bluuebunny/crossref_metadata_2025 huggingface dataset:
Long-Slit CCD Spectroscopy of Very Faint Objects
Authors: Djorgovski S. , Spinrad H.
Published: February 2023

With the appearance of CCD-based astronomical spectrographs, faint object spectroscopy has entered a new era. We are now able to do spectroscopy of objects as faint as m ≈ 24, and possibly even fainter. Improvement over the previous generation of the astronomical spectrographs is easily a factor of 10 or 20. This gain is mostly due to three factors : 1) high quantum efficiencies of CCDs (30-40%), 2) their enhancement-friendly white noise properties, and 3) ability to do local sky subtraction, thanks to their 2-dim. imaging nature. In this paper, we would like to share our experiences in long-slit CCD spectroscopy, hoping that they may be of some use to others. We do not discuss the aperture plate work, but the procedures outlined here do apply to multiple slit spectroscopy.
OMVPE growth of low-threshold, high-efficiency GaAs/AIGaAs and strained layer InGaAs/AIGaAs diode lasers
Authors: Wang C. A.
Published: February 2023

High-power arrays of GaAs/AIGaAs and InGaAs/AIGaAs diode lasers are under intensive development as sources for pumping rare earth ions in solid-state lasers, as well as for other applications. Graded-index separate-confinement heterostructure single quantum-well (GRIN-SCH SQW) lasers are attractive for this application because of their low-threshold current density and high differential quantum efficiency. For efficient pumping, the diode-laser emission wavelength must coincide with the absorption band of the rare earth ion. This requirement necessitates close control of the properties of wafers used for diode fabrication. We have used a specially designed vertical rotating-disk reactor for growth by organometallic vapor-phase epitaxy (OMVPE) of GaAs, InGaAs, and AlGaAs layers with exceptional thickness and composition uniformity over5-cm-diameter GaAs wafers.
Direct Access Compact Disc vs. CD-ROM Reliability Estimates
Authors: Tehranchi Babak , Howe Dennis G.
Published: February 2023

The Cross Interleaved Reed-Solomon Code (CIRC) used in CD-ROM for basic error correction/detection consists of two catenated, distance 5 Reed-Solomon codes. These two subcodes, which are called the C1 and C2 codes, have length 32 bytes and 28 bytes respectively. C1 and C2 can each correct any combination ofterrors andeerasures in a given codeword, wheretandeare jointly constrained by the inequality Specific values oftandemay be selected by a decoder when each C1 and C2 codeword is processed. The algorithm used to adaptively select thetandevalues that apply when the C1 and C2 codes are jointly decoded is called the CIRC decoding strategy.
JUGGLER: Real-Time Sensorimotor Control Using Independent Agents
Authors: Yamauchi Brian
Published: February 2023

JUGGLER is a control system implemented on a real-world robot which integrates real-time vision and motor control through the use of non-communicating agents.
Coupling ultrasound and coherent light for high resolution, large depth imaging in tissues
Authors: Lévêque-Fort S. , Selb J. , Pottier L. , Boccara A. C.
Published: February 2023

We develop an original method that combines optical and ultrasonic fields. This acousto-optic imaging allows one to reveal a difference of optical properties with a millimeter resolution inside several centimeters biological tissues. The focused acoustic field modulates the light crossing its focal zone. For each position of the transducer, the ultrasound-modulated light reflects the local optical properties in the focal zone. An original detection scheme allows parallel processing of a large number of speckle grains, which improves the signal to noise ratio. 2D and 3D images were successfully obtained in 15 - 35 mm thick biological tissues, bothin transillumination and in backscattering geometry.
Optical Tomography of the Human Forearm
Authors: Hebden Jeremy C. , Schmidt Florian E. W. , Hillman Elizabeth M. C. , Arridge Simon R. , Schweiger Martin , Delpy David T.
Published: February 2023

