order terms can arise from complex systems, but the effects of misalignment are nearly always dominated by the lowest order effects which can be fully characterized by measuring images on axis and the on-axis offense against the sine condition. By understanding the form of the on-axis images and the OSC, the state of alignment can be determined.

Burge, James H.; Zhao, Chunyu; Lu, Sheng Huei

2010-07-01

185

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

SciTech Connect

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

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

2005-10-27

186

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

187

Application of adaptive Kalman filter technique in initial alignment of strapdown inertial navigation system  

Microsoft Academic Search

In order to improve the alignment precision and convergence speed of strap-down inertial navigation system, an initial alignment method based on Sage-Husa adaptive filter is presented. We also derived the exactitude alignment error model and adaptive Kalman filter equation in the azimuth of small misalignment angle. As usual, known the noise statistical characteristics, Kalman filter is suitable; but in the

Huang Chunmei; Su Wanxin; Liu Peiwei; Ma Minglong

2010-01-01

188

Nova laser alignment control system  

SciTech Connect

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

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

1984-03-29

189

Role of dopants on the electro-optic effect in nematic liquid crystals aligned with doped polypyrrole  

NASA Astrophysics Data System (ADS)

In order to estimate electro-optical response times, measurements of the transmitted light intensity through positive uniaxial nematic thin films in planar alignment have been performed. Very fast relaxation times were experimentally found for nematic samples aligned with conductive polymers, namely, polypyrrole doped with 5 types of anions having different molecular sizes and geometries. Using undoped polypyrrole alignment layers, slower electro-optical responses were obtained. Given that the improvement in the relaxation times is induced by the presence of the anions in the polypyrrole films, the increasing of the total restoring torque of the nematic molecules to the confining surfaces--responsible for the short relaxation times--is related to the charges accumulated at the nematic-conductive polymer interface.

Raicopol, Matei; Dascalu, Constanta; Atasiei, Ruxandra; Ionescu, Andrei Th

2011-06-01

190

Realization of reliable GaN nanowire transistors utilizing dielectrophoretic alignment technique  

NASA Astrophysics Data System (ADS)

We have utilized dielectrophoretic force for assembling long (50 ?m to 200 ?m) GaN nanowires for device fabrication. These catalyst-free nanowires were grown by direct reaction of NH3 and Ga, which resulted in free-standing nanowires along with GaN microplatelets. GaN nanowires were suspended in a solvent using sonication, and using dielectrophoretic forces nanowires were assembled on prepatterned substrates (SiO2 coated Si and sapphire). With fabrication sequence using batch fabrication processes such as standard photolithography, etching, and oxide deposition we were able to realize stable GaN nanowire devices. The present technique is potentially compatible with complementary metal-oxide semicondoctor technology, and integrating nanodevices with conventional Si microelectronics on the same chip can be made possible with this technique. Utilizing this technique, high mobility (230 cm2 V-1 s-1) GaN nanowire field effect transistors with reliable electrical characteristics have been achieved. These nanowire transistors even after prolonged period of conduction exhibited no deteriorations of their electrical properties. Several key factors in the processing that affect the device yield and reliability have been identified. Simple calculations predicted the effects of nanowire geometry, dispersing solvent, and alignment frequency on the dielectrophoretic force experienced by the nanowires.

Motayed, Abhishek; He, Maoqi; Davydov, Albert V.; Melngailis, John; Mohammad, S. N.

2006-12-01

191

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

192

Optical switching: switch fabrics, techniques, and architectures  

Microsoft Academic Search

The switching speeds of electronics cannot keep up with the transmission capacity offered by optics. All-optical switch fabrics play a central role in the effort to migrate the switching functions to the optical layer. Optical packet switching provides an almost arbitrary fine granularity but faces significant challenges in the processing and buffering of bits at high speeds. Generalized multiprotocol label

Georgios I. Papadimitriou; Chrisoula Papazoglou; Andreas S. Pomportsis

2003-01-01

193

Spectroelectrochemistry: The Combination of Optical and Electrochemical Techniques.  

ERIC Educational Resources Information Center

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

Heineman, William R.

1983-01-01

194

Spectroelectrochemistry: The Combination of Optical and Electrochemical Techniques.  

ERIC Educational Resources Information Center

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

Heineman, William R.

1983-01-01

195

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

196

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

197

Optical inspection techniques for security instrumentation  

NASA Astrophysics Data System (ADS)

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

van Renesse, Rudolf L.

1996-03-01

198

Antares beam-alignment-system performance  

Microsoft Academic Search

The beam alignment system for the 24-beam-sector Antares CO2 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

Q. D. Appert; S. C. Bender

1983-01-01

199

Computational modeling techniques in charged-particle optics  

NASA Astrophysics Data System (ADS)

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 analysis; treatment of asymmetry errors in construction and alignment of electron lenses, using perturbation methods; analysis of electrostatic and magnetic deflection fields by finite difference, boundary integral and finite element methods; design of complete electron and ion beam columns containing arbitrary combinations of lenses and deflectors; simulation of discrete Coulomb interaction effects and diffraction effects; 3D simulation of fields and trajectories in secondary electron detectors for topographic and voltage contrast; design of electron sources, using second-order finite element method; design and aberration analysis of curved axis systems, such as imaging energy filters, using wavefront aberrations; and the dynamic correction of deflection aberrations in high- performance scanning systems. All the examples presented in the paper have been run and plotted on a personal computer system.

Munro, Eric

1993-09-01

200

Antares beam-alignment-system performance  

NASA Astrophysics Data System (ADS)

The beam alignment system for the 24-beam-sector Antares CO2 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 CO2 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.

201

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

202

Field validation of optical turbulence lidar technique  

NASA Astrophysics Data System (ADS)

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

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

2005-05-01

203

Aligning and attaching a lens to an optical fiber using light pressure force  

NASA Astrophysics Data System (ADS)

We demonstrate two simple and inexpensive methods of using the force exerted by the light transmitted through an optical fiber to center a lens on the fiber core, with submicron accuracy. By choosing the appropriate lens one can either focus, collimate, or defocus the light emerging from the fiber. We discuss extensions of this technique to a wider variety of lenses and light sources, including semiconductor lasers.

Mervis, J.; Bloom, A. H.; Bravo, G.; Mills, L.; Zarinetchi, F.; Prentiss, M.; Smith, S. P.

1993-03-01

204

Principles and techniques of optical data storage  

Microsoft Academic Search

We review the field of optical data storage and describe the various technologies that either are in use today or are likely to play a role in the near future. Our emphasis will be on optical-disk and holographic optical storage

MASUD MANSURIPUR; GLENN SINCERBOX

1997-01-01

205

Fabrication of optical switch arrays with auto-aligning fibers and latching micromirrors  

NASA Astrophysics Data System (ADS)

This paper presents an innovative device for self-parking in a v-groove and a self-latching vertical mirror on the suspension diaphragm using the out of plane fiber-optical switch array technique. The self-parking offers integrating the optical fiber and mirror within the same optical switch. The self-latching vertical mirror is supported on the suspension diaphragm by four cantilever beams. The theoretical analysis includes a dynamic simulation using the ANSYS software and corner compensation using the IntelliCAD software. The fabrication process consists of wet etching mircromachining, lithography, and excimer laser ablation. This proposed process is simpler than those proposed in other works. An electrostatic driving voltage is used to operate the optical switch. The mirror is made of a photoresist coating with gold film as the switching element. The reflectivity of the gold film mirror is higher than 85% using a wavelength of 1310nm. The micro-optical switch has a maximum of displacement of 48 micrometers and the switching time is below 0.4 ms with a driving voltage of 100 VDC.

Yang, Hsiharng; Pan, Chengtang; Shen, S. C.

2002-04-01

206

An Automatic Alignment Procedure for a Four-Source Photometric Stereo Technique Applied to Scanning Electron Microscopy  

Microsoft Academic Search

This paper presents an automatic alignment procedure for a four-source photometric stereo (PS) technique for reconstructing the depth map in the scanning electron microscope (SEM). PS, which is based on the so-called reflectance map, used several images of a surface to estimate the surface depth at each image point, in which the Lambertian reflectivity function is the simplest. In the

Ruggero Pintus; Simona Podda; Massimo Vanzi

2008-01-01

207

Surface diffusion studies by optical diffraction techniques  

SciTech Connect

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

Xiao, X.D.

1992-11-01

208

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

209

Use of field aberrations in the alignment of the Large Binocular Telescope optics  

NASA Astrophysics Data System (ADS)

It is now well-known that measurement of field-aberration, and in particular the asymmetric field-astigmatism, is required to break the degeneracy of tip-induced and de-centre-induced aberration that exists when only on-axis misalignment aberrations are considered. This paper discusses the application of the measurement of field-aberrations to the alignment of LBT optics. This application ranges from the use of wide field out-of-focus images to determine corrector tip for the red and blue prime-focus correctors, to the use of data acquired by off-axis Shack-Hartman wavefront sensors to actively reposition the hexapod-mounted primary and secondary mirrors so as to simultaneously remove both de-centre and tip/tilt such that the only remaining field-astigmatism has rotational symmetry about the centre of the detector. Also introduced is a novel method to calculate the misalignment aberrations based on an extension of the plate-diagram analysis. It is shown that this method is readily applicable to the calculation of misalignment aberrations for systems of three-or-more powered mirrors, with almost no more computational difficulty than that of the two-mirror case. Results are discussed, as well as work in progress in this area.

Rakich, A.; Hill, J. M.; Biddick, C. J.; Miller, D. L.; Leibold, T.

2008-08-01

210

Antares automatic beam alignment system  

SciTech Connect

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

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

1980-01-01

211

Quantitative optical techniques for dense sprays investigation: A survey  

Microsoft Academic Search

The experimental study of dense sprays by optical techniques poses many challenges and no methods have proven to be completely reliable when accurate quantitative data are required, for example to validate breakup models and CFD simulations. The present survey is aimed to a critical analysis of optical techniques capable to provide quantitative and reliable data in dense sprays and to

A. Coghe; G. E. Cossali

2012-01-01

212

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

PubMed

We demonstrate self-aligned and high-performance liquid crystal (LC) systems doped with 1-dimensional (1D) chain-like clusters of CuInS(2) (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 (V(th)) and a 36.6% decrease in the response time were observed for ECB mode LCDs, and a 47.0% reduction in the V(th) 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. PMID:23142966

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

2012-11-12

213

Ultralong quantum optical data storage using an optical locking technique  

Microsoft Academic Search

Several types of quantum memory protocols have been presented over the last ten years, including photon echoes, off-resonant Raman scattering, ultraslow light-based quantum mapping processes and resonant Raman optical echoes. These quantum optical memory protocols are limited by a storage time on a scale as short as milliseconds, determined by the spin phase decay time of the storage medium. For

Byoung S. Ham

2009-01-01

214

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

215

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

216

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

217

Stability comparison between two optical refractometer techniques  

NASA Astrophysics Data System (ADS)

Two optical fibre refractometers are presented; both measure the change in refractive index of an external medium via measurement of the reflectivity of an optical fibre tip. One application of this technology lies in detection of hydrogen using palladium coatings. The first refractometer uses a single source with a probe and reference arm on separate optical fibres, while the second is a dual-wavelength system with a common path for probe and reference beam. We have characterised both systems to compare their sensitivity and long term stability to determine the most suitable configuration in terms of minimising drift and noise.

Chowdhury, S. A.; Chehura, E.; Correia, R.; Francis, D.; Hodgkinson, J.; Tatam, R. P.

2013-06-01

218

Alignment Properties of Liquid Crystal Molecules under AC and DC Voltage Application Studied by Surface Plasmon Resonance and Optical Waveguide Spectroscopy  

NASA Astrophysics Data System (ADS)

In this study, we report the evaluation of the tilt angle of liquid crystal (LC) molecules near the surface of SiO2 alignment layers and in the whole cell when AC and/or DC voltages are applied. The LC molecule 4-cyano-4'-n-pentylbiphenyl was used. The LC cell consisted of a Au (50 nm)/SiO2 (30 nm)/LC (3 ?m)/SiO2 (30 nm)/Au (100 nm) system. Surface plasmon resonance (SPR) spectroscopy and optical waveguide spectroscopy (OWS) in an attenuated total-reflection configuration were used to monitor the alignment properties of LC molecules. From the SPR/OWS angular scan properties, the profile of the tilt angle from the surface to inside the cell was obtained. Furthermore, the effect of space-charge polarization on the LC alignment properties was observed from the SPR kinetic properties. As demonstrated in this report, this technique should provide useful information for understanding the interfacial phenomena in LC displays.

Aya Ikarashi,; Akira Baba,; Kazunari Shinbo,; Keizo Kato,; Futao Kaneko,

2010-04-01

219

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

NASA Astrophysics Data System (ADS)

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 to obtain the design tolerances for both MLIAA and the imprinting process. The maximum intensity of the optical probes at the Talbot [Philos. Mag. 9, 401 (1836)] position from the fabricated MLIAA was 12 times higher than that from the aperture array without a MLA.

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

2006-06-01

220

Electro Optical Performance Characteristic of In-Plane Switching Cell Treated on Nitrogen-Doped Diamond-Like Carbon Thin Film Surfaces by Ion Beam Alignment  

NASA Astrophysics Data System (ADS)

The nematic liquid crystal (NLC) alignment capability achieved by ion beam alignment on a nitrogen-doped diamond-like carbon (NDLC) thin film was investigated. To characterize the NDLC thin film, we analyzed the obtained atomic force microscopy (AFM) images and pretilt angle. Moreover, we investigated the electro optical (EO) performance characteristics of ion-beam-aligned in-plane switching (IPS) cell with the NDLC thin film. The EO performance characteristics of the ion-beam-aligned IPS cell were observed by ion beam exposure on the NDLC thin film and compared with those of a rubbing aligned polyimide (PI) thin film. Finally, similarly prominent capacitance-voltage (C-V) characteristics were achieved in the ion-beam-aligned NDLC thin film compared with the rubbing-aligned PI thin film.

Kim, Sang-Hoon; Choi, Sung-Ho; Lee, Sang-Keuk; Ok, Chul-Ho; Hwang, Jeoung-Yeon; Kim, Byoung-Yong; Han, Jeong-Min; Kang, Dong-Hun; Han, Jin-Woo; Ryu, Je-Hwang; Jang, Jin; Seo, Dae-Shik

2007-07-01

221

Near Infrared Optical Characterization Techniques for Photonic Crystals  

Microsoft Academic Search

In this chapter we review the different techniques used for the optical characterization of photonic crystals (PhC). The chapter\\u000a is divided in three parts, the first one on optical measurement techniques based on an external light source, the second one\\u000a on techniques relying on the presence of a light source inside the PhC under investigation and the third one on

Romuald Houdré

2008-01-01

222

Phase retrieval techniques for adaptive optics.  

National Technical Information Service (NTIS)

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 al...

C. Carrano

1998-01-01

223

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

224

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

225

Optical nondestructive evaluation technique capable of predicting failure  

NASA Astrophysics Data System (ADS)

An optical interferometric nondestructive evaluation technique is introduced. Based on electronic speckle-pattern interferometry and a recent theory of plastic deformation, this technique is capable of visualizing stress concentration and predicting the location and timing of the failure of the object. The operation of the technique is demonstrated for tensile analyses of aluminum alloy samples.

Yoshida, Sanichiro J.; Pardede, M. H.; Siahaan, B.; Pardede, M.; Muhamad, I.; Sijabat, N.; Simangunsong, H.; Simbolon, T.; Adlin; Jubir; Kusnowo, A.

1999-02-01

226

A study of overlay mark robustness and enhanced alignment techniques for alignment improvement on metal layers of sub-100nm technology  

NASA Astrophysics Data System (ADS)

The rapid advancement in lithography and continuing shrink in feature dimensions demand tighter overlay tolerances for fabrication of memory circuits with higher yields (Refer to table 1 for ITRS overlay requirements). To meet tight overlay tolerances, sources of alignment errors need to be identified and corrected accurately. Alignment errors can be contributed by 3 factors; wafer induced shift (WIS), tool induced shift (TIS) and WIS-TIS interaction. WIS is introduced by wafer processing while TIS is introduced by the alignment tool (i.e. scanner or metrology). This paper introduces methods for improvement of alignment performance at layers that experience WIS. A study on mark reflectivity was done. A number of various alignment mark designs were evaluated. The most robust mark to Tungsten Chemical Mechanical Polishing (WCMP) process, based on experimental results, will be illustrated. The concept of the 'Alignment Parameter Optimizer' to select the best alignment illumination mode for each mark and the best sample shots for alignment within the wafer, taking throughput into consideration, will be discussed. A new alignment algorithm that is able to compensate for asymmetric alignment marks will also be presented in this paper. Finally, production data from a Dynamic Random Access Memory (DRAM) manufacturer with the implementation of the above-mentioned concepts will be illustrated.

