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1

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

NASA Technical Reports Server (NTRS)

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

Hagopian, John G.

2010-01-01

2

Optical coupling modeling and passive alignment techniques for parallel optoelectronic interfaces  

NASA Astrophysics Data System (ADS)

Emerging applications related to Wavelength Division Multiplexing (WDM) and Plastic Optical Fiber (POF) applications pose many challenging optoelectronic packaging problems. Models of optical performance and packaging processes can aid determination of low-cost packaging solutions. Parallel optical links offer a potential low-cost solution to demands for increased bandwidths. Cost-effective fabrication and assembly of laser array to fiber array coupler packages is challenging due to precision alignment requirements for each source-fiber pair. A multimode coupling model has been developed which predicts coupling efficiencies and receiving fiber modal energy distributions. The model has been validated with measurements using laser diode, single-mode fiber, and multimode fiber sources, and it provides insight into prediction of link bandwidth for short distance links. Fiber arrays can be accurately aligned to Si substrates using KOH-H2O etched V- grooves. Measurements of KOH/H2O etch rates in Si as a function of etch temperature and wafer orientation have been performed. Etch rate uniformity was also measured across the surface of test wafers. Passive alignment of GaAs laser array substrates to Si V-groove substrates using solder bumps has been modeled based on the number of solder pads and their diameters, along with solder ball volume distributions. The model provides predictions of substrate separations after solder reflow and lateral realignment forces. A parallel laser array to fiber array coupler has been fabricated to validate some of the models developed in this research effort. A GaAs 12-channel ring laser array is attached to a Si V-groove substrate using an array of 50 ?m diameter solder balls using a solder jet technique.

Sutherland, James Scott

3

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.

2012-03-01

4

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

NASA Technical Reports Server (NTRS)

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

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

1976-01-01

5

Optics Alignment Panel  

NASA Technical Reports Server (NTRS)

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

Schroeder, Daniel J.

1992-01-01

6

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

7

Alignment Tolerances for ALMA Optics  

Microsoft Academic Search

A tolerance analysis of the alignment of the ALMA FE optics is presented. The following performance criteria are taken into account: a) loss of on- axis efficiency from aperture plane misalignment; b) focal plane co- alignment of the two beams of each band; c) aberrations when off-axis mirrors operate between wavefronts not centered on the foci of the ellipsoid; d)

B. Lazareff

8

Prism Window for Optical Alignment  

NASA Technical Reports Server (NTRS)

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

Tang, Hong

2008-01-01

9

Systematic Image Based Optical Alignment and Tensegrity  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

10

Optical alignments of the Cosmic Background Explorer (COBE) observatory  

NASA Technical Reports Server (NTRS)

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

Sampler, Henry P.

1990-01-01

11

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

SciTech Connect

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

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

2007-07-31

12

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

13

Micro actuators for aligning optical fibers  

Microsoft Academic Search

Two microactuators to align fiber optics are described. One, an actuator using a thin strand of shape memory alloy, is used to align an input fiber with one of two output fibers. This component is useful for switching fiber-optic signals. The second is an electrostatic actuator capable of switching optical fibers and making fine adjustments to correct for misalignments. Single-point

R. Jebens; W. Trimmer; J. Walker

1989-01-01

14

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

NASA Astrophysics Data System (ADS)

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

Lizotte, Todd E.

2011-10-01

15

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

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

2007-08-31

16

Nanomechanical optical devices fabricated with aligned wafer bonding  

Microsoft Academic Search

This paper reports on a new method for making some types of integrated optical nanomechanical devices. Intensity modulators as well as phase modulators were fabricated using several silicon micromachining techniques, including chemical mechanical polishing and aligned wafer bonding. This new method enables batch fabrication of the nanomechanical optical devices, and enhances their performance

C. Gui; G. J. Veldhuis; T. M. Koster; P. V. Lambeck; J. W. Berenschot; J. G. E. Gardeniers; M. Elwenspoek

1998-01-01

17

Training manual on optical alignment instruments  

NASA Technical Reports Server (NTRS)

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

1968-01-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

19

Optical Alignment Device For Laser Communication  

NASA Technical Reports Server (NTRS)

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

Casey, William L.

1988-01-01

20

Scalable cell alignment on optical media substrates.  

PubMed

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

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

2013-07-01

21

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

22

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

23

Computer vision applications for coronagraphic optical alignment and image processing  

E-print Network

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

2013-01-01

24

Rapid Test Bed Concentrator (TBC) Alignment Techniques  

NASA Technical Reports Server (NTRS)

A new, labor and cost saving method was developed to eliminate the procedure of covering all (220) mirrors and uncovering then one-by-one in sequence to adjust each to the focal plane. This latest method being used to align mirrors of a parabolic solar concentrator utilizes a computer-derived target of discreet images made up of individual mirror reflections on a plane in front of the intended, nominal, focal point. Incorporating this computer technique increases accuracy and gives potential to develop flux distributions required by different receiver designs.

Argoud, M. J.

1984-01-01

25

AGORA: Assembly Guided by Optical Restriction Alignment  

PubMed Central

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

2012-01-01

26

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

27

FOB Undergoing Test and Alignment in FAS at Ball Aerospace OPTICAL TESTS AND ALIGNMENTS  

E-print Network

to RAS/HOMS for system level testing. The "final" ground adjustment of the PAM to get the system focusedFOB Undergoing Test and Alignment in FAS at Ball Aerospace OPTICAL TESTS AND ALIGNMENTS After the FOB alignment is complete, and it passes environmental tests, it will be checked out in a second HST

Schneider, Glenn

28

Optical alignment of Centaur's inertial guidance system  

NASA Technical Reports Server (NTRS)

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

Gordan, Andrew L.

1987-01-01

29

Real-time sensing of optical alignment  

NASA Technical Reports Server (NTRS)

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

Stier, Mark T.; Wissinger, Alan B.

1988-01-01

30

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. PMID:19543344

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

2009-01-01

31

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

32

Alignment-free three-dimensional optical metamaterials.  

PubMed

Three-dimensional optical metamaterials based on multilayers typically rely on critical vertical alignment to achieve the desired functionality. Here the conditions under which three-dimensional metamaterials with different functionalities may be realized without constraints on alignment are analyzed and demonstrated experimentally. This study demonstrates that the release of alignment constraints for multilayered metamaterials is allowed, while their anomalous interaction with light is preserved. PMID:24307266

Zhao, Yang; Shi, Jinwei; Sun, Liuyang; Li, Xiaoqin; Alù, Andrea

2014-03-01

33

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. PMID:23722769

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

2013-01-01

34

Novel alignment techniques used in multiphoton ionization experiments for laser plasma beat wave  

SciTech Connect

This paper describes the techniques used to create a fully ionized plasma by the multiphoton ionization of gases at pressures of a few Torr to give an initial electron density precision of better than a few percent, necessary for beat-wave experiments. A gas containment vessel has been constructed using high vacuum techniques with a temperature control system to maintain the fill gas pressure constant. Novel alignment techniques are used that do not require an alignment target placed in the vessel. This involves the use of a rotating pencil beam to determine the focusing of the optics.

Amiranoff, F. (Laboratoire d'Utilisation des Lasers Intenses, Unite Mixte de Recherche C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Benkheiri, P. (Laboratoire de Physique Nucleaire des Hautes Energies, 1N2P3-C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Dyson, A. (Laboratoire d'Utilisation des Laser Intenses, Unite Mixte de Recherche C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Gregory, C.; Jacquet, F. (Laboratoire de Physique Nucleaire des Hautes Energies, 1N2P3-C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Marques, J.R. (Laboratoire d'Utilisation des Laser Intenses, Unite Mixte de Recherche C.N.R.S., Ecole Polytechnique, 91128 Palaiseau Cedex (France)); Matthieussent, G. (Laboratoire de Physique des Gas et des Plasmas, Laboratoire associe au C.N.R.S., Universite Paris XI, 91405 Orsay Cedex (France)); Mine, P.; Montes, B.; Poilleux, P. (Laboratoire de Physique Nucleaire des Hautes Energies, 1N2P3-C.N.R.S.,

1990-08-01

35

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

NASA Technical Reports Server (NTRS)

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

Chavez, Melissa A.

2011-01-01

36

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

37

Method for computer-aided alignment of complex optical system  

NASA Astrophysics Data System (ADS)

For making complex optical system meet the design requirement, such as the space camera used in remote sensing and UVX lithophotography, especially for off-axis all-reflecting optical system, alignment technology is so necessary. In this paper, a method is presented. Based on the ideas of linearity instead of non-linearity and difference quotient instead of differential quotient, a mathematical model for computer-aided alignment is proposed. This model included the characteristics of the optical system, wavefront difference of its exit pupil and its misalignment of the misaligned optical system. Then comparing self-compiled software with alignment package of CODE V, as a result, this self-compiled software is much more valid than alignment package of CODE V. For a large aperture, long focal length and off-axis three-mirror optical system, computer-aided alignment is successful. Finally, the wavefront error of the middle field is 0.094 waves RMS and the wavefront error of +0.7 field is 0.106 waves RMS and the wavefront error of -0.7 field is 0.125 waves RMS at ?=632.8nm are obtained.

Yang, Xiaofei; Han, ChangYuan; Yu, Jingchi

2006-02-01

38

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

39

Automatic alignment of double optical paths in excimer laser amplifier  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

40

Proposed technique for vertical alignment of a crane's cable  

NASA Technical Reports Server (NTRS)

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

Gera, J., Jr.

1969-01-01

41

Focal Plane Alignment Utilizing Optical CMM  

NASA Technical Reports Server (NTRS)

In many applications, an optical detector has to be located relative to mechanical reference points. One solution is to specify stringent requirements on (1) mounting the optical detector relative to the chip carrier, (2) soldering the chip carrier onto the printed circuit board (PCB), and (3) installing the PCB to the mechanical structure of the subsystem. Figure 1 shows a sketch of an optical detector mounted relative to mechanical reference with high positional accuracy. The optical detector is typically a fragile wafer that cannot be physically touched by any measurement tool. An optical coordinate measuring machine (CMM) can be used to position optical detectors relative to mechanical reference points. This approach will eliminate all requirements on positional tolerances. The only requirement is that the PCB is manufactured with oversized holes. An exaggerated sketch of this situation is shown in Figure 2. The sketch shows very loose tolerances on mounting the optical detector in the chip carrier, loose tolerance on soldering the chip carrier to the PCB, and finally large tolerance on where the mounting screws are located. The PCB is held with large screws and oversized holes. The PCB is mounted loosely so it can move freely around. The optical CMM measures the mechanical reference points. Based on these measurements, the required positions of the optical detector corners can be calculated. The optical CMM is commanded to go to the position where one detector corner is supposed to be. This is indicated with the cross-hairs in Figure 2(a). This figure is representative of the image of the optical CMM monitor. Using a suitable tapping tool, the PCB is manually tapped around until the corner of the optical detector is at the crosshairs of the optical CMM. The CMM is commanded to another corner, and the process is repeated a number of times until all corners of the optical detector are within a distance of 10 to 30 microns of the required position. The situation is sketched in Figure 2(b) (the figure also shows the tapping tool and where to tap). At this point the fasteners for the PCB are torqued slightly so the PCB can still move. The PCB location is adjusted again with the tapping tool. This process is repeated 3 to 4 times until the final torque is achieved. The oversized mounting holes are then filled with a liquid bonding agent to secure the board in position (not shown in the sketch). A 10- to 30-micron mounting accuracy has been achieved utilizing this method..

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

2012-01-01

42

Optical alignment of multiple components to a common coordinate system.  

PubMed

An improved method of optical tooling for the determination of angular alignment of randomly oriented multicomponent systems is described. The method was developed for alignment of the Orbiting Astronomical Observatory. A test object is mounted on a precision rotary table and viewed in autocollimation by a first-order theodolite. Azimuth and elevation readings from subject mirrors and relay mirrors, and azimuth readings from a dihedral mirror reference system are transformed into test object coordinates of roll, pitch, and yaw by a computer program. The program uses matrix optics methods. Errors are discussed. PMID:20068732

Appler, R L; Howell, B J

1968-06-01

43

Previous R&D of vibrating wire alignment technique for HEPS  

E-print Network

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

Wu, Lei; Li, Chunhua; Qu, Huamin

2014-01-01

44

Precision alignment and calibration of optical systems using computer generated holograms  

NASA Astrophysics Data System (ADS)

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

Coyle, Laura Elizabeth

45

Optical Properties of Aligned Carbon Nanotube Mats for Photonic Applications  

Microsoft Academic Search

We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0) and (8, 4) mats for photonic device applications. We employed the ab-initio density functional calculations in the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions of

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

2006-01-01

46

Optical properties of aligned carbon nanotube mats for photonic applications  

Microsoft Academic Search

We studied the optical properties of the aligned carbon nanotube (16, 0), (10, 0), and (8, 4) mats for photonic device applications. We employed ab initio density functional potentials and utlized the linear combination of atomic orbital formalism. We calculated the electronic structure of the carbon nanotube mats and the real and imaginary parts of the dielectric functions as functions

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

2006-01-01

47

The development of an optical fiber alignment and fusion machine  

Microsoft Academic Search

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

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

2005-01-01

48

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

49

Optical alignment measurements at Goddard Space Flight Center  

NASA Technical Reports Server (NTRS)

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

Eichhorn, W. L.

1982-01-01

50

Aligning Optical Fibers by Means of Actuated MEMS Wedges  

NASA Technical Reports Server (NTRS)

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

Morgan, Brian; Ghodssi, Reza

2007-01-01

51

Aligning Arrays of Lenses and Single-Mode Optical Fibers  

NASA Technical Reports Server (NTRS)

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

Liu, Duncan

2004-01-01

52

Hydrodynamic optical alignment for microflow cytometry†  

PubMed Central

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

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

2013-01-01

53

Optical alignment of electrodes on electrical discharge machines  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

54

Optical digital techniques  

NASA Technical Reports Server (NTRS)

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

1979-01-01

55

An alignment strategy for the optics of LINC-NIRVANA  

NASA Astrophysics Data System (ADS)

LINC-NIRVANA is an instrument to combine the light from both LBT primary mirrors in an imaging Fizeau interferometer. The goals in terms of resolution and field of view are quite ambitious, which leads to a complex instrument consisting of a bunch of subsystems. The layer oriented MCAO system alone is already quite complicated and to get everything working together properly is not a small challenge. As we are reaching the completion of LINC-NIRVANA's subsystems, it becomes more and more important to define a strategy to align all these various subsystems. The specific layout of LINC-NIRVANA imposes some restrictions and difficulties on the sequence and the method of this alignment. The main problem for example is that we have to get two perfectly symmetrical focal planes to be able to properly combine them interferometrically. This is the major step on which all further alignment is based on, since all the subsystems (collimator and camera optics, wavefront sensors, cold IR optics, etc.) rely on these focal planes as a reference. I will give a small introduction on the optics of the instrument and line out the resulting difficulties as well as the strategy that we want to apply in order to overcome these.

Meschke, Daniel; Bertram, Thomas; Bizenberger, Peter

2012-09-01

56

Active optical alignment of the Advanced Technology Solar Telescope  

NASA Astrophysics Data System (ADS)

The Advanced Technology Solar Telescope (ATST) is a complex off-axis Gregorian design to be used for solar astronomy. In order the counteract the effects of mirror and telescope structure flexure, the ATST requires an active optics alignment strategy. This paper presents an active optics alignment strategy that uses three wavefront sensors distributed in the ATST field-of-view to form a least-squares alignment solution with respect to RMS wavefront error. The least squares solution is realized by means of a damped least squares linear reconstructor. The results of optical modelling simulations are presented for the ATST degrees-of-freedom subject to random perturbations. Typical results include residual RMS wavefront errors less than 20 nm. The results quoted include up to 25 nm RMS wavefront sensor signal noise, random figure errors on the mirrors up to 500 nm amplitude, random decenter range up to 500 ?m, and random tilts up to 10e - 03 degrees (36 arc-secs) range.

Upton, Robert; Rimmele, Thomas; Hubbard, Robert

2006-06-01

57

Optical Alignment Support Of The Magnetic Field Satellite (MAGSAT) Vector Magnetometer Calibration  

NASA Astrophysics Data System (ADS)

The Magnetic Field Satellite (MAGSAT) was launched into low earth orbit on October 30, 1979, and reentered on June 11, 1980. It included a vector magnetometer which was successfully used to accurate-ly map the magnitude and direction of the magnetic field over most of the surface of the earth. To achieve the accuracy sought required arc second precision determination of the relative orientations of the three sensor axes in a coordinate system defined by optical references attached to the magnetometer. The calibration procedure consisted basically of accurate and repeatable positioning of the vector magnetometer within a unique magnetic test facility which nulls the earth's magnetic field, then generates magnetic fields of selected orientations and strengths. Analysis of the magnetometer sensor outputs together with data on the accurate positioning and optical reference alignment gave the axes orientations. We used precision theodolites and methods related to surveying techniques to do the accurate positioning and optical component alignment measurements.

Hinkal, Sanford W.

1982-06-01

58

Survey techniques developed to align stacked beamlines at CEBAF  

SciTech Connect

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

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

1994-04-01

59

Assembly, alignment, and cold focus test methods utilized on CLAES optics  

NASA Technical Reports Server (NTRS)

This paper describes the techniques and the equipment used in the assembly and alignment of the Cryogenic Limb Array Etalon Spectrophotometer (CLAES) Telescope and Spectrometer, together with those used to test the system at operating temperatures in order to establish the correct focus for the detector array and other system components. In addition, cryogenic tests were used to determine the stability of the optics over the specified environment, and blur size measurements were performed at operational temperatures.

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

1989-01-01

60

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

SciTech Connect

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

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

2014-02-21

61

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

NASA Astrophysics Data System (ADS)

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

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

2005-04-01

62

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

SciTech Connect

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

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

2012-10-15

63

Optical interconnection between different spatial modes using double phase conjugate mirror with polarization alignment system  

NASA Astrophysics Data System (ADS)

We propose a fundamental interconnection method using a polarization alignment system for waveguides having different spatial modes. In addition, as an example for the verification of the fundamental operation, we demonstrate an interconnection between a photonic crystal fiber and a laser that have obviously different spatial modes. The polarization alignment system operates synergistically with a self-written waveguide formed with a double phaseconjugate mirror. This technique enables us to interconnect a photonic crystal fiber with a laser source without complicated and time-consuming optical alignment. In this method, although it is not necessary to perform an external control for interconnection, the waveguide most suitable for connection is formed autonomously in a Sn2P2S6:Sb crystal developed for this purpose. There was a marked reduction in the polarization dependence of coupling efficiency, compared with that observed using a stand-alone double phase-conjugate mirror.

Wakayama, Yuta; Okamoto, Atsushi; Grabar, Alexander A.; Sato, Kunihiro

2011-01-01

64

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

65

Optical Properties of Aligned Carbon Nanotube Mats for Photonic Applications  

NASA Astrophysics Data System (ADS)

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

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

2006-03-01

66

Beam-based alignment technique for the SLC (Stanford Linear Collider) linac  

SciTech Connect

Misalignment of quadrupole magnets and beam position monitors (BPMs) in the linac of the SLAC Linear Collider (SLC) cause the electron and positron beams to be steered off-center in the disk-loaded waveguide accelerator structures. Off-center beams produce wakefields which limit the SLC performance at high beam intensities by causing emittance growth. Here, we present a general method for simultaneously determining quadrupole magnet and BPM offsets using beam trajectory measurements. Results from the application of the method to the SLC linac are described. The alignment precision achieved is approximately 100 ..mu..m, which is significantly better than that obtained using optical surveying techniques. 2 refs., 4 figs.

Adolphsen, C.E.; Lavine, T.L.; Atwood, W.B.; Himel, T.M.; Lee, M.J.; Mattison, T.S.; Pitthan, R.; Seeman, J.T.; Williams, S.H.; Trilling, G.H.

1989-03-01

67

Electro-optical Synergy Technique  

PubMed Central

Objectives: Electro-optical synergy technology is one of the most recently described methods for nonablative skin rejuvenation. The aim of this study is to evaluate the effects of electro-optical synergy on connective tissue composition by histological and immunohistochemical techniques coupled with computerized morphometric analysis. Design: A prospective clinical study. Participants: Six volunteers with Fitzpatrick skin types 3 to 4 and Glogau class I to II wrinkles were subjected to three months (6 sessions at 2-week intervals) of electro-optical synergy treatment. Measurements: Standard photographs and skin biopsies were obtained at baseline as well as three and six months after the start of treatment. The authors performed quantitative evaluation of total elastin, tropoelastin, collagen types I, III, and VII, and newly synthesized collagen. Results: Noticeable clinical and histological improvement was observed after electro-optical synergy treatment. A statistically significant increase in the means of collagen types I, III, and VII, as well as newly synthesized collagen, together with increased levels of tropoelastin, were detected, while the mean level of total elastin was significantly decreased at the end of treatment and three months post-treatment. Conclusion: Electro-optical synergy is an effective treatment for contouring facial skin laxity. This modality stimulates the repair processes and reverses the clinical, as well as the histopathological, signs of aging with the advantage of being a relatively risk-free procedure with minimal patient recovery time. PMID:21203352

El-Domyati, Moetaz; El-Ammawi, Tarek S.; Medhat, Walid; Moawad, Osama; Mahoney, My G.

2010-01-01

68

Theoferometer for High Accuracy Optical Alignment and Metrology  

NASA Technical Reports Server (NTRS)

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

Toland, Ronald; Leviton, Doug; Koterba, Seth

2004-01-01

69

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

NASA Technical Reports Server (NTRS)

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

Taylor, Jaime; Rakoczy, John; Steincamp, James

2003-01-01

70

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

71

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

NASA Technical Reports Server (NTRS)

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

Decker, Arthur J.; Krasowski, Michael J.

1991-01-01

72

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

73

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

74

High-resolution optical fiber reflectometry techniques  

Microsoft Academic Search

This paper reviews optical reflectometry techniques that are capable of achieving spatial resolutions of less than 1 cm. Advantages and disadvantages of these techniques are discussed. A white light interferometry technique known as optical low-coherence reflectometry is emphasized. This technique has been used to obtain spatial resolutions on the order of tens of microns and reflection sensitivities as low as

Wayne V. Sorin

1993-01-01

75

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

76

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

77

Holographic Weapons Sight as Crew Optical Alignment Sight  

NASA Technical Reports Server (NTRS)

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

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

2011-01-01

78

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

79

Enzyme activity assays within microstructured optical fibers enabled by automated alignment  

PubMed Central

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

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

2012-01-01

80

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

81

Alignment control study for the solar optical telescope  

NASA Technical Reports Server (NTRS)

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

1976-01-01

82

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

NASA Technical Reports Server (NTRS)

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

Taylor, Jaime R.

2003-01-01

83

Figure 1: Optical absorbance spectra indicating average diameter of vertically aligned single-walled carbon  

E-print Network

spectroscopy. We found that there is some critical concentration or catalyst density below which SWNTsFigure 1: Optical absorbance spectra indicating average diameter of vertically aligned single-walled carbon nanotubes synthesized using different concentrations of molybdenum catalyst. Diameter

Maruyama, Shigeo

84

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

85

Optical image subtraction techniques, 1975-1985  

NASA Technical Reports Server (NTRS)

Real- and nonreal-time optical image subtraction (OIS) techniques are reviewed. Real-time OIS techniques include source encoding, polarization modulation, pseudocolor image difference detection, the holographic shear lens technique, and nonlinear optics. Included in the nonreal-time category are speckle diffuser encoding, speckle-pattern encoding, halftone screen encoding, and polarization-shifted encoding. It is concluded that the most useful techniques are the real-time operations. It is noted that some nonreal-time optical techniques can be applied directly while others may be converted into real-time ones through the use of advance real-time spatial light modulators or electrooptic devices.