A novel diagnostic imaging device based on the transmission of laser light has produced its first clinical image, of an adult forearm. The instrument makes very precise measurements of the time taken for near-infrared (NIR) photons to travel through the tissue. These data, which provide greater sensitivity to internal structure than conventional intensity measurements, are used to compute images tomographically which represent the internal distribution of scattering and absorbing properties. The measurements reported here represent part of a program of preliminary tests prior to use of the instrument to image oxygenation in the brains of newborn infants.
Optical Topography System for Functional Brain Imaging: Mapping human occipital cortex during visual stimulation
Authors: Eda Hideo , Sase Ichiro , Seiyama Akitoshi , Tanabe Hiroki C. , Imaruoka Toshihide , Tsunazawa Yoshio , Yanagida Toshio
Published: February 2023

We developed an optical topography system with a time resolution of less than one second using Continuous Wave laser diodes. We measured human occipital brain during visual stimulation employing this equipment and functional Magnetic Resonance Imaging. These results agreed well. Our optical topography system has potential to measure brain function.
Virtual Pinhole Confocal Microscope
Authors: Barros Kipton M. , Rector David M. , George John S.
Published: February 2023

We developed a Virtual Pinhole Confocal Microscope (VPM) that achieves the benefits of conventional confocal instruments but eliminates much of the mechanical and optical complexity. Structured illumination grids produced by a micro-lens array, micro-mirror array or liquid crystal display allow faster sample scanning than conventional methods, with simultaneous illumination at many points. Light is detected with a CCD camera, and confocal images are reconstructed with image processing algorithms eliminating the need for physical apertures, simplifing implementation, and allowing practical transmission mode confocal imaging. The illumination scanning system is compact, versatile, inexpensive, and can be retrofit into existing microscopes.
Colors Observed when Sunlight is Scattered from Bubble Clouds in Sea Water
Authors: Marston Philip L.
Published: February 2023

Colored bands photographed in sunlit subsurface bubble clouds are discussed. The colors are associated with the transition from partial-to-total reflection from the bubbles.
Cirrus Ice Crystal Corona Displays
Authors: Sassen Kenneth
Published: February 2023

The corona is a diffraction phenomenon that, in its most spectacular form, is manifested by a concentric series of three or four brilliantly colored rings about the sun or moon. In its simplest form, the corona (literally a crown) is represented by the aureole (or halo of the magico-religious variety), which is a white disk boarded near the sun or moon by a bluish ring and terminated by a reddish brown band. Iridescence is a related display whose patches of brilliant color, usually seen at large angular separations from the sun, can be considered as fragments of corona rings. To obtain a unified understanding of these phenomena, it is only necessary to consider basic diffraction theory and have general knowledge of the microphysical contents of the clouds causing the displays (see, e.g., Sassen 1979). According to simple diffraction theory, the purest effects are produced by monodispersed particle sizes, with the radius of any particular order of colored rings increasing with decreasing particle size. Thus, aureole may be produced by relatively large particles that tightly compress the rings, or by the presence of a broad particle size distribution that causes the colored rings to overlap; corona by appropriately sized and uniform particles that provide a favorable angular separation of the colored rings; and iridescence by restricted groups of relatively small uniform particles, as near the edges of growing or evaporating clouds.
Simulation of Disk-Like and Cross-Like Difraction Structures in Halo Phenomena
Authors: Tränkle E. , Greenler Robert
Published: February 2023

Using a Monte Carlo method, we traced many paths of sun rays through a population of ice crystals. The sun rays are scattered diffractively (in Fraunhofer approximation) or refractively without internal reflections (in geometrical optics approximation). In this way we produce point plots representing the intensity of diffraction structures around the sun, the 22° - parhelia, and the the 22°-halo for specified populations of ice crystals. By simulation of two halo displays with cross-like and disk-like diffraction structures around the sun, we obtain a mean diameter of 40 µm for well oriented ice crystals, and 10 µm for randomly oriented ice crystals.
Green Icebergs and Atmospheric Optics
Authors: Lee Raymond L.
Published: February 2023