Dubey, Kaushalia; Nakamura, Toru; Tanaka, Hiroshi; Hayashi, Nozomu; Egashira, Shinichi; Mishima, Kazuhiko; Mase, Tomohiro; Takeuchi, Tamio; Honda, Akihiko; Kakizaki, Takatoshi

2007-03-01

227

A novel self-aligned fabrication process for nickel-indiffused lithium niobate ridge optical waveguides  

Microsoft Academic Search

A novel self-aligned fabrication process for LiNbO3:Ni ridge waveguides has been proposed. By using the self-aligned trilayered structure composed of Ni-Ti-Si, the fabrication process is significantly simplified, and takes advantage of suppression of the unwanted planar waveguides and high-coupling efficiency to a single-mode fiber as compared to the conventional processes. Detailed investigations into the characteristics of the ridge waveguides have

Wen-Ching Chang; Chao-Yung Sue; Hung-Ching Hou; Shih-Jung Chang; Pei-Kuen Wei

1999-01-01

228

Aligning Chips Face-to-Face for Dense Capacitive and Optical Communication  

Microsoft Academic Search

We report a new method that precisely self-aligns face-to-face semiconductor chips or wafers to enable communication between the chips using electromagnetic waves. Our alignment mechanism takes advantage of miniaturized versions of two of nature's idealized shapes: an inverse pyramidal shape defined by a self-terminating wet-etch process in silicon and micro-spheres with radii accurate to submicron accuracy. This approach allows chips

John E. Cunningham; Ashok V. Krishnamoorthy; Ivan Shubin; Xuezhe Zheng; Mehdi Asghari; Dazeng Feng; James G. Mitchell

2010-01-01

229

Optical Fourier transform techniques for advanced Fourier spectroscopy systems.  

PubMed

A review of multichannel long integration time, optical Fourier transform techniques for advanced Fourier spectroscopy systems is followed by the description of a new multichannel time-integrating optical Fourier transform chirp-Z system and a discussion of its use in Fourier spectroscopy signal processing. PMID:20221177

Casasent, D; Psaltis, D

1980-06-15

230

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

231

An optical fiber based technique for continuous level sensing  

Microsoft Academic Search

An optical fiber-based technique for liquid level measurement is proposed. It is based on the power attenuation occurring in an optical fiber, immersed in a liquid, when the liquid level varies. This phenomenon is theoretically approached by using the perturbation theory, which allows information useful for the sensor design to be obtained. The experimental results confirm the theoretical forecasts and

G. Betta; L. Ippolito; A. Pietrosanto; A. Scaglione

1994-01-01

232

Construction of optical networks by virture of the IWOP technique  

Microsoft Academic Search

By mapping the classical c-number transformation in a coherent state basis onto quantum mechanical operators of Fock space and using the technique of integration within an ordered product of operators, we give a systematic prescription for obtaining Hamilton operators for N-port linear optical networks. This prescription may be extended to some nonlinear optical network systems.

Hong-yi Fan; Min Xiao

1997-01-01

233

Response Surface Methods for Spatially-Resolved Optical Measurement Techniques.  

National Technical Information Service (NTIS)

Response surface methods (or methodology), RSM, have been applied to improve data quality for two vastly different spatial ly-re solved optical measurement techniques. In the first application, modern design of experiments (MDOE) methods, including RSM, a...

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

2003-01-01

234

A fuzzy alignment approach to sizing surface cracks by the AC field measurement technique  

Microsoft Academic Search

In real world applications, one major issue with most of non-phenomenological methods is the need for a large and complete databanks. In most practical cases, it is impossible to obtain a complete and representative database that includes sufficient number of representative examples. This fact renders most of available defects and cracks databases useless. In this paper, an aligning method is

R. P. R. Hasanzadeh; S. H. H. Sadeghi; M. Ravan; A. R. Moghaddamjoo; R. Moini

2011-01-01

235

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

PubMed Central

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.

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

2013-01-01

236

Redesign of the image processing techniques used for the alignment of the LMJ amplifier section  

Microsoft Academic Search

The laser Megajoule (LMJ) project was launched in 1995 by the French Atomic Energy Commission and is aimed at developing a facility to achieve inertial confinement fusion. The LMJ architecture is based on 176 laser beamlines. To provide these 176 high-powered beams when required for subsequent operations, one of the main issues consists in reliably aligning the laser amplifier sections.

Laurent Hilsz; Sylvain Challois; Frédéric Nicaise; Michel Luttmann; Alain Adolf

2010-01-01

237

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

Microsoft Academic Search

The Megajoule laser (LMJ) project was launched in 1995 by the French Atomic Energy Commission and is aimed at developing a facility to achieve inertial confinement fusion. The LMJ architecture is based on 176 laser beamlines. To provide these 176 high-powered beams when required for subsequent operations, one of the main issues consists of aligning reliably the laser Transportation Section

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

2010-01-01

238

Optical heterodyne technique for generating and distributing microwave signals  

NASA Astrophysics Data System (ADS)

In this work we report the photonic generation of microwave signals for distributing point to point analog TV signals by using microstrip antennas. The experimental setup is based on optical heterodyne technique where two optical waves at different wavelengths are mixed and applied to a photodetector. The microwave signal obtained by using this technique is used in a wireless communication system for transmitting and receiving analog TV signals.

García-Juárez, A.; Zaldívar-Huerta, I. E.; Aguayo-Rodríguez, G.; Rodríguez-Asomoza, J.; Gómez-Colín, R.; Vera-Marquina, A.; Acosta-Enriquez, M. C.; Rojas-Hernández, A.

2010-01-01

239

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

240

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

241

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

NASA Astrophysics Data System (ADS)

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.; Raymond, M.; Bersch, E. J.; Doris, B. B.; Diebold, A. C.

2010-05-01

242

Alignment telescope for Antares  

SciTech Connect

The Antares Automatic Alignment System employs a specially designed telescope for alignment of its laser beamlines. There are two telescopes in the system, and since each telescope is a primary alignment reference, stringent boresight accuracy and stability over the focus range were required. Optical and mechanical designs, which meet this requirement as well as that of image quality over a wide wavelength band, are described. Special test techniques for initial assembly and alignment of the telescope are also presented. The telescope, which has a 180-mm aperture FK51-KZF2 type glass doublet objective, requires a boresight accuracy of 2.8 ..mu..rad at two focal lengths, and object distances between 11 meters and infinity. Travel of a smaller secondary doublet provides focus from 11 m to infinity with approximately 7.8 m effective focal length. By flipping in a third doublet, the effective focal length is reduced to 2.5 m. Telescope alignment was accomplished by using a rotary air bearing to establish an axis in front of the system and placing the focus of a Laser Unequal Path Interferometer (LUPI) at the image plane.

Appert, Q.D.; Swann, T.A.; Ward, J.H.; Hardesty, C.; Wright, L.

1983-01-01

243

Alignment telescope for Antares  

NASA Astrophysics Data System (ADS)

The Antares Automatic Alignment System employs a specially designed telescope for alignment of its laser beamlines. There are two telescopes in the system, and since each telescope is a primary alignment reference, stringent boresight accuracy and stability over the focus range were required. Optical and mechanical designs, which meet this requirements as well as that of image quality over a wide wavelength band, are described. Special test techniques for initial assembly and alignment of the telescope are also presented. The telescope, which has a 180-mm aperture FK51-KZF2 type glass doublet objective, requires a boresight accuracy of 2.8 (SIGMA)rad at two focal lengths, and object distances between 11 meters and infinity. Travel of a smaller secondary doublet provides focus from 11 m to infinity with approximately 7.8 m effective focal length. By flipping in a third doublet, the effective focal length is reduced to 2.5 m. Telescope alignment was accomplished by using a rotary air bearing to establish an axis in front of the system and placing the focus of a Laser Unequal Path Interferometer (LUPI) at the image plane.

Appert, Q. D.; Swann, T. A.; Ward, J. H.; Hardesty, C.; Wright, L.

244

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

245

Advanced Techniques for Improving Laser Optical Surfaces.  

National Technical Information Service (NTIS)

Chemical and chemical-mechanical polishing, ion-beam polishing, bowl-feed and continuously recycled abrasive 'super-polishing' techniques were evaluated for single crystal and polycrystalline potassium chloride and calcium fluoride, and polycrystalline zi...

C. B. Willingham D. P. Bua M. R. Schapira R. H. Cosgro

1975-01-01

246

Optical Diffraction Techniques for Strain Measurement.  

National Technical Information Service (NTIS)

New techniques are developed that extend the use of the diffraction grating strain gage to the measurement of axial strains when diffraction angle changes are large and that permit these integral gages to be used for measuring the circumferential strains ...

H. W. Blake H. H. Stadelmaier R. A. Douglas

1969-01-01

247

Advanced Sensor Signal Processing Using Optical Techniques.  

National Technical Information Service (NTIS)

A Fourier transform based iterative technique is presented for solution of Toeplitz and general matrix equations resulting in an algorithm for the determination of an adaptive beam steering vector from the radar covariance matrix. An associated optoelectr...

L. A. Eichel W. R. Franklin L. H. Gesell R. Kallman S. Evanko

1997-01-01

248

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

249

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

PubMed

Single-walled carbon nanotubes (SWNTs) are widely thought to be a strong contender for next-generation printed electronic transistor materials. However, large-scale solution-based parallel assembly of SWNTs to obtain high-performance transistor devices is challenging. SWNTs have anisotropic properties and, although partial alignment of the nanotubes has been theoretically predicted to achieve optimum transistor device performance, thus far no parallel solution-based technique can achieve this. Herein a novel solution-based technique, the immersion-cum-shake method, is reported to achieve partially aligned SWNT networks using semiconductive (99% enriched) SWNTs (s-SWNTs). By immersing an aminosilane-treated wafer into a solution of nanotubes placed on a rotary shaker, the repetitive flow of the nanotube solution over the wafer surface during the deposition process orients the nanotubes toward the fluid flow direction. By adjusting the nanotube concentration in the solution, the nanotube density of the partially aligned network can be controlled; linear densities ranging from 5 to 45 SWNTs/?m are observed. Through control of the linear SWNT density and channel length, the optimum SWNT-based field-effect transistor devices achieve outstanding performance metrics (with an on/off ratio of ~3.2 × 10(4) and mobility 46.5 cm(2) /Vs). Atomic force microscopy shows that the partial alignment is uniform over an area of 20 × 20 mm(2) and confirms that the orientation of the nanotubes is mostly along the fluid flow direction, with a narrow orientation scatter characterized by a full width at half maximum (FWHM) of <15° for all but the densest film, which is 35°. This parallel process is large-scale applicable and exploits the anisotropic properties of the SWNTs, presenting a viable path forward for industrial adoption of SWNTs in printed, flexible, and large-area electronics. PMID:23441038

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

2013-02-26

250

Teaching optical fiber communications and optical data storage techniques using a compact disc player  

NASA Astrophysics Data System (ADS)

The principles of optical fiber communication and optical data storage have evolved over the past decade into industry standards for transmission, distribution, storage, and archival of digital audio, multimedia, and computer data. The fundamentals of these sophisticated systems are traditionally taught in the lecture hall, and laboratory exposure to the hardware is at the device rather than the system level. In our educational approach, after the student has been introduced to the device basics, the compact disc audio player is used as a tool to teach the fundamentals of optical communication and storage. The ubiquitous compact disc audio system, from analog input, through optical storage and distribution, to audio reproduction, provides an excellent model of a complete real world optical transmission and storage system. The laboratory time is divided into three segments: Introduction to Electro- Optic Devices, Optical Storage, and Optical Communication. During the introduction, students learn the basics of emitters, detectors, and optical fiber. The optical data storage and retrieval function of the compact disc player is investigated in the second segment. Students are introduced to optical information storage techniques, information density limits, the optical pick-up, laser diodes, photodiode arrays, eye patterns, and the tracking and focusing sub-systems. In the third segment, the compact disc system is used as a model of an entire optical communication system. Students are introduced to sampling and quantization, channel encoding techniques, modulation, high-speed transmitters and receivers, demodulation, decoding, error correction, digital signal processing, and digital-to-analog conversion.

Lane, Pierre M.; van Dommelen, Ronnie F.; Cada, Michael

1997-12-01

251

Synthesis of well aligned silicon nanowire arrays by reflow of photoresist techniques  

Microsoft Academic Search

Well aligned Si nanowires (SiNWs) by Vapor-Liquid-Solid growth process are presented. Instead of using H2, the current work uses N2 as carrier gas. The growth conditions of SiNWs are controlled by the ratio of nitrogen versus silane gas. Tapering of nanowires was found at T=620degC and P=333 m torr, and the tapering parameter was reduced by increasing the N2 gas.

Chien-Wei Liu; Cheng-Yung Kuo; Chuan-Po Wang; Chie Gau; Shiuan-Hua Shiau; Bau-Tong Dai

2007-01-01

252

Recursive alignment block classification technique for word reordering in statistical machine translation  

Microsoft Academic Search

Statistical machine translation (SMT) is based on alignment models which learn from bilingual corpora the word correspondences\\u000a between source and target language. These models are assumed to be capable of learning reorderings. However, the difference\\u000a in word order between two languages is one of the most important sources of errors in SMT. In this paper, we show that SMT\\u000a can

Marta R. Costa-Jussà; José A. R. Fonollosa; Enric Monte

2011-01-01

253

Alignment validation  

SciTech Connect

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

ALICE; ATLAS; CMS; LHCb; Golling, Tobias

2008-09-06

254

Magneto-optical studies of Gd-implanted GaN: No spin alignment of conduction band electrons  

NASA Astrophysics Data System (ADS)

Gd-implanted wurtzite GaN as a candidate for a ferromagnetic dilute magnetic semiconductor is investigated by time-resolved magneto-optical spectroscopy. We observe a strong increase of the electron spin lifetimes for increasing Gd doses, while the electron spin Larmor precession frequency is independent of the Gd concentration. These findings are well explained by carrier localization at defects and a negligible interaction with Gd ions. The data show that Gd-implanted GaN cannot be used for an electron spin aligner.

Buß, J. H.; Rudolph, J.; Shvarkov, S.; Semond, F.; Reuter, D.; Wieck, A. D.; Hägele, D.

2013-08-01

255

Optical correlation technique for characterizing of rough surfaces  

Microsoft Academic Search

Summary form only. It is known that power spectral density function, (PSDF), describing inhomogeneity distribution among different spatial frequencies is considered as preferable and the most comprehensive technique. But conventional profilometric techniques for reconstruction of PSDF are rather labor- and time-consuming and are implemented using expensive measuring equipment. In the report we will consider as example a new optical correlation

O. V. Angelsky

2000-01-01

256

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

NASA Astrophysics Data System (ADS)

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

Wilkerson, Gary W.; Huegele, Vinson B.

1998-09-01

257

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

SciTech Connect

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

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

2010-09-15

258

High speed optical interrogator calibration technique  

Microsoft Academic Search

We present a novel technique for the calibration of a high speed FBG interrogation system which incorporates an Arrayed Waveguide Grating (AWG). It uses temperature tuning to wavelength sweep the AWG to generate calibration data and to determine the optimum temperature of AWG for the actual test. For ideal operation the FBG wavelengths under zero stimulus would lie midway between

David S. George; Stephen Hill; Robert I. Howden; Graham W. Smith

2009-01-01

259

Application of ELID grinding technique to precision machining of optics  

NASA Astrophysics Data System (ADS)

ELID (Electrolytic In-process Dressing) grinding is a new ultra-precision machining technique which employs in-process electrolysis to dress the metal bond diamond wheel in grinding process. In this paper, the principle of ELID grinding is introduced. An optical glass sample is ground by using cast iron bond diamond wheel and ELID technique. Tested by WYKO RST Plus, the grinding surface roughness Ra is 2.48 nm. A conclusion can be drawn that using ELID technique can realize the ultra-precision grinding of optical glass.

Zhang, Feihu; Li, Wei; Qiu, Zhongjun; Ohmori, Hitoshi

2000-10-01

260

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

261

Alignment telescope for Antares  

Microsoft Academic Search

The Antares Automatic Alignment System employs a specially designed telescope for alignment of its laser beamlines. There are two telescopes in the system, and since each telescope is a primary alignment reference, stringent boresight accuracy and stability over the focus range were required. Optical and mechanical designs, which meet this requirements as well as that of image quality over a

Q. D. Appert; T. A. Swann; J. H. Ward; C. Hardesty; L. Wright

1983-01-01

262

Optical imaging techniques in microfluidics and their applications.  