Liu, Hua-Kuang; Chao, Tien-Hsin

1986-01-01

86

Self-aligning silicon groove technology platform for the low cost optical module  

Microsoft Academic Search

The SASGT (Self-Aligning Silicon Groove Technology) platform has been developed for use as a real passive alignment. Key technologies of this platform are precise size control technology for optical active chips, three-step anisotropic etching technology for the silicon optical bench, and flux-and pressure-free die bonding technology. Precisely size controlled laser diode chip was fabricated by etching of V-grooves for cleaving

M. H. Choi; H. J. Koh; E. S. Yoon; K. C. Shin; K. C. Song

1999-01-01

87

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

88

PROBING SOFT MATTER WITH OPTICAL TECHNIQUES  

E-print Network

PROBING SOFT MATTER WITH OPTICAL TECHNIQUES PROBING SOFT MATTERPROBING SOFT MATTER WITH OPTICAL 3) Conclusions #12;RESPONSE OF MATTER TO LIGHTRESPONSE OF MATTER TO LIGHTRESPONSE OF MATTER TO LIGHT looks dark) . E D = 0 E = 0 E + P In optically isotropic medium dielectric response (described

Â?umer, Slobodan

89

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

NASA Astrophysics Data System (ADS)

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

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

2000-06-01

90

Optical alignment tolerances in double-side irradiated self-written waveguide-induced fiber arrays packages  

NASA Astrophysics Data System (ADS)

In this paper, we present our experimental study on the optical alignment tolerance between the couplings of single-mode fibers (SMFs) connected with a double-side irradiation-induced self-written waveguide (SWW). The study firstly focuses on the coupling of two SMFs and then on the two fiber arrays (FAs) for parallel optical communication. The SWW was formed in dye-dispersed epoxy materials by the photopolymerization technique. Rhodamine 6G dye was dispersed in epoxy, which is commonly used in the photonic packaging industry as a bonding adhesive. Using double-side irradiated SWW, we found the alignment tolerance for such optical interconnect to relax significantly. All the formed SWWs were evaluated in terms of optical loss. In our study, up to 4 µm misalignment tolerance was allowed for only 1 dB loss penalty. In addition, the optical interconnect formed by this technique was also able to tolerate up to ± 10 µm lateral shift with only 1 dB extra loss. The wavelength-dependent loss (from 1520 to 1610 nm) and polarization-dependent loss were less than 0.4 dB. The double-side irradiated SWW-induced couplings between two FAs also provided low optical loss. They were found to be less sensitive to temperature changes, and no significant distortion in the digital signal transmission test was observed. We believe that the findings are useful and applicable to other dye-dispersed epoxy material systems for relaxing the alignment tolerance of the optical interconnects in various photonic packaging situations.

Cheng, K. W.; Uddin, M. A.; Chan, H. P.; Chan, S. C.

2010-07-01

91

Synthesis, optical properties and alignment of poly(9,9-dioctylfuorene) nanofibers.  

PubMed

Poly(9,9-dioctlylfluorene) (PFO) nanofibers were fabricated by solution template wetting of anodic alumina membranes. Nanofibers with controlled thickness of 23 nm and length between 0.8 and 10 ?m, were obtained, regulated by the dimensions of the used template. Nanofibers displayed spectroscopic characteristics associated with the formation of significant percentages of planar and elongated ? phase within the amorphous PFO glassy-phase. Optical polarized microscopy displayed high birefringence resulting from the high degree of internal order induced by ? phase generation within the fibers. The structural intra-chain reorganization associated with formation of ? phase was promoted by the strong geometrical confinement imposed on the material by the porous template during polymer wetting and solvent evaporation. Flow and shear force alignment techniques were used to control the orientation of fabricated PFO nanofibers, yielding to formation of large oriented nanofiber arrays on transparent substrates. PMID:25299850

Iacopino, Daniela; Redmond, Gareth

2014-10-31

92

The optical wing aligning device of the Langley Field tunnel  

NASA Technical Reports Server (NTRS)

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

Norton, F H; Bacon, D L

1921-01-01

93

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

94

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

NASA Technical Reports Server (NTRS)

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

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

1975-01-01

95

Optical trapping and alignment of single gold nanorods using plasmon resonances  

E-print Network

-wavelength side of the resonance; by contrast, light detuned to the short- wavelength side repels rods fromOptical trapping and alignment of single gold nanorods using plasmon resonances Matthew Pelton nanorods in solution, taking advantage of the longitudinal surface-plasmon resonance to enhance optical

Scherer, Norbert F.

96

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

NASA Technical Reports Server (NTRS)

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

Rakoczy, John; Steincamp, James; Taylor, Jaime

2003-01-01

97

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

NASA Astrophysics Data System (ADS)

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

Elsafi, Ahmed; Zewail, Rami; Durdle, Nelson

2009-05-01

98

Current progress of optical alignment procedure of CLASP's Lyman-alpha polarimetry instrument  

NASA Astrophysics Data System (ADS)

The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a sounding-rocket instrument currently under development at the National Astronomical Observatory of Japan (NAOJ) as a part of an international collaboration. CLASP's optics are composed of a Cassegrain telescope and a spectro-polarimeter which are designed to achieve an unprecedentedly accurate polarization measurement of the Ly-? line at 121.6nm emitted from the solar upper-chromosphere and transition region. CLASP's first flight is scheduled for August 2015. Reaching such accuracy requires a careful alignment of the optical elements to optimize the image quality at 121.6 nm. However Ly-? is absorbed by air and therefore the optics alignment has to be done under vacuum condition which makes any experiment difficult. To bypass this issue, we proposed to align the telescope and the spectrograph separately in visible light. Hence we present our alignment procedure for both telescope and spectro-polarimeter. We will explain details about the telescope preliminary alignment before mirrors coating, which was done in April 2014, present the telescope combined optical performance and compare them to CLASP tolerance. Then we will present details about an experiment designed to confirm our alignment procedure for the CLASP spectro-polarimeter. We will discuss the resulting image quality achieved during this experiment and the lessons learned.

Giono, G.; Ishikawa, R.; Katsukawa, Y.; Bando, T.; Kano, R.; Suematsu, Y.; Narukage, N.; Sakao, Taro; Kobayashi, K.; Auchère, F.

2014-07-01

99

Fabrication and experimental techniques in integrated optics  

NASA Astrophysics Data System (ADS)

A program to investigate the characteristics of integrated optical components, coupling between optical waveguides and other optical components and waveguide fabrication technology was initiated in February 20, 1981 for Naval Avionics Center under contract N00163 81 M 1798. The work performed under this contract is summarized in this report. The Navy technical monitor was Dr. K. J. Jones. A coupling measurement system was modified and improved. Numerical techniques for computing the refractive index and the thickness of the optical films from the experimental data are discussed. Techniques based on optical fibers and TV cameras for measuring the waveguide attenuation, and techniques related to end-fire coupling and near infrared radiation are considered. Methods for fabricating solution-deposited waveguides and waveguides on glass, lithium niobate and lithium tantalate substrates are also reviewed.

Chen, C. L.

1981-09-01

100

New techniques in optical interferometry  

Microsoft Academic Search

The first section deals with the optical properties of thin films, especially their reflection and transmission coefficients. Multiple dielectric films, deposited on glass surfaces, can be made to have reflection coefficients up to 0·9 for visible light, with very small absorption losses. Considerably higher reflectivities can be reached with silver films, but the absorption losses are higher and increase with

H. Kuhn

1951-01-01

101

Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms  

E-print Network

Optical control of ground-state atomic orbital alignment: Cl,,2 P3/2... atoms from HCl,,v=2,J=1-of-flight mass spectrometry. The 35 Cl 2 P3/2 atoms are aligned by two mechanisms: 1 the time-dependent transfer is conserved during the photodissociation and thus contributes to the total 35 Cl 2 P3/2 photofragment atomic

Zare, Richard N.

102

Automated alignment of optical components for high-power diode lasers  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

103

Simple technique for the generation of plane surface normal to optic axis direction of uniaxial crystal.  

PubMed

What we believe to be a new experimental technique for the generation of a plane crystal surface perpendicular to the optic axis direction of a transparent birefringent uniaxial crystal is presented. A simple setup has been described for the initial optic axis alignment of a raw uniaxial crystal blank. Error correction methods have been illustrated. A technique for producing high optical quality surfaces by block polishing plane parallel crystal surfaces normal to the direction of the optic axis, in one setting, is discussed. The block with angular graduations facilitates the correction of angular error. A new conoscopy setup has been coupled to a Fizeau interferometer for high accuracy testing of the optic axis alignment with respect to the surface normal of the relevant polished surface of the uniaxial crystal. The results obtained for a quartz crystal blank are presented. PMID:17334433

Chatterjee, Sanjib; Kumar, Y Pavan

2007-03-20

104

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

105

Real-time Optical Alignment and Diagnostic System (ROADS)  

NASA Technical Reports Server (NTRS)

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

1972-01-01

106

Tear film measurement by optical reflectometry technique  

PubMed Central

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

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

2014-01-01

107

Tear film measurement by optical reflectometry technique.  

PubMed

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

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

2014-02-01

108

Integration, alignment, and verification of optical system assembly for FORMOSAT-5  

NASA Astrophysics Data System (ADS)

FORMOSAT-5 consists of a spacecraft bus and an electro-optical payload. The payload is an f/8 Cassegrain type telescope with 3.6-m effective focal length. The spacecraft has a ground sampling distance of 2-m for panchromatic and 4-m for multispectral bands, with a 24-km swath width. FORMOSAT-5 is the first space program that National Space Organization (NSPO) takes full responsibility for the complete satellite and payload system engineering. The optical system assembly (OSA) has been successfully aligned and is now undergoing final performance verification tests at system level. To help create this unique instrument, NSPO has developed the computer aided alignment method assisted with the mechanical ground support equipment to carry out the assembly, alignment, and verification of the complex systems. This method offers an integrated capability for interferometric alignment and characterization of the large instrument. A detail OSA integration and verification steps, including primary mirror, secondary mirror, corrector lens and baffles alignment are presented. This paper describes the overall capability of this method and uses decomposed Zernike polynomials from the alignment and characterization of the OSA to verify the reduction of the wavefront errors and misalignments. It further demonstrates the successful completion of the instrument and satisfaction with the main system requirements.

Chen, Ching-Wei; Huang, Po-Hsuan; Chen, Chia-Ray; Chan, Chia-Yen; Lien, Chun-Chieh; Huang, Po-Han; Hsu, Ming-Ying; Chang, Shenq-Tsong; Huang, Ting-Ming

2014-09-01

109

Techniques for Solution- Assisted Optical Contacting  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

110

Enzyme-etching technique to fabricate micropatterns of aligned collagen fibrils  

PubMed Central

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

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

2014-01-01

111

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

PubMed

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

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

2014-06-01

112

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

SciTech Connect

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

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

2012-10-15

113

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

SciTech Connect

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

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

1985-01-01

114

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

NASA Astrophysics Data System (ADS)

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

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

115

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

Microsoft Academic Search

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

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

1994-01-01

116

Optical trapping and alignment of single gold nanorods by using plasmon resonances  

E-print Network

is tuned to the long- wavelength side of this resonance, with a maximum when the detuning is equal to halfOptical trapping and alignment of single gold nanorods by using plasmon resonances Matthew Pelton of individual Au nanorods by using laser light slightly detuned from their longitudinal plasmon mode. Detuning

Scherer, Norbert F.

117

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

E-print Network

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

118

Aligning and testing non-null optical system with deflectometry  

NASA Astrophysics Data System (ADS)

We present our analysis methodology for a 20.3 cm prototype optical tracker to determine why instabilities occur below 50 Hz and suggest improvements. The Navy Precision Optical Interferometer makes use of six small optical telescope stations spaced along a Y-array to synthesize an equivalent single larger telescope. Piezoelectric-driven optical trackers steer 12.5 cm output beams from each station to an optics laboratory up to 700 m distant. A percentage of this starlight is split off and used in a closed-loop feedback to update the pointing of the telescope and steering of the tracker. Steering stabilizes atmospheric induced beam trajectory deviations, required for fringe generation. Because of closedloop feedback, we require all fundamental frequencies to be at least 3 times the desired operational frequency, or 150 Hz. These trackers are modified commercial aluminum gimbal mounts with flex-pivot axles and very small damping ratio. Steering is tip/tilt mirror rotation by push-only actuators and a return spring. It is critical contact be maintained between actuator, mirror mount and return spring. From our dynamic analysis, the 122 N return spring is 2.9 times that required, and has a natural frequency equal to 238 Hz. The range of steering, 140 microradian, is double that required and the 0.077 microradian precision is 2.6 times that required. The natural frequency of the tracker is 66 Hz and the tuned closed-loop operational frequency is only 22 Hz. We conclude the low fundamental frequency of the mount limits its performance below 50 Hz and stiffening the structure is required.

Zhao, Weirui; Huang, Run; Su, Peng; Burge, James H.

2014-09-01

119

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

120

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

NASA Technical Reports Server (NTRS)

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

Anderson, Richard

1994-01-01

121

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. PMID:18624561

Füsti-Molnár, László; Merz, Kenneth M.

2008-01-01

122

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

NASA Astrophysics Data System (ADS)

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

Mahanandia, Pitamber; Nanda, Karuna Kar

2008-04-01

123

Optically induced angular alignment of birefringent micro-objects by linear polarization  

NASA Astrophysics Data System (ADS)

Fluorinated polyimide micro-objects having large birefringence of ?n=-0.13 (refractive index n1=1.62, n2=1.49 for the wavelength ?=1.06 ?m), which were fabricated by reactive ion etching and suspended in water (n=1.33), were trapped and angularly aligned in a single Gaussian laser beam (?=1.06 ?m, power P>3 ?W). The optically induced angular alignment effect is caused by the transfer of spin angular momentum due to the interaction between their birefringence and the linearly polarized light.

Higurashi, E.; Sawada, R.; Ito, T.

1998-11-01

124

Optical Measurement Technique for Space Column Characterization  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

125

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

126

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

PubMed

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

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

2006-01-15

127

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

PubMed

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

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

2014-06-16

128

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

129

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

NASA Astrophysics Data System (ADS)

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

Gubarev, Mikhail; Alexander, Cheryl; Ramsey, Brian

2005-08-01

130

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

131

A three-dimensional polymeric optical circuit fabrication using a femtosecond laser-assisted self-written waveguide technique  

NASA Astrophysics Data System (ADS)

We demonstrated a femtosecond pulse laser-assisted self-written waveguide technique that can fabricate three-dimensional (3D) optical waveguides in a photopolymerizing resin. A 488nm Ar+ laser and an 800nm pulse laser were used in this technique. Using the femtosecond laser scanning technique, two optical fibers were connected three dimensionally by a waveguide. The alignment-free aspect of the light-induced self-written waveguide-fabrication technique and the possibilities of 3D waveguide creation inherent in the femtosecond laser polymerization technique were combined to yield a highly versatile technique for the fabrication of 3D waveguides.

Cai, Bin; Komatsu, Kyoji; Sugihara, Okihiro; Kagami, Manabu; Tsuchimori, Masaaki; Matsui, Takayuki; Kaino, Toshikuni

2008-06-01

132

Optical techniques for biological triggers and identifiers  

NASA Astrophysics Data System (ADS)

Optical techniques for the classification and identification of biological particles provide a number of advantages over traditional 'Wet Chemistry" methods, amongst which are speed of response and the reduction/elimination of consumables. These techniques can be employed in both 'Trigger" and 'Identifier" systems. Trigger systems monitor environmental particulates with the aim of detecting 'unusual" changes in the overall environmental composition and providing an indication of threat. At the present time there is no single optical measurement that can distinguish between benign and hostile events. Therefore, in order to distinguish between these 2 classifications, a number of different measurements must be effected and a decision made on the basis of the 'integrated" data. Smiths Detection have developed a data gathering platform capable of measuring multiple optical, physical and electrical parameters of individual airborne biological particles. The data from all these measurements are combined in a hazard classification algorithm based on Bayesian Inference techniques. Identifier systems give a greater level of information and confidence than triggers, -- although they require reagents and are therefore much more expensive to operate -- and typically take upwards of 20 minutes to respond. Ideally, in a continuous flow mode, identifier systems would respond in real-time, and identify a range of pathogens specifically and simultaneously. The results of recent development work -- carried out by Smiths Detection and its collaborators -- to develop an optical device that meets most of these requirements, and has the stretch potential to meet all of the requirements in a 3-5 year time frame will be presented. This technology enables continuous stand-alone operation for both civil and military defense applications and significant miniaturisation can be achieved with further development.

Grant, Bruce A. C.

2004-12-01

133

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

PubMed

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

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

2014-02-24

134

Study cell invasion by optical techniques  

NASA Astrophysics Data System (ADS)

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

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

2006-02-01

135

An Approach to Ontology Alignment Problems based on Category Matching Technique  

NASA Astrophysics Data System (ADS)

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

Hoshiai, Tadashi; Yamane, Yasuo; Tsuda, Hiroshi

136

Using naturally occurring polysaccharides to align molecules with nonlinear optical activity  

NASA Technical Reports Server (NTRS)

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

Prasthofer, Thomas

1996-01-01

137

Technique for precision optical timing measurements  

NASA Astrophysics Data System (ADS)

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

Anderson, Kent L.

1993-01-01

138

Progress in ETA-II magnetic field alignment using stretched wire and low energy electron beam techniques  

SciTech Connect

Flux line alignment of the solenoidal focus magnets used on the ETA-II linear induction accelerator is a key element leading to a reduction of beam corkscrew motion. Two techniques have been used on the ETA-II accelerator to measure and establish magnet alignment. A low energy electron beam has been used to directly map magnetic field lines, and recent work has utilized a pulsed stretched wire technique to measure magnet tilts and offsets with respect to a reference axis. This paper reports on the techniques used in the ETA-II accelerator alignment, and presents results from those measurements which show that accelerator is magnetically aligned to within {approximately}{plus minus}200 microns. 3 refs., 8 figs.

Deadrick, F.J.; Griffith, L.V.

1990-08-17

139

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

140

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

141

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

142

Rethinking Program Assessment through the Use of Program Alignment Mapping Technique  

ERIC Educational Resources Information Center

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

Liu, Min; Wrobbel, Duff; Blankson, Isaac

2010-01-01

143

Space optical navigation techniques: an overview  

NASA Astrophysics Data System (ADS)

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

Rebordão, J. M.

2013-11-01

144

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

NASA Technical Reports Server (NTRS)

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

Katow, M. S.

1986-01-01

145

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

146

Alignment method combining interference lithography with anisotropic wet etch technique for fabrication of high aspect ratio silicon gratings.  

PubMed

A method was developed for aligning interference fringes generated in interference lithography to the vertical {111} planes of <110> oriented silicon wafers. The alignment error is 0.036°. This high precision method makes it possible to combine interference lithography with anisotropic wet etch technique for the fabrication of high aspect ratio silicon gratings with extremely smooth sidewalls over a large sample area. With this alignment method, 320 nm and 2 ?m period silicon gratings have been successfully fabricated. The highest aspect ratio is up to 100. The sample area is about 50 mm × 60 mm. The roughness (root mean square) of the sidewall is about 0.267 nm. PMID:25321825

Zheng, Yanchang; Qiu, Keqiang; Chen, Huoyao; Chen, Yong; Liu, Zhengkun; Liu, Ying; Xu, Xiangdong; Hong, Yilin

2014-09-22

147

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

148

New metrology techniques improve the production of silicon diffractive optics  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

149

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

NASA Astrophysics Data System (ADS)

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

Zhou, Dayong

150

Optical replication techniques for image slicers  

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

151

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

152

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

153

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

154

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

155

Construction of fuzzy logic by optical techniques  

Microsoft Academic Search

Our main interest is to establish connections between Optics and Fuzzy Set Theory. We formulate the t-norms based algebraic description of both geometrical and Fourier- approximations of optics. Geometrical optics implements probabilistic operators under the linear approximation of negative recording process. For real recording media not Zadeh's, but Sugeno negation is more appropriate approximation. It gives dual to the product

Alexander V. Pavlov

1999-01-01

156

Optical techniques for determining dynamic material properties  

SciTech Connect

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

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

1996-12-31

157

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

158

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

NASA Astrophysics Data System (ADS)

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

Kudo, Takuya; Ishigure, Takaaki

2014-03-01

159

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

PubMed Central

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

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

2014-01-01

160

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

161

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

NASA Astrophysics Data System (ADS)

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

Wulfken, Philip J.; Law, Nicholas M.

2015-01-01

162

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

163

Advanced technique in fiber optic sensors  

NASA Astrophysics Data System (ADS)

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

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

1993-04-01

164

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

NASA Astrophysics Data System (ADS)

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

Cabib, Dario; Segal, Alon; Dolev, Jacob

2008-10-01

165

Optical addressing technique for a CMOS RAM  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

166

Compact optical technique for streak camera calibration  

NASA Astrophysics Data System (ADS)

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

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

2004-10-01

167

Optical Signal Processing Techniques for Signal Regeneration and Digital Logic  

Microsoft Academic Search

This chapter presents recent developments in optical signal processing techniques and digital logic. The first section focuses\\u000a on techniques to obtain key functionalities as signal regeneration and wavelength conversion exploiting nonlinear effects\\u000a in high nonlinear fibres and semiconductor optical amplifiers. The second section covers techniques for clock recovery and\\u000a retiming at high-speed transmission up to 320 Gb\\/s. In addition a

Karin Ennser; Slavisa Aleksic; Franco Curti; Davide Massimiliano Forin; Michael Galili; M. Karasek; L. K. Oxenløwe; Francesca Parmigiani; Periklis Petropoulos; R. Slav'ik

2009-01-01

168

Optical receiver techniques for integrated photonic links  

E-print Network

Integrated photonics has emerged as an I/O technology set to disrupt the communication fabric of many-core computer systems. The optical technology uses wavelength-division-multiplexing and a high degree of integration in ...

Georgas, Michael S. (Michael Stephen)

2014-01-01

169

Etching Profile Control of Alignment Spring for Combining MEMS Micro-Channel Device and Optical Fibers  

NASA Astrophysics Data System (ADS)

The hetero-integration of the micro-fluidic device and the optical fiber is realized. Since the micro-fluidic device and the optical fiber are different in their production methods, the assembly method becomes essential. The technique reported for the telecom communication of the optical switch does not become the solution requiring some improvement. A new bias spring with reverse taper is proposed and realized with the control of Si etching profile. The higher transmission ratio of the light is confirmed. This device is attractive for combining with the super-continuum light passing through the liquid channel for measuring the spectrum information including the infra-red absorption of the sample.

Iimura, Hikaru; Deng, Dinghuan; Ohishi, Yasutake; Kumagai, Shinya; Sasaki, Minoru

170

Optical fiber sensor technique for strain measurement  

DOEpatents

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

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

1989-01-01

171

A Study of Synchronization Techniques for Optical Communication Systems  

NASA Technical Reports Server (NTRS)

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

Gagliardi, R. M.