Icebergs are hardly colorless monoliths, and even nominally white bergs routinely display many hues.1-3 However, satisfactorily accounting for vivid bottle-green icebergs4-8 has proven to be an elusive goal. Obviously, the colors of some sea and glacier ice are caused by intrinsically colored9 minerals or organisms.10-12 Yet ice recently taken from (or near) green icebergs indicates that they may not be dominated by green inclusions. Amos reported that an unusual ice sample taken near a green iceberg was “remarkably bubble-free” and included "a large number of fibers …ranging from colorless to blue, orange, and green; obsidian flakes; a few quartz grains; amorphous aggregates; black, charcoal-like fragments; pieces of shelly material; and diatoms …."7 Dieckmann et al. sampled a green iceberg in the Weddell Sea, and they found ice containing "grey mineral and biogenic material apparently of marine origin" distributed in “relatively well defined layers" throughout.8 They reached the same tentative conclusion as Amos, holding that: "Our analyses and observations confirm that the green colouration was not caused by green pigmentation, but probably by reflection and/or absorption of light due to the more or less densely spaced, parallel layers of incorporated debris. Green feldspars which could have been responsible for the colour were rarely found. "8 They also note that their ice block "changed from green to a translucent white upon separation from the iceberg. "8 (Gerhard Dieckmann kindly provided me with some original color slides of this green iceberg.)
Bottlinger’s Rings
Authors: Lynch David K. , Mertz Frederick C.
Published: February 2023

Bottlinger’s rings are rare, elliptical rings that encircle the subsun. We suggest two possible explanations - gyration and pendulum motion - and model each with numerical simulations.
Secondary and Higher-Order Generalized Rainbows and Unfolded Glories of Oblate Drops: Analysis and Laboratory Observations
Authors: Marston Philip L. , Kaduchak Gregory
Published: February 2023

Previous laboratory observations with laser1-3 and white light4 illumination of oblate drops of water have shown that the primary rainbow becomes distorted and an additional caustic, having the form of a transverse cusp, can be produced when the drop's aspect ratio is sufficiently large.
Identification of Odd-Radius Halo Arcs and of 44°/46° Parhelia by their Inner-Edge Polarization
Authors: Können G.P.
Published: February 2023

Birefringence of ice causes inner edges of refraction halos to be polarized. The direction of this polarization relates directly with the projection of the crystal optic axis (C-axis) onto the sky. Hence, the inner-edge polarisation can serve as an observational diagnostic for determining the actual nature of halo arcs that resembles each other closely. It can be e.g. decisive for the identification of a spot that might be either a 44° parhelion or a 46° parhelion, of an arc that might be either a 22° sunvex Parry arc or a 20° Parroid arc that arises from plate-oriented pyramidal crystals, and of an arc that might be either a 22° suncave Parry arc or a 23° Parroid arc from plate-oriented pyramidal crystals (with Parriod arcs I mean arcs that arise from a wedge in a doubly oriented pyramidal crystal for which the refracting edge is horizontal). Polarization properties of other rare arcs will be discussed. Practical hints are given for observing the inner edge polarization of halos, arcs and spots.
Optical Characterization of III-V Semiconductors
Authors: Reynolds D.C. , Bajaj K.K.
Published: February 2023

During the past several years considerable attention has been focused on artificially structured materials. These materials consist of layered structures of the same or different materials. With the advent of the metal organic chemical vapor deposition (MOCVD) and the molecular beam epitaxy (MBE) growth techniques, atomic layers of one material can be grown on another material with sharp, reproducible interfaces. For layer thicknesses of a few angstroms or less, well defined quasi two-dimensional electronic sub-bands are formed. The confined carriers result in novel electronic and optical properties. The heterostructure system that has received the most extensive investigation is the AlGaAs/GaAs system. The characterization of this system is the focus of the current paper.
A DIAL System for High Resolution Water Vapor Measurements in the Troposphere
Authors: Bösenberg Jens
Published: February 2023