PubMed

Microfluidic devices have undergone rapid development in recent years and provide a lab-on-a-chip solution for many biomedical and chemical applications. Optical imaging techniques are essential in microfluidics for observing and extracting information from biological or chemical samples. Traditionally, imaging in microfluidics is achieved by bench-top conventional microscopes or other bulky imaging systems. More recently, many novel compact microscopic techniques have been developed to provide a low-cost and portable solution. In this review, we provide an overview of optical imaging techniques used in microfluidics followed with their applications. We first discuss bulky imaging systems including microscopes and interferometer-based techniques, then we focus on compact imaging systems that can be better integrated with microfluidic devices, including digital in-line holography and scanning-based imaging techniques. The applications in biomedicine or chemistry are also discussed along with the specific imaging techniques. PMID:22878811

Wu, Jigang; Zheng, Guoan; Lee, Lap Man

2012-10-01

263

Terrestrial optical aperture synthesis technique (TOAST)  

NASA Astrophysics Data System (ADS)

An aperture-synthetic, high-resolution imaging technique, for obtaining near diffraction-limited images from a single telescope is described. The scheme yields model-independent reconstructions of the object under study and is suitable for operation simultaneously with other observing programmes such as spectroscopic studies or speckle imaging. A specific scheme suitable for use on the 2m5 Isaac Newton Telescope is presented, which would have a magnitude limit of about -11.

Greenaway, A. H.

1986-06-01

264

Electro-optical techniques for diesel engine research  

Microsoft Academic Search

The results of research to determine the feasibility of applying electro-optical diagnostic techniques to the study of combustion phenomena in diesel engines is described and evaluated. The techniques that were investigated included: high-speed laser-augmented photography, holography, fringe techniques (laser anemometry and particle sizing), mass spectroscopy, and resonance absorption. A conventional Army TACOM diesel engine and a Turner engine were modified

A. E. Lennert; R. E. Sowls; R. A. Belz; W. H. Goethert; H. T. Bentley III; H. M. Powell; A. B. Bailey; T. D. McCay

1977-01-01

265

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

SciTech Connect

Colloid dispersions of magnetite were used at SLAC and KEK to locate multipole magnet centers. We study the 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.

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

1993-06-01

266

Synthesis and optical properties of rutile TiO2 microspheres composed of radially aligned nanorods  

Microsoft Academic Search

Rutile titania microspheres with diameters of about 2 5 mum have been synthesized by a facile hydrothermal method. The products are characterized by scanning electron microscopy, transmission electron microscope, EDXA, X-ray diffractometer, and UV Vis NIR. It is found that each microsphere is composed of radially aligned nanorods with diameters of about 100 nm and lengths of 2 mum. The

Yi Han; Guicun Li; Zhikun Zhang

2006-01-01

267

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

268

Multidimensional VCSEL-array push\\/pull module fabricated using the self-alignment mounting technique  

Microsoft Academic Search

We have developed plastic-molded receptacle-lope vertical-cavity surface-emitting laser (VCSEL)-array modules directly push\\/pull connectable with the one-dimensional (1-D) conventional mechanically-transferable multifiber push-on (MPO) fiber connector and with a new two-dimensional (2-D) MPO-compatible fiber connector developed for this module. The VCSEL was mounted on the plastic-molded package using a highly precise completely alignment-free process using flip-chip solder bonding and ball-guide die bonding.

Hideo Kosaka; Mikihiro Kajita; Yoshimasa Sugimoto

1998-01-01

269

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

270

Routing techniques in optical packet-switched networks  

Microsoft Academic Search

In the last few years research on optical packet-switching has mainly concentrated on issues at the single node level. This paper intends to discuss about the problems arising when the focus is moved towards a network-wide scope. In particular, an overview of routing techniques that may be adopted in an optical packet-switched backbone is presented, showing the effects of adaptive

Franco Callegati; Walter Cerroni; Carla Raffaelli

2005-01-01

271

Measuring polarizability anisotropies of rare gas diatomic molecules by laser-induced molecular alignment technique.  

PubMed

The polarizability anisotropies of homonuclear rare gas diatomic molecules, Ar(2), Kr(2), and Xe(2), are investigated by utilizing the interaction of the induced electric dipole moment with a nonresonant, nanosecond laser pulse. The degree of alignment, which depends on the depth of the interaction potential created by the intense laser field, is measured, and is found to increase in order of Ar(2), Kr(2), and Xe(2) at the same peak intensity. Compared with a reference I(2) molecule, Ar(2), Kr(2), and Xe(2) are found to have the polarizability anisotropies of 0.45 ± 0.13, 0.72 ± 0.13, and 1.23 ± 0.21 A?(3), respectively, where the uncertainties (one standard deviation) in the polarizability anisotropies are carefully evaluated on the basis of the laser intensity dependence of the degree of alignment. The obtained values are compared with recent theoretical calculations and are found to agree well within the experimental uncertainties. PMID:21663360

Minemoto, Shinichirou; Sakai, Hirofumi

2011-06-01

272

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

PubMed

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

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

2013-04-30

273

Highly sensitive optical measurement techniques based on acousto-optic devices.  

PubMed

An optical measurement technique is presented that permits a direct measurement of the differential transmission or reflectivity of a sample. The technique is based on the use of an acousto-optic device to modulate rapidly the incident angle or wavelength of the probe beam. Detection of the resulting modulated signal by means of a lock-in amplifier gives a direct measure of the differential optical properties of the sample. It is demonstrated that this direct measurement of the differential can strongly enhance normally undetectable optical features, such as weakly coupled, Otto geometry surface plasmon polaritons. A development of the technique, which uses the optical analog of a phase-locked loop, is demonstrated to have an angular resolution of 6 × 10(-6) deg. This permits the detection of the shift in the critical angle caused by a change of 10(-6) in the refractive index of a gas mixture. PMID:20941315

Gass, P A; Schalk, S; Sambles, J R

1994-11-01

274

Synthesis and optical properties of rutile TiO2 microspheres composed of radially aligned nanorods  

NASA Astrophysics Data System (ADS)

Rutile titania microspheres with diameters of about 2 5 ?m have been synthesized by a facile hydrothermal method. The products are characterized by scanning electron microscopy, transmission electron microscope, EDXA, X-ray diffractometer, and UV Vis NIR. It is found that each microsphere is composed of radially aligned nanorods with diameters of about 100 nm and lengths of 2 ?m. The influence of the reaction time on the morphologies of TiO2 microspheres has been investigated.

Han, Yi; Li, Guicun; Zhang, Zhikun

2006-09-01

275

Optical accelerometer based on grating interferometer with phase modulation technique.  

PubMed

In this paper, an optical accelerometer based on grating interferometer with phase modulation technique is proposed. This device architecture consists of a laser diode, a sensing chip and an optoelectronic processing circuit. The sensing chip is a sandwich structure, which is composed of a grating, a piezoelectric translator and a micromachined silicon structure consisting of a proof mass and four cantilevers. The detected signal is intensity-modulated with phase modulation technique and processed with a lock-in amplifier for demodulation. Experimental results show that this optical accelerometer has acceleration sensitivity of 619 V/g and high-resolution acceleration detection of 3 ?g in the linear region. PMID:23052079

Zhao, Shuangshuang; Zhang, Juan; Hou, Changlun; Bai, Jian; Yang, Guoguang

2012-10-10

276

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

SciTech Connect

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

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

2009-01-29

277

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

Microsoft Academic Search

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

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

2008-01-01

278

X-ray optics simulation using Gaussian superposition technique.  

PubMed

We present an efficient method to perform x-ray optics simulation with high or partially coherent x-ray sources using Gaussian superposition technique. In a previous paper, we have demonstrated that full characterization of optical systems, diffractive and geometric, is possible by using the Fresnel Gaussian Shape Invariant (FGSI) previously reported in the literature. The complex amplitude distribution in the object plane is represented by a linear superposition of complex Gaussians wavelets and then propagated through the optical system by means of the referred Gaussian invariant. This allows ray tracing through the optical system and at the same time allows calculating with high precision the complex wave-amplitude distribution at any plane of observation. This technique can be applied in a wide spectral range where the Fresnel diffraction integral applies including visible, x-rays, acoustic waves, etc. We describe the technique and include some computer simulations as illustrative examples for x-ray optical component. We show also that this method can be used to study partial or total coherence illumination problem. PMID:21996845

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

2011-09-26

279

X-ray optics simulation using Gaussian superposition technique  

SciTech Connect

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

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

2011-09-15

280

Optical Imaging Techniques for Point-of-care Diagnostics  

PubMed Central

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

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

2012-01-01

281

Vibration compensation technique for an optical current transducer  

Microsoft Academic Search

Details are presented on a technique for compensation of vibration-induced noise in an optical current transducer (OCT). The light intensity changes that result from vibration are reciprocal, i.e., their magnitude does not depend on the direction of light propagation. However, intensity changes that result from the Faraday rotation induced as the light travels through the OCT are dependent on the

Pawel Niewczas; Andrew Cruden; W. Craig Michie; W. Iain Madden; J. R. McDonald; Ivan Andonovic

1999-01-01

282

Optical Techniques for the Generation of Microlens Arrays  

Microsoft Academic Search

A technique is described for the manufacture of regular closely packed arrays of very small lenses of good optical quality. Hexagonal fringes from three-beam interference are first recorded in photoresist to produce a hexagonal array of quasi-cylindrical lenses. These are then used to image a point source of light into an array of narrow lines, which are recorded in photoresist

M. C. Hutley

1990-01-01

283

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

284

Evaluation of optical reflectance techniques for imaging of alveolar structure  

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

285

Can optical remote sensing techniques detect air contaminants?  

Microsoft Academic Search

The American Petroleum Institute (API) is sponsoring a program to evaluate if and how optical remote sensing techniques can be used to detect air contaminant emissions at a processing facility. This study is also gathering database information to assess whether dispersion modeling accurately depicts air plume migrations within a petrochemical site. In early 1995, an initial field study was conducted

R. J. Paine; J. O. Zwicker; H. J. Feldman

1998-01-01

286

Evaluation of optical reflectance techniques for imaging of alveolar structure.  

PubMed

Three-dimensional (3-D) visualization of the fine structures within the lung parenchyma could advance our understanding of alveolar physiology and pathophysiology. Current knowledge has been primarily based on histology, but it is a destructive two-dimensional (2-D) technique that is limited by tissue processing artifacts. Micro-CT provides high-resolution three-dimensional (3-D) imaging within a limited sample size, but is not applicable to intact lungs from larger animals or humans. Optical reflectance techniques offer the promise to visualize alveolar regions of the large animal or human lung with sub-cellular resolution in three dimensions. Here, we present the capabilities of three optical reflectance techniques, namely optical frequency domain imaging, spectrally encoded confocal microscopy, and full field optical coherence microscopy, to visualize both gross architecture as well as cellular detail in fixed, phosphate buffered saline-immersed rat lung tissue. Images from all techniques were correlated to each other and then to corresponding histology. Spatial and temporal resolution, imaging depth, and suitability for in vivo probe development were compared to highlight the merits and limitations of each technology for studying respiratory physiology at the alveolar level. PMID:22894464

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

2012-07-01

287

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

SciTech Connect

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

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

2000-03-10

288

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

SciTech Connect

Nonlinear magneto-optical rotation is investigated at high light 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{yields}F+1 transitions compared to the low light power limit. The effect is demonstrated by measurements in rubidium and density matrix calculations. The results are important for applications of nonlinear optical rotation such as sensitive magnetometry. (c) 2000 The American Physical Society.

Budker, D. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kimball, D. F. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Rochester, S. M. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States); Yashchuk, V. V. [Department of Physics, University of California at Berkeley, Berkeley, California 94720-7300 (United States)

2000-09-04

289

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

290

REVIEW ARTICLE: Scan-free optical correlation techniques: history and applications to optical coherence tomography  

NASA Astrophysics Data System (ADS)

In parallel with progress in generating ultrafast pulse sources and characterization techniques, optical time correlation techniques have seen tremendous development over many years and paved the way for novel applications in non-destructive and high resolution 'optical coherence tomography' (OCT) imaging. Amongst the known correlation techniques, the scan-free approach presents the advantage of single shot detection and real-time acquisition for pulse measurements, but this is not generally considered and applied for OCT imaging. The aim of this paper is to review the scan-free correlation method, analyze its performance and extended features and discuss its application to OCT.

Froehly, Luc; Leitgeb, Rainer

2010-08-01

291

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

292

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

293

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

SciTech Connect

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

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

2010-09-15

294

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

295

Simulation tools for advanced mask aligner lithography  

Microsoft Academic Search

Contact- and proximity lithography in a Mask Aligner is a very cost effective technique for photolithography, as it provides a high throughput and very stable mature processes for critical dimensions of typically some microns. For shadow lithography, the printing quality depends much on the proximity gap and the properties of the illumination light. SUSS MicroOptics has recently introduced a novel

Arianna Bramati; Uwe Vogler; Balint Meliorisz; Kristian Motzek; Michael Hornung; Reinhard Voelkel

2011-01-01

296

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

Microsoft Academic Search

A great deal segmented mirror errors consisting of piston and tip-tilt exist when space large aperture segmented optics system deploys. These errors will result in the departure of segmented mirrors images from the view. For that, proper scanning function should be adopted to control actuators rotating the segmented mirror, so that the images of segmented mirror can be put into

Xiaofang Zhang; Xin Yu; Xia Wang; Lei Zhao

2008-01-01

297

All-optical label processing techniques for pure DPSK optical packets  

Microsoft Academic Search

We present two all-optical label processing schemes for pure differential phase shift keying packets. The two techniques are based on the already used optical correlators and on a novel time-to-wavelength conversion of the label information. They require that the label information is encoded by using pulse position modulation, which makes the label processor simpler and can allow very fast processing

Nicola Calabretta; Giampiero Contestabile; Antonio D'Errico; Ernesto Ciaramella

2006-01-01

298

Optical modulation techniques for underwater detection, ranging and imaging  

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

299

A new optical technique for probing clear air turbulence  

NASA Astrophysics Data System (ADS)

A new optical technique for probing the small scales turbulence has been developed. When light is transmitted through the atmosphere, it can scatter off vortex filaments in the air that are at different densities from the surrounding air, and hence, have different indices of refraction. These filaments, or eddies are distributed through a turbulent flow. Our experiment illuminated a turbulent flow with an expanded Gaussian laser beam. Two detectors, capable of translation perpendicular to the beam path, observed intensity fluctuations at different points. By analysis of two point spatial transmission correlation functions, the smallest length scales of clear air turbulence can be determined in real time without disturbing the flow. By changing the type of air flow, different length scales associated with different conditions have been measured optically. The measured scales agree with measurements done by hotwire techniques and correspond to the Kolmogorov microscale.

Harris, Joseph Daniel

300

Optical techniques for the intraoperative assessment of nodal status.  

PubMed

The lymphatic system is an important pathway in the metastatic spread of many malignancies and a key prognostic indicator. Nondestructive assessment of the nodal status during surgery could limit the amount of lymph nodes that need to be resected and allow for immediate regional lymphadenectomy during sentinel lymph node biopsy procedures. This review looks into the possibilities of conventional medical imaging methods that are capable of intraoperative nodal assessment and discusses multiple newly developed optical techniques. The physical background behind these techniques is reviewed and a concise overview of their main advantages and disadvantages is provided. These recent innovations show that while the application of optical modalities for intraoperative nodal staging is not yet applied routinely, there is reason enough to expect their introduction in the near future. PMID:24156334

Grootendorst, Diederik J; Steenbergen, Wiendelt; Manohar, Srirang; Ruers, Theo Jm

2013-11-01

301

10-channel fiber array fabrication technique for parallel optical coherence tomography system  

NASA Astrophysics Data System (ADS)

Optical Coherence Tomography (OCT) shows great promise for low intrusive biomedical imaging applications. A parallel OCT system is a novel technique that replaces mechanical transverse scanning with electronic scanning. This will reduce the time required to acquire image data. In this system an array of small diameter fibers is required to obtain an image in the transverse direction. Each fiber in the array is configured in an interferometer and is used to image one pixel in the transverse direction. In this paper we describe a technique to package 15?m diameter fibers on a siliconsilica substrate to be used in a 2mm endoscopic probe tip. Single mode fibers are etched to reduce the cladding diameter from 125?m to 15?m. Etched fibers are placed into a 4mm by 150?m trench in a silicon-silica substrate and secured with UV glue. Active alignment was used to simplify the lay out of the fibers and minimize unwanted horizontal displacement of the fibers. A 10-channel fiber array was built, tested and later incorporated into a parallel optical coherence system. This paper describes the packaging, testing, and operation of the array in a parallel OCT system.