1975-01-01

172

100-nm-Scale Alignment using Laser Beam Diffraction Pattern Observation Techniques and Wafer Fusion for Realizing Three-Dimensional Photonic Crystal Structure  

Microsoft Academic Search

We previously proposed a new method for realizing three-dimensional photonic crystals in the optical wavelength region, where two-dimensional basic structures are aligned using a laser beam diffraction pattern observation techniqueand stacked by means of a wafer fusion.In this method, it is essential to align the two-dimensional basic structures with an accuracy of optical wavelength order at wafer fusion.In this work,

Noritsugu Yamamoto; Susumu Noda

1998-01-01

173

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

PubMed

We demonstrate an interference cancellation technique of optical AND gate receiver using optical thyristor for fiber-optic code division multiple access (FO-CDMA) systems. In particular, we fabricate the optical thyristor operating as optical hard-limiter and evaluate that the optical AND gate receiver using fabricated optical thyristor excludes the peaks of side-lobe and cross-correlation result in the system performance degradation. It found that the optical AND gate receiver using optical thyristor excludes the intensity of interference signal resulting in that the peaks of side-lobe and cross-correlation can be fully eliminated for any two users. Therefore, the optical AND gate receiver using optical thyristor is shown to be effective to accommodate more simultaneous users. PMID:18773033

Kang, Tae-Gu

2008-09-01

174

Information-Optical 3D-Techniques for Corrosion Monitoring  

Microsoft Academic Search

Methodical basis of using information-optical 3D-techniques and computer optical video microprobes in a high-performance monitoring of the thickness, topography, and statistical properties of thin corrosion layers on microscopic surface areas of a metal or semiconductor is considered. Forming a microscopic video image of such an area of an electrode and measuring the intensity distribution of the reflected optical signal in

V. A. Kotenev

2004-01-01

175

Fast and Efficient Stored Matrix Techniques for Optical Tomography  

E-print Network

image distortion. Simulations indicate that the technique can dramatically reduce the storage tomography methods such as optical diffusion to- mography (ODT), fluorescence optical diffusion tomography it efficiently. The first step to lossy compression is to derive an appropriate distortion metric. We show

176

New Method of Character Reading by Optical Correlation Technique  

Microsoft Academic Search

A new method of code transformation and character recognition technique is proposed. The essential aspect of the method is to obtain the optical correlation between an input character and a specially designed reference pattern which are juxtaposed in the input plane of a Fourier transforming optical system. If the input character matches the reference pattern, the output is obtained as

Seiro Moroto; Hiroyoshi Saito

1974-01-01

177

(Optical characterization techniques applied to ceramic oxides)  

SciTech Connect

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

Abraham, M.M.

1990-10-15

178

Applying the optical engine technique to output remote sensing image  

NASA Astrophysics Data System (ADS)

In order to research the global change and analyze the characteristics of land surface or atmosphere, an Earth Observation Station usually needs a high-definition large screen to display the satellite remote sensing image. Under the development of digital imaging technology, this application can be put into practice. In this paper, the optical engine, a key technique in the digital imaging, is introduced. Then the basic principle and technical difficulties of optical engine are discussed in detail. It is testified that the optical engine technique can make the satellite remote sensing image displayed in high-definition model.

Zhao, Bo; Yan, Lei; Yan, Ming; Zhen, Jianghua

2003-06-01

179

Techniques for optically compressing light intensity ranges  

DOEpatents

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

Rushford, Michael C. (Livermore, CA)

1989-01-01

180

Techniques for optically compressing light intensity ranges  

DOEpatents

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

Rushford, M.C.

1989-03-28

181

RCS prediction comparison between physical optics and moment method techniques  

Microsoft Academic Search

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

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

1997-01-01

182

Optical techniques for shock visualization and detection  

NASA Technical Reports Server (NTRS)

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

Adamovsky, G.; Johnson, D. K.

1995-01-01

183

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

PubMed

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

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

2013-01-01

184

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. PMID:23322105

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

2013-01-01

185

Light deviation based optical techniques applied to solid propellant combustion  

NASA Astrophysics Data System (ADS)

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

Cauty, F.; Eradès, C.; Desse, J.-M.

2011-10-01

186

Liquidus temperature and optical properties measurement by containerless techniques  

NASA Technical Reports Server (NTRS)

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

Anderson, Collin D.

1993-01-01

187

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

2013-09-01

188

Tumor margin detection using optical biopsy techniques  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

189

Optical beam forming techniques for phased array antennas  

NASA Technical Reports Server (NTRS)

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

Wu, Te-Kao; Chandler, C.

1993-01-01

190

Neurovascular coupling: in vivo optical techniques for functional brain imaging  

PubMed Central

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

2013-01-01

191

Optical techniques for time and frequency transfer  

NASA Technical Reports Server (NTRS)

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

Baumont, Francoise; Gaignebet, Jean

1994-01-01

192

OBS networks using optical code division multiple access techniques  

Microsoft Academic Search

The use of optical code division multiple access (OCDMA) techniques for contention resolution in optical burst switching (OBS) is proposed. Further a service differentiation scheme is proposed for QoS support. This novel approach achieves wider range of differentiated services than the existing offset-time-based scheme, by assigning prioritized codewords which are embedded in the signature sequence used for OCDMA. Steady-state throughput

Koji Kamakura; Ognian Kabranov; Dimitorios Makrakis; Iwao Sasase

2004-01-01

193

Elucidation of the growth process of vertically aligned SWNT films via in situ optical absorbance measurements  

E-print Network

aligned SWNTs with equal thicknesses, are addressed. Laser Prism or Mirror Quartz tube Electric furnace SubstrateLaser light detector PC USB cable Gas flow Laser Prism or Mirror Quartz tube Electric furnace

Maruyama, Shigeo

194

A comparative review of optical surface contamination assessment techniques  

NASA Technical Reports Server (NTRS)

This paper will review the relative sensitivities and practicalities of the common surface analytical methods that are used to detect and identify unwelcome adsorbants on optical surfaces. The compared methods include visual inspection, simple reflectometry and transmissiometry, ellipsometry, infrared absorption and attenuated total reflectance spectroscopy (ATR), Auger electron spectroscopy (AES), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), and mass accretion determined by quartz crystal microbalance (QCM). The discussion is biased toward those methods that apply optical thin film analytical techniques to spacecraft optical contamination problems. Examples are cited from both ground based and in-orbit experiments.

Heaney, James B.

1987-01-01

195

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

PubMed Central

Background The aim of this study was to investigate the efficacy of orthodontic treatment using the Invisalign® system. Particularly, we analyzed the influence of auxiliaries (Attachment/Power Ridge) as well as the staging (movement per aligner) on treatment efficacy. Methods We reviewed the tooth movements of 30 consecutive patients who required orthodontic treatment with Invisalign®. In all patients, one of the following tooth movements was performed: (1) Incisor Torque >10°, (2) Premolar derotation >10° (3) Molar distalization >1.5 mm. The groups (1)-(3) were subdivided: in the first subgroup (a) the movements were supported with the use of an attachment, while in the subgroup (b) no auxiliaries were used (except incisor torque, in which Power Ridges were used). All tooth movements were performed in a split-mouth design. To analyze the clinical efficacy, pre-treatment and final plaster cast models were laser-scanned and the achieved tooth movement was determined by way of a surface/surface matching algorithm. The results were compared with the amount of tooth movement predicted by ClinCheck®. Results The overall mean efficacy was 59% (SD?=?0.2). The mean accuracy for upper incisor torque was 42% (SD?=?0.2). Premolar derotation showed the lowest accuracy with approximately 40% (SD?=?0.3). Distalization of an upper molar was the most effective movement, with efficacy approximately 87% (SD?=?0.2). Conclusion Incisor torque, premolar derotation and molar distalization can be performed using Invisalign® aligners. The staging (movement/aligner) and the total amount of planned movement have an significant impact on treatment efficacy. PMID:24923279

2014-01-01

196

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

PubMed

We perform optical, surface anchoring, and textural studies of an organo-siloxane "tetrapode" material in the broad temperature range of the nematic phase. The optical, structural, and topological features are compatible with the uniaxial nematic order rather than with the biaxial nematic order, in the entire nematic temperature range -25 °C < T < 46 °C studied. For homeotropic alignment, the material experiences surface anchoring transition, but the director can be realigned into an optically uniaxial texture by applying a sufficiently strong electric field. The topological features of textures in cylindrical capillaries, in spherical droplets and around colloidal inclusions are consistent with the uniaxial character of the long-range nematic order. In particular, we observe isolated surface point defects - boojums and bulk point defects - hedgehogs that can exist only in the uniaxial nematic liquid crystal. PMID:24651889

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

2014-01-21

197

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

PubMed

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

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

2014-12-01

198

Optical knife-edge technique for nanomechanical displacement detection  

SciTech Connect

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

Karabacak, D.; Kouh, T.; Huang, C.C.; Ekinci, K.L. [Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215 (United States); Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215 (United States); Department of Aerospace and Mechanical Engineering, Boston University, Boston, Massachusetts 02215 (United States)

2006-05-08

199

Optical strain measuring techniques for high temperature tensile testing  

NASA Technical Reports Server (NTRS)

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

Gyekenyesi, John Z.; Hemann, John H.

1987-01-01

200

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

201

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

PubMed Central

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

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

2014-01-01

202

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

PubMed

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

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

2014-01-01

203

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

NASA Technical Reports Server (NTRS)

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

Lee, George

1992-01-01

204

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

205

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

206

GBT active optics systems and techniques Donald C. Wells  

E-print Network

GBT active optics systems and techniques Donald C. Wells National Radio Astronomy Observatory, 1 meters from the 1 The National Radio Astronomy Observatory is a facility of the National Science 520 Edgemont Road, Charlottesville, Virginia 22903-2475 USA Abstract. The GBT is a 100-meter radio

Wells, Donald C.

207

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. PMID:23044793

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

2012-01-01

208

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

209

Optical coherence tomography as film thickness measurement technique  

NASA Astrophysics Data System (ADS)

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

Manallah, Aissa; Bouafia, Mohamed; Meguellati, Said

2015-01-01

210

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

NASA Technical Reports Server (NTRS)

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

Wilkerson, Gary W.; Huegele, Vinson

1998-01-01

211

Electro-optic techniques in electron beam diagnostics  

SciTech Connect

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

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

2011-06-17

212

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

Microsoft Academic Search

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

Ali Salehiomran; Jawad A. Salehi

2009-01-01

213

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

NASA Technical Reports Server (NTRS)

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

Nguyen, Hung D.

1999-01-01

214

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

215

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

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

216

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

217

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

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

218

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

219

Advanced optical techniques for monitoring dosimetric parameters in photodynamic therapy  

NASA Astrophysics Data System (ADS)

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

Li, Buhong; Qiu, Zhihai; Huang, Zheng

2012-12-01

220

Optical fiber technique for in-reactor mechanical properties measurement  

SciTech Connect

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

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

2013-01-25

221

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

222

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

PubMed

Accurate automated alignment of laser beams in the National Ignition Facility (NIF) is essential for achieving extreme temperature and pressure required for inertial confinement fusion. The alignment achieved by the integrated control systems relies on algorithms processing video images to determine the position of the laser beam images in real time. Alignment images that exhibit wide variations in beam quality require a matched-filter algorithm for position detection. One challenge in designing a matched-filter-based algorithm is to construct a filter template that is resilient to variations in imaging conditions while guaranteeing accurate position determination. A second challenge is to process images for thousands of templates in under a second, as may be required in future high-energy laser systems. This paper describes the development of a new analytical template that captures key recurring features present in the beam image to accurately estimate the beam position under good image quality conditions. Depending on the features present in a particular beam, the analytical template allows us to create a highly tailored template containing only those selected features. The second objective is achieved by exploiting the parallelism inherent in the algorithm to accelerate processing using parallel hardware that provides significant performance improvement over conventional processors. In particular, a Xilinx Virtex II Pro field programmable gate array (FPGA) hardware implementation processing 32 templates provided a speed increase of about 253 times over an optimized software implementation running on a 2.2 GHz AMD Opteron core. PMID:19767937

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

2009-09-20

223

Characterization of oxide thin films using optical techniques  

Microsoft Academic Search

Thin films of oxide materials are playing a growing role as critical elements in optoelectronic devices and nanoscale devices. In this work, thin films of some typical oxides such as WO3, Ga2O3 and SrTiO3 were investigated. We present measurements of those films, using various optical techniques like photoconductivity transients over a wide time range and photo-Hall measurements. Analysis of the

J. H. Hao; J. Gao

2006-01-01

224

Optical fiber modulation techniques for single mode fiber sensors  

Microsoft Academic Search

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

R. P. Tatam

225

Fiber distributed Brillouin sensing with optical correlation domain techniques  

NASA Astrophysics Data System (ADS)

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

Hotate, Kazuo

2013-12-01

226

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

PubMed

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

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

2014-11-18

227

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

228

Survey and alignment of an MLI model 1.2-400 synchrotron light source  

Microsoft Academic Search

A cost effective technique was developed for the timely alignment of the magnets, support stands, and diagnostic equipment using readily available instrumentation. The procedure includes use of a commercially available theodolite coordinate measurement system for alignment of the dipole magnets, and optical tooling techniques for smoothing out errors in the position of the quadrupoles to submillimeter tolerances. The monument network,

W. J. Pearce

1991-01-01

229

New room-temperature deposition technique for optical coatings  

NASA Astrophysics Data System (ADS)

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

Belleville, Philippe F.; Floch, Herve G.

1993-06-01

230

Recent developments of optical turbulence measurement techniques (Invited Paper)  

NASA Astrophysics Data System (ADS)

With the advent of new developments in tracking, pointing, and compensation of laser beams over the past several years, a requirement has been established for increasing knowledge of optical turbulence along the propagation path. This has stimulated the development of new methodologies to sense the refractive index structure parameter (Cn2) and derived parameters such as the transverse coherence length (rO), the isoplanatic angle (?O), and the Rytov variance (??2). A historical perspective of these methodologies and instrumentation is presented and both in situ and remote sensing techniques are discussed. Recent designs of rO meters are shown. Of particular interest is the development of techniques to derive turbulence parameters such as Cn2, the eddy dissipation rate (?), the inner scale (lO), and the outer scale (LO). Observational results are discussed using sodar and radar of phenomena generating turbulence including gravity wave activity, jet streams, Kelvin-Helmholtz instabilities, convection, and frontal activity. Both frequency modulated-continuous wave (FMCW) and mesosphere-stratosphere-troposphere (MST) radar are discussed. New techniques and results are shown examining if the turbulent atmosphere is truly Kolmogorov (how often is the structure function represented by the r2/3 law), stationary, isotropic, and homogeneous. Emerging techniques for sensing turbulence such as optical path profilers and lidar are discussed.

Eaton, Frank D.

2005-05-01

231

Optical trapping and alignment of single gold nanorods by using plasmon resonances.  

PubMed

We demonstrate three-dimensional trapping and orientation of individual Au nanorods by using laser light slightly detuned from their longitudinal plasmon mode. Detuning to the long-wavelength side of the resonance allows stable trapping for several minutes, with an exponential dependence of trapping time on laser power (consistent with a Kramer's escape process). Detuning to the short-wavelength side causes repulsion of the rods from the laser focus. Alignment of the long axis of the rods with the trapping laser polarization is observed as a suppression of rotational diffusion about the short axis. PMID:16770437

Pelton, Matthew; Liu, Mingzhao; Kim, Hee Y; Smith, Glenna; Guyot-Sionnest, Philippe; Scherer, Norbert F

2006-07-01

232

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

233

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

PubMed

In this work, an anti-drift and auto-alignment mechanism is applied to an astigmatic detection system (ADS)-based atomic force microscope (AFM) for drift compensation and cantilever alignment. The optical path of the ADS adopts a commercial digital versatile disc (DVD) optical head using the astigmatic focus error signal. The ADS-based astigmatic AFM is lightweight, compact size, low priced, and easy to use. Furthermore, the optical head is capable of measuring sub-atomic displacements of high-frequency AFM probes with a sub-micron laser spot (~570 nm, FWHM) and a high-working bandwidth (80 MHz). Nevertheless, conventional DVD optical heads suffer from signal drift problems. In a previous setup, signal drifts of even thousands of nanometers had been measured. With the anti-drift and auto-alignment mechanism, the signal drift is compensated by actuating a voice coil motor of the DVD optical head. A nearly zero signal drift was achieved. Additional benefits of this mechanism are automatic cantilever alignment and simplified design. PMID:22299958

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

2012-01-01

234

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

235

Oriented growth of pentacene films on vacuum-deposited polytetrafluoroethylene layers aligned by rubbing technique  

E-print Network

We investigated structure and morphology of PTFE layers deposited by vacuum process in dependence on deposition parameters: deposition rate, deposition temperature, electron activation energy and activation current. Pentacene (PnC) layers deposited on top of those PTFE films are used as a tool to demonstrate the orienting ability of the PTFE layers. The molecular structure of the PTFE films was investigated by use of infrared spectroscopy. By means of ellipsometry, values of refractive index between 1.33 and 1.36 have been obtained for PTFE films in dependence on deposition conditions. Using the cold friction technique orienting PTFE layers with unidirectional grooves are obtained. On top of these PTFE films oriented PnC layers were grown. The obtained order depends both on the PTFE layer thickness and on PnC growth temperature.

M. Prelipceanu; O. S. Prelipceanu; O. G. Tudose; K. Grytsenko; S. Schrader

2007-04-04

236

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

PubMed Central

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

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

2013-01-01

237

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. PMID:21483100

Chen, Xiaodong; Zheng, Bin; Liu, Hong

2012-01-01

238

Optical multiple access techniques for on-board routing  

NASA Technical Reports Server (NTRS)

The purpose of this research contract was to design and analyze an optical multiple access system, based on Code Division Multiple Access (CDMA) techniques, for on board routing applications on a future communication satellite. The optical multiple access system was to effect the functions of a circuit switch under the control of an autonomous network controller and to serve eight (8) concurrent users at a point to point (port to port) data rate of 180 Mb/s. (At the start of this program, the bit error rate requirement (BER) was undefined, so it was treated as a design variable during the contract effort.) CDMA was selected over other multiple access techniques because it lends itself to bursty, asynchronous, concurrent communication and potentially can be implemented with off the shelf, reliable optical transceivers compatible with long term unattended operations. Temporal, temporal/spatial hybrids and single pulse per row (SPR, sometimes termed 'sonar matrices') matrix types of CDMA designs were considered. The design, analysis, and trade offs required by the statement of work selected a temporal/spatial CDMA scheme which has SPR properties as the preferred solution. This selected design can be implemented for feasibility demonstration with off the shelf components (which are identified in the bill of materials of the contract Final Report). The photonic network architecture of the selected design is based on M(8,4,4) matrix codes. The network requires eight multimode laser transmitters with laser pulses of 0.93 ns operating at 180 Mb/s and 9-13 dBm peak power, and 8 PIN diode receivers with sensitivity of -27 dBm for the 0.93 ns pulses. The wavelength is not critical, but 830 nm technology readily meets the requirements. The passive optical components of the photonic network are all multimode and off the shelf. Bit error rate (BER) computations, based on both electronic noise and intercode crosstalk, predict a raw BER of (10 exp -3) when all eight users are communicating concurrently. If better BER performance is required, then error correction codes (ECC) using near term electronic technology can be used. For example, the M(8,4,4) optical code together with Reed-Solomon (54,38,8) encoding provides a BER of better than (10 exp -11). The optical transceiver must then operate at 256 Mb/s with pulses of 0.65 ns because the 'bits' are now channel symbols.

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

1992-01-01

239

Laser-formed bumps on glass for precision alignment of planar optical components  

NASA Astrophysics Data System (ADS)

This paper describes hybrid assembly of a wavelength selective switch using laser-formed glass bumps. Recently, a process was developed for forming raised bumps on IR-absorbing glass substrates using a focused laser beam. Glass bumps with heights exceeding 90 ?m have been formed with an accuracy of ~100 nm using multiple laser shots. Proper selection of materials permits the bump height to be raised or lowered via subsequent laser shots by adjusting laser power. Processes are described for precision alignment of planar AWG components to a pedestal-mounted planar SOA array by forming three glass laser bumps beneath the AWG components. While the iterative process of bump formation and component position assessment was performed manually, this work demonstrates that the process is predictable and well-suited for automation.

Sutherland, James S.; Streltsov, Alexander M.; Grzybowski, Richard R.; Hemenway, B. Roe

2010-02-01

240

Technology of alignment mark in electron beam lithography  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

241

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

242

Study on the passive-drawn fiber optic liquid analysis technique  

Microsoft Academic Search

The passive-drawn fiber optic liquid analysis technique, which is one new kind liquid analysis technique, is proposed. Based on the analysis technique, the passive-drawn fiber optic liquid analyzer is designed. The working principle of the analyzer and the design of the fiber-optic probe are introduced. The drawn type analysis technique is different from the traditional feeding liquid drop analysis technique.

Ai Zhou; Jiaxing Sun; Libo Yuan; Hui Xiao

2007-01-01

243

Detecting nanoparticles in tissue using an optical iterative technique  

PubMed Central

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

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

2014-01-01

244

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

Microsoft Academic Search

Optical tooling evolved from traditional surveying, and both technologies are sometimes used interchangeably in large industrial installations, since the instruments and their specialized adapters and supports complement each other well. A unique marriage of both technologies was accomplished in a novel application at LAMPF, the Los Alamos Meson Physics Facility. LAMPF consists of a linear accelerator with multiple target systems,

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

1985-01-01

245

High-density channel alignment of graded index core polymer optical waveguide and its crosstalk analysis with ray tracing method.  

PubMed

We fabricate graded index (GI) multi-channel polymer optical waveguides comprised of poly methyl methacrylate (PMMA)-poly benzyl methacrylate copolymer for the purpose of achieving high thermal stability in the GI profiles. The waveguides obtained show slightly higher propagation loss (0.033 dB/cm at 850 nm) than doped PMMA based GI-core polymer waveguides we have reported, due to the excess scattering loss inherent to the mixture of copolymer and homo-polymer in the core area. In this paper, we focus on the influence of the excess scattering loss on mode conversion and inter-channel crosstalk. We simulate the behavior of light propagating inside the core with and without the scattering effect. Using the simulation, the excess loss experimentally observed in the copolymer-core waveguide is successfully reproduced, and then, we find that the excess scattering loss of 0.008 dB/cm could increase the inter-channel crosstalk from -30 dB to -23 dB which agrees with the experimentally observed value. Although the simulation of the inter-channel crosstalk was performed only on our GI-core polymer optical waveguides, it is capable of modeling the conventional SI rectangular-core waveguides. Some amount of excess scattering is generally observed in the conventional SI-core waveguides, and thus, the application of this simulation to SI-core waveguides allows a feasible design for high-density alignment of the waveguides. PMID:20588466

Hsu, Hsiang-Han; Ishigure, Takaaki

2010-06-21

246

Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: the double-astigmatic method.  

PubMed

The astigmatic-focusing/push-pull tracking-error detection method is an elegant and sensitive optical servo technique. Unfortunately the formation of error signals far from either line focus of the astigmat (for relaxing alignment tolerances and broadening the servo's acquisition range) gives rise to undesired diffraction effects in the focus servo channel owing to track crossings of the pregrooved disk by the optical stylus, especially if certain aberrations are present. These undesired effects are given several names: pattern noise, optical servo cross talk, and feedthrough. By combining two astigmatic lenses and their associated detectors, one can configure a differential variant of the astigmatic technique. This double-astigmatic method greatly reduces pattern noise caused by the presence of spurious astigmatism oriented with its line foci at ±45° to the disk tracks. In this paper we present numerical modeling and experimental data that demonstrate the effectiveness of this focusing/tracking technique in feedthrough suppression. PMID:20856401

Bernacki, B E; Bates, K; Mansuripur, M; Hansen, D; Cisneros, D

1993-10-10

247

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

248

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

NASA Astrophysics Data System (ADS)

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

Sapega, V. F.

2008-11-01

249

Techniques for the Study of High-Frequency Optical Phenomena  

NASA Astrophysics Data System (ADS)

Literature confirms the presence of rapid quasi periodic and periodic optical phenomena in accreting binary systems. These low intensity oscillations in the few Hz to KHz region are typically detected using fast photodiodes with the data recorded and later correlated. This paper investigates alternate real-time techniques using a low noise, high-speed photodiode and both a PC based FFT spectrum analyzer and a communications receiver for detection and analysis. Using a 14-inch Schmidt-Cassegrain telescope, detection is possible for objects of magnitude 7 or brighter over a frequency range of 10 Hz to 20 KHz where the phenomena modulation level is 1-2% or greater. Trial observations of the Sun during low activity periods indicate broad spectral components in the 50 Hz to 3 KHz range. The brief studies of the Sun and X Persei (HD 24534) indicate opportunities for future high frequency photometric investigation.