Water vapor is a minor constituent of the atmosphere which is of great importance for many atmospheric processes. Rather small changes in concentration can strongly affect other parameters, e.g. the radiation budget by formation of clouds. In our institute the request for experimental data on water vapor originated from studies of organized convection, where the transport of water vapor and the associated condensation obviously is one of the key processes. From this we derived our definition of the term "high resolution", it is meant to be a spatial and temporal resolution sufficient for studies of at least medium scale convective processes, or in approximate numbers, 30 sec in time, 100 m in height, 5% accuracy within the mixed layer (about 1.5 km). The same system can be used for measurements up to greater heights. Temporal and spatial resolution are of course decreasing with height, but compared to conventional radiosonde measurements this resolution can still be considered "high" throughout the troposphere.
Excess-Photon Ionization and Dressing of Continuum States.
Authors: van Linden van den Heuvell H.B. , Muller H.G.
Published: February 2023

Among the features of (quasi-)one-electron atoms in a strong radiation field, the process of excess-photon ionization is one of the most spectacular. For a short time an electron is coupled both to the remaining core of an atom and to a radiation field. This leads to a gain af kinetic energy of the electron. This gain is not possible if only one of the two couplings is present.
Resonantly-Enhanced Multiphoton Ionization Photoelectron Angular Distributions for Xenon
Authors: Blazewicz P. R. , Compton R. N. , Stockdale J.A.D. , Miller John C.
Published: February 2023

Multiphoton ionization (MPI) of Xe atoms resonantly enhanced through the three-photon allowed

6
s

[
3
/
2
]

1
0

and

6

s
′

[
1
/
2
]

1
0

states has been extensively studied for high- and low-gas densities (see, e.g., Ref. 1). Limited data exist on the angular distributions of the photoelectrons ejected under these conditions.2,3
Wannier Two-Electron Ionization Ladder in Many-Electron Systems: The 1P0 Doubly Excited States in H−, He, and Li+
Authors: Komninos Yannis , Nicolaides Cleanthes A.
Published: February 2023

Doubly excited states have been in the focus of experimental and theoretical research of atomic and molecular physics for a number of decades. An outstanding problem in this field is the so-called Wannier problem (1-3). The related progress has not yet been able to provide rigorous quantum mechanical, many-electron explanations and the concepts and information currently employed are either classical or semiquantitative.
General Relativistic Ponderomotive Force in a Moving Medium
Authors: Shitong Zhu , Wenda Shen
Published: February 2023

ponderomotive force is an important factor in intense field electrodynamics and plays a fundamental role in the ultrapowerful laser interaction with free electrons, atoms and plasma and in determining the electron energy spectrum in multiple- photon ionization. Therfore, the study of the ponderomotive force and its various effects has stimulated people's great interest.
Ablation with Ultrashort UV - Excimer Laser Pulses
Authors: Küper S. , Stuke M.
Published: February 2023

Surfaces can be structured by exposure to intense uv laser light1. A wide variety of materials with different penetration depths for uv laser light and different chemical constitution show for certain fluence ranges high removal rates on the order of micrometers per pulse, along with little or no thermal damage to the edges. Thus the surfaces of many solids have been patterned with a resolution down to less than one micrometer2.
Time Dependent Studies of Vibrational Relaxation Dynamics of CO (v=1) on Metal Surfacesa
Authors: Beckerle J.D. , Casassa M.P. , Heilweil E.J. , Cavanagh R.R. , Stephenson J.C.
Published: February 2023

Knowledge of the rates and mechanisms of vibrational relaxation of molecules adsorbed on surfaces is essential to understand the dynamics of surface processes such as sticking, desorption, and surface chemical reactions. For metallic surfaces, an important outstanding question is the role played by the bulk metal conduction electrons in the damping of adsorbate vibrations. Theoretical studies have predicted lifetimes for the stretch vibration of chemisorbed CO of less than 10 ps as a result of efficient electron hole pair damping on metal surfaces [1,2]. This lifetime is one to two orders of magnitude shorter than that expected for relaxation directly to surface phonons [3]. Experimentally, a lower limit on the vibrational T1 lifetime of ≈2 ps for CO on single crystal surfaces has been inferred from infrared absorption bandshape measurements [4,5]. However, the inability of frequency domain experiments to distinguish among the contributions to the measured bandwidth from depopulation, dephasing and inhomogeneity makes the interpretation ambiguous [6,7]. In order to clearly resolve this issue, direct measurements of the vibrational lifetimes of CO chemisorbed on metal surfaces are required.
Selective Area Epitaxy of II-VI Compounds by Laser-induced Photo-MOVPE
Authors: Irvine S J C , Hill H , Brown G T , Hails J E , Mullin J B
Published: February 2023