Arauz, Lina J.; Luo, Yuan; Castillo, Jose E.; Kostuk, Raymond K.; Barton, Jennifer

2007-03-01

302

Optical Analyzer Technique for Spall Investigations in Metal Plates  

SciTech Connect

Possible experimental set-up for investigation of the stage of spalls closing in plates before impact on base plate are considered. Multi-wave configurations in indicator-matter situated on the base plate are observed by optical analyzer technique. Oscillograms and results of their processing are presented. Thickness and average density of the spall layer in the plate immediately before its impact on the base plate are estimated.

Kovalenko, G. V.; Kozlov, E. A.; Nogin, V. N.; Pankratov, D. G.; Yakunin, A. K. [Federal State Unitary Enterprise 'Russian Federal Nuclear Center - Zababakhin All-Russia Research Institute of Technical Physics', 456770, Snezhinsk, Chelyabinsk region (Russian Federation)

2006-08-03

303

An optical phase amplification technique for interrogating fiber resonator sensors  

Microsoft Academic Search

We describe a technique for the effective amplification of small phase changes induced by cavity perturbations of a resonant fiber-optic sensor. The scheme utilizes an unbalanced two-beam “read-out” interferometer to monitor weak frequency shifts in a laser source locked to the resonant sensor. Results are presented using a fiber ring resonator sensor and Mach-Zehnder read-out interferometer with a system phase

K. P. Koo; A. D. Kersey

1995-01-01

304

Optical phase amplification technique for interrogating fiber resonator sensors  

Microsoft Academic Search

We describe a technique for the effective amplification of small phase changes induced by cavity perturbations of a resonant fiber-optic sensor. The scheme utilizes an unbalanced two-beam 'read-out' interferometer to monitor weak frequency shifts in a laser source locked to the resonant sensor. Results are presented using a fiber ring resonator sensor and Mach-Zehnder read-out interferometer with a system phase

K. P. Koo; A. D. Kersey

1995-01-01

305

Alignment and Performance Considerations for Capacitive, Inductive, and Optical Proximity Communication  

Microsoft Academic Search

We present a comparative analysis of different physical approaches to chip-to-chip proximity communication, PxC, based on capacitive, inductive and optical signalling. Each method is modeled theoretically and the tolerances for packaging are identified. Analytical formulas for performance in terms of the pad size and pad spacing are derived and compared to reported experimental data. The tolerance of each communication method

Arka Majumdar; John E. Cunningham; Ashok V. Krishnamoorthy

2010-01-01

306

Diffractive optics development with stack-and-draw technique  

NASA Astrophysics Data System (ADS)

We present a novel approach to the fabrication of diffractive optical elements. Unlike traditional diffractive optical elements, the different phase shifts are obtained through a refractive index variation by using different types of glass. This approach results in a completely flat element which is easy to integrate with other optical components. For fabrication of the test DOE structures we have used the stack-and-draw technique. This method, which was originally developed for the fabrication of photonic crystal fibres, has been modified to allow the fabrication of nanostructured micro-optical components. In this paper we present the results from proof of concept periodic checkerboards fabricated on a square and hexagonal lattice with feature sizes of 8?m and 46?m. The components were fabricated from two types of rods made of the low refractive index silicate glass and the high refractive index of lead-silicate glass. The measured characteristics of the fabricated components are presented The influence of fabrication-induced structure distortions on the optical performance of the components is discussed.

Nowosielski, J. M.; Filipkowski, A.; Waddie, A. J.; Kujawa, I.; Stepien, R.; Buczynski, R.; Taghizadeh, M. R.

2012-05-01

307

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 natural frequency, changes in the modulus of elasticity can be monitored. The technique is demonstrated by monitoring the elastic property changes of a beam fabricated from copper, as the copper undergoes recrystallization at elevated temperature.

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

2012-07-01

308

Optical fiber technique for in-reactor mechanical properties measurement  

NASA Astrophysics Data System (ADS)

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.; Hua, Z. A.

2013-01-01

309

An Optical Transimpedance Amplifier Using an Inductive Buffer Stage Technique  

NASA Astrophysics Data System (ADS)

An inductive buffer peaking technique is proposed and demonstrated to extend the bandwidth of a 10-Gbit/s transimpedance amplifier (TIA) for optical communications. A TIA using this peaking technique is fabricated based on InGaP/GaAs HBT technology. The advantage of the proposed technique is verified by comparisons based on simulations and experiments. For these comparisons, three different types of TIAs using a basic gain stage, a shunt peaking gain stage and the proposed gain stage, respectively, are fabricated and measured. The measured performance of the proposed TIA shows that this bandwidth extension technique using inductive buffer peaking can be applied to circuit designs which demand wideband frequency response with low power consumption.

Park, Sang Hyun; Le, Quan; Choi, Bo-Hun

310

Nonlinear optical Fourier filtering technique for medical image processing.  

PubMed

Real-time nonlinear optical Fourier filtering for medical image processing is demonstrated, exploiting light modulating characteristics of thin films of the biophotonic material bacteriorhodopsin (bR). The nonlinear transmission of bR films for a 442 nm probe beam with a 568 nm control beam and vice versa is experimentally studied in detail. The spatial frequency information carried by the blue probe beam is selectively manipulated in the bR film by changing the position and intensity of the yellow control beam. The feasibility of the technique is first established with different shapes and sizes of phantom objects. The technique is applied to filter out low spatial frequencies corresponding to soft dense breast tissue and displaying only high spatial frequencies corresponding to microcalcifications in clinical screen film mammograms. With the aid of an electrically addressed spatial light modulator (SLM), we successfully adapt the technique for processing digital phantoms and digital mammograms. Unlike conventional optical spatial filtering techniques that use masks, the technique proposed can easily accommodate the changes in size and shape of details in a mammogram. PMID:16178661

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

311

Superpenetration optical microscopy by iterative multiphoton adaptive compensation technique  

PubMed Central

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

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

2012-01-01

312

Thickness-modulated optical dielectric constants and band alignments of HfO{sub x}N{sub y} gate dielectrics  

SciTech Connect

Thickness-modulated optical dielectric constants and band alignments of HfO{sub x}N{sub y} films grown by sputtering have been investigated by spectroscopic ellipsometry (SE) and x-ray photoelectron spectroscopy. Based on SE measurements, it has been noted that an increase in optical dielectric constant and band gap has been observed as a function of the film thickness. Analyses of thickness-dependent band alignment of the HfO{sub x}N{sub y}/Si system indicate that the valence band offset increases, but only slight change in the conduction band offset, resulting from the thickness-induced change in the structure. The suitable optical dielectric constants and band offsets relative to Si make sputtering-derived HfO{sub x}N{sub y} film a promising candidate for high-k gate dielectrics.

He, G.; Zhang, L. D.; Liu, M.; Zhang, J. P.; Wang, X. J. [Key Laboratory of Materials Physics, Anhui Key Laboratory of Nanomaterials and Nanostructure, Institute of Solid State Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zhen, C. M. [Department of Physics, Hebei Advanced Thin Films Laboratory, Hebei Normal University, Shijiazhuang 050016 (China)

2009-01-01

313

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

PubMed Central

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

2013-01-01

314

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

PubMed

BACKGROUND: Widely used rod rotation and translation techniques for idiopathic scoliosis (IS) are effective in correcting spinal coronal deformity. Bilateral apical vertebral derotation technique by vertebral column manipulation (VCM) and vertebral coplanar alignment (VCA) technique are two strategies for three-dimensional (3D) correction for IS. The purpose of this study is to compare the post-surgical results and technical features of the bilateral apical vertebral derotation technique by VCM against the VCA technique in patients with Lenke type 1 IS. METHODS: Forty-eight patients with Lenke type 1 IS were enrolled in the present prospective clinical assay. They were divided into groups A (bilateral apical vertebral derotation technique by VCM, n=24) and B (VCA technique, n=24). Radiographic parameters measured before and after surgery included the Cobb angle, thoracic kyphosis, and apical vertebral rotation. Scoliosis Research Society (SRS)-22 scores were evaluated during the final follow-up. The differences in the demographics, surgical details, and radiographic measurements between the two groups were determined using a T test. The Mann--Whitney U test was used to evaluate the differences in the SRS-22 scores. A value of P<0.05 was considered statistically significant. RESULTS: In the coronal plane, a significant difference was found in the correction rate of the major curve (group A: 84.8%, group B: 78.4%; P=0.045) and in the Cincinnati Correction Index between two groups (group A: 2.21, group B: 1.98; P=0.047). In the sagittal plane, no difference was found in the postoperative thoracic kyphosis between the two groups (P=0.328). In the transverse plane, no difference was found between the two groups in the correction rates of the rotation angle sagittal (P=0.298), rib hump (P=0.934), apical vertebral body-to-rib ratio (P=0.988), or apical rib spread difference (P=0.184). Patients underwent follow up for an average of 21.9 and 22.2 months in groups A and B, respectively. Results obtained at the final follow-up indicated no significant loss of correction. No differences were found in the SRS-22 scores between the two groups. No aortic or neurological complications were observed. CONCLUSIONS: The 3D deformity of the spine was effectively corrected using the bilateral apical vertebral derotation technique by VCM and the VCA technique, and encouraging post-surgical results were obtained for patients with Lenke type 1 IS. The two techniques were effective in allowing 3D correctional force that was applied in different ways. PMID:23724963

Sun, Lin; Song, Yueming; Liu, Limin; An, Yonggang; Zhou, Chunguang; Zhou, Zhongjie

2013-05-31

315

Rapid cost-effective silicon carbide optical component manufacturing technique  

NASA Astrophysics Data System (ADS)

Silicon carbide may well be the best known material for the manufacture of high performance optical components. A combination of extremely high specific stiffness (r/E), high thermal conductivity and outstanding dimensional stability make silicon carbide superior overall to beryllium and low- expansion glass ceramics. A major impediment to wide use of silicon carbide in optical systems has been the costs of preliminary pressing, casting, shaping and final finishing of silicon carbide. Diamond grinding of silicon carbide is a slow and expensive process even on machines specially designed for the task. The process described here begins by machining the component from a special type of graphite. This graphite is easily machined with multi-axis CNC machine tools to any level of complexity and lightweighting required. The graphite is then converted completely to silicon carbide with very small and very predictable dimensional change. After conversion to silicon carbide the optical surface is coated with very fine grain silicon carbide which is easily polished to extreme smoothness using conventional optical polishing techniques. The fabrication process and a 6 inch diameter development mirror is described.

Casstevens, John M.; Plummer, Ronald; Jarocki, Jim

1999-10-01

316

Influence of the alignment surface on the characteristics of optically addressed liquid-crystal modulators  

NASA Astrophysics Data System (ADS)

Two optically addressed transmission-type liquid-crystal modulators based on a nematic liquid crystal-a-Si: C: H photoconductor structure are studied. The modulators differ in the initial tilt angle of the director and in the barrier height at the interface. It is shown that these parameters influence the dependence of the diffraction efficiency on the feed conditions, recording pulse repetition rate, and spatial frequency of the recorded grating. The spatial resolution of the modulators at a level of half the diffraction efficiency is equal to 75 mm-1. The maximal diffraction efficiency is high, 69%, owing to the asymmetric profile of the grating, which arises at a large initial tilt angle of the liquid crystal director.

Amosova, L. P.; Chaika, A. N.

2010-10-01

317

Antares automatic beam alignment system  

NASA Astrophysics Data System (ADS)

Antares is a high-power (80-TW), high-energy (35-40 kJ), pulsed CO2 laser system for the investigation of inertial confinement fusion. The system consists of three major optical sections, including the front end, the power amplifier, and the target chamber system. The front-end system consists of those components necessary to generate two separate laser beams that are fed into two main power amplifiers. Each power amplifier has 12 trapezoidal-shaped output beams. The 24 beams originating from the power amplifiers are independently controlled beams and must be automatically aligned through the system and independently centered and focused upon the target. The final optical elements in the target chamber can independently center and focus the energy of each sector in a focal spot less than 280 micrometers in diameter. The beam-alignment technique used to align the 24-beam system makes use of variable-focus telescope/TV cameras. Automatic alignment is accomplished by means of a video centroid tracker, which nulls the error with a computer-controlled, closed-loop mirror actuator system

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

1980-01-01

318

NICMOS Intermediate Focus/Alignment  

NASA Astrophysics Data System (ADS)

# The purpose of this activity is to perform a series of iterative adjustments of the NICMOS pupil alignment mechanism to establish the initial optical alignment in focus and tilt for all three cameras. This proposal has been broken down into 4 sub-proposals to make implementation easier. The four phases of the NICMOS Focus/Alignment activity are: # 1} Pre-Alignment Check-out {prop 7134} 2} Coarse Optical Alignment {Initial Focus Sweep} {prop 7041} 3} Intermediate Focus/Alignment {prop 7135} 4} Fine Optical Alignment {prop 7042} # This is proposal 7135; Intermediate Focus/Alignment -------------------------- Objectives: a} Estimate PAM focus and X/Y tilt for each camera b} Check performance over camera fields of view c} Allow sufficient time for dewar temperatures to equilibrate before next activity

Schneider, Glenn

1997-12-01

319

Current modulation technique used in resonator micro-optic gyro.  

PubMed

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

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

2013-01-10

320

Techniques for reconfigurable optical add/drop multiplexer  

NASA Astrophysics Data System (ADS)

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

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

2004-06-01

321

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

322

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

323

Absorber Alignment Measurement Tool for Solar Parabolic Trough Collectors: Preprint  

SciTech Connect

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

Stynes, J. K.; Ihas, B.

2012-04-01

324

Antares alignment gimbal positioner  

NASA Astrophysics Data System (ADS)

Antares is a 24-beam 40-TW carbon dioxide (CO2) laser fusion system currently under construction at the Los Alamos National Laboratory. The Antares alignment gimbal positioner (AGP) is an optomechanical instrument that will be used for target alignment and alignment of the 24 laser beams, as well as beam quality assessments. The AGP will be capable of providing pointing, focusing, an wavefront optical path difference, as well as aberration information at both helium neon (He-Ne) and CO2 wavelengths. It is designed to allow the laser beams to be aligned to any position within a 1 cm cube to a tolerance of 10 micrometers.

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

325

Microrheological investigations in ionic liquids using optical trapping techniques.  

PubMed

In this paper, we demonstrate optical trapping of melamine particles (d ? 2.3 ?m) within the pure ionic liquid ethylammonium nitrate (EAN) and show the first microrheological investigations of these important compounds using this technique. By analyzing the power spectrum of a particle trapped in EAN, we monitor the variation in viscous drag that it experiences in proximity to the sample coverslip, showing excellent agreement with Faxén's law. We also demonstrate hydrodynamic coupling between pairs of trapped particles. Finally, we explore temperature-dependent viscosity changes in ??L samples of EAN as a further example of microrheological investigations of ILs. PMID:24001322

Dear, Richard D; Worrall, Emma K; Gault, William D; Ritchie, Grant A D

2013-09-04

326

Optical techniques in fluid, thermal, and combustion flow  

SciTech Connect

This conference is unique in providing a genuine forum for those interested in diagnostic technique development and application. It is truly multidisciplinary, with the contributions coming from various fields that involve characterizations of single-phase flow, two-phase flow, high-speed aerodynamics, temperature and heat flux, and combustion and emissions to name just a few. The presented papers are thus broad in scope, spanning various fields but they are cohesive and interrelated, adhering to the conference theme of optical measurements of fluid phenomena. Separate abstracts were prepared for most papers in this volume.

Cha, S.S.; Trolinger, J.D. [eds.

1995-12-31

327

Precision alignment device  

DOEpatents

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

Jones, N.E.

1988-03-10

328

Precision alignment device  

DOEpatents

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

Jones, Nelson E. (Huntington Beach, CA)

1990-01-01

329

Optical control of ground-state atomic orbital alignment: Cl({sup 2}P{sub 3/2}) atoms from HCl(v=2,J=1) photodissociation  

SciTech Connect

H{sup 35}Cl(v=0,J=0) molecules in a supersonic expansion were excited to the H{sup 35}Cl(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7 {mu}m. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220 nm after a time delay, and the velocity-dependent alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The {sup 35}Cl({sup 2}P{sub 3/2}) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the H{sup 35}Cl(v=2,J=1,M=0) molecule to the {sup 35}Cl({sup 2}P{sub 3/2}) nuclear spin [which is conserved during the photodissociation and thus contributes to the total {sup 35}Cl({sup 2}P{sub 3/2}) photofragment atomic polarization] and (2) the alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the {sup 35}Cl({sup 2}P{sub 3/2}) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state {sup 35}Cl({sup 2}P{sub 3/2}) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.