Vander Haagen, Gary A.

2008-05-01

250

Optimum Character Encryption And Extraction For Optical Correlation Techniques  

NASA Astrophysics Data System (ADS)

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

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

1990-02-01

251

Scalable synthesis of vertically aligned, catalyst-free gallium arsenide nanowire arrays: towards optimized optical absorption  

NASA Astrophysics Data System (ADS)

Recently nanostructure materials have emerged as a building block for constructing next generation of photovoltaic devices. Nanowire based semiconductor solar cells, among other candidates, have shown potential to produce high efficiency. In a radial pn junction light absorption and carrier collection can be decoupled. Also nanowires can increase choice of materials one can use to fabricate high efficiency tandem solar cells by relaxing the lattice-match constraint. Here we report synthesis of vertical III-V semiconducting nanowire arrays using Selective-Area Metal Organic Chemical Vapor Deposition (SA-MOCVD) technique, which can find application in various optoelectronic devices. We also demonstrate nanosphere lithography (NSL) patterning techniques to obtain ordered pattern for SAMOCVD. Reflection spectrum of nanowires array made by this technique shows excellent light absorption performance without additional anti-reflection coating layer. Thus, we show that highly ordered nanowire structure is 'not needed' to maximize the absorption in vertical nanowire array. Our scalable approach for synthesis of vertical semiconducting nanowire can have application in high throughput and low cost optoelectronic devices including photovoltaic devices.

Yao, Maoqing; Madaria, Anuj R.; Chi, ChunYung; Huang, Ningfeng; Lin, Chenxi; Povinelli, Michelle L.; Dapkus, P. Daniel; Zhou, Chongwu

2012-06-01

252

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

253

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

SciTech Connect

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

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

1996-03-01

254

Optical knife-edge technique for nanomechanical displacement detection D. Karabacak and T. Kouha  

E-print Network

Optical knife-edge technique for nanomechanical displacement detection D. Karabacak and T. Kouha an optical knife-edge technique for nanomechanical displacement detection. Here, one carefully focuses. To demonstrate nanomechanical displacement detection using the knife-edge technique, we have measured in

255

Novel Folding 8 × 8 Silicon-Based Optical Matrix Switch With Tapered Waveguides and Self-Aligned Corner Mirrors  

NASA Astrophysics Data System (ADS)

Novel folding 8 × 8 matrix switches based on silicon on insulator were demonstrated. In the design, single-mode rib waveguides and multimode interferences are connected by optimized tapered waveguides to reduce the mode coupling loss between the two types of waveguides. The self-aligned method was applied to the key integrated turning mirrors for perfect positions and low loss of them. A mixed etching process including inductively coupled plasma and chemical etching was employed to etch waveguides and mirrors, respectively. The compact size of the device is only 20 × 3.2 mm2. The switch element with high switching speed and low power consumption is presented in the matrix. The average insertion loss of the matrix is about -21 dB, and the excess loss of one mirror is measured of -1.4 dB. The worst crosstalk is larger than 21 dB. Experimental results illuminate that some of the main characteristics of optical matrix switches are developed in the modified design, which is in accord with theoretic analyses.

Li, Zhiyong; Yu, Jinzhong; Chen, Shaowu; Liu, Jingwei

2006-12-01

256

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

257

In-Plane Aligned Y1Ba2Cu3O7-x Tapes on Metallic Substrate by Chemical Vapor Deposition Technique  

Microsoft Academic Search

In-plane aligned Y1Ba2Cu3O7- x thin-film tapes have been prepared by the chemical vapor deposition technique on a metallic substrate at 700° C. For continuous deposition on a long substrate, tetrahydrofuran solution of Y, Ba and Cu beta-diketonate chelate was slowly introduced to a vaporizer with argon gas by a liquid flow controller. The generated gas, including source metals, was carried

Taichi Yamaguchi; Yasuhiro Iijima; Naoki Hirano; Shigeo Nagaya; Osamu Kohno

1994-01-01

258

Aligned 3D human aortic smooth muscle tissue via layer by layer technique inside microchannels with novel combination of collagen and oxidized alginate hydrogel.  

PubMed

Tissue engineering of the small diameter blood vessel medial layer has been challenging. Recreation of the circumferentially aligned multilayer smooth muscle tissue has been one of the major technical difficulties. Some research has utilized cyclic stress to align smooth muscle cells (SMCs) but due to the long time conditioning needed, it was not possible to use primary human cells because of expeditious senescence occurred . We demonstrate rapid buildup of a homogeneous relatively thick (30-40 ?m) aligned smooth muscle tissue via layer by layer (LBL) technique within microchannels and a soft cell-adhesive hydrogel. Using a microchannelled scaffold with gapped microwalls, two layers of primary human SMCs separated by an interlayer hydrogel were cultured to confluence within the microchannels. The SMCs aligned along the microchannels because of the physically constraining microwalls. A novel double layered gel consisting of a mixture of pristine and oxidized alginate hydrogel coated with collagen was designed to place between each layer of cells, leading to a thicker tissue in a shorter time. The SMCs penetrated the soft thin interlayer hydrogel within 6 days of seeding of the 2nd cell layer so that the entire construct became more or less homogeneously populated by the SMCs. The unique LBL technique applied within the micropatterned scaffold using a soft cell-adhesive gel interlayer allows rapid growth and confluence of SMCs on 2D surface but at the same time aligns the cells and builds up multiple layers into a 3D tissue. This pseudo-3D buildup method avoids the typical steric resistance of hydrogel embedding. PMID:21548018

Rayatpisheh, Shahrzad; Poon, Yin Fun; Cao, Ye; Feng, Jie; Chan, Vincent; Chan-Park, Mary B

2011-08-01

259

Planar-integrated free-space optics: an integration technique for 3D microoptics  

Microsoft Academic Search

Microoptics and integrated optics are becoming viable technologies for many applications in optical communications, storage, sensing and processing. Both waveguide and free-space optical techniques are of interest. Here, we consider three-dimensional, or: free-space optics. The use of the third spatial dimension is used for imaging, for non-contact probing and sensing and also for high-density optical interconnection in computers and switching

Jürgen Jahns; Manfred Jarczynski

2006-01-01

260

Alignment of rotational prisms.  

PubMed

An analytical expression is derived for the alignment of optical elements, such as the Dove or Pechan prism, that are used to rotate optical images. Improper alignment is characterized by a nutation of the system boresight as the prism is rotated. An analytical description is developed for this nutational boresight error in terms of specific misalignments between the prism, mechanical, and optical axes. This error is shown to be similar in form to that given by a mathematical expression commonly known as thelimacon of Pascal. Unique nutation patterns are noted by which one can distinguish and measure specific misalignments. Proper alignment is seen to involve both lateral and angular adjustments. Appropriate adjustment axes are chosen, and suitable alignment procedures are developed. PMID:20119276

Sullivan, D L

1972-09-01

261

Practical studies on bridge compensating technique in fiber optic sensors  

Microsoft Academic Search

The use of optical bridge compensating structure in fiber optic sensor is studied thoroughly in this article. The stability of the compensating structure is essential to achieve good results. A fiber optic pressure sensor based on this compensating structure has been put into practical operation for oil storage measurement in tanks, and the long term stability of the sensor is

Bing Qi; Wei Peng; Jianhua Ding; Junxiu Lin

1998-01-01

262

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

263

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

E-print Network

for radiation sources ­ ranging from coherent THz to free electron laser (FEL) x-ray sources and Thomson laser mode asymmetry, pulse-front tilt [5], and plasma gradients). Fluctuations in laser pointing cause Wcm-2 ) laser pulses at the output of a plasma chan- nel is used to achieve accurate alignment

Geddes, Cameron Guy Robinson

264

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

PubMed

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

Piper, T; Piper, J

2012-09-01

265

Joint Bayesian Estimation of Alignment and Phylogeny  

Microsoft Academic Search

We describe a novel model and algorithm for simultaneously estimating multiple molecular sequence alignments and the phylogenetic trees that relate the sequences. Unlike current techniques that base phylogeny estimates on a single estimate of the alignment, we take alignment uncertainty into account by considering all possible alignments. Furthermore, because the alignment and phylogeny are constructed simultaneously, a guide tree is

BENJAMIN D. REDELINGS; Marc Suchard

2005-01-01

266

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

PubMed

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

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

2009-03-01

267

An Optical Imaging Technique Using Deep Illumination in the Angular Domain  

Microsoft Academic Search

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

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

2007-01-01

268

Angular measurements in optical testing  

SciTech Connect

The measurement of angles plays an important role in practically every discipline of optics, including prism manufacture, optical assembly and alignment. It is the purpose of this paper to review some of the angle measurement techniques and how they are used in optical testing.

Thomas, N.L.

1980-09-25

269

Differential Deposition Technique for Figure Corrections in Grazing Incidence X-ray Optics  

NASA Technical Reports Server (NTRS)

A differential deposition technique is being developed to correct the low- and mid-spatial-frequency deviations in the axial figure profile of Wolter type grazing incidence X-ray optics. These deviations arise due to various factors in the fabrication process and they degrade the performance of the optics by limiting the achievable angular resolution. In the differential deposition technique, material of varying thickness is selectively deposited along the length of the optic to minimize these deviations, thereby improving the overall figure. High resolution focusing optics being developed at MSFC for small animal radionuclide imaging are being coated to test the differential deposition technique. The required spatial resolution for these optics is 100 m. This base resolution is achievable with the regular electroform-nickel-replication fabrication technique used at MSFC. However, by improving the figure quality of the optics through differential deposition, we aim at significantly improving the resolution beyond this value.

Kilaru, Kiranmayee; Ramsey, Brian D.; Gubarev, Mikhail

2009-01-01

270

Fiber optic pressure sensors employing reflective diaphragm techniques  

NASA Astrophysics Data System (ADS)

In this paper, details will be presented of fiber optic pressure sensors that utilize the deflection of a thin diaphragm as the sensing mechanism. The magnitude of the deflection is monitored optically by either: (1) measurement of the change in intensity distribution of light reflected from the diaphragm due to the changing shape of the reflecting surface, or (2) interferometric measurement of the optical cavity thickness formed by the fiber end and the reflecting diaphragm surface.

Corke, M.; Gillham, F.; Hu, A.; Stowe, D. W.; Sawyer, L.

1989-06-01

271

Optical coatings on plastic lenses by PICVD-technique  

NASA Astrophysics Data System (ADS)

PICVD has been proven as a versatile tool for preparation of optical fibers and planar wave guides as well as for deposition of IR-transparent mirrors, which are implemented in miniature incandescent light sources. These PICVD coatings provide a high potential of applications due to their unconditionally high resistivity to heat and stability to environmental attack. From its basic principles, the PICVD process is well suited for the treatment of thermally labile substrates as for instance plastic lenses. As it is well known, plasma treatment acts as adhesion promoter (at low temperatures), so that excellent interfacial adhesion (between bulk material and coating) even on polymer substrates (low specific surface energy) is one of the most striking features of PICVD. Pulsed plasma mode provides an almost ideal monolayer-by- monolayer growth control in conjunction with high deposition rates. Suitable choice of precursor materials (e.g. Ti-, Si-containing compounds) allows multilayer and/or tailored gradient designs in order to obtain anti-scratch or antireflective properties of the coatings on polymer substrates, which are used for ophthalmic purposes. Up-scaling problems are avoided by using a single working station arrangement. Production proofed microwave technique (2.45 GHz) is implemented for plasma generation, so that substrate temperature can be held at about 70 degree(s)C. Large scale field tests on the durability of the coating, according to DIN prescriptions, demonstrate an excellent endurance of PICVD-coatings. Full computer control, low production costs as well as high throughput guarantees a customer tailored solution.

Moehl, Wolfgang; Lange, U.; Paquet, Volker

1994-11-01

272

Simultaneous alignment and multiple surface figure testing of optical system components via wavefront aberration measurement and reverse optimization  

NASA Astrophysics Data System (ADS)

Simultaneous alignment and figure testing have been simulated by computer for components of a Cooke triplet and a two-. Petzval telescope using end-to-end wavefront aberration measurement and computer model reverse optimization. Experimental confirmation is discussed. 2.

Lundgren, Mark A.; Wolfe, William L.

1991-01-01

273

Simultaneous alignment and multiple surface figure testing of optical system components via wavefront aberration measurement and reverse optimization  

Microsoft Academic Search

Simultaneous alignment and figure testing have been simulated by computer for components of a Cooke triplet and a two-Petzval telescope using end-to-end wavefront aberration measurement and computer model reverse optimization. Experimental confirmation is discussed.

M. A. Lundgren; W. L. Wolfe

1990-01-01

274

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

NASA Astrophysics Data System (ADS)

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

Pint, Cary L.

275

Optical Processing Techniques For Advanced Intelligent Robots And Computer Vision  

NASA Astrophysics Data System (ADS)

Coherent optical processors capable of producing various feature spaces in parallel exist. Those feature spaces that can be optically generated include fourier coefficients, space variant Mellin transforms and polar transform coefficients, moments, chord distribu-tions and Hough/Radon transforms. Optical correlators capable of simultaneous identification and location of multiple objects are well-known and have reached significant levels of compact fabrication. New methods of matched spatial filter synthesis allow these correlators to achieve multi-class distortion-invariant object recognition. New optical computer architectures performing matrix-vector and linear algebra operations represent a class of general purpose systems similiar to digital systolic and multiple processor systems. These various optical architectures will be reviewed and reference will be made to initial results obtained on these systems. In all instances, all architectures are hybrid optical/digital systems that utilize the best features of optical and digital processors. In all cases, attention is given to multi-class distortion-invariant pattern recognition.

Jain, Y. K.; Babu, N. J.; Rao, D. V.

1985-12-01

276

Real-time high-resolution measurement of collagen alignment in dynamically loaded soft tissue  

NASA Astrophysics Data System (ADS)

A technique for creating maps of the direction and strength of fiber alignment in collagenous soft tissues is presented. The method uses a division of focal plane polarimeter to measure circularly polarized light transmitted through the tissue. The architecture of the sensor allows measurement of the retardance and fiber alignment at the full frame rate of the sensor without any moving optics. The technique compares favorably to the standard method of using a rotating polarizer. How the new technique enables real-time capture of the full angular spread of fiber alignment and retardance under various cyclic loading conditions is illustrated.

York, Timothy; Kahan, Lindsey; Lake, Spencer P.; Gruev, Viktor

2014-06-01

277

IOO Assignment Integrated Optical Microsystems Group (IOMS) Optical Loss Spectra with Prism Coupling Technique  

E-print Network

IOO Assignment ­ Integrated Optical Microsystems Group (IOMS) Optical Loss Spectra with Prism of integrated optics are best characterized optically by making use of the prism coupling method. It can provide measurements using another prism coupling setup and employing lasers at various wavelengths, instead

Al Hanbali, Ahmad

278

On the alignment for precession electron diffraction  

PubMed Central

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

Liao, Yifeng; Marks, Laurence D.

2013-01-01

279

Alignment fixture  

Microsoft Academic Search

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

G. C. Bell; O. T. Gibson

1980-01-01

280

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

281

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

282

Evaluation of spectrally efficient indoor optical wireless transmission techniques   

E-print Network

existing RF systems. In OWC, data is transmitted by modulating the intensity of light sources, typically incoherent light emitting diodes (LEDs). Thus, OWC systems employ intensity modulation (IM) and direct detection (DD) of the optical carrier. Since off...

Fath, Thilo Christian Martin

2014-06-30

283

Optical See-Through Head Mounted Display Direct Linear Transformation Calibration Robustness in the Presence of User Alignment Noise  

NASA Technical Reports Server (NTRS)

Augmented Reality (AR) is a technique by which computer generated signals synthesize impressions that are made to coexist with the surrounding real world as perceived by the user. Human smell, taste, touch and hearing can all be augmented, but most commonly AR refers to the human vision being overlaid with information otherwise not readily available to the user. A correct calibration is important on an application level, ensuring that e.g. data labels are presented at correct locations, but also on a system level to enable display techniques such as stereoscopy to function properly [SOURCE]. Thus, vital to AR, calibration methodology is an important research area. While great achievements already have been made, there are some properties in current calibration methods for augmenting vision which do not translate from its traditional use in automated cameras calibration to its use with a human operator. This paper uses a Monte Carlo simulation of a standard direct linear transformation camera calibration to investigate how user introduced head orientation noise affects the parameter estimation during a calibration procedure of an optical see-through head mounted display.

Axholt, Magnus; Skoglund, Martin; Peterson, Stephen D.; Cooper, Matthew D.; Schoen, Thomas B.; Gustafsson, Fredrik; Ynnerman, Anders; Ellis, Stephen R.

2010-01-01

284

Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys  

Microsoft Academic Search

Machine learning techniques are utilised in several areas of astrophysical research today. This dissertation addresses the application of ML techniques to two classes of problems in astrophysics, namely, the analysis of individual astronomical phenomena over time and the automated, simultaneous analysis of thousands of objects in large optical sky surveys. Specifically investigated are (1) techniques to approximate the precise orbits

N. Daniel Kumar

2008-01-01

285

Characterization of optical components using contact and non-contact interferometry techniques: advanced metrology for optical components  

NASA Astrophysics Data System (ADS)

Advanced metrology plays an important role in the research, production and quality control of optical components. With surface finish, form error and other parameter specifications becoming more stringent, precision measurements are increasingly demanded by optics manufacturers and users. The modern metrologist now has both contact and noncontact measurement solutions available and a combination of these techniques now provides a more detailed understanding of optical components. Phase Grating Interferometry (PGI) with sub-nanometre vertical resolution and sub-micron lateral resolution can provide detailed characterization of a wide range of components including shallow and steep-sided optics. PGI is ideal for precision form measurement of a comprehensive range of lenses, moulds and other spherical or aspheric products. Because of the complex nature of these components, especially precision aspheric and asphero-diffractive optics, control of the form is vital to ensure they perform correctly. Recent hardware and software developments now make it possible to gain a better understanding and control of the form and function of this optics. Another change is the use of high speed 3D non-contact measurement of optics which is becoming more popular. Often scanning interferometric techniques such as coherence correlation interferometry (CCI) can be used to study components not suited to 2D contact analysis, including fragile surfaces and structured surfaces. Scanning interferometry can also be used to measure film thickness and uniformity of any coating present. In this paper the use of both PGI and CCI to measure optical lenses and coatings is discussed.

Yu, Yang; Conroy, Mike; Smith, Richard

2012-10-01

286

High speed and low side lobe optical phased array steering by phase correction technique  

NASA Astrophysics Data System (ADS)

Laser beam scanners are important optical elements with a large variety of applications in the measurement techniques, optical communications, laser imaging ladar, etc. Agile beam steering of optical radiation using phased arrays offers significant advantages, such as weight, stability and power requirements over conventional beam steering systems. There are several kinds of optical phased array technology to be developed, such as Lithium tantalite phase shifters, lithium niobate electro-optic prism deflectors, and liquid crystal and ferroelectric liquid crystal phase modulations. However, one of the major drawbacks of these approaches is low light efficiencies because of the side lobes in far-field pattern of the steering beam. In this paper, a new low side lobe optical beam steering technique using phase correction technique is proposed. A stable and fast single-lobed far-field pattern in steering beam can be obtained from the optical phased array with a phase plate by optima design. It can result in a substantially increased light efficiency and beam quality. The quantitative calculation results of typical optical phased array are demonstrated. The low side lobe optical beam steering technology of optical phased array will benefit many practical applications such as laser ladar, laser communications and high resolution displays.

Jin, Yadong; Yan, Aimin; Hu, Zhijuan; Zhao, Zhenyu; Shi, Wangzhou

2013-09-01

287

Weather watch studies by means of an optical technique  

NASA Technical Reports Server (NTRS)

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

Turner, R. E. (editor)

1974-01-01

288

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

289

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

290

Detection and Alignment of 3D Domain Swapping Proteins Using Angle-Distance Image-Based Secondary Structural Matching Techniques  

PubMed Central

This work presents a novel detection method for three-dimensional domain swapping (DS), a mechanism for forming protein quaternary structures that can be visualized as if monomers had “opened” their “closed” structures and exchanged the opened portion to form intertwined oligomers. Since the first report of DS in the mid 1990s, an increasing number of identified cases has led to the postulation that DS might occur in a protein with an unconstrained terminus under appropriate conditions. DS may play important roles in the molecular evolution and functional regulation of proteins and the formation of depositions in Alzheimer's and prion diseases. Moreover, it is promising for designing auto-assembling biomaterials. Despite the increasing interest in DS, related bioinformatics methods are rarely available. Owing to a dramatic conformational difference between the monomeric/closed and oligomeric/open forms, conventional structural comparison methods are inadequate for detecting DS. Hence, there is also a lack of comprehensive datasets for studying DS. Based on angle-distance (A-D) image transformations of secondary structural elements (SSEs), specific patterns within A-D images can be recognized and classified for structural similarities. In this work, a matching algorithm to extract corresponding SSE pairs from A-D images and a novel DS score have been designed and demonstrated to be applicable to the detection of DS relationships. The Matthews correlation coefficient (MCC) and sensitivity of the proposed DS-detecting method were higher than 0.81 even when the sequence identities of the proteins examined were lower than 10%. On average, the alignment percentage and root-mean-square distance (RMSD) computed by the proposed method were 90% and 1.8Å for a set of 1,211 DS-related pairs of proteins. The performances of structural alignments remain high and stable for DS-related homologs with less than 10% sequence identities. In addition, the quality of its hinge loop determination is comparable to that of manual inspection. This method has been implemented as a web-based tool, which requires two protein structures as the input and then the type and/or existence of DS relationships between the input structures are determined according to the A-D image-based structural alignments and the DS score. The proposed method is expected to trigger large-scale studies of this interesting structural phenomenon and facilitate related applications. PMID:20976204

Wang, Hsin-Wei; Hsu, Yen-Chu; Hwang, Jenn-Kang; Lyu, Ping-Chiang; Pai, Tun-Wen; Tang, Chuan Yi

2010-01-01

291

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

PubMed

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

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

2014-01-01

292

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

PubMed Central

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

2014-01-01

293

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

294

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

295

Fiber optic diagnostic techniques for the electrical discharge machining process  

E-print Network

were used along with current pulse waveforms from the EDM machine to study the temporal characteristics of the spark. During this experiment an optical pattern was identified that indicated when an arc was being formed in the EDM machine instead of a...

Pillans, Brandon William

2012-06-07

296

The Universe Viewed in Gamma-Rays 1 Mirror Alignment and Optical Quality of the H.E.S.S.  

E-print Network

triangle carrying one fixed mirror sup- port point and two motor-driven actuators. A motor unit includes to be adjustable, the mirror facets are mounted onto supports which are equipped with two motor- driven actuators of the mirror facets is crucial. A fully automated alignment system has been developed, including motorized

Enomoto, Ryoji

297

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

E-print Network

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

Lim, Michael H. (Michael Hong)

2002-01-01

298

A technique for computation of star magnitudes relative to an optical sensor  

NASA Technical Reports Server (NTRS)

The theory and techniques used to compute star magnitudes relative to any optical detector (such as the Mariner Mars 1971 Canopus star tracker) are described. Results are given relative to various star detectors.

Rhoads, J. W.

1972-01-01

299

QUALIFICATION OF A TRULY DISTRIBUTED FIBER OPTIC TECHNIQUE FOR STRAIN AND TEMPERATURE MEASUREMENTS IN CONCRETE STRUCTURES  

E-print Network

1 QUALIFICATION OF A TRULY DISTRIBUTED FIBER OPTIC TECHNIQUE FOR STRAIN AND TEMPERATURE - Methodology for qualification of non-destructive tests", a qualification method was developed. Tests were, involving major economical and environmental repercussions. Fundamental issues such as optimization

Paris-Sud XI, Université de

300

Serially grafted polymer optical waveguides fabricated by light-induced self-written waveguide technique.  