A 257nm frequency doubled argon ion laser has been used to photo-dissociate Me2Cd (dimethylcadmium) together with tellurium precursors for low temperature epitaxial growth of CdTe(1). By projecting the laser onto the substrate surface, through a suitable mask, epitaxial growth can be achieved selectively within the illuminated regions following dissociation of the precursors by the UV radiation. However, a number of conditions must be satisfied in order to bring about selective area epitaxy and the following factors will be considered in this paper.
Particle Size Measurements in Ultra-thin Pd Vapor Deposits: Comparison between Temperature Programmed Desorption (TPD) and Transmission Electron Microscopy (TEM)
Authors: Kieken Laurent , Poppa Helmut , Boudart Michel
Published: February 2023

Due to a lack of z-sensitivity, standard high resolution transmission electron microscopy has been unable, so far, to determine the full 3-diniensional shape of small (less than 3 nm in diameter) metal particles supported on planar oxide carriers. The projected average particle size is often the only parameter that can be reliably deduced from standard electron micrographs, and below -1 nm even this becomes very questionable because of image interferences caused by the background structure of the support. Also, great care must be taken when interpreting TEM information because of possible damages of the sample either by electron radiation, well documented by Poppa et al. [1], or exposure to atmospheric pressure during the transfer of the sample from the preparation chamber to the microscope. Therefore, an alternative UHV-compatible technique which allows for in situ particle size estimation is most desirable. Chemisorption of a probe gas like CO followed by temperature programmed desorption is certainly the simplest method since it gives a measure of the percentage of metal exposed, E, which can be directly related to a characteristic dimension of the particle. This characteristic length is a function of particle shape. In some cases [1], the analysis of TPD peak shapes can also supply additional information about the crystallographic shape of metal particles; only in exceptional cases can similar information be obtained directly by specialized TEM techniques (profile-TEM). The usefulness of X-ray photoelectron spectroscopy for particle size determination [2] has also been investigated but the relationship between measured quantities and particle size is much more complex and still controversial.
Laser-Surface Interaction in Air Studied by Photoacoustic Probe Beam Deflection
Authors: Petzoldt S. , Elg A.P. , Reif J. , Matthias E.
Published: February 2023

In the interaction of high intensity pulsed laser radiation with surfaces of transparent solids the emission of neutral and charged particles or the ignition of a plasma is observed1. While the underlying processes are mostly studied under vacuum conditions by detecting the emitted particles2, their investigation in ambient air is also highly desirable from the applied point of view.
Electronic and Chemical Properties of Small Silicon Clusters
Authors: Mandich M. L. , Reents W. D.
Published: February 2023

Plasma assisted chemical vapor deposition of silicon films from silanes is widely used in the fabrication of silicon devices. A fundamental understanding of the mechanisms responsible for film growth would have considerable utility in the optimization of processing parameters. Reactive silicon surfaces sites and gas phase ion chemistry are believed to have important roles in the film growth process. Yet, the natures of such surface species and chemistry are highly uncertain. The trend towards increasing subminiaturization of silicon devices also demands a solution to the deleterious formation of silicon dust during film deposition.
Low-Energy Ion/Surface Interactions During Vapor-Phase Film Growth For Manipulating Microchemistry and Microstructure at the Atomic Level
Authors: Greene J.E.
Published: February 2023