Sofikitis, Dimitris; Rubio-Lago, Luis; Martin, Marion R.; Ankeny Brown, Davida J.; Bartlett, Nathaniel C.-M.; Alexander, Andrew J.; Zare, Richard N.; Rakitzis, T. Peter [Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete, Greece and Department of Physics, University of Crete, P.O. Box 2208, 71003 Voutes-Heraklion (Greece); Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete (Greece); Department of Chemistry, Stanford University, Stanford, California 94305-5080 (United States); School of Chemistry, University of Edinburgh, West Mains Road, Edinburgh EH9 3JJ (United Kingdom); Department of Chemistry, Stanford University, Stanford, California 94305-5080 (United States); Institute of Electronic Structure and Laser, Foundation of Research and Technology-Hellas, 71110 Heraklion-Crete, Greece and Department of Physics, University of Crete, P.O. Box 2208, 71003 Voutes-Heraklion (Greece)

2007-10-14

330

Optical control of ground-state atomic orbital alignment: Cl(2P3/2) atoms from HCl(v=2,J=1) photodissociation  

NASA Astrophysics Data System (ADS)

H35Cl(v=0,J=0) molecules in a supersonic expansion were excited to the H35Cl(v=2,J=1,M=0) state with linearly polarized laser pulses at about 1.7 ?m. These rotationally aligned J=1 molecules were then selectively photodissociated with a linearly polarized laser pulse at 220 nm after a time delay, and the velocity-dependent alignment of the 35Cl(2P3/2) photofragments was measured using 2+1 REMPI and time-of-flight mass spectrometry. The 35Cl(2P3/2) atoms are aligned by two mechanisms: (1) the time-dependent transfer of rotational polarization of the H35Cl(v=2,J=1,M=0) molecule to the 35Cl(2P3/2) nuclear spin [which is conserved during the photodissociation and thus contributes to the total 35Cl(2P3/2) photofragment atomic polarization] and (2) the alignment of the 35Cl(2P3/2) electronic polarization resulting from the photoexcitation and dissociation process. The total alignment of the 35Cl(2P3/2) photofragments from these two mechanisms was found to vary as a function of time delay between the excitation and the photolysis laser pulses, in agreement with theoretical predictions. We show that the alignment of the ground-state 35Cl(2P3/2) atoms, with respect to the photodissociation recoil direction, can be controlled optically. Potential applications include the study of alignment-dependent collision effects.

Sofikitis, Dimitris; Rubio-Lago, Luis; Martin, Marion R.; Ankeny Brown, Davida J.; Bartlett, Nathaniel C.-M.; Alexander, Andrew J.; Zare, Richard N.; Rakitzis, T. Peter

2007-10-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

332

Experimental comparison of particle interaction measurement techniques using optical traps.  

SciTech Connect

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

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

2008-06-01

333

Three-dimensional imaging technique using optical diffraction  

NASA Astrophysics Data System (ADS)

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

Tan, Sheng; Hart, Douglas P.

2002-02-01

334

Spectral sampling signal recovery technique for wavelength encoded fiber optic sensors  

Microsoft Academic Search

A variation of the traditional signal-decoding scheme, utilizing multiple discrete spectral sources and interpolating polynomials is discussed. A fiber-optic rotary sensor using a spectral-sampling decoding scheme combining advantages of intensity and wavelength encoding is presented. It is shown that the system is simpler to align and more optically stable than grating-CCD systems. Rotation angles over a 20-deg range are determined

Peter J. Kajenski; Peter L. Fuhr; W. B. Spillman Jr.

1990-01-01

335

Iterative Nonlinear Optimization Techniques for Diffractive Optical Applications and Their Implementations  

Microsoft Academic Search

This research focused on the development of iterative nonlinear optimization techniques for diffractive optical applications and their implementations. Five iterative optimization techniques for diffractive optical applications have been developed. The iterative interlacing technique (IIT) for synthesis of CGH involves dividing a hologram into a set of subholograms and designing them iteratively. This technique can be used with most existing algorithms

Jieyao Zhuang

1994-01-01

336

A conceptual design for the Thirty Meter Telescope alignment and phasing system  

Microsoft Academic Search

The primary, secondary and tertiary mirrors of the Thirty Meter Telescope (TMT), taken together, have approximately 12,000 degrees of freedom in optical alignment. The Alignment and Phasing System (APS) will use starlight and a variety of Shack-Hartmann based measurement techniques to position the segment pistons, tips, and tilts, segment figures, secondary rigid body motion, secondary figure and the tertiary figure

Mitchell Troy; Gary Chanan; Scott Michaels; Randy Bartos; Graham Bothwell; Amir Give'on; Randy Hein; Max Radin; Jenny Roberts; J. Michael Rodgers; Lawrence M. Scherr; Byoung-Joon Seo; David Zimmerman

2008-01-01

337

Tolerancing and alignment of a three-mirror off-axis telescope  

NASA Astrophysics Data System (ADS)

When the optical elements of a system are not collinear, there are advantages to aligning all elements simultaneously. This paper presents the steps taken to prepare for system alignment and the alignment plan for such a system. A tolerance analysis of the system defines the compensators necessary for system alignment and allows an estimate of the expected magnitude of initial aberrations present in the system. Polarization and pupil aberrations are characterized in order to further understand expected system aberrations before alignment. A two step alignment plan is outlined. First, a CCD array placed at the focal plane indicates spot size and shape as elements are aligned. Once spot size is minimized, the CCD array is replaced by a ball bearing for retroreflection. Useful interferograms can be obtained with which remaining aberrations can be minimized. This technique is presented as the alignment plan for an off-axis telescope system consisting of one spherical and two ellipsoidal mirrors.

Mahler, Anna-Britt; Chipman, Russell

2007-09-01

338

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

Microsoft Academic Search

This paper addresses the particular need to develop suitable fabrication techniques of glasses to improve the radiation-resistance and extend the lifetime of optical fibres in high radiation background. Two radiation hardening techniques based on hydrogen and fluorine doping of glass have been applied on step index pure silica core optical fibres. The radiation-induced optical absorption and luminescence have been measured

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

2004-01-01

339

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

ERIC Educational Resources Information Center

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

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

2012-01-01

340

Optical techniques for millimeter-wave detection and imaging  

NASA Astrophysics Data System (ADS)

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

Schuetz, Christopher Arnim

341

Orbit IMU Alignment: Error Analysis.  

National Technical Information Service (NTIS)

A comprehensive accuracy analysis of orbit inertial measurement unit (IMU) alignments using the shuttle star trackers was completed and the results are presented. Monte Carlo techniques were used in a computer simulation of the IMU alignment hardware and ...

R. W. Corson

1980-01-01

342

Can optical remote sensing techniques detect air contaminants?  

SciTech Connect

The American Petroleum Institute (API) is sponsoring a program to evaluate if and how optical remote sensing techniques can be used to detect air contaminant emissions at a processing facility. This study is also gathering database information to assess whether dispersion modeling accurately depicts air plume migrations within a petrochemical site. In early 1995, an initial field study was conducted at an open field site (Duke Forest, North Carolina). To duplicate actual air contaminant transport, tracer gas was released from simulated point, area and volume sources. Tracer gas bag samples and optical remote sensing (ORS) measurements located up to 200 m from the source captured samples and gathered data. Using results from the first test, API moved forward with a second field study, Project OPTEX (Operational Petrochemical Tracer Experiment). This field study investigated and tried to duplicate actual air contaminant migrations occurring within an operating facility. In Project OPTEX, researchers used open-path Fourier transform infrared (OP-FTIR) spectroscopy to infer air contaminant emissions in an actual industrial environment. Information gathered from this study would then be used to model and verify air plume migrations from plant sources and to beyond the fenceline.

Paine, R.J. [ENSR Corp., Acton, MA (United States); Zwicker, J.O. [Remote Sensing-Air, St. Louis, MO (United States); Feldman, H.J. [American Petroleum Inst., Washington, DC (United States)

1998-01-01

343

Induction heating assisted optical fiber bonding and sealing technique  

NASA Astrophysics Data System (ADS)

A novel technique for providing hermetic sealing within an optical fiber feed-through or high-performance fiber attachment to a metal part is presented. The system utilizes a specially designed heat concentrator surrounding the metal part and metal coated fiber that is heated to above 800°C using an induction heating method to achieve melting of a hightemperature brazing material used to join the two parts. The strength of the bond and sealing between the fiber and metal part is evaluated by constructing a simple extrinsic Fabry-Perot pressure transducer subjected to temperature and pressure variations in the range of 20-350°C and 0-15,000 psi, demonstrating the expected spectral responses from the transducer.

Niewczas, Pawel; Fusiek, Grzegorz

2011-05-01

344

Algebraic reconstruction techniques for spectral reconstruction in diffuse optical tomography  

SciTech Connect

Reconstruction in diffuse optical tomography (DOT) necessitates solving the diffusion equation, which is nonlinear with respect to the parameters that have to be reconstructed. Currently applied solving methods are based on the linearization of the equation. For spectral three-dimensional reconstruction, the emerging equation system is too large for direct inversion, but the application of iterative methods is feasible. Computational effort and speed of convergence of these iterative methods are crucial since they determine the computation time of the reconstruction. In this paper, the iterative methods algebraic reconstruction technique (ART) and conjugated gradients (CGs) as well as a new modified ART method are investigated for spectral DOT reconstruction. The aim of the modified ART scheme is to speed up the convergence by considering the specific conditions of spectral reconstruction. As a result, it converges much faster to favorable results than conventional ART and CG methods.

Brendel, Bernhard; Ziegler, Ronny; Nielsen, Tim

2008-12-01

345

Design of an Illumination Technique to Improve the Identification of Surface Flaws on Optics.  

National Technical Information Service (NTIS)

An edge illumination technique has been designed using a monochromatic light source that improves the identification of surface flaws on optics. The system uses a high-resolution CCD camera to capture images of the optics. Conventional edge illumination m...

R. R. Prasad M. Bernacil J. Halpin J. Peterson S. Mills R. P. Hackel

2004-01-01

346

Linear and Nonlinear Optical Techniques to Characterize Narrow Gap Semiconductors:  

NASA Astrophysics Data System (ADS)

Several methods have been developed and used to characterize the narrow gap semiconductors Hg(,1-x)Cd(,x)Te (HgCdTe) (0.20 < x < 0.32) and InSb both in the presence of CO(,2) laser radiation and in the dark. The results have allowed the determination of certain band parameters including the fundamental energy bandgap E(,g) which is directly related to x, the mole fraction of Cd. In the dark, characterization of several different samples of HgCdTe and InSb were carried out by analyzing the temperature dependence of the Hall coefficient and the magnetic field positions of the magnetophonon extrema from which their x-values were determined. The quality of the magnetophonon spectral is also shown to be related to the inhomogeneity (DELTA)x of the HgCdTe samples. One-photon magneto-absorption (OPMA) spectra have been obtained for x (TURN) 0.2 samples of p-HgCdTe thin films and n-HgCdTe bulk samples. Analysis of the OPMA transition energies allows the x-value to be determined to within (DBLTURN)(+OR-)0.001. A method is also discussed which can be used to estimate the sample inhomogeneity (DELTA)x. Nonlinear optical properties of semiconductors are not only scientifically interesting to study, but are also proving to be technologically important as various nonlinear optical devices are being developed. One of the most valuable nonlinear optical characterization method uses two-photon absorption (TPA). Two techniques using TPA processes were developed and used to measure the cut -off wavelength of several different samples of HgCdTe (x (TURN) 0.3) from which x-values were determined to within (DBLTURN)(+OR-)0.0005. Intensity and temperature dependent measurements on impurity and TPA processes have also been carried out and the results are compared with rate equations describing the photo-excited carrier dynamics. These results have yielded important information about the optical and material properties of HgCdTe such as the detection of impurity and trapping levels, TPA coefficients, carrier lifetimes, and recombination mechanisms. TPA and impurity absorption studies were also carried out on n- and p-InSb in order to obtain information about impurity levels, carrier lifetimes, and recombination mechanisms.

McClure, Stephen Warren

347

Novel failure analysis techniques using photon probing with a scanning optical microscope  

Microsoft Academic Search

Three new failure analysis techniques for integrated circuits (ICs) have been developed using localized photon probing with a scanning optical microscope (SOM). The first two are light-induced voltage alteration (LIVA) imaging techniques that (1) localize open-circuited and damaged junctions and (2) image transistor logic states. The third technique uses the SOM to control logic states optically from the IC backside.

Edward I. Cole Jr; Jerry M. Soden; James L. Rife; Daniel L. Barton; Christopher L. Henderson

1994-01-01

348

Antares beam alignment system  

Microsoft Academic Search

The paper describes the Antares beam alignment system used for the Antares CO2 gas laser for the investigation of inertial confinement fusion. The light energy produced by the 200-TW, 100-kJ laser is transmitted in 72 beams extending from the input sections of the power amplifiers through the target system optics and finally focused on the target. Two beam alignment schemes

A. C. Saxman; T. Swann; W. C. Sweatt; O. Appert; K. C. Jones; J. Hudgens

1979-01-01

349

Technique for calculating the field aligned conductance and ionospheric Pedersen conductivity from high altitude electric and magnetic field data.  

National Technical Information Service (NTIS)

A model of auroral arcs is developed for use with high altitude electric and magnetic field satellite data. The model incorporates a magnetic field aligned Ohm's law as an approximation to the linear part of the Fridman-Lemaire equation. Also included is ...

M. Shapshak L. P. Block J. Woch R. Elphinstone L. Zanetti

1994-01-01

350

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame. I. Source detection  

NASA Astrophysics Data System (ADS)

Context. The European space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames with the highest possible accuracy. It has been found that only 70 (10%) of the sources from the International Celestial Reference Frame (ICRF) are suitable for establishing this link, either because they are not bright enough at optical wavelengths or because they have significant extended radio emission which precludes reaching the highest astrometric accuracy. Aims: In order to improve the situation, we have initiated a VLBI survey dedicated to finding additional suitable radio sources for aligning the two frames. Methods: The sample consists of 447 optically-bright (magnitude ?18) extragalactic radio sources, typically 20 times weaker than the ICRF sources, which have been selected by cross-correlating an optical quasar catalog with the NRAO VLA Sky Survey (NVSS). Results: This paper presents the observing strategy to detect, image, and measure accurate radio positions for these sources. It also provides results on the VLBI detectability of the sources, as derived from initial observations with the European VLBI Network in June and October 2007. Based on these observations, a high detection rate of 89% is found, which is promising for the continuation of this project. This high VLBI detection rate for sources from the NVSS catalog is probably due to the selection process, suggesting that optically-bright quasars have compact radio structures. The entire list of radio sources detected (i.e. complete Table 3) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/520/A113

Bourda, G.; Charlot, P.; Porcas, R. W.; Garrington, S. T.

2010-09-01

351

Correction of Phase Distortion by Nonlinear Optical Techniques.  

National Technical Information Service (NTIS)

This is the final report on a program designed to explore a recently recognized property of certain nonlinear optical interactions of generating conjugate wavefronts that can be used to correct optical distortions in laser systems. These distortions inclu...

R. C. Lind W. B. Brown R. K. Jain J. F. Lam R. A. McFarlane

1981-01-01

352

Remote sensing of stress using electro-optics imaging technique  

NASA Astrophysics Data System (ADS)

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

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

2009-09-01

353

Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications.  

PubMed

We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115 degrees C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 microm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically. PMID:20147316

Mathur, A; Roy, S S; McLaughlin, J A

2010-02-10

354

Transferring vertically aligned carbon nanotubes onto a polymeric substrate using a hot embossing technique for microfluidic applications  

PubMed Central

We explored the hot embossing method for transferring vertically aligned carbon nanotubes (CNTs) into microfluidic channels, fabricated on poly-methyl-methacrylate (PMMA). Patterned and unpatterned CNTs were synthesized by microwave plasma-enhanced chemical vapour deposition on silicon to work as a stamp. For hot embossing, 115°C and 1 kN force for 2 min were found to be the most suitable parameters for the complete transfer of aligned CNTs on the PMMA microchannel. Raman and SEM studies were used to analyse the microstructure of CNTs before and after hot embossing. The PMMA microparticles with dimensions (approx. 10 µm in diameter) similar to red blood cells were successfully filtered using laminar flow through these microfluidic channels. Finally, a microfluidic-based point-of-care device for blood filtration and detection of bio-molecules is drawn schematically.