PubMed

Serially grafted polymer optical waveguides were fabricated by the light-induced self-written (LISW) waveguide technique for the first time to our knowledge. To realize functional waveguide cores by the LISW technique, transparent materials at the writing wavelength were selected. By inserting thin transparent partitions, a serial-graft structure consisting of passive and active waveguides without any misalignment was realized automatically. This technique is advantageous for its extremely easy process over conventional fabrication techniques. PMID:18246159

Sugihara, Okihiro; Yasuda, Shuhei; Cai, Bin; Komatsu, Kyoji; Kaino, Toshikuni

2008-02-01

301

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

NASA Astrophysics Data System (ADS)

Over the past few years, DWDM has been widely adopted across the telecommunications industry to expand capacity in telecommunication infrastructure. The success of DWDM in increasing raw capacity on point-to-point fiber routes and the rapid growth of data communications accelerates the pace to all-optical networking. The goal of all- optical networking is to create a transparent optical layer that can easily manage the transport of signal entirely in the optical domain, reducing the need for processing and interpretation of signals, while increasing the reliability and restorability of high- bandwidth networks. However, the premise of transparent or all-optical networks requires the availability of tools to measure and control the smallest granular component of such networks-the wavelength channel, not only in the transportation system, but also in core switching segments. This dissertation studied the optical performance measuring tools for WDM networks, and categorized the optical performance monitoring into two layers: optical-physical-layer performance monitoring and optical-path-layer performance monitoring. With potential mass-production capability for future wide range application, planar waveguide technology is selected as the focus of this dissertation. In the optical-physical-layer, arrayed waveguide grating (AWG) based multi-channel wavelength, power and OSNR monitoring circuit were proposed. Modeling and design were performed to provide optimized performance. Multi- channel wavelength monitoring circuit was demonstrated with precise wavelength monitoring capability. Optical-path-layer performance layer monitoring becomes necessary while optical cross-connect (OXC) is implemented. Focusing on one type of OXC, this dissertation studied the possibility to build a low cost, robust and transparent monitoring scheme using similar planar waveguide technology which been used in optical- physical-layer monitoring. Furthermore, the applications of optical performance monitoring in all-optical networks were discussed, including system turn-up, dynamic gain spectrum flattening and power equalizing after OXC.

Zhong, Shan

302

Application of R-ICOS laser spectroscopy technique for measurement of absorption in optically dense media  

NASA Astrophysics Data System (ADS)

The integral R-ICOS method of three-beam diode laser spectroscopy allows extending the dynamic range of measurements of the absorption coefficient of particles in a medium compared to the conventional ICOS (CEAS) integral absorption technique in an external optical cell. The application of the method for optically dense media is discussed.

Kostenko, A. S.; Nikolaev, I. V.; Ochkin, V. N.; Tskhai, S. N.; Zaytsev, A. A.

2015-01-01

303

Traveling Electrical Waves in Cortex: Measurements with Optical Imaging Techniques and Insights from Phase Dynamics  

E-print Network

Traveling Electrical Waves in Cortex: Measurements with Optical Imaging Techniques and Insights, both with standard electrodes and with optical imaging technology in conjunction with voltage sensitive by the NSF and the NIH/NCRR. 1. Kuramoto, Y., Chemical Oscillations, Waves and Turbulence. 1984, New York

Kleinfeld, David

304

Fundamentals and techniques of nonimaging optics for solar energy concentration. Final report  

Microsoft Academic Search

Nonimaging optics is a new discipline with techniques, formalism and objectives quite distinct from the traditional methods of focusing optics. These new systems achieve or closely approach the maximum concentration permitted by the Second Law of Thermodynamics for a given angular acceptance and are often called ideal. Application of these new principles to solar energy over the past seven years

1980-01-01

305

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

2011-03-01

306

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

307

Segmentation of the optic tracts using graph-based techniques  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

308

Pupil Alignment Considerations for Large, Deployable Space Telescopes  

NASA Technical Reports Server (NTRS)

For many optical systems the properties and alignment of the internal apertures and pupils are not critical or controlled with high precision during optical system design, fabrication or assembly. In wide angle imaging systems, for instance, the entrance pupil position and orientation is typically unconstrained and varies over the system s field of view in order to optimize image quality. Aperture tolerances usually do not receive the same amount of scrutiny as optical surface aberrations or throughput characteristics because performance degradation is typically graceful with misalignment, generally only causing a slight reduction in system sensitivity due to vignetting. But for a large deployable space-based observatory like the James Webb Space Telescope (JWST), we have found that pupil alignment is a key parameter. For in addition to vignetting, JWST pupil errors cause uncertainty in the wavefront sensing process that is used to construct the observatory on-orbit. Furthermore they also open stray light paths that degrade the science return from some of the telescope s instrument channels. In response to these consequences, we have developed several pupil measurement techniques for the cryogenic vacuum test where JWST science instrument pupil alignment is verified. These approaches use pupil alignment references within the JWST science instruments; pupil imaging lenses in three science instrument channels; and unique pupil characterization features in the optical test equipment. This will allow us to verify and crosscheck the lateral pupil alignment of the JWST science instruments to approximately 1-2% of their pupil diameters.

Bos, Brent J.; Ohl, Raymond G.; Kubalak, Daivd A.

2011-01-01

309

Alignment reference device  

DOEpatents

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

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

1987-01-01

310

High-speed terahertz time-domain polarimeter based on an electro-optic modulation technique  

NASA Astrophysics Data System (ADS)

We present a method of developing a high-speed terahertz time-domain polarimeter based on an electro-optic sampling setup, which consists of a rapid polarization analysis of the probe optical beam within 1 ms with an angular resolution of ?100 mrad using an electro-optic modulator (EOM). A fast optical delay line enabled us to obtain the vector waveform of the terahertz pulse within 100 ms. The setup does not utilize a manual/mechanical rotational stage, but the use of the polarization modulation technique employing the EOM ensures a high-speed and high-accuracy measurement of the state of polarization of terahertz waves.

Yasumatsu, Naoya; Kasatani, Atsushi; Oguchi, Kenichi; Watanabe, Shinichi

2014-09-01

311

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

PubMed

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

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

2014-01-01

312

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

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

2009-08-01

313

Technique for simultaneously multiplying the repetition rate of multiwavelength optical pulse trains  

Microsoft Academic Search

In this letter, we propose and numerically demonstrate a technique for synchronized multiplication of the repetition rate in multiwavelength optical pulse trains launched over a single fiber. The technique only requires linear reflection of the original signal in a single structure of superimposed chirped in-fiber Bragg gratings, which are specifically designed to provide a suitable group delay dispersion within each

José Azaña; Miguel A. Muriel

2001-01-01

314

MOLECULAR OPTICAL SPECTROSCOPIC TECHNIQUES FOR HAZARDOUS WASTE SITE SCREENING  

EPA Science Inventory

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

315

Development of Off-Plane Reflection Grating Alignment Fixtures  

NASA Astrophysics Data System (ADS)

Currently, grating spectrometers are used onboard the Chandra X-ray Observatory and XMM-Newton in orbit around the Earth. However, future goals of greater spectral resolving power and greater effective areas necessitate a new generation of high-quality spectrometers. Off-plane reflection gratings can be used to provide high throughput and spectral resolution in the 0.3-2.0 keV band, allowing for unprecedented diagnostics of energetic astrophysical processes. A grating spectrometer consists of multiple aligned gratings intersecting the converging beam of a Wolter-I telescope. Each grating will be aligned such that the diffracted spectra overlap at the focal plane. Misalignments will degrade both spectral resolution and effective area. With analytical alignment tolerances calculated, laboratory techniques to achieve these tolerances for flight-like optics must be developed. We present the results from our first and second generation alignment fixtures, as well as wavefront stitching methods.

Donovan, Benjamin D; Allured, Ryan; McEntaffer, Randall L.

2014-06-01

316

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

NASA Astrophysics Data System (ADS)

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

Shadaram, Mehdi; Medrano, John; Pappert, Stephen A.; Berry, Mark H.; Gookin, Debra M.

1995-12-01

317

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. PMID:23758858

2013-01-01

318

Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys  

Microsoft Academic Search

Machine learning techniques are utilised in several areas of astrophysical\\u000aresearch today. This dissertation addresses the application of ML techniques to\\u000atwo classes of problems in astrophysics, namely, the analysis of individual\\u000aastronomical phenomena over time and the automated, simultaneous analysis of\\u000athousands of objects in large optical sky surveys. Specifically investigated\\u000aare (1) techniques to approximate the precise orbits

N. Daniel Kumar

2008-01-01

319

Integrated-optical techniques for near-millimeter-wave technology  

NASA Astrophysics Data System (ADS)

All-dielectric guides, especially the type known as 'slab-coupled' or 'rib' waveguides, are discussed as a promising integrated optical technology for the near-millimeter band. The advantages of this type of guide include easy fabrication using photolithography; improved performance with increasing frequency; acceptably low loss; compatibility with other components such as filters, couplers, and resonators; for semiconductor dielectrics, integration with semiconductor devices to form millimeter wave integrated circuits. These guides are studied by means of X-band simulation, and various devices have been constructed at several frequencies ranging from 70 to 2500 GHz. A cross section of the waveguide is shown, along with a diagram of the monolithic integration of dielectric waveguide antenna, dielectric waveguide, V-coupler, and Schottky diode. Coupling from free space propagation into these guides is discussed, as are coupling between guides and diodes, waveguide-based components and systems, and integration with semiconductor devices.

Schwarz, S. E.

1982-08-01

320

Novel x-ray optics for medical diagnostic techniques  

NASA Astrophysics Data System (ADS)

A new hard X - ray hologram with using crystal Fresnel zone plates (ZP) has been described. An image of Fourier hologram for hard X- ray is presented. X-ray phase contrast methods for medical diagnostics techniques are presented. We have developed an X-ray microscope, based on micro focus source which is capable of high resolution phasecontrast imaging and holograms. We propose a new imaging technique with the x-ray energy 8 keV. The method is expected to have wide applications in imaging of low absorbing samples such as biological and medical tissue. We used FIB to reproduction three dimension structures of damaged spinal cord of rat before and after combined treatment with NT3 and NR2D. PUBLISHER'S NOTE 12/16/09: This SPIE Proceedings paper has been updated with an erratum correcting several issues throughout the paper. The corrected paper was published in place of the earlier version on 9/1/2009. If you purchased the original version of the paper and no longer have access, please contact SPIE Digital Library Customer Service at CustomerService@SPIEDigitalLibrary.org for assistance.

Kuyumchyan, A.; Arvanian, V.; Kuyumchyan, D.; Aristov, V.; Shulakov, E.

2009-08-01

321

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

322

Novel signal-processing techniques for low-cost fiber optic gyroscopes (FOGs)  

NASA Astrophysics Data System (ADS)

The paper describes three examples of low-cost, low-power signal processing techniques used in building prototypes of low/medium performance Fiber Optic Gyroscopes. The prototypes were developed at the Mercer Engineering Research Center, in an ongoing U.S. Air Force funded effort to develop a Fiber Optic Gyroscope replacement for existing mechanical rate gyroscopes used in a wide variety of applications. The novelty of applied methods consists of a very small number of elements used, and a very low power consumed by the signal processing electronics. The noise suppression was achieved due to small number of elements, synchronous homodyne detection scheme, and resonance amplifier/filter techniques. The Sagnac interferometric optics with 50/50 splitter/combiner, and 2 X 2 directional coupler, and optical phase shifter at 820 nm and 1500 nm wavelengths have been developed as a part of this ongoing effort and were used in the experiments.

Klimkiewicz, Wojciech; Duryea, Jeffrey L.

1994-11-01

323

Localized and distributed fiber optic strain sensors based on white light interferometric techniques  

Microsoft Academic Search

Strain, deformation and temperature measurements constitute the most interesting parameters to be monitored in smart structures. White-light interferometry offers these performances even for long-term measurements. Based on the Michelson interferometer, a fiber optic localized strain sensor and multiplexing strain-sensing techniques are demonstrated in this paper. Related problem about the spatial division limitation of fiber optic sensors is discussed. Finally, application

Libo Yuan; Limin M. Zhou; Wei Jin

2000-01-01

324

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

Microsoft Academic Search

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

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

2011-01-01

325

An optical surveillance technique based on cavity mode analysis of SL-RSOA for GPON  

NASA Astrophysics Data System (ADS)

An optical in-service surveillance technique based on cavity mode analysis of self-injection locked reflective semiconductor optical amplifier (SL-RSOA) for gigabit-capable passive optical network (GPON) is proposed. At each optical network unit (ONU), an upstream transmitter utilizing SL-RSOA can generate both upstream data signal and surveillance signal due to presence of external cavity. We can able to detect both upstream data and surveillance signals from all ONUs simultaneously at the optical line terminal (OLT) by assigning a distinct cavity mode frequency to each upstream transmitter. We also estimate the power penalty induced by the surveillance signals on the upstream data channel during simultaneous detection mechanism. Further, we propose an alternative method to detect the surveillance signals by allocating a separate monitoring time slot in upstream GPON transmission convergence (GTC) frame so as to reduce the influence of surveillance signals on the upstream data channel.

Thollabandi, Madhan; Bang, Hakjeon; Shim, Kyung-Woo; Hann, Swook; Park, Chang-Soo

2009-10-01

326

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

327

New techniques for optical absorption measurement of implanted nanoparticles in float glass  

NASA Astrophysics Data System (ADS)

New techniques are reported for optical absorption and waveguide loss measurement of copper, gold and silver implanted float glass. Implantations were carried out on the tin face of the float glass since this face is an optical waveguide. Specially made triangle shape masks were used during implantation to study the optical loss-implant length relation. Absorption coefficients were extracted as 2.4 and 1 cm -1 for the gold and silver implants at 633 nm, respectively. These values were found to be implant condition dependent. To analyse the shape of nanoparticles a sandwiched structure was used in an optical absorption measurement set-up in which two guiding faces were put in contact. The sandwiched structure places the colloids at the centre of the optical field distribution rather than on the boundary zone. These experiments have revealed that the copper and the gold particles may have non-spherical shapes, whereas for silver, the formation of spherical nanoparticles is more likely.

Okur, I.; Townsend, P. D.; Chandler, P. J.

1999-01-01

328

Controlled formation of Ag\\/poly(methyl-methacrylate) thin films by RAFT technique for optical switcher  

Microsoft Academic Search

The functional group of sulfur was introduced into the PMMA terminus by the reversible addition-fragmentation transfer (RAFT) technique and the PMMA\\/Ag nanocomposite film was prepared by the in situ synthetic method. The third-order nonlinear optical properties of the material were further investigated by the Z-scan technique. The result shows that the ?(3) nonlinearity of the material depend on the doped

Youyi Sun; Yaqing Liu; Guizhe zhao; Xing Zhou; Qijin Zhang; Yan Deng

2008-01-01

329

Electrical spectral technique for measuring cross-phase modulation impact in WDM optical systems  

Microsoft Academic Search

An electrical spectral technique to correctly evaluate cross-phase modulation behavior in intensity modulation-direct detection systems is proposed. Intrinsic advantages of the technique, in terms of high accuracy, are discussed in comparison with the classical time-domain method, which requires precise receiver noise characterization. Measures have been performed with a pump-and-probe scheme on different standard optical communications fibers (i.e., G.652, G.655). The

Livio Paradiso; Pierpaolo Boffi; Lucia Marazzi; Giandomenico Pozzi; Massimo Artiglia; Mario Martinelli

2005-01-01

330

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

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

331

Technique to improve carrier-to-interference ratio of optical single sideband with carrier modulated signals  

NASA Astrophysics Data System (ADS)

We propose and demonstrate a simple technique to improve the carrier-to-interference ratio (CIR) of optical single sideband with carrier modulated signals for fiber-radio applications. The proposed scheme is demonstrated via experiment and simulation with a two-tone test showing that an improvement in CIR of 9 dB can be achieved.

Lim, Christina; Lee, Ka-Lun; Nirmalathas, Ampalavanapillai; Novak, Dalma; Waterhouse, Rod

2006-11-01

332

Matter Wave Optical Techniques for Probing Many-body Scott Nicholas Sanders  

E-print Network

Matter Wave Optical Techniques for Probing Many-body Targets by Scott Nicholas Sanders A by . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Thomas Greytak Chairman, Department Committee on Graduate Theses #12;#12;to my family #12;#12;Matter Wave of Philosophy in Physics Abstract This thesis reports on our investigation of the uses of matter waves to probe

Heller, Eric

333

Hardware Implementation of Multiple Fan Beam Projection Technique in Optical Fibre Process Tomography  

Microsoft Academic Search

The main objective of this project is to implement the multiple fan beam projection technique using optical fibre sensors wi th the aim to achieve a high data acquisition rate. Multiple fan beam projection tech nique here is defined as allowing more than one emitter to transmit light at the same time using the switch-mode fan beam method. For the

Ruzairi Abdul Rahim; Mohd Hafiz Fazalul Rahiman; Leong Lai Chen; Chan Kok San; Pang Jon Fea

2008-01-01

334

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

Microsoft Academic Search

Attractive features of soft magnetic composites (SMCs) are high resistivity, isotropic three-dimensional flux behavior, and easy compression into the complicated shapes required in electromagnetic devices. Comprehensive understanding of the materials will help optimize design of electromagnetic devices. This paper presents the magnetization processes in a SMC sample in micron scale by means of the magneto-optical imaging technique. The sample was

Zhi Wei Lin; Jian Guo Zhu; Jin Jiang Zhong; Tom H. Johansen; Xiao Lin Wang; Wei Yang Yu

2007-01-01

335

Bandwidth Scheduling Techniques for Differentiated Services Support in Ethernet Passive Optical Networks  

E-print Network

Bandwidth Scheduling Techniques for Differentiated Services Support in Ethernet Passive Optical and providing broadband access in the "last mile" area. Ethernet PONs (EPON) gain the most attention from and electrical domains. Two protocols, Asynchronous Transfer Mode (ATM) and Ethernet, have been proposed

336

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

SciTech Connect

Three new failure analysis techniques for integrated circuits (ICs) have been developed using localized photon probing with a scanning optical microscope (SOM). The first two are light-induced voltage alteration (LIVA) imaging techniques that (1) localize open-circuited and damaged junctions and (2) image transistor logic states. The third technique uses the SOM to control logic states optically from the IC backside. LIVA images are produced by monitoring the voltage fluctuations of a constant current power supply as a laser beam is scanned over the IC. High selectivity for localizing defects has been demonstrated using the LIVA approach. Logic state mapping results, similar to previous work using biased optical beam induced current (OBIC) and laser probing approaches have also been produced using LIVA. Application of the two LIVA based techniques to backside failure analysis has been demonstrated using an infrared laser source. Optical logic state control is based upon earlier work examining transistor response to photon injection. The physics of each method and their applications for failure analysis are described.

Cole, E.I. Jr.; Soden, J.M.; Rife, J.L.; Barton, D.L.; Henderson, C.L.

1993-12-31

337

VisualAudio: an Optical Technique to Save the Sound of Phonographic Records  

Microsoft Academic Search

The optical retrieval and storage technique called VisualAudio provides a way to extract sound information from a phonographic record without any mechanical contact. The process is straightforward: we take a picture of each side of the disk using a dedicated analog camera, we store the film as our working copy, and when needed, we scan the film and process the

Sylvain Stotzer; Ottar Johnsen; Frédéric Bapst; Cédric Milan; Christoph Sudan; S. Cavaglieri; Pio Pellizzari; Nazionale Svizzera

338

Application of the double optic probe technique to distorted tumbling bubbles in aqueous or organic liquid  

Microsoft Academic Search

The optic probe technique is widely used to investigate bubble reactors. To derive values of bubble local velocities and bubble local sizes, a specific signal treatment is usually applied under severe assumptions for bubble path and shape. However, in most industrial reactors, bubble motion is chaotic and no common shape can be assumed.In this work, the reliability of the signal

H. Chaumat; A. M. Billet-Duquenne; F. Augier; C. Mathieu; H. Delmas

2005-01-01

339

ADVANCES IN OPTICALLY PUMPED He4 MAGNETOMETERS : RESONANCE AND NONRESONANCE TECHNIQUES  

E-print Network

109. ADVANCES IN OPTICALLY PUMPED He4 MAGNETOMETERS : RESONANCE AND NONRESONANCE TECHNIQUES By R. E pumped 23S1 helium atoms are currently studied in our laboratory for use in advanced magnetometer pumping process is used to construct a non- resonance magnetometer (no magnetic resonance) suitable

Boyer, Edmond

340

A Survivable WDM-PON Architecture Using Optical Carrier Suppression Technique  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

341

Improvement of the optical imaging technique for intact rat brain using a plano-concave lens.  

PubMed

Use of a plano-concave lens improved the quality of optical signals from the rat cerebral cortex by improving the focus. When detecting neural activity from a curved surface of an in vivo brain by optical techniques, it is not possible to adjust the focus equally over the entire detecting area in the two-dimensional plane, since the active window of the optical detector is usually flat, while the intact brain surface is spherical. It has been known that the size of the optical signal is reduced as the distance of the real image to the active window of the detector increases; therefore, the level of the signal-to-noise ratio obtained from the unfocused area often becomes insufficient for quantitative physiological analyses. By placing a plano-concave lens on the cerebral cortex, we succeeded in obtaining a two-dimensional image that has no unfocused area over an entire image recorded by the detector. PMID:25249031

Kawai, Minako; Hama, Noriyuki; Ito, Shin-Ichi; Hirota, Akihiko

2014-11-01

342

Ultraprecision machining techniques for the fabrication of freeform surfaces in highly integrated optical microsystems  

NASA Astrophysics Data System (ADS)

The application of multi-axis micromilling and flycutting is investigated for the fabrication of complex optical microsystems incorporating different classes of aspherical and freeform optical elements. Such elements provide the necessary degrees of freedom for aberration correction in integrated optical microsystems and are specifically interesting for applications like beam shaping or computational imaging. Especially for elements with small radii of curvature, high aspect ratios and spatial frequencies, micromilling and flycutting are interesting alternatives to the more established diamond turning technology. We present the results of the fabrication of a monolithically integrated optical microsystem consisting of two tilted flat surfaces used as coupling prisms and a freeform imaging element. On the resulting surfaces the average roughness height without subsequent polishing was found to be Ra = 18.2 ... 25.5 nm (depending on the fabrication technique) with an overall shape accuracy < 0.5 ... 2.9 ?m (based on the determination of the radii of curvature).

Stoebenau, Sebastian; Sinzinger, Stefan

2009-08-01

343

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

NASA Astrophysics Data System (ADS)

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

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

2001-01-01

344

Freeform mirror fabrication and metrology using a high performance test CGH and advanced alignment features  

NASA Astrophysics Data System (ADS)

The metrology of mirrors with an off-axis aspheric or freeform shape can be based on optical testing using a Computer Generated Hologram as wavefront matching element in an interferometric setup. Since the setup can be understood as optical system consisting of multiple elements with six degrees of freedom each, the accuracy strongly depends on the alignment of the surface under test with respect to the transmission element of the interferometer and the micro optics of the CGH. A novel alignment approach for the relative positioning of the mirror and CGH in six degrees of freedom is reported. In the presented work, a proper alignment is achieved by illuminating alignment elements outside the Clear Aperture (CA) of the optical surface with the help of auxiliary holograms next to the test CGH on the substrate. The peripheral holograms on the CGH substrate are used to generate additional phase maps in the interferogram, that indicate positioning errors. Since the reference spheres represent the coordinate system of the mirror and are measured in the same precision as the optical surface, the registration and shape has to be appropriate to embody the mirrors coordinate system. The alignment elements on the mirror body are diamond machined using freeform turning or micro milling processes in the same machine setup used for the mirror manufacturing. The differences between the turning and milling of alignment lenses is discussed. The novel approach is applied to correct the shape error of a freeform mirror using ultra precision machining. The absolute measurement of the quality of freeform mirror shapes including tilt and optical power is possible using the presented alignment concept. For a better understanding, different metrology methods for aspheres and freeforms are reviewed. To verify the novel method of alignment and the measurement results, the freeform surface is also characterized using ultra high accuracy 2½D profilometry. The results of the different techniques for the absolute measurement of freeforms are compared.