Mathur, A.; Roy, S. S.; McLaughlin, J. A.

2010-01-01

355

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

NASA Astrophysics Data System (ADS)

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 regime. In addition, the silicon nanowire structure with diameter of about 10 nm has been successfully formed by reducing of the local channel. In the fabricated device, we have confirmed that it has excellent device characteristics in terms of the sub-threshold swing (SS), drain induced barrier lowering (DIBL), and low level of off-state leakage current in spite of the short-channel effect (SCE).

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

2010-08-01

356

Effect of divergence of light wave and alignment of crystal on the response of electro-optic modulators  

NASA Astrophysics Data System (ADS)

In this work we report on numerical investigations of the effect of the light beam divergence or imperfect crystal alignment on the response of electrooptic modulators. Resulting non linearities are discussed both in terms of nonlinear distortion of modulators and as related to errors in measurements of quadratic electrooptic coefficients. Our calculations based on the Jones calculus have been performed for uniaxial crystals including KDP, and its isomorphs, and LiNbO3. The results obtained confirm that either the response of the modulators or results of electrooptic measurements can be significantly affected by the light divergence or imperfections in the crystals alignment.

Izdebski, Marek; Kucharczyk, Wlodzimierz

2001-08-01

357

Non-contact measurement of the mechanical properties of materials using an all-optical technique  

Microsoft Academic Search

Describes an optically-based measurement mechanism which realizes a totally noncontact assessment of the most important mechanical properties of structural materials - namely effective stiffness and Poisson ratio. These parameters are sensitive indicators of material integrity. The technique uses laser generated broadband ultrasound as a probe and interferometric optical detection as the detector again exploiting the broadband capability of optics in

Brian Culshaw; Gareth Pierce; Pan Jun

2003-01-01

358

Flexible polymeric rib waveguide with self-align couplers system  

PubMed Central

The authors report a polymeric based rib waveguide with U shape self-align fiber couplers system using a simple micromolding process with SU8 as a molding material and polydimethysiloxane as a waveguide material. The material is used for its good optical transparency, low surface tension, biocompatibility, and durability. Furthermore, the material is highly formable. This unique fabrication molding technique provides a means of keeping the material and manufacturing costs to a minimum. The self-align fiber couplers system also proves a fast and simple means of light coupling. The flexible nature of the waveguide material makes this process ideal for a potential wearable optical sensor.

Huang, Cheng-Sheng; Wang, Wei-Chih

2011-01-01

359

Frequency-Domain Techniques Enhance Optical Mammography: Initial Clinical Results  

Microsoft Academic Search

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

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

1997-01-01

360

Self-referencing frequency division multiplexing technique for fiber optic sensors  

NASA Astrophysics Data System (ADS)

An RF optical modulation technique for multiplexing and self-referencing a number of fiber optic intensity sensors is described. The optical transducers are incorporated into recirculating optical fiber loops connected in parallel between transmit and receive optical fibers. A linear RF ramped optical signal is coupled into the system and the detected optical signal is electronically mixed with the input. Beat signals are produced in the frequency domain in the form of pulse trains that characterize the output of each sensor module. The relative magnitudes of the frequency components are insensitive to varying optical loss characteristics between the sensor modules and the signal processing location. The theoretical basis of the technique is presented and experimental results are given.

Spillman, W. B., Jr.; Kline, B. R.; Lord, J. R.; Fuhr, Peter L.

361

Feedback controlled single wavelength interrogation technique for miniature all-silica EFPI fibre optic pressure sensors  

Microsoft Academic Search

This paper proposes a novel technique to stabilise the output wavelength of a tuneable laser source to operate always in the linear range of a miniature all-silica Extrinsic Fabry-Perot Interferometric (EFPI) fibre optic pressure sensor. The technique is based on a fibre optic hybrid sensor, which consists of a miniature all-silica EFPI fibre optic pressure sensor with an incorporated in-Fibre

K. Bremer; E. Lewis; G. Leen; B. Moss; S. Lochmann; I. Mueller

2010-01-01

362

Installation alignment of a multi-beam ICF target illumination system  

NASA Astrophysics Data System (ADS)

Target illumination systems for inertial confinement fusion (ICF) experiments require precise alignment of a multitude of mirrors, usually spherically arranged around the ICF target. The mechanical support structure for these mirrors generally consists of a large space frame with many voids. This makes direct alignment or boresighting impossible, since alignment instruments and references cannot be placed at the coordinate centers representing the mirror arrays or focal points. Nevertheless, the structural members must be accurately aligned during the assembly phase, to provide the focusing precision required by the completed illumination system. This paper describes the techniques used to assemble and align the Antares Laser space frame where a total of 48 mirrors fold and focus 24 laser beams onto the ICF target, within a 7.3 meter space frame. The alignment procedures described use optical tooling and test techniques supplemented by surveying instruments and auxiliary devices, as required by the unique geometry of the space frame.

Bauke, W.; Stahl, D. B.

363

Installation alignment of a multi-beam ICF target illumination system  

SciTech Connect

Target illumination systems for inertial confinement fusion (ICF) experiments require precise alignment of a multitude of mirrors, usually spherically arranged around the ICF target. The mechanical support structure for these mirrors generally consists of a large space frame with many voids. This makes direct alignment or boresighting impossible, since alignment instruments and references cannot be placed at the coordinate centers representing the mirror arrays or focal points. Nevertheless, the structural members must be accurately aligned during the assembly phase, to provide the focusing precision required by the completed illumination system. This paper describes the techniques used to assemble and align the Antares Laser space frame where a total of 48 mirrors fold and focus 24 laser beams onto the ICF target, within a 7.3 meter space frame. The alignment procedures described use optical tooling and test techniques supplemented by surveying instruments and auxiliary devices, as required by the unique geometry of the space frame.

Bauke, W.; Stahl, D.B.

1985-01-01

364

Antares alignment gimbal positioner  

SciTech Connect

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

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

1981-01-01

365

Verification of the accuracy in patient alignment using a laser-optical 3D-surface imaging system  

Microsoft Academic Search

Accurate and reproducible patient setup is a prerequisite to fractionated radiotherapy. To evaluate the applicability and\\u000a technical performance of a commercial 3Dsurface imaging system (Galaxy, LAP Laser, Lüneburg, Germany) for patient alignment,\\u000a measurements were performed in a rigid anthropomorphic phantom as well as in a healthy volunteer. In addition, we launched\\u000a a study, which investigates the 3D-laser surface imaging system

T. Moser; S. Fleischhacker; K. Schubert; G. Sroka-Perez; M. Uhl; K. Herfarth; J. Debus; C. P. Karger

366

Ion beam induced defects in solids studied by optical techniques  

Microsoft Academic Search

Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems. X- and Y-cut LiNbO3 crystals implanted with 8 MeV Au3+ ions with a fluence of 1 × 1017 ions\\/cm2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie

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

2009-01-01

367

Ion beam induced defects in solids studied by optical techniques  

Microsoft Academic Search

Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems.X- and Y-cut LiNbO3 crystals implanted with 8MeV Au3+ ions with a fluence of 1×1017ions\\/cm2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie theory provide the average nanoparticle

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

2009-01-01

368

Operational performance of the Antares alignment system  

Microsoft Academic Search

A review of the operational performance of the alignment system for the large Antares optical system is presented. The alignment of twenty-four optical channels consisting of two hundred optical elements is verified and established as required prior to each target shot for this COâ laser fusion test facility. The overall system design included features such as automatic operation, data base

S. C. Bender; Q. D. Appert

1984-01-01

369

Large Optical Birefringence in Poly(p-phenylene vinylene) Films Measured by Optical Waveguide Techniques.  

National Technical Information Service (NTIS)

Organic polymeric systems are emerging as an important class of optical materials for photonics applications. Polymeric systems offer two main advantages. First, their flexibility to be fabricated in forms of films or fibres of optical quality makes them ...

R. Burzynski P. N. Prasad F. E. Karasz

1990-01-01

370

Gas flow effects on precision solder self-alignment  

Microsoft Academic Search

Self-aligning soldering technology is being developed for low cost, passive, precision optical alignments. To avoid contamination problems, the solder reflow process must use reacting or inert gas instead of chemical flux materials. Since the accuracy of these optical alignments should reach the range of a few micrometers (?m), the gas flow may affect the aligning process. Therefore, the effects of

Bingzhi Su; M. Gershovich; Y. C. Lee

1997-01-01

371

An alternative technique for optically stimulated luminescence (OSL) experiment  

Microsoft Academic Search

An alternative technique is developed for observation of OSL by linearly increasing the intensity of the excitation source during readout. The technique allows the observation of OSL signals in the form of peaks unlike the decaying curves. The parameters of the new OSL peak can be used to obtain the intensity and the lifetime of the decay. With the technique

Enver Bulur

1996-01-01

372

High efficiency, modular, optical pulse shaping technique for tunable terahertz generation from InAs  

NASA Astrophysics Data System (ADS)

We demonstrate a high energy throughput, modular optical laser pulse shaping technique for generating tunable, narrowband, terahertz radiation from the surface of InAs. We achieve a frequency selectivity (?f/f) of 0.10 at 1.18 THz and demonstrate an energy throughput of up to 98% using two etalons to create a sequence of optical pulses. In contrast with previously reported schemes, our technique does not rely on interferometry or involve diffractive optical elements, making it robust and relatively inexpensive to implement. This technique can be expanded with additional etalons in order to achieve greater frequency selectivity without sacrificing efficiency.

Adipa, Samuel; Lytle, Amy L.; Gagnon, Etienne

2013-02-01

373

Feedback controlled single wavelength interrogation technique for miniature all-silica EFPI fibre optic pressure sensors  

NASA Astrophysics Data System (ADS)

This paper proposes a novel technique to stabilise the output wavelength of a tuneable laser source to operate always in the linear range of a miniature all-silica Extrinsic Fabry-Perot Interferometric (EFPI) fibre optic pressure sensor. The technique is based on a fibre optic hybrid sensor, which consists of a miniature all-silica EFPI fibre optic pressure sensor with an incorporated in-Fibre Bragg Grating (FBG). The FBG temperature reference sensor is used as a feedback element to stabilise the output wavelength of a tuneable laser source. Therefore the novel interrogation technique allows high speed pressure measurements in high temperature environments.

Bremer, K.; Lewis, E.; Leen, G.; Moss, B.; Lochmann, S.; Mueller, I.

2010-09-01

374

GMPLS-based dynamic OVPN technique in automatically switched optical network (ASON)  

NASA Astrophysics Data System (ADS)

Optical Virtual Private Network (OVPN) is an increasingly important application of Automatic Switched Optical Network (ASON). To meet the demands of today's different types of network services, dynamic OVPN technique is studied and two new functions are brought forward, which are dynamic connection management, and fast protection/restoration. We realize dynamic OVPN technique in the first ASON testbed in China, based on GMPLS signaling mechanism. The dynamic OVPN technique makes the optical network able to provide customers with reliable and flexible services by more functional and intelligent methods.

Zhu, Jia; Xu, Zhengchun; Li, Yanhe; Ren, Jian; Jiao, Yueguang; Zheng, Xiaoping; Zhang, Hanyi

2004-04-01

375

Development of a new optical technique for measuring diesel spray penetration  

Microsoft Academic Search

A new optical measuring technique of tip penetration of a diesel fuel spray was developed by detecting the arrival times of the spray tip at several light sheets which were preset at various axial locations downstream. Verified by the instantaneous photographic technique, it was confirmed that this technique is effective, with sufficient accuracy, for measuring the spray tip penetration much

M. Xu; H. Hiroyasu

1990-01-01

376

Camera Models and Optical Systems Used in Computer Graphics: Part II, Image-Based Techniques  

Microsoft Academic Search

In our companion paper (5), we described the optics under- lying camera models that have been used in computer graphics, and presented object space techniques for rendering with those models. In this paper, we survey image space techniques to simulate these models, and address topics including linear flltering, ray distribution bufiers, light flelds, and simulation techniques for interactive applications.

Brian A. Barsky; Daniel R. Horn; Stanley A. Klein; Jeffrey A. Pang; Meng Yu

2003-01-01

377

Ultrafast optical technique for the characterization of altered materials  

DOEpatents

Disclosed herein is a method and a system for non-destructively examining a semiconductor sample having at least one localized region underlying a surface through into which a selected chemical species has been implanted or diffused. A first step induces at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample. A second step measures a response of the sample to an optical probe beam, either pulsed or continuous wave, at least during a time that the optical constants are varying. A third step associates the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage. The method and apparatus in accordance with this invention can be employed in conjunction with a measurement of one or more of the following effects arising from a time-dependent change in the optical constants of the sample due to the application of at least one pump pulse: (a) a change in reflected intensity; (b) a change in transmitted intensity; (c) a change in a polarization state of the reflected and/or transmitted light; (d) a change in the optical phase of the reflected and/or transmitted light; (e) a change in direction of the reflected and/or transmitted light; and (f) a change in optical path length between the sample`s surface and a detector. 22 figs.

Maris, H.J.

1998-01-06

378

Ultrafast optical technique for the characterization of altered materials  

DOEpatents

Disclosed herein is a method and a system for non-destructively examining a semiconductor sample (30) having at least one localized region underlying a surface (30a) through into which a selected chemical species has been implanted or diffused. A first step induces at least one transient time-varying change in optical constants of the sample at a location at or near to a surface of the sample. A second step measures a response of the sample to an optical probe beam, either pulsed or continuous wave, at least during a time that the optical constants are varying. A third step associates the measured response with at least one of chemical species concentration, chemical species type, implant energy, a presence or absence of an introduced chemical species region at the location, and a presence or absence of implant-related damage. The method and apparatus in accordance with this invention can be employed in conjunction with a measurement of one or more of the following effects arising from a time-dependent change in the optical constants of the sample due to the application of at least one pump pulse: (a) a change in reflected intensity; (b) a change in transmitted intensity; (c) a change in a polarization state of the reflected and/or transmitted light; (d) a change in the optical phase of the reflected and/or transmitted light; (e) a change in direction of the reflected and/or transmitted light; and (f) a change in optical path length between the sample's surface and a detector.

Maris, Humphrey J. (Barrington, RI)

1998-01-01

379

Monte Carlo simulation on how optical clearing technique influences predicting precision of non-invasive optical blood glucose sensing  

NASA Astrophysics Data System (ADS)

It is necessary to get optical information within tissue in order to improve the application of non-invasive blood glucose sensing. However, the light penetration depth is seriously limited due to high scattering effects of biological tissues, which restricts the detection precision of non-invasive blood glucose sensing. Tissue optical clearing technique is one of the effective approaches to reduce the scattering effect and increase the light penetration depth into biological tissues. In this talk, it is our aim to study the preliminary application of optical clearing to non-invasive blood glucose sensing based on Monte Carlo simulation. Firstly, optical properties of intralipid solutions mixing with different concentration of glucose were calculated within the wavelengths of 1000~1700nm. The transmittance spectra of intralipid solutions with and without glycerol as optical clearing agent were investigated through Monte Carlo simulation. Different concentrations of glycerol were taken into account. Furthermore, the root mean square error of prediction (RMSEP) was obtained by performing partial least squares (PLS) modelling. Simulation results showed that the transmittance increased gradually with the increase of glycerol concentration, which suggested that the optical clearing effect appeared. Meanwhile, the RMSEP decreased as the glycerol concentration increased. RMSEP has improved by 30.91% in the simulation, which showed the great potential of tissue optical clearing technique to effectively improve the predicting precision of non-invasive blood glucose sensing.