Scheiding, Sebastian; Beier, Matthias; Zeitner, Uwe-Detlef; Risse, Stefan; Gebhardt, Andreas

2013-03-01

345

Applications of the particle-in-cell technique to liquid crystal optical devices  

NASA Astrophysics Data System (ADS)

For the first time we demonstrate the application of the particle-in-cell (PIC) technique in modeling liquid crystal (LC) optical devices. We apply the technique to a two-dimensional cell including splay and bend deformations. The simulation method is validated by comparing the numerical results with analytical theory of Fredericksz transition in a parallel-plate LC cell. The phenomenon of the Fredericksz transition and the formation and dynamics of defect walls in highly inhomogeneous electric fields are investigated, demonstrating the applicability of the technique for modeling the dynamic behavior of LC devices.

Singh, Nagendra; Leung, W. C.

1998-10-01

346

A UNIFIED APPROACH TO REAL TIME AUDIO-TO-SCORE AND AUDIO-TO-AUDIO ALIGNMENT USING SEQUENTIAL MONTECARLO INFERENCE TECHNIQUES  

E-print Network

A UNIFIED APPROACH TO REAL TIME AUDIO-TO-SCORE AND AUDIO-TO-AUDIO ALIGNMENT USING SEQUENTIAL discrete. The major contribution of this paper is addressing both problems of audio-to-score and audio-to-audio signal to music events. In this paper, we focus our attention on the alignment of a streaming audio

Paris-Sud XI, Université de

347

Precoding techniques for PAPR reduction in asymmetrically clipped OFDM based optical wireless system  

NASA Astrophysics Data System (ADS)

In this paper, we have analyzed different precoding based Peak-to-Average-Power (PAPR) reduction techniques for asymmetrically-clipped Orthogonal Frequency Division Multiplexing (OFDM) optical wireless communication systems. Intensity Modulated Direct Detection (IM/DD) technique is among the popular techniques for optical wireless communication systems. OFDM cannot be directly applied to IM systems because of the bipolar nature of the output signal. Therefore some variants of OFDM systems have been proposed for (IM/DD) optical wireless systems. Among them are DC-biased-OFDM, Asymmetrically-Clipped Optical OFDM (ACO-OFDM) [2] and Pulse Amplitude Modulated Discrete Multitone (PAM-DMT) [3]. Both ACO-OFDM and PAM-DMT require low average power and thus are very attractive for optical wireless systems. OFDM systems suffer from high PAPR problem that can limit its performance due to non-linear characteristics of LED. Therefore PAPR reduction techniques have to be employed. This paper analyzes precoding based PAPR reduction methods for ACO-OFDM and PAM-DMT. We have used Discrete Fourier Transform (DFT) coding, Zadoff-Chu Transform (ZCT) [8] and Discrete Cosine Transform (DCT) for ACOOFDM and only DCT for PAM-DMT since the modulating symbols are real. We have compared the performance of these precoding techniques using different QAM modulation schemes. Simulation results have shown that both DFT and ZCT offer more PAPR reduction than DCT in ACO-OFDM. For PAM-DMT, DCT precoding yields significant PAPR reduction compared to conventional PAM-DMT signal. These precoding schemes also offer the advantage of zero signaling overhead.

Ranjha, Bilal; Kavehrad, Mohsen

2013-01-01

348

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

349

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 atop Magdalena Ridge, 30 miles west of Socorro, NM. Depending on the location of each unit telescope, 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, beam reducing telescope, switchyards and finally to the beam combiners. All of these sub-systems comprise the three major optical axes of the MROI defined by the unit telescope (UT), the delay lines and the beam reducer (DL/BR), and the beam combiners (BC). The purpose of the alignment system is to provide a method of coaligning these three axes. 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 the AAS has been completed and is currently in its preliminary design phase with some prototyping already commenced. Here is presented the current outline and progress of MROI's automated alignment system design and some results of the prototyping.

Shtromberg, Alisa V.; Jurgenson, C. A.; Paz, M. T.; Steenson, J. M.; Berger, L.

2007-12-01

350

An optical pump-probe technique for measuring the thermal conductivity of liquids  

NASA Astrophysics Data System (ADS)

We present a pump-probe optical technique for measuring the thermal conductivity of liquids. The technique uses a reflective geometry which does not depend on the optical properties of the liquid and requires as little as a single droplet to produce a result. An analytical solution is given for bidirectional heat flow in layered media, including the effects of radial heat flow from coaxial Gaussian laser spots, thermal interface resistances, and the accumulation of multiple laser pulses. In addition, several experimental improvements over previous pump-probe configurations are described, resulting in an improved signal to noise ratio and smaller errors at long stage delay times. The technique is applied to a range of liquids and solids. Results are in good agreement with literature values.

Schmidt, Aaron; Chiesa, Matteo; Chen, Xiaoyuan; Chen, Gang

2008-06-01

351

AIMFAST : an alignment tool based on fringe reflection methods applied to dish concentrators.  

SciTech Connect

The proper alignment of facets on a dish engine concentrated solar power system is critical to the performance of the system. These systems are generally highly concentrating to produce high temperatures for maximum thermal efficiency so there is little tolerance for poor optical alignment. Improper alignment can lead to poor performance and shortened life through excessively high flux on the receiver surfaces, imbalanced power on multicylinder engines, and intercept losses at the aperture. Alignment approaches used in the past are time consuming field operations, typically taking 4-6 h per dish with 40-80 facets on the dish. Production systems of faceted dishes will need rapid, accurate alignment implemented in a fraction of an hour. In this paper, we present an extension to our Sandia Optical Fringe Analysis Slope Technique mirror characterization system that will automatically acquire data, implement an alignment strategy, and provide real-time mirror angle corrections to actuators or labor beneath the dish. The Alignment Implementation for Manufacturing using Fringe Analysis Slope Technique (AIMFAST) has been implemented and tested at the prototype level. In this paper we present the approach used in AIMFAST to rapidly characterize the dish system and provide near-real-time adjustment updates for each facet. The implemented approach can provide adjustment updates every 5 s, suitable for manual or automated adjustment of facets on a dish assembly line.

Yellowhair, Julius; Stone, Brad (Stirling Energy Systems, Scottsdale, AZ); Myer, Brian (Appalachian State University, Boone, NC); Hunt, Kirby (Stirling Energy Systems, Scottsdale, AZ); Trapeznikov, Kirill; Andraka, Charles E.; Carlson, Jeffrey J.

2010-08-01

352

Interstellar Grain Alignment: Observational Status  

NASA Astrophysics Data System (ADS)

Interstellar polarization in the optical/infrared has long been known to be due to asymmetrical dust grains aligned with the magnetic field and can potentially provide a resource effective way to probe both the topology and strength of the magnetic-field. However, to do so with confidence, the physics and variability of the alignment mechanisms must be quantitatively understood. The last 15 years has seen major advancements in both the theoretical and observational understanding of this problem. I here review the current state of the observational constraints on the grain alignment physics. While none of the three classes of proposed grain alignment theories: mechanical, paramagnetic relaxation and radiative alignment torque, can be viewed as having been empirically confirmed, the first two have failed some critical observational tests, whereas the latter has recently been given specific observational support and must now be viewed as the leading candidate.

Andersson, B.-G.

353

Optical Properties of Astronomical Silicates with Infrared Techniques (OPASI-T)  

NASA Technical Reports Server (NTRS)

Astronomical dust is observed in a variety of astrophysical environments and plays an important role in radiative processes and chemical evolution in the galaxy. Depending upon the environment, dust can be either carbon-rich or oxygen-rich (silicate grains). Both astronomical observations and ground-based data show that the optical properties of silicates can change dramatically with the crystallinity of the material, and recent laboratory research provides evidence that the optical properties of silicate dust vary as a function of temperature as well. Therefore, correct interpretation of a vast array of astronomical data relies on the understanding of the properties of silicate dust as functions of wavelength, temperature, and crystallinity. The OPASI-T (Optical Properties of Astronomical Silicates with Infrared Techniques) project addresses the need for high quality optical characterization of metal-enriched silicate condensates using a variety of techniques. A combination of both new and established experiments are used to measure the extinction, reflection, and emission properties of amorphous silicates across the infrared (near infrared to millimeter wavelengths), providing a comprehensive data set characterizing the optical parameters of dust samples. We present room temperature measurements and the experimental apparatus to be used to investigate and characterize additional metal-silicate materials.

Rinehart, Stephen

2010-01-01

354

Advanced mask aligner lithography (AMALITH)  

NASA Astrophysics Data System (ADS)

Mask aligners were the dominating lithography tool for the first 20 years of semiconductor industry. In the 1980s industry changed over to projection lithography. However, mask aligners were never sorted out and still today hundreds of new mask aligners are sold each year. This continuing success of mask aligner lithography is due to two basic trends in lithography: (a) Costs for leading-edge lithography tools double approximately every 4.4 years; and (b) the number of lithography steps per wafer was increasing from a few litho layers to more than 35 layers now. This explains why mask aligners, a very cost-effective solution for uncritical litho layers, are still widely used today. In over 50 years of semiconductor industry the mask aligner system has changed tremendously. However, only little effort was undertaken to improve the shadow printing process itself. We now present a new illumination system for mask aligners, the MO Exposure Optics (MOEO), which is based on two microlens-type Köhler integrators located in Fourier-conjugated planes. The optics stabilizes the illumination against misalignment of the lamp-to-ellipsoid position. It provides improved light uniformity, telecentric illumination and allows freely shaping the angular spectrum of the illumination light by spatial filtering. It significantly improves the CD uniformity, the yield in production and opens the door to a new era of Advanced Mask Aligner Lithography (AMALITH), where customized illumination, optical proximity correction (OPC), Talbot-lithography, phase shift masks (AAPSM) and source mask optimization (SMO) are introduced to mask aligner lithography.

Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna; Weichelt, Tina; Stuerzebecher, Lorenz; Zeitner, Uwe D.; Motzek, Kristian; Erdmann, Andreas; Hornung, Michael; Zoberbier, Ralph

2012-03-01

355

Using Complementary Acoustic and Optical Techniques for Quantitative Monitoring of Biomolecular Adsorption at Interfaces  

PubMed Central

The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject. PMID:25586027

Konradi, Rupert; Textor, Marcus; Reimhult, Erik

2012-01-01

356

Multiposition alignment of strapdown inertial navigation system  

Microsoft Academic Search

The authors demonstrate that the stationary alignment of strapdown inertial navigation system (SDINS) can be improved by employing the multiposition\\/technique. Using an observability analysis, it is shown that an optimal two-position alignment not only satisfies complete observability conditions but also minimizes alignment errors. This is done by analytic rank testing of the stripped observability matrix and numerical calculation of the

J. G. Lee; C. G. Park; H. W. Park

1993-01-01

357

Fusion bonding and alignment fixture  

DOEpatents

An improved vacuum fusion bonding structure and process for aligned bonding of large area glass plates, patterned with microchannels and access holes and slots, for elevated glass fusion temperatures. Vacuum pumpout of all the components is through the bottom platform which yields an untouched, defect free top surface which greatly improves optical access through this smooth surface. Also, a completely non-adherent interlayer, such as graphite, with alignment and location features is located between the main steel platform and the glass plate pair, which makes large improvements in quality, yield, and ease of use, and enables aligned bonding of very large glass structures.

Ackler, Harold D. (Sunnyvale, CA); Swierkowski, Stefan P. (Livermore, CA); Tarte, Lisa A. (Livermore, CA); Hicks, Randall K. (Stockton, CA)

2000-01-01

358

The Optical Flow Technique on the Research of Solar Non-potentiality  

NASA Astrophysics Data System (ADS)

Several optical flow techniques, which have being applied to the researches of solar magnetic non-potentiality recently, have been summarized here. And a few new non-potential parameters which can be derived from them have been discussed, too. The main components of the work are presented as follows: (1) The optical flow techniques refers to a series of new image analyzing techniques arisen recently on the researches of solar magnetic non-potentiality. They mainly include LCT (local correlation tracking), ILCT (inductive equation combining with LCT), MEF (minimum energy effect), DAVE (differential affine velocity estimator) and NAVE (nonlinear affine velocity estimator). Their calculating and applying conditions, merits and deficiencies, all have been discussed detailedly in this work. (2) Benefit from the optical flow techniques, the transverse velocity fields of the magnetic features on the solar surface may be determined by a time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space. Consequently, several new non-potential parameters may be acquired, such as the magnetic helicity flux, the induced electric field in the photosphere, the non-potential magnetic stress (whose area integration is the Lorentz force), etc. Then we can determine the energy flux across the photosphere, and subsequently evaluate the energy budget. Former works on them by small or special samples have shown that they are probably related closely to the erupting events, such as flare, filament eruptions and coronal mass ejections.

Liu, Ji-hong; Zhang, Hong-qi

2010-06-01

359

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

NASA Technical Reports Server (NTRS)

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

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

1992-01-01

360

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

PubMed

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

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

2010-08-01

361

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

Microsoft Academic Search

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

Petrak Dieter; Dietrich Stefan; Eckardt Günter; Köhler Michael

2011-01-01

362

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

Microsoft Academic Search

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

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

2006-01-01

363

Identification of optical nonlinearities of dye-doped nematic and polymer-dispersed liquid crystals using Z-scan technique  

Microsoft Academic Search

This study investigates the nonlinear optical properties of azo-dye-doped nematic and polymer-dispersed liquid crystal (ADDPDLC) films with nano-sized LC droplets using the Z-scan technique, which is a simple but powerful technique for measuring the optical Kerr constants of materials. The results indicate that the optical Kerr constant (n2) of the azo-dye-doped nematic LC (ADDLC) film is large because of the

Hui-Chi Lin; Chin-Hui Chen; Ting-Shan Mo; Ming-Shian Li; Chia-Rong Lee; Feng-Ming Hsieh; Jui-Hsiang Liu; Andy Ying-Guey Fuh

2010-01-01

364

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

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

365

Object oriented software for simulation and reconstruction of big alignment systems  

NASA Astrophysics Data System (ADS)

Modern high-energy physics experiments require tracking detectors to provide high precision under difficult working conditions (high magnetic field, gravity loads and temperature gradients). This is the reason why several of them are deciding to implement optical alignment systems to monitor the displacement of tracking elements in operation. To simulate and reconstruct optical alignment systems a general purpose software, named COCOA, has been developed, using the object oriented paradigm and software engineering techniques. Thanks to the big flexibility in its design, COCOA is able to reconstruct any optical system made of a combination of the following objects: laser, x-hair laser, incoherent source—pinhole, lens, mirror, plate splitter, cube splitter, optical square, rhomboid prism, 2D sensor, 1D sensor, distance-meter, tilt-meter, user-defined. COCOA was designed to satisfy the requirements of the CMS alignment system, which has several thousands of components. Sparse matrix techniques had been investigated for solving non-linear least squares fits with such a big number of parameters. The soundness of COCOA has already been stressed in the reconstruction of the data of a full simulation of a quarter plane of the CMS muon alignment system, which implied solving a system of 900 equations with 850 unknown parameters. Full simulation of the whole CMS alignment system, with over 30,000 parameters, is quite advanced. The integration of COCOA in the CMS software framework is also under progress.

Arce, P.

2003-04-01

366

MUSE alignment onto VLT  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

367

Grain Alignment in Starless Cores  

NASA Astrophysics Data System (ADS)

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

Jones, T. J.; Bagley, M.; Krejny, M.; Andersson, B.-G.; Bastien, P.

2015-01-01

368

Structural, Compositional, and Optical Characterizations of Vertically Aligned AlAs/GaAs/GaP Heterostructure Nanowires Epitaxially Grown on Si Substrate  

NASA Astrophysics Data System (ADS)

We structurally, compositionally, and optically characterize vertically aligned AlAs/GaAs/GaP heterostructured nanowires (NWs) grown on a Si substrate used for the integration of an optically active material into Si-based technology and its band-gap engineering. The NWs were grown using Au colloidal nanoparticles as catalysts via the vapor-liquid-solid mode. By alternately changing the source material between Ga and Al, we grew GaAs/AlAs/GaAs/AlAs/GaAs NWs with a well-controlled periodic structure and composition on a GaP segment, which was epitaxially grown on a Si substrate. No dislocations induced by the lattice mismatch were found in the GaAs segment of the NWs grown on the GaP segment despite a lattice mismatch of as large as 4%. This is because the NWs have a particular columnar structure with nanoscale diameters and can therefore relax laterally and accommodate a high strain. Stacking faults exist in zinc-blende-structured GaP and GaAs segments, while the AlAs segment has a pure wurtzite crystal structure without any stacking faults. It is found that the stacking fault in III-V NWs is significantly dependent on the stacking fault energy and ionicity. With increasing ionicity, stacking faults can be more easily introduced, and these NWs tend to have a wurtzite crystal structure. In addition, owing to the high surface nonradiative recombination rate resulting from the surface states on the GaAs NW surface, the excitonic emission of photoluminescence from the bare GaAs NW segment has a decay time of as short as 30 ps. With the growth of an AlGaAs capping layer and GaAs outer shell layer, the decay time of the excitonic emission increased 46-fold, indicating an excellent passivation effect on the GaAs segment surface.

Zhang, Guoqiang; Tateno, Kouta; Gotoh, Hideki; Sogawa, Tetsuomi; Nakano, Hidetoshi

2010-01-01

369

Simple electro-optic technique to generate temporally flat-top laser pulses  

NASA Astrophysics Data System (ADS)

A simple technique is presented to generate temporally flat-top shaped laser pulses using electro-optic modulator (Pockels cell). It involves splitting of input laser pulse into two halves of equal intensity and then stacking together with appropriate optical delay to get a temporally flat-top laser pulse. It also allows generation of other pulse shapes by varying the relative intensity, delay, and phase between two halves of the input laser pulse. Temporally flat-top laser pulses of duration ~ 9 ns have been generated using ~ 7 ns duration incident laser pulses from a flash lamp pumped Q-switched Nd:glass laser oscillator. The rise and fall-time of the shaped pulse is limited by speed of electro-optic switch (Pockels cell), which is ~ 2 ns in the present case.

Sharma, A. K.; Patidar, R. K.; Raghuramaiah, M.; Naik, P. A.; Gupta, P. D.

2011-09-01

370

Coherent optical adaptive techniques: design and performance of an 18-element visible multidither COAT system.  

PubMed

Coherent Optical Adaptive Techniques (COAT) offer promise for overcoming the deleterious effects of phase distortions experienced by optical beams propagating in a turbulent and absorbing atmosphere. An 18-element, visible wavelength, multidither COAT system is described. The all solid-state servosystem design was based on the results of an extensive computer simulation. The optical system uses a 0.488-microm argon laser and an array of beam splitters, phase shifters, and beam combiners (termed a phasor matrix) to form the output array. To date, 6- and 8-element linear arrays and an 18-element axisymmetric array have been investigated. The system has demonstrated a convergence time of 1.2 msec and can form the array with a strehl ratio of 0.67. Moving glint tracking, multiple glint discrimination, and offset pointing from a fixed reference have been demonstrated. Good agreement has been observed between measured system results and theoretical predictions. PMID:20165030

Pearson, J E; Bridges, W B; Hansen, S; Nussmeier, T A; Pedinoff, M E

1976-03-01

371

Applications and potential of the mask structured ion exchange technique (MSI) in micro-optics  

NASA Astrophysics Data System (ADS)

The mask structured silver sodium ion exchange in glass (MSI) is a powerful tool for the realization of high precision refractive micro optical GRIN components. Commonly the distribution of the silver ions in GRIN elements and thus the index distribution is determined by the laws of thermal diffusion. By the use of a structured metal mask, which defines the areas of contact between the glass and the silver salt melt, an additional degree of freedom in optical design is introduced. A photolithographic pattern generator provides the accuracy of the mask structure to realize wave front optimized micro lens arrays with 100% filling factor in Cartesian, hexagonal and also in nearly any other arbitrary geometrical arrangements for several applications such as high precision Shack-Hartmann systems. In this paper we want to discuss the potential and limits of this technique. We report on the family of optical functions, which can be realized with MSI. Furthermore we give an overview over the actual applications.

Baehr, Jochen; Brenner, Karl-Heinz

2003-11-01

372

Beam profile measurements on the advanced test accelerator using optical techniques  

SciTech Connect

Beam current density profiles of ATA have been measured both spatially and temporally using a number of diagnostics. An extremely important technique involves measuring optical emissions from either a target foil inserted into the beam path or gas atoms and molecules excited by beam electrons. This paper describes the detection of the optical emission. A 2-D gated television camera with a single or dual micro-channel-plate (MCP) detector for high gain provides excellent spatial and temporal resolution. Measurements are routinely made with resolutions of 1 mm and 5 ns respectively. The optical line of sight allows splitting part of the signal to a streak camera or photometer for even higher time resolution.

Chong, Y.P.; Kalibjian, R.; Cornish, J.P.; Kallman, J.S.; Donnelly, D.

1986-01-01

373

Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys  

E-print Network

Machine learning techniques are utilised in several areas of astrophysical research today. This dissertation addresses the application of ML techniques to two classes of problems in astrophysics, namely, the analysis of individual astronomical phenomena over time and the automated, simultaneous analysis of thousands of objects in large optical sky surveys. Specifically investigated are (1) techniques to approximate the precise orbits of the satellites of Jupiter and Saturn given Earth-based observations as well as (2) techniques to quickly estimate the distances of quasars observed in the Sloan Digital Sky Survey. Learning methods considered include genetic algorithms, particle swarm optimisation, artificial neural networks, and radial basis function networks. The first part of this dissertation demonstrates that GAs and PSOs can both be efficiently used to model functions that are highly non-linear in several dimensions. It is subsequently demonstrated in the second part that ANNs and RBFNs can be used as ef...

Kumar, N Daniel

2008-01-01

374

Muscle tissue saturation in humans studied with two non-invasive optical techniques: a comparative study  

NASA Astrophysics Data System (ADS)

Muscle tissue saturation (StO2) has been measured with two non-invasive optical techniques and the results were compared. One of the techniques is widely used in the hospitals - the CW-NIRS technique. The other is the photon timeof- flight spectrometer (pTOFS) developed in the Group of Biophotonics, Lund University, Sweden. The wavelengths used in both the techniques are 730 nm and 810 nm. A campaign was arranged to perform measurements on 21 (17 were taken for comparison) healthy adult volunteers (8 women and 13 men). Oxygen saturations were measured at the right lower arm of each volunteer. To observe the effects of different provocations on the oxygen saturation a blood pressure cuff was attached in the upper right arm. For CW-NIRS, the tissue saturation values were in the range from 70-90%, while for pTOFS the values were in the range from 55-60%.

Shaharin, Alfi; Krite Svanberg, Emilie; Ellerström, Ida; Subash, Arman Ahamed; Khoptyar, Dmitry; Andersson-Engels, Stefan; Åkeson, Jonas

2013-11-01

375

Image alignment  

DOEpatents

Disclosed is a method and device for aligning at least two digital images. An embodiment may use frequency-domain transforms of small tiles created from each image to identify substantially similar, "distinguishing" features within each of the images, and then align the images together based on the location of the distinguishing features. To accomplish this, an embodiment may create equal sized tile sub-images for each image. A "key" for each tile may be created by performing a frequency-domain transform calculation on each tile. A information-distance difference between each possible pair of tiles on each image may be calculated to identify distinguishing features. From analysis of the information-distance differences of the pairs of tiles, a subset of tiles with high discrimination metrics in relation to other tiles may be located for each image. The subset of distinguishing tiles for each image may then be compared to locate tiles with substantially similar keys and/or information-distance metrics to other tiles of other images. Once similar tiles are located for each image, the images may be aligned in relation to the identified similar tiles.