Jiang, Jingying; Chen, Wei; Zhang, Lingling; Wang, Ruikang K.; Xu, Kexin

2011-02-01

380

Optical techniques for the studies on shock propagation in solids  

Microsoft Academic Search

Optical methods of recording the shock propagation in solids are described. A small air pocket or a tiny explosive pallet senses the shock arrival and produces a light flash which is transmitted through fibre cables to a Rotating Mirror Streak Camera and Logic Analyzer through an opto-electronic interface unit. The system has been used to measure the velocity and symmetry

Manjit Singh; M. P. Singh; V. S. Sethi; M. S. Bola

1997-01-01

381

Estimation of aerosol optical depth over ocean: Intercept technique  

Microsoft Academic Search

The study of atmospheric aerosols is an important element to understand the earth's solar radiation budget, water cycle balance, and climate change dynamics. Estimating aerosol properties is also one of the first steps in generating high-level land and ocean surface products from satellite observations. In this paper, a simple method to estimate the aerosol optical depth (AOD) over ocean is

Abd Rahman Mat Amin; Khiruddin Abdullah; Mohd Rivaie

2011-01-01

382

The Evaluation of Modulation Techniques for Underwater Wireless Optical Communications  

Microsoft Academic Search

Currently, there are lots of efforts at using underwater vehicles, gliders and moorings for the spatial and temporal measurements in oceanography research. Sensor data collected by these platforms is usually internally recorded and then transmitted via a cable or wireless communication. Traditional acoustic links are fundamentally bandwidth limited to low rates of bit per second (bps). Optical methods are well

Meihong Sui; Xinsheng Yu; Fengli Zhang

2009-01-01

383

Observing techniques for astronomical laser guide star adaptive optics  

SciTech Connect

We discuss astronomical observing requirements and their implementation using sodium-layer laser guide star adaptive optics. Specific issues requiring implementation include the ability to place the astronomical object at different locations within the field of view; reliable subtraction of Rayleigh-scattered light; efficient focusing; and stable point-spread-function characterization.

Max, C.E.; Macintosh, B.; Olivier, S.S.; Gavel, D.T.; Friedman, H.W.

1998-05-01

384

Designing new integrated LGP of backlight system using binary optical technique  

Microsoft Academic Search

A method of designing new light guide plate (LGP) of backlight system is presented in this paper using binary optical technique. Only one such new micro-optical LGP can integrate the function of multi-layer structures which include LGP, diffusion sheet and two prism sheets in the backlight system. The cell aperture\\

Ping Xu; Zelin Yan; Lili Wan; Haixuan Huang

2005-01-01

385

Thermal and Optical Properties of Yb - and Nd -Doped Phosphate Glasses Determined by Thermal Lens Technique  

Microsoft Academic Search

In this work, we study the thermal and optical prop- erties of ion-doped phosphates glasses using the thermal lens (TL) technique. Three samples were characterized: Nd -doped Q-98; Nd -doped Q-100; and Yb -doped QX. We report multiwave- length TL measurements for a more accuracy determination of the fluorescence quantum efficiency and temperature coefficient of the optical path length change

Djalmir N. Messias; Carlos Jacinto; Maria Jose; V. Bell; Tomaz Catunda

2007-01-01

386

Vernier-effect optical interrogation technique for fiber Bragg grating sensors  

Microsoft Academic Search

This work demonstrates a new technique for real-time optical sensor interrogation by exploiting a novel Vernier effect between the multiple (comb) wavelength responses of a multiplexed fiber Bragg grating array and the fixed discrete wavelengths of an all-solid-state tunable laser. Sets of output photodetector voltages serve as high-resolution optical \\

Gregory B. Tait

2007-01-01

387

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

Microsoft Academic Search

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

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

1991-01-01

388

Investigation of ferroelectric properties of bismuth ferrite films by the second optical harmonic generation technique  

Microsoft Academic Search

The specific features of the ferroelectric polarization switching in bismuth ferrite thin films doped with neodymium ions are investigated by the optical second harmonic generation technique. The structure and nonlinear optical properties of the samples prepared are studied in the course of ferroelectric polarization switching in planar geometry over wide ranges of film thicknesses and electric field frequencies.

N. É. Sherstyuk; N. A. Il'in; S. V. Semin; E. D. Mishina; V. M. Mukhortov

2009-01-01

389

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

National Technical Information Service (NTIS)

Integration and multiplexing techniques for smart skin applications using optical fibers has become an increasingly important topic of research in recent years. This paper reviews the initial stages of research in this area at the Oak Ridge National Labor...

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

1991-01-01

390

Implementation of Ramped Pressure Technique to Measure Acoustic Sensitivity of Fibre Optic Hydrophone Transducers.  

National Technical Information Service (NTIS)

The theoretical and practical implementation of a measurement technique to obtain both the low frequency acoustic and thermal sensitivities of a fibre optic hydrophone is discussed. An analysis program based on the theory was implemented in Microsoft Exce...

E. C. Magi

1994-01-01

391

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

NASA Astrophysics Data System (ADS)

The process of vertical alignment (VA) mode color filter liquid crystal on silicon (CF-LCoS) microdisplay was developed. In order to minimize the fringing field effect in small color pixels, a three dimensional (3D) optical model was established and performed to analyze this VA mode CF-LCoS microdisplay. The simulated result was compared with the experimental data and they coincided well. Optimization of this breed of VA mode CF-LCoS microdisplay was proposed with optimal pretilt angle and pixel size. With the pretilt angle of 86 degrees and the pixel size of 15 ?m, the color purity of the VA mode CF-LCoS microdisplay could attain more than 60% National Television Standards Committee (NTSC) level, and the contrast was larger than 400.

Zhang, Baolong; Li, Dan; Dai, Fengzhi; Yang, Shifeng; Kwok, Hoising

2011-09-01

392

Alignment maps of tissues: I. Microscopic elliptical polarimetry.  

PubMed Central

An automated method for generating a fiber alignment map in tissues, tissue-equivalents, and other fibrillar materials exhibiting linear and circular optical properties and scattering is presented. This method consists of interrogating the sample with elliptically polarized light from a rotated quarter-wave plate and an effective circular analyzer, and implementing nonlinear regression techniques to estimate parameters defining the optical properties of the optic train and the sample. Thus, an account is made for imperfect and misaligned optic elements. The optic train was modeled using the Mueller matrix representation and the combined sample properties by an exponential matrix. Because a sample's Mueller matrix does not uniquely determine the linear, circular, or scattering properties, the circular properties and effective scattering are estimated for a matched isotropic sample to determine and correct for the linear birefringence of an aligned sample. The method's utility is demonstrated by generating an alignment map of an arterial media-equivalent, a relevant test case because of its circumferential alignment and thus showing the method's sample orientation independence.

Tower, T T; Tranquillo, R T

2001-01-01

393

Multiplexed reflective-matched optical fiber grating interrogation technique  

Microsoft Academic Search

The multiplexed-reflective matched fiber grating interrogation technique was presented in this paper. The interrogation technique was based on the use of two (or more) wavelength-matched fiber Bragg gratings (FBGs) to receive the reflected signal from the sensing FBG. The two (or more) matched gratings were arranged parallelly and used as filters to convert wavelength into intensity encoded information for interrogation.

Yage Zhan; Shaolin Xue; Qinyu Yang

2007-01-01

394

Role of optical techniques in combined use of selected methods of medical imaging  

Microsoft Academic Search

The subject matter of this paper concerns advanced techniques of imaging used in diagnosis and minimally invasive procedures\\u000a applied in non-operable cases of the digestive tract tumour therapy. The role of optical techniques in current medical imaging\\u000a is significant. Optical properties of transilluminated or illuminated tissues and organs depend on strong light absorption\\u000a and scattering. Numerous issues related to the

A. Cysewska-Sobusiak; G. Wiczynski; Z. Krawiecki; A. Sowier

2008-01-01

395

Realization of binary radial diffractive optical elements by two-photon polymerization technique.  

PubMed

Application of the two-photon polymerization (2PP) technique for the fabrication of submicron-size relief of radial binary diffractive optical elements (DOE's) is studied. Binary DOE's for the formation of special longitudinal intensity distribution (axial light segment) are realized. Interferometric investigations of the diffractive relief produced by the 2PP-technique and investigations of optical properties of the formed elements are presented. Results of computer simulations are in good agreement with the experimental observations. PMID:21164925

Osipov, Vladimir; Pavelyev, Vladimir; Kachalov, Denis; Zukauskas, Albertas; Chichkov, Boris

2010-12-01

396

Developments in fibre-optic techniques for spectro-photometry on large telescopes  

NASA Astrophysics Data System (ADS)

This paper reviews automated fiber-optic placing techniques and describes a new fiber-placing system which uses optical feedback techniques to control the fiber positioning in the telescope image plane, and describes the method of operation. The system will significantly improve the positioning accuracy of earlier systems and reduce the dead area around each target object. Schematic diagrams of the pallet and the positioning head of the system are presented.

Baruch, J. E. F.; Brooke, G.; Johnson, P.; Hindle, A.

397

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

SciTech Connect

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

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

1991-12-31

398

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

SciTech Connect

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

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

1991-01-01

399

Infrared optical element mounting techniques for wide temperature ranges  

SciTech Connect

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

Saggin, Bortolino; Tarabini, Marco; Scaccabarozzi, Diego

2010-01-20

400

Improving optical measurement accuracy using multi-technique nested uncertainties  

NASA Astrophysics Data System (ADS)

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

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

2009-03-01

401

OPTICAL GAS FLOW METERS - A NOVEL GAS FLOW MEASUREMENT TECHNIQUE  

Microsoft Academic Search

New compact and non-intrusive gas flow meters were developed based on laser two- focus anemometry. Such optical gas flow meters do not require seeding, as they rely on the presence of naturally occurring particles flowing in the pipe with gas. Minimum detectable velocity recorded by a 2-in meter was 0.1m\\/s while the same meter was able to measure pressurized natural

Ivan Melnyk; Derek Montgomery; Daryl James; Chip Letton

402

An Integrated Optical Biochemical Sensor Fabricated Using Rapid Prototyping Techniques  

Microsoft Academic Search

This paper details the design and fabrication of an integrated optical biochemical sensor using a select oxygen- sensitive fluorescent dye, tris(2,2'-bipyridyl) dichlororuthenium(II) hexahydrate, combined with polymeric waveguides that are fabricated on a glass substrate. The sensor uses evanescent interaction of light confined within the waveguide with the dye that is immobilized on the waveguide surface. Adhesion of the dye to

David A. Chang-Yen; Bruce K. Gale

403

Optical techniques for the molecular imaging of angiogenesis  

Microsoft Academic Search

The process of angiogenesis, an essential hallmark for tumour development as well as for several inflammatory diseases and\\u000a physiological phenomena, is of growing interest for diagnosis and therapy in oncology. In the context of biochemical characterisation\\u000a of key molecules involved in angiogenesis, several targets for imaging and therapy could be identified in the last decade.\\u000a Optical imaging (OI) relies on

Michel Eisenblätter; Carsten Höltke; Thorsten Persigehl; Christoph Bremer

2010-01-01

404

An in-situ optical particle sizing technique  

Microsoft Academic Search

This paper discusses the application of an in-situ optical counter to the measurement of liquid fuel droplets and solid coal particles under combustion conditions. Mie theory computations are used to determine an optimal near-forward light-scattering geometry for sizing both spherical transparent particles and irregularly shaped light-absorbing particles in the 5-80 micron range. Results are presented for a burning methanol spray

D. J. Holve

1980-01-01

405

Emerging optical techniques in advanced cystoscopy for bladder cancer diagnosis: A review of the current literature  

PubMed Central

Background and objective: The current standard for the diagnosis and followup of bladder cancer remains white light cystoscopy, despite its well-known limitations. The aim of this paper is to review the current literature on three optical diagnostics that have been developed to improve the performance of white light cystoscopy: photodynamic diagnosis, narrow-band imaging and optical coherence tomography. Materials and Methods: A PubMed search was performed for all articles on bladder cancer and photodynamic diagnosis, narrow-band imaging, and optical coherence tomography. Relevant papers on the working mechanism or clinical performance of the techniques were selected. Results: Photodynamic diagnosis and narrow-band imaging both aim to improve the visualization of bladder cancer. Both techniques have demonstrated an improved detection rate of bladder cancer. For photodynamic diagnosis, decreased residual tumor rates and increased recurrence free survival after photodynamic diagnosis-assisted transurethral resection have been shown. Both techniques have a relatively high false positive rate. Optical coherence tomography is a technique aiming at real-time noninvasive pathological diagnosis. Studies have shown that optical coherence tomography can accurately discriminate bladder cancer from normal bladder mucosa, and even suggest that a reliable estimation of the stage of a bladder tumor can be made. Conclusions: Photodynamic diagnosis is the technique with most evidence of clinical effectiveness to date, but low specificity is limiting a widespread use. For the novelties, narrow-band imaging, and optical coherence tomography, more evidence is needed before these techniques can be implemented in daily urological practice.

Cauberg Evelyne, C.C.; de la Rosette, Jean J.M.C.H.; de Reijke, Theo M.

2011-01-01

406

Correction of phase distortion by nonlinear optical techniques  

NASA Astrophysics Data System (ADS)

This is the final report on a program designed to explore a recently recognized property of certain nonlinear optical interactions of generating conjugate wavefronts that can be used to correct optical distortions in laser systems. These distortions include optical train aberrations, laser medium distortions, and atmospheric propagation aberrations. The program was divided into three basic areas that bridge the gap between a preliminary exploration of the applicable nonlinear processes and realization of their potential usefulness to laser systems. The areas were to measure quantitatively the properties of phase conjugation by four-wave mixing and SBS, to develop a theoretical understanding of nonlinear phase conjugation, and to determine the applicability of nonlinear phase conjugation to various systems of interest to DARPA. Experimentally Demonstrated: Four-wave reflectivity exceeding unity in the green; Complete aberration correction by four-wave mixing and SBS for severely aberrated beams (approx. 35X diffraction limit), Viable approaches to angle offset using four-wave mixing; and Input/output separation using polarization properties of four-wave mixing.

Lind, R. C.; Brown, W. B.; Jain, R. K.; Lam, J. F.; McFarlane, R. A.; Omeara, T. R.; Giuliano, C. R.; Merchant, B. M.; Valley, G. C.

1981-05-01

407

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

408

Analysis of cracks and damages in optical elements by a swept-source optical coherence tomography technique  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT) is a non- invasive technique where a near-infrared laser beam penetrates a sample and through the analysis of its scattered light information about the internal structure of the sample is calculated. Although OCT is mainly used in medicine its application to areas of enginery has been increased recently. Important features of recent OCT systems allow us to determine accurately volumetric structure not only slices. In this works we report such volumetric analysis applied to the study of scratches and damages in optical elements in order to quantify not only the scratch sizes but also its depths. This study is compared with an Schlieren technique. Experimental results are presented. The finding reveals clearly the faults locations which may be an attractive results for the optical work shop and the application of norms.

Muñoz Moreno, Gilberto; Alcalá Ochoa, Noé

2011-08-01

409

Nonlinear optical study of palladium Schiff base complex using femtosecond differential optical Kerr gate and Z-scan techniques  

NASA Astrophysics Data System (ADS)

A femtosecond differential optical Kerr gate (DOKG) and Z-scan techniques, have been applied to investigate the third-order optical nonlinearity of composite film of the coordination complex [PdLPPh3] (L=N-(2-pyridyl)-N?-(salicylidene)hydrazine, PPh3=triphenylphosphine). Film exhibits superior nonlinear optical properties in the near-infrared spectral region. The nonlinear response time and third-order nonlinear optical susceptibility of complex were found to be?90 fs and 3.9×10-10 esu, respectively. The Z-scan result shows that saturable absorption property of the film and its nonlinear absorption coefficient of the sample was found to be -23 cm/GW.

Rudresha, Bada Jayappa; Bhat, Badekai Ramachandra; Ramakrishna, Dileep; Anthony, John Kiran; Lee, H. W.; Rotermund, F.

2012-06-01

410

Optical Trapping Techniques Applied to the Study of Cell Membranes  

NASA Astrophysics Data System (ADS)

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

Morss, Andrew J.

411

Optical techniques for the measurement of frazil ice  

NASA Astrophysics Data System (ADS)

We have investigated the possibility of using optical instruments to detect the presence of frazil ice in Arctic leads. Frazil ice was successfully detected with a transmissometer but could not be seen with scattering sensors. Field measurements were made in Arctic leads north of Alaska during the spring of 1992 as a part of the lead experiment (LEADEX). On two occasions, the temperature, salinity, and transmission signals show the presence of frazil. Because a transmissometer cannot distinguish ice from other types of particles, we present a concept for a dual wavelength absorption meter that would be able to distinguish between frazil ice and biological particles.

Pegau, W. S.; Paulson, Clayton A.; Zaneveld, J. Ronald V.