Dowell, Larry Jonathan

2014-04-22

376

Direct period measurement for fiber Bragg grating using an optical imaging technique.  

PubMed

This paper proposes an approach based on an optical imaging technique for the period measurement of fiber Bragg gratings (FBG). The simple, direct technique involves a differential interface contrast (DIC) microscope and a high-resolution CCD camera. Image processing is performed on the microscope images to obtain low-noise grating profiles and then the grating periods. Adopting a large image sample size in the image processing can reduce uncertainty. During the investigation, FBGs of different grating periods are fabricated by prestraining the photosensitive fibers during the UV-writing process. A good linearity between the measured Bragg wavelengths and grating periods is observed and the measured strain-optics coefficient was found to be in agreement with reported literature. PMID:23913056

Ali, M M; Lim, K S; Yang, H Z; Chong, W Y; Lim, W S; Ahmad, H

2013-08-01

377

Using optical remote sensing techniques to track the development of ozone-induced stress.  

PubMed

In this paper, a literature review about optical remote sensing (RS) of O(3) stress is presented. Studies on O(3)-induced effects on vegetation reflectance have been conducted since late '70s based on the analysis of optical RS data. Literature review reveals that traditional RS techniques were able to detect changes in leaf and canopy reflectance related to O(3)-induced stress when visible symptoms already occurred. Only recently, advanced RS techniques using hyperspectral sensors, demonstrated the feasibility of detecting the stress in its early phase by monitoring excess energy dissipation pathways such as chlorophyll fluorescence and non-photochemical quenching (NPQ). Steady-state fluorescence (Fs), measured by exploiting the Fraunhofer line depth principle and NPQ related xanthophyll-cycle, estimated through the photochemical reflectance index (PRI) responded to O(3) fumigation before visible symptoms occurred. This opens up new possibilities for the early detection of vegetation O(3) stress by means of hyperspectral RS. PMID:18976842

Meroni, Michele; Panigada, Cinzia; Rossini, Micol; Picchi, Valentina; Cogliati, Sergio; Colombo, Roberto

2009-05-01

378

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

NASA Astrophysics Data System (ADS)

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

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

2012-11-01

379

An optical authentication system based on encryption technique and multimodal biometrics  

NASA Astrophysics Data System (ADS)

A major concern nowadays for a biometric credential management system is its potential vulnerability to protect its information sources. To prevent a genuine user's templates from both internal and external threats, a novel and simple method combined optical encryption with multimodal biometric authentication technique is proposed. In this method, the standard biometric templates are generated real-timely by the verification keys owned by legal user so that they are unnecessary to be stored in a database. Compared with the traditional recognition algorithms, storage space and matching time are greatly saved. In addition, the verification keys are difficult to be forged due to the utilization of optical encryption technique. Although the verification keys are lost or stolen, they are useless for others in absence of the legal owner's biometric. A series of numerical simulations are performed to demonstrate the feasibility and performance of this method.

Yuan, Sheng; Zhang, Tong; Zhou, Xin; Liu, Xuemei; Liu, Mingtang

2013-12-01

380

A novel noninvasive all optical technique to monitor physiology of an exercising muscle  

NASA Astrophysics Data System (ADS)

An all optical technique based on near-infrared spectroscopy and mid-infrared imaging (MIRI) is applied as a noninvasive, in vivo tool to monitor the vascular status of skeletal muscle and the physiological changes that occur during exercise. A near-infrared spectroscopy (NIRS) technique, namely, steady state diffuse optical spectroscopy (SSDOS) along with MIRI is applied for monitoring the changes in the values of tissue oxygenation and thermometry of an exercising muscle. The NIRS measurements are performed at five discrete wavelengths in a spectral window of 650-850 nm and MIRI is performed in a spectral window of 8-12 µm. The understanding of tissue oxygenation status and the behavior of the physiological parameters derived from thermometry may provide a useful insight into muscle physiology, therapeutic response and treatment.

Saxena, Vishal; Marcu, Laura; Karunasiri, Gamani

2008-11-01

381

Gaussian beam and physical optics iteration technique for wideband beam waveguide feed design  

NASA Technical Reports Server (NTRS)

The Gaussian beam technique has become increasingly popular for wideband beam waveguide (BWG) design. However, it is observed that the Gaussian solution is less accurate for smaller mirrors (approximately less than 30 lambda in diameter). Therefore, a high-performance wideband BWG design cannot be achieved by using the Gaussian beam technique alone. This article demonstrates a new design approach by iterating Gaussian beam and BWG parameters simultaneously at various frequencies to obtain a wideband BWG. The result is further improved by comparing it with physical optics results and repeating the iteration.

Veruttipong, W.; Chen, J. C.; Bathker, D. A.

1991-01-01

382

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

383

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

PubMed

We discuss a method to control the coating thickness deposited onto large and strongly curved optics by ion beam sputtering. The technique uses an original design of the mask used to screen part of the sputtered materials. A first multielement mask is calculated from the measured two-dimensional coating thickness distribution. Then, by means of an iterative process, the final mask is designed. By using such a technique, it has been possible to deposit layers of tantalum pentoxide having a high thickness gradient onto a curved substrate 500 mm in diameter. Residual errors in the coating thickness profile are below 0.7%. PMID:19571934

Sassolas, B; Flaminio, R; Franc, J; Michel, C; Montorio, J-L; Morgado, N; Pinard, L

2009-07-01

384

Optimal control techniques for the adaptive optics system of the LBT  

NASA Astrophysics Data System (ADS)

In this paper we will discuss the application of different optimal control techniques for the adaptive optics system of the LBT telescope which comprises a pyramid wavefront sensor and an adaptive secondary mirror. We have studied the application of both the Kalman and the H? filter to estimate the temporal evolution of the phase perturbations due to the atmospheric turbulence and the telescope vibrations. We have evaluated the performance of these control techniques with numerical simulations in preparation of the laboratory tests that will be carried out in the Arcetri laboratories.

Agapito, G.; Quiros-Pacheco, F.; Tesi, P.; Esposito, S.; Xompero, M.

2008-07-01

385

Effect of preparation technique on the optical parameters of biological tissue  

NASA Astrophysics Data System (ADS)

The absorption coefficient (mu) a, the scattering coefficient (mu) s, and the scattering anisotropy factor g of porcine liver were studied in vitro using the integrating sphere technique and inverse Monte Carlo simulation in the wavelength range 450 to 700 nm. A reference preparation technique was developed using a dermatome providing specimens of 200 to 800 micrometers thickness without pre-freezing the tissue. The optical parameters as measured applying the reference preparation were compared to those measured after cryo-homogenization. We found significant deviations of the scattering coefficient and the anisotropy factor which were compensated when the reduced scattering coefficient (mu) s' was calculated. We also compared the effects of freezing reference specimens at - 20 degree(s)C and at 77 K without homogenization. For both freezing protocols noticeable deviations were found in all three optical parameters as well as in (mu) s'. The impact of tissue storage at 4 degree(s)C was measured in the range 4 to 48 hours post mortem and showed a clear reduction of (mu) a and a significant increase of (mu) s even after 24 hours of storage. Short time storage of the specimens in saline solution reduced all three optical parameters significantly. In conclusion, the tissue preparation must be controlled in order to provide in vitro optical parameters that sufficiently mimic the in vivo situation.

Roggan, Andre; Schaedel, D.; Netz, Uwe; Ritz, Joerg-Peter; Germer, Christoph-Thomas; Mueller, Gerhard J.

2001-05-01

386

The effect of preparation technique on the optical parameters of biological tissue  

NASA Astrophysics Data System (ADS)

The absorption coefficient ?a, the scattering coefficient ?s, and the scattering anisotropy factor g of porcine liver were studied in vitro using the integrating sphere technique and inverse Monte Carlo simulation in the wavelength range 450 to 700 nm. A reference preparation technique was developed using a dermatome providing specimens of 200 to 800 ?m thickness without pre-freezing the tissue. The optical parameters as measured applying the reference preparation were compared to those measured after cryo-homogenisation. We found significant deviations of the scattering coefficient and the anisotropy factor which were compensated when the reduced scattering coefficient ?s' was calculated. We also compared the effects of freezing reference specimens at -20 °C and at 77 K without homogenisation. For both freezing protocols noticeable deviations were found in all three optical parameters as well as in ?s'. The impact of tissue storage at 4 °C was measured in the range 4 to 48 h post mortem and showed a clear reduction of ?a and a significant increase of ?s even after 24 h of storage. Short-time storage of the specimens in saline solution reduced all three optical parameters significantly. In conclusion, the tissue preparation must be controlled in order to provide in vitro optical parameters that sufficiently mimic the in vivo situation.

Roggan, A.; Schädel, D.; Netz, U.; Ritz, J.-P.; Germer, C.-T.; Müller, G.

387

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

NASA Technical Reports Server (NTRS)

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

Lee, George

1993-01-01

388

Structural, electrical and optical properties of copper selenide thin films deposited by chemical bath deposition technique  

Microsoft Academic Search

A low cost chemical bath deposition (CBD) technique has been used for the preparation of Cu2-xSe thin films on glass substrates. Structural, electrical and optical properties of these films were investigated. X-ray diffraction (XRD) study of the Cu2-xSe films annealed at 523 K suggests a cubic structure with a lattice constant of 5.697 Å. Chemical composition was investigated by X-ray

Al-Mamun; A. B. M. O. Islam; A. H. Bhuiyan

2005-01-01

389

X-Ray Photoresist Characterization Using in Situ Optical Monitoring Techniques  

Microsoft Academic Search

X-ray photoresists were studied using two in situ optical techniques (ellipsometry and imaging interferometry) during development. A conventional photoresist (polymethylmethacrylate\\/KTI Chemicals) and two chemically-amplified photoresists (XP -90104C\\/Shipley and AZ-PF\\/Hoechst) were investigated. Computer programs were used to model the effects of surface roughening, swelling, and dissolution of these resists. A 2048 channel linear CCD array dissolution rate monitor (DRM) was constructed

Monroe Brian Sullivan

1993-01-01

390

Potential applications of photothermal interferometric detection technique in the single-layer optical thin film system  

NASA Astrophysics Data System (ADS)

The sensitive photothermal interferometric detection technique, in which an interference fringe pattern formed by overlapping two reflected probe beams from the front and rear surfaces of the sample with two interfaces was used to measure the photothermal signal, and its application for characterization of transparent (or partially transparent) plate samples had been theoretically and experimentally investigated in detail. Theoretical and experimental results demonstrated the proposed photothermal interferometric detection technique to be a sensitive photothermal method for the study of the thermophysical properties of transparent samples. Can this method be applied to the field of single-layer optical thin film system? We all know that a single-layer optical thin film is usually deposited on a substrate and has three interfaces. In this paper, based on the transmission theory of Gauss-beam, the interference effect of the reflection beams from a single layer film-substrate is studied. A theory is developed to describe the intensity profile of the interference fringe and the corresponded modulated photothermal interferometric signal. An experiment is performed with a ZnS-BK7 glass single-layer sample to measure the intensity distribution of the interference fringe pattern and the photothermal signal with CW laser excitation. Agreement is obtained between the theoretical predictions and experimental results. It shows the photothermal interferometric detection technique can be used to study the thermophysical properties of the single-layer optical thin film system.

Hao, Honggang; Fang, Jianwen; Liu, Xiangming

2010-10-01

391

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

NASA Astrophysics Data System (ADS)

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

Balderas-López, J. A.

2012-06-01

392

Methodology for optimal in situ alignment and setting of bendable optics for nearly diffraction-limited focusing of soft x-rays  

NASA Astrophysics Data System (ADS)

We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the Advanced Light Source Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal)×100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal)×130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik H.; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

2013-03-01

393

Methodology for optimal in situ alignment and setting of bendable optics for diffraction-limited focusing of soft x-rays  

NASA Astrophysics Data System (ADS)

We demonstrate a comprehensive and broadly applicable methodology for the optimal in situ configuration of bendable soft x-ray Kirkpatrick-Baez mirrors. The mirrors used for this application are preset at the ALS Optical Metrology Laboratory prior to beamline installation. The in situ methodology consists of a new technique for simultaneously setting the height and pitch angle of each mirror. The benders of both mirrors were then optimally tuned in order to minimize ray aberrations to a level below the diffraction-limited beam waist size of 200 nm (horizontal) × 100 nm (vertical). After applying this methodology, we measured a beam waist size of 290 nm (horizontal) × 130 nm (vertical) with 1 nm light using the Foucault knife-edge test. We also discuss the utility of using a grating-based lateral shearing interferometer with quantitative wavefront feedback for further improvement of bendable optics.

Merthe, Daniel J.; Yashchuk, Valeriy V.; Goldberg, Kenneth A.; Kunz, Martin; Tamura, Nobumichi; McKinney, Wayne R.; Artemiev, Nikolay A.; Celestre, Richard S.; Morrison, Gregory Y.; Anderson, Erik; Smith, Brian V.; Domning, Edward E.; Rekawa, Senajith B.; Padmore, Howard A.

2012-09-01

394

To develop a geometric matching method for precision mold alignment  

NASA Astrophysics Data System (ADS)

In order to develop a high accuracy optical alignment system for precision molding machine, a geometric matching method was developed in this paper. The alignment system includes 4 high magnification lenses, 4 CCD cameras and 4 LED light sources. In the precision molding machine, a bottom metal mold and a top glass mold are used to produce a micro lens. The two molds combination does not use any pin or alignment part. They only use the optical alignment system to alignment. In this optical alignment system, the off-axis alignment method was used. The alignment accuracy of the alignment system is about 0.5 ?m. There are 2 cross marks on the top glass mold and 2 cross marks on the bottom metal mod. In this paper did not use edge detection to recognize the mask center because the mask easy wears when the combination times increased. Therefore, this paper develops a geometric matching method to recognize mask center.

Chen, Chun-Jen; Chang, Chun-Li; Jywe, Wenyuh

2014-09-01

395

IUS prerelease alignment  

NASA Technical Reports Server (NTRS)

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

Evans, F. A.

1978-01-01

396

Low cost packaging techniques for active waveguide devices  

Microsoft Academic Search

Recent developments in WDM systems have created an increased demand for low cost active waveguide devices (modulators, electro-optic switches etc). Standard packaging for these devices includes individual alignment and hermetic sealing in order to meet both the performance and Bellcore type reliability requirements. Passive optical devices have been demonstrated using lower cost packaging techniques, however when applied to active waveguide

Mark Shaw; Marco Marazzi; Stefano Bonino

2000-01-01

397

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

NASA Technical Reports Server (NTRS)

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

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

2003-01-01

398

Audio extraction from silent high-speed video using an optical technique  

NASA Astrophysics Data System (ADS)

It is demonstrated that audio information can be extracted from silent high-speed video with a simple and fast optical technique. The basic principle is that the sound waves can stimulate objects encountered in the traveling path to vibrate. The vibrations, although usually with small amplitudes, can be detected by using an image matching process. The proposed technique applies a subset-based image correlation approach to detect the motions of points on the surface of an object. It employs the Gauss-Newton algorithm and a few other measures to achieve very fast and highly accurate image matching. Because the detected vibrations are directly related to the sound waves, a simple model is introduced to reconstruct the original audio information of the sound waves. The proposed technique is robust and easy to implement, and its effectiveness has been verified by experiments.

Wang, Zhaoyang; Nguyen, Hieu; Quisberth, Jason

2014-11-01

399

A Test of Three Optical Flow Techniques-LCT, DAVE, and NAVE  

NASA Astrophysics Data System (ADS)

A time sequence of high-quality images currently produced by high-resolution observations either from the ground or in space may be utilized to determine the transverse flow field on the plane of the sky with the help of optical flow techniques. We have examined the performance of three different methods-a well-known technique called local correlation tracking (LCT), a recently developed technique called the differential affine velocity estimator (DAVE), and a new technique called the nonlinear affine velocity estimator (NAVE)-using three kinds of image data: mapping-based synthetic images, a set of MHD simulation data, and real images (magnetograms) taken by the Solar Optical Telescope on board Hinode. We have generalized the model equation of image evolution by adding to the continuity equation a source term that is proportional to the image value. Synthetic images were constructed based on the analytical solution of this equation with different velocity profiles: uniform, affine, or nonaffine. The tests with the synthetic data indicated that NAVE is very good at detecting subpixel motions, superpixel motions, and nonuniform motions, while LCT is not good at detecting nonuniform motions, especially around critical points, and the performance of DAVE is degraded in the presence of superpixel motions. In all the methods, the performance became worse as the velocity field deviated more from an affine one. We also found that the MHD simulation data we used are not quite suited for discriminating between the three methods, maybe because the data do not contain enough structural information to be used for tracing. In contrast, the determination of velocity fields from the real image data was somewhat sensitive to the technique adopted. The technique of NAVE with the source term produced velocity fields that are the most consistent with the data.

Chae, Jongchul; Sakurai, Takashi

2008-12-01

400

Evaluation of accuracy and workflow between different alignment techniques for correction of CTAC and PET misalignment in cardiac PET-CT imaging  

NASA Astrophysics Data System (ADS)

Small errors in the alignment between CT Attenuation Correction (CTAC) images and Positron Emission Tomography (PET) acquisitions can result in significant changes in PET attenuation corrected images. Misalignment due to respiratory or cardiac motion can produce mismatch between the PET and CTAC acquisitions. This contributes to artifactual hypoperfusion defects that are interpretable as myocardial ischemia or infarct. Correction for the misalignment between the PET and CTAC images can eliminate these false positive artifacts. Two methods for correcting for this respiratory and cardiac misalignment were compared. The first was an existing procedure, the manual-shift method, using point-to-point, in-plane, two-dimensional (2D) measurements of the shifts in axial, sagittal, and coronal planes. A new PET image reconstruction using the corrected attenuation map shifted by the 2D measurements was then performed. In the second method, the Interactive ACQC method, visual alignment was performed between the left ventricle boundaries on fused images and automated calculation of necessary rigid three-dimensional (3D) alignment parameters was performed. A new PET image reconstruction was then performed with an attenuation map shifted by the prescribed alignment parameters. The two methods were compared for accuracy and workflow efficiency using five cardiac PET/CT cases, scanned on GE Discovery VCT and Discovery ST systems. Alignment measurements using the visual alignment process (the interactive ACQC method) improved productivity by over five minutes, on average. The results show that the interactive ACQC procedure yields similar results to those of the point-to-point procedure while providing improved workflow for cardiac PET attenuation correction quality control.

Philps, Elizabeth B.; Aivano, Sarah J.

2007-03-01

401

Advanced Electro-Optic Surety Devices  

SciTech Connect

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

Watterson, C.E.

1997-05-01

402

Coated photodiode technique for the determination of the optical constants of reactive elements: La and Tb  

NASA Astrophysics Data System (ADS)

A novel technique, utilizing thin films with protective capping layers deposited onto silicon photodiode substrates, has been developed to accurately determine the optical constants of reactive elements such as the rare earths and transition metals. Depositing protected layers on photodiode substrates has three primary advantages over the study of the transmittance of free-standing films and the angle-dependent reflectance of coatings on mirror substrates. First, it is easy to deposit a thin protective capping layer that prevents oxidation or contamination of the underlying reactive layer. Second, very thin layers of materials that have intrinsically low transmittance can be studied. Third, the optical constants are determined from the bulk properties of the protected layer and are not influenced by reflectance from the top surface that can be affected by oxidation or contamination. These and other benefits of this technique will be discussed, and results for La and Tb will be presented. The determined optical constants are significantly different from the CXRO and other tabulated values. The rare earth (lanthanide) elements with atomic numbers 57-71 have 5d or 4f open shells, and this open shell structure results in transmission windows in the extreme ultraviolet wavelength range >45 nm where materials typically have low transmittance. These transmission windows make possible the fabrication of a new class of multilayer interference coatings, based on rare earth elements, with relatively high peak reflectances and narrow reflectance profiles, both important factors for the imaging of solar and laboratory radiation sources with multilayer telescopes.

Seely, John F.; Uspenskii, Yurii A.; Kjornrattanawanich, Benjawan; Windt, David L.

2006-08-01

403

Three-dimensional whole circumference shape measurement system using optical patterns projection technique  

NASA Astrophysics Data System (ADS)

An automatic three-dimensional whole circumference shapes measurement system using an optical patterns projection technique has been developed. The system is composed of an optical spatial modulator from which grating patterns are projected on the surface of the object set on a turntable stage, a CCD camera controlled by a robot arm, and a computer. The patterns on the surface of the object are taken into the computer by the CCD camera, and the three-dimensional coordinates of the patterns on the surface of the object are calculated according to a principle of a trigonometry measurement. The patterns faced to the CCD camera are taken into the computer by the CCD camera, four photographs at each turntable angle of 0, 90, 180, and 270 degrees are processed and the image processing data are composed as whole circumference shapes. This improved system using mechanical and optical method and data analysis has the following advantages. (1) It is possible to capture the surface topography without any contact. (2) The time required for the measurements is shorter than the light-section method. (3) The optical spatial modulator using a liquid crystal projector enables to control the striped patterns accurately by the computer. (4) It is possible to measure precisely and to expand the measurement area using a zoom camera. (5) The improved system has whole circumference shapes measurement area as well as high resolution.

Tsujioka, Katsumi; Uchida, Yoshihisa; Liu, Jing-Nan; Furuhashi, Hideo; Uchida, Yoshiyuki

2008-12-01

404

High-resolution fiber optic temperature sensors using nonlinear spectral curve fitting technique.  

PubMed

A generic new data processing method is developed to accurately calculate the absolute optical path difference of a low-finesse Fabry-Perot cavity from its broadband interference fringes. The method combines Fast Fourier Transformation with nonlinear curve fitting of the entire spectrum. Modular functions of LabVIEW are employed for fast implementation of the data processing algorithm. The advantages of this technique are demonstrated through high performance fiber optic temperature sensors consisting of an infrared superluminescent diode and an infrared spectrometer. A high resolution of 0.01 °C is achieved over a large dynamic range from room temperature to 800 °C, limited only by the silica fiber used for the sensor. PMID:23635225

Su, Z H; Gan, J; Yu, Q K; Zhang, Q H; Liu, Z H; Bao, J M

2013-04-01

405

Optical asymmetric cryptography based on elliptical polarized light linear truncation and a numerical reconstruction technique.  

PubMed

We demonstrate a novel optical asymmetric cryptosystem based on the principle of elliptical polarized light linear truncation and a numerical reconstruction technique. The device of an array of linear polarizers is introduced to achieve linear truncation on the spatially resolved elliptical polarization distribution during image encryption. This encoding process can be characterized as confusion-based optical cryptography that involves no Fourier lens and diffusion operation. Based on the Jones matrix formalism, the intensity transmittance for this truncation is deduced to perform elliptical polarized light reconstruction based on two intensity measurements. Use of a quick response code makes the proposed cryptosystem practical, with versatile key sensitivity and fault tolerance. Both simulation and preliminary experimental results that support theoretical analysis are presented. An analysis of the resistance of the proposed method on a known public key attack is also provided. PMID:24979424

Lin, Chao; Shen, Xueju; Wang, Zhisong; Zhao, Cheng

2014-06-20

406

Phase-shifting technique for improving the imaging capacity of sparse-aperture optical interferometers.  

PubMed

We describe the principle of a multiaperture interferometer that uses a phase-shifting technique and is suitable for quick snapshot imaging of astrophysical objects at extreme angular resolution through Fourier inversion. A few advantages of the proposed design are highlighted, among which are radiometric efficiency, field of view equivalent to those of Fizeau interferometers, and a preliminary calibration procedure allowing characterization of instrumental errors. For large telescope numbers, the proposed design also results in considerable simplification of the optical and mechanical design. Numerical simulations suggest that it should be possible to couple hundreds of telescopes on a single 4K × 4K detector array, using only conventional optical components or emerging technologies. PMID:21772409

Hénault, François

2011-07-20

407

Realization of a polymer nanowire optical transducer by using the nanoimprint technique.  

PubMed

An optical transducer using an integrated optics polymer nanowire is proposed. The nanoimprint technique is used to fabricate an OrmoComp nanowire with 1.0 ?m width and 0.5 ?m height, but the resulting sidewalls are not perfectly vertical. Maximum sensitivity is achieved by enhancing the evanescent field in the cladding region. The possible mode fields and power confinement of the nanowire are studied with respect to their structural dimensions, the operating wavelength, and the cladding material by using the H-field finite element method. The attenuation coefficient is extracted and calculated over the different cladding media, specifically air, water, and glycerol solution. It is observed that the scattering caused due to the surface roughness is the dominant effect that provides a larger attenuation coefficient. PMID:25402916

Viphavakit, Charusluk; Atthi, Nithi; Boonruang, Sakoolkan; Themistos, Christos; Komodromos, Michael; Mohammed, Waleed S; Azizur Rahman, B M

2014-11-01

408

Structural and optical properties of CdO thin films deposited by RF magnetron sputtering technique  

SciTech Connect

Cadmium oxide (CdO) thin films were deposited on glass substrate by r.f. magnetron sputtering technique using a high purity (99.99%) Cd target of 2-inch diameter and 3 mm thickness in an Argon and oxygen mixed atmosphere with sputtering power of 50W and sputtering pressure of 2×10{sup ?2} mbar. The prepared films were characterized by X-ray diffraction (XRD), optical spectroscopy and scanning electron microscopy (SEM). The XRD analysis reveals that the films were polycrystalline with cubic structure. The visible range transmittance was found to be over 70%. The optical band gap increased from 2.7 eV to2.84 eV with decrease of film thickness.

Kumar, G. Anil, E-mail: anilhcu@gmail.com; Reddy, M. V. Ramana, E-mail: anilhcu@gmail.com [Department of Physics, Osmania University, Hyderabad-500007 (India); Reddy, Katta Narasimha, E-mail: anilhcu@gmail.com [Department of Physics, Mahatma Gandhi University, Nalgonda-508003 (India)

2014-04-24

409

Cure monitoring of uv coatings using fiber-optic fluorescence technique  

SciTech Connect

In this paper, we present recent results of our continuing investigation of the applicabilities of the fiber-optic fluorescence probe technique for monitoring UV curable coatings. A variety of intramolecular charge transfer (ICT) fluorescence probes with different sensitivities and selectivities were evaluated for cure monitoring applications. The fluorescence emission spectra of the ICT probes were all found to exhibit spectral blue shifts as the curing process proceeded and linear correlations between probe fluorescence intensity ratios and the degree of cure were obtained. In practice, by doping a small amount of an appropriate probe into an uncured coating formulation, the degree of cure can be readily measured using a commercially available fiber-optic fluorescence cure monitor.

Song, J.C.; Wang, Z.J.; Bao, R. [Bowling Green State Univ., OH (United States)

1995-12-01

410

Optical techniques provide information on various effective diffusion coefficients in the presence of traps  

NASA Astrophysics Data System (ADS)

In many cell-signaling pathways information is transmitted via the diffusion of messenger molecules. In most cases, messengers react with other substances and diffuse at the same time. Effective diffusion coefficients may be introduced to characterize the net transport rate that results from the combined effect of these two processes. It was shown in [B. Pando , Proc. Natl. Acad. Sci. U.S.A. 103, 5338 (2006)10.1073/pnas.0509576103] that even in the simplest scenario in which one bimolecular reaction is involved, two different effective coefficients are relevant. One gives the rate at which small perturbations spread out with time while the other relates the mean square displacement of a single particle to the time elapsed. They coincide in the absence of reactions but may be very different in other cases. Optical techniques provide a relatively noninvasive means by which transport rates can be estimated. In the above mentioned paper it was discussed why, under certain conditions, fluorescence recovery after photobleaching (FRAP), a technique commonly used to estimate diffusion rates in cells, provides information on one of the two effective coefficients. In the present paper we show that, under the same conditions, another commonly used optical technique, fluorescence correlation spectroscopy (FCS), gives information on the other one. This opens up the possibility of combining experiments to obtain information that goes beyond effective transport rates. In the present paper we discuss different ways to do so.

Sigaut, Lorena; Ponce, María Laura; Colman-Lerner, Alejandro; Dawson, Silvina Ponce

2010-11-01

411

Efficient optical design and measurement technique to six sigma laser processing  

NASA Astrophysics Data System (ADS)

A six sigma laser processing system is proposed that utilizes real time measurement of ISO 11146 and ISO 13694 laser beam parameters without disrupting the process beam and with minimal loss. If key laser beam parameters can be measured during a laser process, without a disruption to the process, then a higher level of process control can be realized. The difficulty in achieving this concept to date is that most accepted beam measurement techniques are time averaged and require interruption of the laser beam and therefore have made it impractical for real time measurement which is necessary to consider six sigma process control. Utilizing an all passive optical technique to measure a laser's beam waist and other parameters for both focused and unfocused beams, the direct measurement of the ISO laser beam parameters are realized without disruption to the process and with minimal loss. The technique is simple enough to be applied to low and high power systems well into the multi-kilowatt range. Through careful monitoring of all laser beam parameters via software control of upper and lower limits for these parameters, tighter quality control is possible for achieving a six sigma process. In this paper we describe the optical design for both low and high power laser systems and how six sigma laser processing may be realized.

Scaggs, Michael; Haas, Gil

2014-03-01

412

Polarized light emission by deposition of aligned semiconductor nanorods  

NASA Astrophysics Data System (ADS)

The ability to control the position and orientation of nanorods in a device is interesting both from a scientific and a technological point of view. Because semiconductor nanorods exhibit anisotropic absorption, and spontaneous and stimulated emission, aligning individual NRs to a preferred axis is attractive for many applications in photonics such as solar cells, light-emitting devices, optical sensors, switches, etc. Electric-field-driven deposition from colloidal suspensions has proven to be an efficient method for the controlled positioning and alignment of anisotropic particles. In this work, we present a novel technique for the homogeneous deposition and alignment of CdSe/CdS NRs on a glass substrate patterned with transparent indium tin oxide interdigitated electrodes, with a spacing of a few micrometers. This method is based on applying a strong AC electric field over the electrodes during a dip-coating procedure and subsequent evaporation of the solvent. The reproducible and homogeneous deposition on large substrates is required for large size applications such as solar cells or OLEDs. The accumulation, alignment, and polarized fluorescence of the nanorods as a function of the electrical field during deposition are investigated. A preferential alignment with an order parameter of 0.92 has been achieved.

Mohammadimasoudi, Mohammad; Penninck, Lieven; Aubert, Tangi; Gomes, Raquel; Hens, Zeger; Strubbe, Filip; Neyts, Kristiaan

2014-08-01

413

Spot Scanning Proton Beam Therapy for Prostate Cancer: Treatment Planning Technique and Analysis of Consequences of Rotational and Translational Alignment Errors  

SciTech Connect

Purpose: Conventional proton therapy with passively scattered beams is used to treat a number of tumor sites, including prostate cancer. Spot scanning proton therapy is a treatment delivery means that improves conformal coverage of the clinical target volume (CTV). Placement of individual spots within a target is dependent on traversed tissue density. Errors in patient alignment perturb dose distributions. Moreover, there is a need for a rational planning approach that can mitigate the dosimetric effect of random alignment errors. We propose a treatment planning approach and then analyze the consequences of various simulated alignment errors on prostate treatments. Methods and Materials: Ten control patients with localized prostate cancer underwent treatment planning for spot scanning proton therapy. After delineation of the clinical target volume, a scanning target volume (STV) was created to guide dose coverage. Errors in patient alignment in two axes (rotational and yaw) as well as translational errors in the anteroposterior direction were then simulated, and dose to the CTV and normal tissues were reanalyzed. Results: Coverage of the CTV remained high even in the setting of extreme rotational and yaw misalignments. Changes in the rectum and bladder V45 and V70 were similarly minimal, except in the case of translational errors, where, as a result of opposed lateral beam arrangements, much larger dosimetric perturbations were observed. Conclusions: The concept of the STV as applied to spot scanning radiation therapy and as presented in this report leads to robust coverage of the CTV even in the setting of extreme patient misalignments.

Meyer, Jeff, E-mail: jmeye3@utsouthwestern.ed [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States); Bluett, Jaques; Amos, Richard [University of Texas-M.D. Anderson Cancer Center, Houston, TX (United States)

2010-10-01

414

Structural, Electrical and Optical Properties of Gallium Doped Zinc Oxide Thin Films Prepared by Electron Beam Evaporation Technique  

SciTech Connect

High quality gallium doped zinc oxide (GZO) films are prepared by electron beam evaporation technique. The effect of substrate temperature on structural, electrical and optical properties was studied in detail. The prepared films are polycrystalline in nature with c-axis perpendicular to the substrate. The resistivity of the film decreases and the optical transparency increases as the substrate temperature increases from room temperature to 150 deg. C. The film produce the optical band gap of 3.47 eV.

Nagarani, S.; Sanjeeviraja, C. [School of Physics, Alagappa University, Karaikudi-630 003 (India)

2011-07-15

415

pH biosensor with plastic fiber optic doped with carbone nanotubes used sol-gel technique  

NASA Astrophysics Data System (ADS)

We prepare optrodes of fiber optic plastic with sol-gel technique. Suitable concentration of carbone nanotubes (CNTs), phenol red, bromophenol blue and cresol red, design optrodes with fiber optic plastic. The surface charge of silica and the refractive index, which play an important roll on the fiber, modifies the conditions of light propagation into the plastic optical fiber. We use the transmittance to measure the pH of a solution or fluid in a range between 3 and 9.

Alvarado-Méndez, E.; Flores-Rangel, S. D.; Hernández-Cruz, D.; Trejo-Durán, M.; Andrade-Lucio, J. A.; Rojas-Laguna, R.; Estudillo-Ayala, J. M.; Vargas-Rodríguez, E.; Mata Chávez, R. I.; García-Hernández, M. G.

2010-10-01

416

Machine learning techniques for astrophysical modelling and photometric redshift estimation of quasars in optical sky surveys  

E-print Network

Machine learning techniques are utilised in several areas of astrophysical research today. This dissertation addresses the application of ML techniques to two classes of problems in astrophysics, namely, the analysis of individual astronomical phenomena over time and the automated, simultaneous analysis of thousands of objects in large optical sky surveys. Specifically investigated are (1) techniques to approximate the precise orbits of the satellites of Jupiter and Saturn given Earth-based observations as well as (2) techniques to quickly estimate the distances of quasars observed in the Sloan Digital Sky Survey. Learning methods considered include genetic algorithms, particle swarm optimisation, artificial neural networks, and radial basis function networks. The first part of this dissertation demonstrates that GAs and PSO can both be efficiently used to model functions that are highly non-linear in several dimensions. It is subsequently demonstrated in the second part that ANNs and RBFNs can be used as effective predictors of spectroscopic redshift given accurate photometry, especially in combination with other learning-based approaches described in the literature. Careful application of these and other ML techniques to problems in astronomy and astrophysics will contribute to a better understanding of stellar evolution, binary star systems, cosmology, and the large-scale structure of the universe.

N. Daniel Kumar

2009-01-06

417

MRF applications: measurement of process-dependent subsurface damage in optical materials using the MRF wedge technique  

NASA Astrophysics Data System (ADS)

Understanding the behavior of fractures and subsurface damage in the processes used during optic fabrication plays a key role in determining the final quality of the optical surface finish. During the early stages of surface preparation, brittle grinding processes induce fractures at or near an optical surface whose range can extend from depths of a few ?m to hundreds of ?m depending upon the process and tooling being employed. Controlling the occurrence, structure, and propagation of these sites during subsequent grinding and polishing operations is highly desirable if one wishes to obtain high-quality surfaces that are free of such artifacts. Over the past year, our team has made significant strides in developing a diagnostic technique that combines magnetorheological finishing (MRF) and scanning optical microscopy to measure and characterize subsurface damage in optical materials. The technique takes advantage of the unique nature of MRF to polish a prescribed large-area wedge into the optical surface without propagating existing damage or introducing new damage. The polished wedge is then analyzed to quantify subsurface damage as a function of depth from the original surface. Large-area measurement using scanning optical microscopy provides for improved accuracy and reliability over methods such as the COM ball-dimple technique. Examples of the technique's use will be presented that illustrate the behavior of subsurface damage in fused silica that arises during a variety of intermediate optical fabrication process steps.

Menapace, Joseph A.; Davis, Pete J.; Steele, William A.; Wong, Lana L.; Suratwala, Tayyab I.; Miller, Philip E.

2005-12-01

418

Numerical analysis of localized vibration effects and its compensation technique on reciprocal fiber-optic polarimetric current sensor  

Microsoft Academic Search

Accuracy of current measurement in optical fiber current sensor is affected by the environmental perturbations such as mechanical vibrations, acoustic perturbations and temperature changes to the sensing fiber. This paper presents a novel mathematical model for localized vibration effects on current measurement error in reciprocal fiber-optic polarimetric current sensor (RFOC) and its vibration compensation technique. The results of numerical investigation

P. Tantaswadi; C. Tangtrongbenchasil

2002-01-01

419

Nonlinear optical techniques for imaging and manipulating the mouse central nervous system  

NASA Astrophysics Data System (ADS)

The spinal cord of vertebrates serves as the conduit for somatosensory information and motor control, as well as being the locus of neural circuits that govern fast reflexes and patterned behaviors, such as walking in mammals or swimming in fish. Consequently, pathologies of the spinal cord -such as spinal cord injury (SCI)- lead to loss of motor control and sensory perception, with accompanying decline in life expectancy and quality of life. Despite the devastating effects of these diseases, few therapies exist to substantially ameliorate patient outcome. In part, studies of spinal cord pathology have been limited by the inability to perform in vivo imaging at the level of cellular processes. The focus of this thesis is to present the underlying theory for and demonstration of novel multi-photon microscopy (MPM) and optical manipulation techniques as they apply to studies the mouse central nervous system (CNS), with an emphasis on the spinal cord. The scientific findings which have resulted from the implementation of these techniques are also presented. In particular, we have demonstrated that third harmonic generation is a dye-free method of imaging CNS myelin, a fundamental constituent of the spinal cord that is difficult to label using exogenous dyes and/or transgenic constructs. Since gaining optical access to the spinal cord is a prerequisite for spinal cord imaging, we review our development of a novel spinal cord imaging chamber and surgical procedure which allowed us to image for multiple weeks following implantation without the need for repeated surgeries. We also have used MPM to characterize spinal venous blood flow before and after point occlusions. We review a novel nonlinear microscopy technique that may serve to show optical interfaces in three dimensions inside scattering tissue. Finally, we discuss a model and show results of optoporation, a means of transfecting cells with genetic constructs. Brief reviews of MPM and SCI are also presented.

Farrar, Matthew John

420

Self-aligned double patterning (SADP) compliant design flow  

NASA Astrophysics Data System (ADS)

Double patterning with 193nm optical lithography is inevitable for technology scaling before EUV is ready. In general, there are two major double patterning techniques (DPT): Litho-Etch-Litho-Etch (LELE) and sidewall spacer technology, a Self-Aligned Double Patterning technique (SADP). So far LELE is much more mature than SADP in terms of process development and design flow implementation. However, SADP has stronger scaling potential than LELE due to its smaller design rules on tip-tip and tip-side as well as its intrinsic self-align property. In this paper, we will explain in detail about how to enable a SADP-friendly design flow from multiple perspectives: design constructs, design rules, standard cell library and routing. In addition, the differences between SADP and LELE in terms of design, scaling capability and RC performance will be addressed.

Ma, Yuangsheng; Sweis, Jason; Yoshida, Hidekazu; Wang, Yan; Kye, Jongwook; Levinson, Harry J.

2012-03-01

421

Classification of remotely sensed data using OCR-inspired neural network techniques. [Optical Character Recognition  

NASA Technical Reports Server (NTRS)

Neural networks have been applied to classifications of remotely sensed data with some success. To improve the performance of this approach, an examination was made of how neural networks are applied to the optical character recognition (OCR) of handwritten digits and letters. A three-layer, feedforward network, along with techniques adopted from OCR, was used to classify Landsat-4 Thematic Mapper data. Good results were obtained. To overcome the difficulties that are characteristic of remote sensing applications and to attain significant improvements in classification accuracy, a special network architecture may be required.

Kiang, Richard K.

1992-01-01

422

Structural and optical properties of zinc oxide film using RF-sputtering technique  

SciTech Connect

This paper reports the fabrication of zinc oxide (ZnO) film using RF-sputtering technique. Determination of the structural properties using High Resolution X-ray Diffraction (HRXRD) confirmed that ZnO film deposited on silicon (Si) substrate has a high quality. This result is in line with the Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) which were used to image the morphology of the film, in which a rough surface was demonstrated. Photoluminescence (PL) emission is included to study the optical properties of ZnO film that shows two PL peak in the UV region at 371 nm and in visible region at 530 nm respectively.

Hashim, A. J.; Jaafar, M. S.; Ghazai, Alaa J. [Nano-Optoelectronics Research and Technology Laboratory, School of Physics, Universiti Sains Malaysia, 11800 Pinang (Malaysia); Physics Department, Science College, Thi-Qar University (Iraq)

2012-11-27

423

Active cleaning techniques for removing contamination from optical surfaces in space  

NASA Technical Reports Server (NTRS)

Research in developing an active cleaning technique for removing contaminants from optical surfaces in space is reported. In situ contamination/cleaning experiments were conducted on gold and platimum coated mirrors, which were contaminated by exposure to UV radiation in a 1,3, butadiene environment. Argon and oxygen plasma exposure cleaned the mirrors equally well. Silicone cleaning experiments were also conducted. Exposure of the contaminated mirrors to helium, oxygen, and hydrogen plasmas restored the reflectance at the shorter wavelengths and degraded it at the longer wavelengths.

Shannon, R. L.; Gillette, R. B.

1973-01-01

424

Measuring macular pigment optical density in vivo: a review of techniques  

Microsoft Academic Search

Background  Macular pigment has been the focus of much attention in recent years, as a potential modifiable risk factor for age-related\\u000a macular degeneration. This interest has been heightened by the ability to measure macular pigment optical density (MPOD) in\\u000a vivo.\\u000a \\u000a \\u000a \\u000a \\u000a Method  A systematic literature search was undertaken to identify all available papers that have used in vivo MPOD techniques. The\\u000a papers were

Olivia Howells; Frank Eperjesi; Hannah Bartlett

2011-01-01

425

Coordinate measurement machines as an alignment tool  

SciTech Connect

In February of 1990 the Stanford Linear Accelerator Center (SLAC) purchased a LEITZ PM 12-10-6 CMM (Coordinate measurement machine). The machine is shared by the Quality Control Team and the Alignment Team. One of the alignment tasks in positioning beamline components in a particle accelerator is to define the component's magnetic centerline relative to external fiducials. This procedure, called fiducialization, is critical to the overall positioning tolerance of a magnet. It involves the definition of the magnetic center line with respect to the mechanical centerline and the transfer of the mechanical centerline to the external fiducials. To perform the latter a magnet coordinate system has to be established. This means defining an origin and the three rotation angles of the magnet. The datum definition can be done by either optical tooling techniques or with a CMM. As optical tooling measurements are very time consuming, not automated and are prone to errors, it is desirable to use the CMM fiducialization method instead. The establishment of a magnet coordinate system based on the mechanical center and the transfer to external fiducials will be discussed and presented with 2 examples from the Stanford Linear Collider (SLC). 7 figs.

Wand, B.T.

1991-03-01

426

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

NASA Astrophysics Data System (ADS)

We present a multimodal optical diagnostic approach for simultaneous non-invasive in vivo imaging of blood and lymphatic microvessels, utilising a combined use of fluorescence intravital microscopy and a method of dynamic light scattering. This approach makes it possible to renounce the use of fluorescent markers for visualisation of blood vessels and, therefore, significantly (tenfold) reduce the toxicity of the technique and minimise side effects caused by the use of contrast fluorescent markers. We demonstrate that along with the ability to obtain images of lymph and blood microvessels with a high spatial resolution, current multimodal approach allows one to observe in real time permeability of blood vessels. This technique appears to be promising in physiology studies of blood vessels, and especially in the study of peripheral cardiovascular system in vivo.

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

2011-04-01

427

Development of fiber-optic current sensing technique and its applications in electric power systems  

NASA Astrophysics Data System (ADS)

This paper describes the development and applications of a fiber-optic electric current sensing technique with the stable properties and compact, simple, and flexible structure of the sensing device. The special characteristics of the sensors were achieved by use of the special low birefringence fiber as the Faraday-effect sensing element and were also achieved with creation of sensing schemes which matched with the features of the fiber. Making use of the excellent features of the sensing technique, various current monitoring devices and systems were developed and applied practically for the control and maintenance in the electric power facility. In this paper, the design and performance of the sensing devices are introduced first. After that, examples of the application systems practically applied are also introduced, including fault section/point location systems for power transmission cable lines.

Kurosawa, Kiyoshi

2014-03-01

428

Investigation of carrier transit motion in PCDTBT by optical SHG technique  

NASA Astrophysics Data System (ADS)

We analyze the carrier transit behavior in poly[N-9’-heptadecanyl-2,7-carbazole-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)] (PCDTBT), which has been reported as a donor material for efficient bulk heterojunction photovoltaic devices. The transfer and transient carrier mobilities in the PCDTBT thin films have been measured and analyzed. The transfer mobility has been measured by the transfer curve of the OFET, whereas the transient mobility is recorded using a time-resolved electric field-induced optical second harmonic generation (TRM-SHG) technique. Using the TRM-SHG technique, the dynamic motion of the charge carriers in the PCDTBT thin films has been directly visualized. We anticipate that the analysis of the carrier motion by TRM-SHG will be effective for the understanding of carrier behavior in PCDTBT thin film and will help to make further improvements in the efficiency of the PCDTBT-based photovoltaic devices.

Ahmad, Zubair; Mah Abdullah, Shahino; Taguchi, Dai; Sulaiman, Khaulah; Manaka, Takaaki; Iwamoto, Mitsumasa

2014-10-01

429

Field-free molecular alignment induced by elliptically polarized laser pulses: non invasive 3 dimensional characterization  

E-print Network

An investigation of field-free molecular alignment produced by elliptically polarized laser pulses is reported. Experiments are conducted in CO$_2$ at room temperature. A non invasive all-optical technique, based on the cross defocusing of a probe pulse, is used to measure the alignment along two orthogonal directions that is sufficient to provide a 3 dimensional characterization. The field-free molecular alignment produced by a laser of elliptical polarization is in good agreement in terms of amplitude and shape with theoretical predictions. It turns out to be almost equivalent to the superposition of the effects that one would obtain with two individual cross-polarized pulses. The investigation highlights notably the occurrence of field-free two-direction alignment alternation for a suitably chosen degree of ellipticity. The analogy between this specific ellipticity and the well known "magic angle" used in time resolved spectroscopy to prevent rotational contributions is discussed.

E. Hertz; D. Daems; S. Guérin; H. R. Jauslin; B. Lavorel; O. Faucher

2008-12-17

430

Removal of Lattice Imperfections that Impact the Optical Quality of Ti:Sapphire using Advanced Magnetorheological Finishing Techniques  

SciTech Connect

Advanced magnetorheological finishing (MRF) techniques have been applied to Ti:sapphire crystals to compensate for sub-millimeter lattice distortions that