1992-12-01

412

Ion beam induced defects in solids studied by optical techniques  

NASA Astrophysics Data System (ADS)

Optical methods can provide important insights into the mechanisms and consequences of ion beam interactions with solids. This is illustrated by four distinctly different systems. X- and Y-cut LiNbO3 crystals implanted with 8 MeV Au3+ ions with a fluence of 1 × 1017 ions/cm2 result in gold nanoparticle formation during high temperature annealing. Optical extinction curves simulated by the Mie theory provide the average nanoparticle sizes. TEM studies are in reasonable agreement and confirm a near-spherical nanoparticle shape but with surface facets. Large temperature differences in the nanoparticle creation in the X- and Y-cut crystals are explained by recrystallisation of the initially amorphised regions so as to recreate the prior crystal structure and to result in anisotropic diffusion of the implanted gold. Defect formation in alkali halides using ion beam irradiation has provided new information. Radiation-hard CsI crystals bombarded with 1 MeV protons at 300 K successfully produce F-type centres and V-centres having the I3- structure as identified by optical absorption and Raman studies. The results are discussed in relation to the formation of interstitial iodine aggregates of various types in alkali iodides. Depth profiling of I3- and I5- aggregates created in RbI bombarded with 13.6 MeV/A argon ions at 300 K is discussed. The recrystallisation of an amorphous silicon layer created in crystalline silicon bombarded with 100 keV carbon ions with a fluence of 5 × 1017 ions/cm2 during subsequent high temperature annealing is studied by Raman and Brillouin light scattering. Irradiation of tin-doped indium oxide (ITO) films with 1 MeV protons with fluences from 1 × 1015 to 250 × 1015 ions/cm-2 induces visible darkening over a broad spectral region that shows three stages of development. This is attributed to the formation of defect clusters by a model of defect growth and also high fluence optical absorption studies. X-ray diffraction studies show evidence of a strained lattice after the proton bombardment and recovery after long period storage. The effects are attributed to the annealing of the defects produced.

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

2009-08-01

413

A simple technique for investigating whispering gallery modes in optical fibers  

Microsoft Academic Search

A simple technique for investigating whispering gallery modes in optical fibers is described. Unlike the conventional technique of winding a fiber around a mandrel, a bent fiber is produced simply by inserting it inside a commercial glass tube. The fiber naturally assumes a semicircular shape at the bend. It is shown that the loss spectrum due to whispering gallery modes

Y. Powell-Friend; L. Phillips; T. George; A. Sharma

1998-01-01

414

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

Microsoft Academic Search

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

Karsten Lambers; Fabio Remondino

2007-01-01

415

New perspectives in hydrodynamic radial polishing techniques for optical surfaces  

Microsoft Academic Search

In order to overcome classic polishing techniques, a novel hydrodynamic radial polishing tool (HyDRa) is presented; it is useful for the corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. This tool enables the work on flat or curved

Elfego Ruiz; Erika Sohn; Esteban Luna; Luis Salas; Alberto Cordero; Jorge González; Manuel Núñez; Javier Salinas; Irene Cruz-González; Jorge Valdés; Victor Cabrera; Benjamín Martínez

2004-01-01

416

Optical techniques for millimeter-wave detection and imaging  

Microsoft Academic Search

The benefits of imaging using regions of the electromagnetic spectrum outside the visible range have been known for decades. Infrared and radio frequency imaging techniques have achieved great successes in both military and civilian applications. However, there remains a range of the spectrum between these two regimes that remains relatively unexplored. Millimeter waves, or the range of wavelengths between one

Christopher Arnim Schuetz

2007-01-01

417

Suitability of optical techniques for investigating complex flows in difficult environments  

NASA Astrophysics Data System (ADS)

In recent years, laser based optical techniques have been extensively used in industry to investigate flow. The main application areas vary from complex flow fields in rotating turbo machines to complicated two-phase gas/liquid and liquid/liquid flows. Several measuring systems, based on optical techniques, are commercially available which include laser doppler system, phase doppler system, laser diffraction system and scanning laser microscope. The choice of the measuring system mainly depends on the information required and the nature of flow involved. This paper describes the limitations and the general problems of some of these measuring techniques. Results from several experimental rigs have been presented and in some cases measurements from two different optical systems have been compared for identical flow conditions. The discrepancy in results have been explained to justify the use of these techniques.

Zaidi, Sohail H.

1997-11-01

418

Spatial resolution of confocal XRF technique using capillary optics  

NASA Astrophysics Data System (ADS)

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

Dehlinger, Maël; Fauquet, Carole; Lavandier, Sebastien; Aumporn, Orawan; Jandard, Franck; Arkadiev, Vladimir; Bjeoumikhov, Aniouar; Tonneau, Didier

2013-06-01

419

Spatial resolution of confocal XRF technique using capillary optics  

PubMed Central

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

2013-01-01

420

Spatial resolution of confocal XRF technique using capillary optics.  

PubMed

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

Dehlinger, Maël; Fauquet, Carole; Lavandier, Sebastien; Aumporn, Orawan; Jandard, Franck; Arkadiev, Vladimir; Bjeoumikhov, Aniouar; Tonneau, Didier

2013-06-07

421

Polarization optical reflectometry: the technique for puncture diagnosis  

NASA Astrophysics Data System (ADS)

We propose to realize an endoscopic all-fiber clinical device for polarized reflectance spectroscopy based on polarization-maintaining (PM) fiber. Results of testing the above device in model media and the first data of clinical investigations are presented. Investigations in vivo were carried out on the uterine cervix with benign and malignant alterations. 7 female patients were examined. POR technique confirm a possibility of differentiating neoplastic changes by the depolarization ratio.

Mjakov, Alex V.; Agrba, Pavel D.; Shakhova, Natalia M.; Kamensky, Vladislav A.

2007-05-01

422

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame. II. Imaging candidate sources  

NASA Astrophysics Data System (ADS)

Context. The European space astrometry mission Gaia, to be launched by 2012, will construct a dense optical QSO-based celestial reference frame which will need to be linked to the International Celestial Reference Frame (ICRF; the IAU fundamental frame), with the highest accuracy. However, it has been found that only 10% of the ICRF sources (70 sources) are suitable to establish this link. The remaining sources are not useful either because they are not bright enough at optical wavelengths or because they have significant extended radio emission which precludes reaching the highest astrometric accuracy. Aims: In order to improve the accuracy of this alignment, we have developed a program of VLBI observations based on three steps to detect, image and measure astrometric positions of weak extragalactic radio sources, with bright optical counterparts, from a sample of 447 candidate sources. Methods: The experiments devoted to VLBI detection, carried out with the European VLBI Network (EVN) in June and October 2007, were very successful, with 398 sources detected at both S- and X-bands. From these, 105 sources were observed in March 2008 with a global VLBI array (EVN and VLBA; Very Long Baseline Array) for imaging their VLBI structures. Results: All sources were successfully imaged in both bands and about 50% (47 sources) were found to be point-like on VLBI scales. These images are available at http://www.obs.u-bordeaux1.fr/BVID/GC030/. VLBI positions of these sources will be measured accurately in future astrometric experiments. Full Table 3 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/viz-bin/qcat?J/A+A/526/A102

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

2011-02-01

423

Core-suction technique for the fabrication of optical fiber preforms.  

PubMed

A novel technique, named "core suction," for fabricating optical fiber preforms has been devised. The technique involves drawing the molten nonconventional core glass material into the cladding tube to form the preform. The developed technique is simple, inexpensive, and shows great potential for fabricating preforms of highly nonlinear nonconventional glasses as the core material. Preforms were made with Schott SF6 and a lead-tellurium-germanate glass in silica cladding tubes, and these preforms were then pulled into fibers. PMID:16496879

Goel, Nitin K; Stolen, Roger H; Morgan, Steven; Kim, Jong-Kook; Kominsky, Dan; Pickrell, Gary

2006-02-15

424

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

Microsoft Academic Search

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

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

2006-01-01

425

MROI's automated alignment system  

NASA Astrophysics Data System (ADS)

The Magdalena Ridge Observatory Interferometer (MROI) will be a reconfigurable (7.5-345 meter baselines) 10 element optical/near-infrared imaging interferometer. Depending on the location of each unit telescope (UT), light can travel distances ranging from 460 to 660 meters via several reflections that redirect the beam's path through the beam relay trains, delay lines (DL), beam reducing telescope (BCR), switchyards and finally to the beam combiners (BC). All of these sub-systems comprise three major optical axes of the MROI to be coaligned on a nightly basis by the alignment system. One major obstacle in designing the automated alignment system (AAS) is the required simultaneous measurements from the visible through near-IR wavelengths. Another difficulty is making it fully automated, which has not been accomplished at other optical/near-IR interferometers. The conceptual design of this system has been completed and is currently in its preliminary design phase. Prototyping has also commenced with designs of some hardware near completion. Here is presented the current outline and progress of MROI's automated alignment system design and some results of the prototyping.

Shtromberg, A. V.; Jurgenson, C. A.; Buscher, D. F.; Haniff, C. A.; Young, J. S.; Santoro, F. G.; Paz, M. T.; Steenson, J. M.; Berger, L.

2008-07-01

426

Aligning Sentences in Parallel Corpora  

Microsoft Academic Search

In this paper we describe a statistical technique for aligning sentences with their translations in two parallel corpora. In addition to certain anchor points that are available in our data, the only information about the sentences that we use for calculating alignments is the number of tokens that they contain. Because we make no use of the lexical details of

Peter F. Brown; Jennifer C. Lai; Robert L. Mercer

1991-01-01

427

Parametric optimization of sequence alignment  

Microsoft Academic Search

The optimal alignment or the weighted minimum edit distance between two DNA or amino acid sequences for a given set of weights is computed by classical dynamic programming techniques, and is widely used in Molecular Biology. However, in DNA and amino acid sequences there is considerable disagreement about how to weight matches, mismatches, insertions\\/deletions (indels) and gaps. Parametric Sequence alignment

Dan Gusfield; K. Balasubramanian; Dalit Naor

1992-01-01

428

Differential deposition technique for figure corrections in grazing-incidence x-ray optics  

NASA Astrophysics Data System (ADS)

A differential deposition technique was investigated as a way to minimize axial figure errors in full-shell, grazing-incidence, reflective x-ray optics. These types of optics use a combination of off-axis conic segments--hyperbolic, parabolic, and/or elliptical, to reflect and image x-rays. Several such mirrors or ``shells'' of decreasing diameter are typically concentrically nested to form a single focusing unit. Individual mirrors are currently produced at Marshall Space Flight Center using an electroforming technique, in which the shells are replicated off figured and superpolished mandrels. Several factors in this fabrication process lead to low- and mid-spatial frequency deviations in the surface profile of the shell that degrade the imaging quality of the optics. A differential deposition technique, discussed in this paper, seeks to improve the achievable resolution of the optics by correcting the surface profile deviations of the shells after fabrication. As a proof of concept, the technique was implemented on small-animal radionuclide-imaging x-ray optics being considered for medical applications. This paper discusses the deposition technique, its implementation, and the experimental results obtained to date.

Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail V.; Gregory, Don A.

2011-10-01

429

Directed 3D Cell Alignment and Elongation in Microengineered Hydrogels.  

National Technical Information Service (NTIS)

Organized cellular alignment is critical to controlling tissue microarchitecture and biological function. Although a multitude of techniques have been described to control cellular alignment in 2D, recapitulating the cellular alignment of highly organized...

A. L. Sieminski C. B. Hutson H. Aubin H. Bae J. W. Nichol

2010-01-01

430

Alignment fixture  

DOEpatents

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

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

1980-01-01

431

Novel real-time monitoring technique of the all-optical poling process  

NASA Astrophysics Data System (ADS)

All-optical poling technique permits purely optical orientation of molecules. The experiment consists of two steps: the writing (so-called seeding) period and the readout one. In the seeding phase two beams, the fundamental one ((omega) ) and its second harmonic (SH, 2(omega) ) illuminate the sample and print in the medium the second order (chi) (2) susceptibility grating with a periodicity satisfying the condition of phase matching for SH generation. In the readout period only the fundamental beam irradiates the sample, and the second harmonic generation is observed at the sample output. Efficient all-optical poling requires optimisation of the seeding beam intensities and their relative phase difference. We propose a novel technique for non-perturbative monitoring of the all-optical poling process and the easy method of orienting molecules without any necessity of taking into account the phase difference between seeding beams.

Apostoluk, Aleksandra; Chapron, David; Sahraoui, Bouchta; Gadret, Gregory; Fiorini-Debuisschert, Celine; Raimond, Paul; Nunzi, Jean-Michel

2002-03-01

432

A bidirectional hybrid DWDM PON employing optical injection locking technique and data comparators  

NASA Astrophysics Data System (ADS)

A bidirectional hybrid dense-wavelength-division-multiplexing (DWDM) passive optical network (PON) employing optical injection locking technique on vertical-cavity surface-emitting lasers (VCSELs) and data comparator, as well as optical injection locking technique on distributed feedback laser diodes (DFB LDs) and amplitude/phase compensator is proposed and demonstrated. Improved performances of bit error rate (BER) and carrier-to-noise ratio/composite second order/composite triple beat (CNR/CSO/CTB) were observed in our proposed bidirectional hybrid DWDM PON. Bidirectional transmission in bidirectional hybrid DWDM PON architecture is a very attractive option, the capacity of the optical network can be expanded relatively easily by bidirectional transmission technology.

Tsai, Wen-Shing; Lu, Hai-Han; Tzeng, Shah-Jye; Chen, Shih-Hung; Chien, Tzu-Shen

2006-07-01

433

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

PubMed

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

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

2012-09-20

434

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

435

Precise measurement of the refractive index and optical rotatory power of a suspension by a delayed optical heterodyne technique.  

PubMed

By using an optical heterodyne technique, we have demonstrated the detection of ballistic photons traveling through a suspension. We measured the propagation time of light in a sample with a variable optical delay line in the reference arm of an interferometer, using a superluminescent diode as a light source. The resolution and accuracy in propagation time measurement were 400 and 3 fs, respectively. The minimum detectable rotation angle of 1/10,000 deg was achieved with an integration time of 5 s. This system can measure the refractive index and optical rotatory power of the suspension in a solvent without disturbing heavy scattering from particles in the suspension, because ballistic photons are detected. PMID:21085361

Mitsui, T; Sakurai, K

1996-05-01

436

Versatile Characterization of Specialty Fibers Using the Phase-Sensitive Optical Low-Coherence Reflectometry Technique  

Microsoft Academic Search

Emergence of new fibers families induces considerable requirements in terms of characterization and metrology (group delay, chromatic dispersion, birefringence, bending losses, etc.). The optical low-coherence reflectometry (OLCR) technique is demonstrated as a versatile method for the characterization of most types of optical fiber. A synthesis of multiple analysis concerning different families of specialty fibers including rare-earth-doped fibers, few-mode fibers, and

Renaud Gabet; Philippe Hamel; Yves Jaouen; Anne-Francoise Obaton; Vincent Lanticq; Guy Debarge

2009-01-01

437

An optical fiber-based technique for continuous-level sensing  

Microsoft Academic Search

An optical fiber-based technique for liquid-level measurement is proposed. It is based on the power attenuation which occurs in an optical fiber, immersed in a liquid, when the liquid level varies. The theoretical analysis allowed a low-cost sensor prototype to be set up. The experimental results highlight the prototype capability of measuring liquid levels with acceptable sensitivity and repeatability

Giovanni Betta; Lucio Ippolito; Antonio Pietrosanto; Antonio Scaglione

1995-01-01

438

Investigation of ferroelectric properties of bismuth ferrite films by the second optical harmonic generation technique  

Microsoft Academic Search

The specific features of the ferroelectric polarization switching in bismuth ferrite thin films doped with neodymium ions\\u000a are investigated by the optical second harmonic generation technique. The structure and nonlinear optical properties of the\\u000a samples prepared are studied in the course of ferroelectric polarization switching in planar geometry over wide ranges of\\u000a film thicknesses and electric field frequencies.

N. É. Sherstyuk; N. A. Il’in; S. V. Semin; E. D. Mishina; V. M. Mukhortov

2009-01-01

439

Code division multiple-access techniques in optical fiber networks. II. Systems performance analysis  

Microsoft Academic Search

For pt.I see ibid., vol.37, no.8, p.824-33 (1989). In Part I a technique based on optical orthogonal codes was presented to establish a fiber-optic code-division multiple-access (FO-CDMA) communications system. The results are used to derive the bit error rate of the proposed FO-CDMA system as a function of data rate, code length, code weight, number of users, and receiver threshold.

J. A. Salehi; C. A. Brackett

1989-01-01

440

CSO\\/CTB performances improvement by using optical VSB modulation technique  

Microsoft Academic Search

This study presents an externally modulated NTSC AM-vestigial side-band (VSB) erbium-doped fiber amplifier-repeated system that uses the optical VSB modulation technique to improve the systems' composite second order (CSO) and composite triple beat (CTB) performances. In comparison with conventional externally modulated fiber optical CATV systems, excellent performances of carrier-to-noise ratio ?50 dB, CSO ?69 dB, and CTB ?68 dB were

Hai-Han Lu

2002-01-01