Low-energy (≤ 200 eV) ion irradiation during crystal growth from the vapor phase can be used to provide new chemical reaction pathways, modify film-growth kinetics, and, hence, controllably alter the physical properties of films deposited by a variety of techniques. The latter includes sputter deposition, ion plating, plasma-assisted chemical vapor deposition (PA-CVD), primary-ion deposition (PID), and molecular-beam epitaxy (MBE) using accelerated beam sources. Ion/surface interaction effects such as ion-induced chemistry, trapping, recoil implantation, preferential sputtering, collisional mixing, enhanced diffusion, and alteration in segregation behavior are used to interpret and model experimental results concerning the effects of low-energy particle bombardment on nucleation and growth kinetics, elemental incorporation probabilities, compositional depth distributions, and the growth of metastable phases. Review articles on various aspects of ion irradiation during film growth including effects on nucleation and growth kinetics [1-4], microstructural evolution [4], preferred orientation and stress [2], elemental incorporation probabilities [1-3], dopant incorporation and depth distributions [5], and the synthesis of metastable semiconducting alloys [1-3,6] are available. Monte Carlo and molecular dynamics growth simulations have also been reviewed [4]. In this extended abstract, some of the key features of low-energy ion/surface interactions are outlined and new results are described.
Coherent Strain Changes in Si-Ge Alloys Grown By Ion-Assisted Molecular Beam Epitaxy
Authors: Atwater H.A. , Tsai C.J. , Vreeland T.
Published: February 2023

Although low energy ion bombardment has been employed in various contexts during epitaxial growth, such as enhanced dopant incorporationfl], surface cleaning during plasma-enhanced chemical vapor deposition[2], and direct low energy ion beam deposition[3,4], key questions about the interaction of low energy ions with growing surfaces remain unanswered. Improved understanding of ion-surface interactions during growth may yield additional elements of control over epitaxial film structure, strain state, and composition. Of particular interest for high quality epitaxial films is the identification of the regime in which surface and near-surface processes, such as surface diffusion and incorporation at growth sites, can be enhanced at low temperatures while avoiding or controlling damage in the deposited films.
Bond-Orbital Model of Two-hole Laser-Induced Desorption from GaP (110)
Authors: Haglund Richard F. , Hattori Ken , Itoh Noriaki , Nakai Yasuo
Published: February 2023

The widespread application of lasers in semiconductor processing has produced a voluminous literature on the mechanisms of laser desorption and ablation. There are significant disagreements, however, about the extraordinarily complex physical mechanisms underlying laser desorption and ablation. Here we discuss recent experiments and a model of a particularly simple case: desorption of Ga+ and Ga° by selective excitation of a surface electronic state on GaP (110). By choosing the electronic channel leading to desorption, and by monitoring the condition of the surface, one can determine accurately the threshold fluence above which the surface electronic structure is irreversibly altered by laser ablation. Below this threshold, desorption occurs at isolated defect sites and at perfect three-fold coordinated surface sites. This two-hole laser-induced desorption and ablation can be described by a bond-orbital model of electronic structure.
Mechanism of Chemical Etching of doped GaAs by Cl2
Authors: Houle F. A.
Published: February 2023

Consideration of product volatility and thermodynamic stability have been central to models developed for the thermal etching and deposition of GaAs by Cl21,2 Mass spectrometric studies of the etching chemistry have tended to support some of the basic assumptions of these models: that the thermodynamically most stable product is formed and that product volatility controls the etch rate. Surface analyses, for example, have revealed the presence of a Ga-rich scale after etching, to be expected if the As chlorides arc more volatile and desorb more readily.3-5 Consequently, models of beam modification of GaAs in the presence of Cl2 have focussed on how energetic particles or light might perturb the thermal reaction. In this work the validity of the basis for these models has been examined by investigation of the etching chemistry of doped GaAs by molecular beam mass spectrometry and in situ Auger spectroscopy.
UV Laser-Induced Interaction of Cl2 with GaAs(110)
Authors: Haase G. , Liberman V. , Shih M. C. , Osgood R. M.
Published: February 2023

We have studied the UV laser-induced interaction of molecular chlorine with a GaAs(110) surface under ultra-high vacuum (UHV) conditions. Unlike previous studies of this system [1,2,3], we concentrated on well-defined surfaces, known coverages and low laser fluences.
Photon-Induced Desorption of Adsorbed Water Clusters
Authors: Dirks J. , Drachsel W. , Block J. H.
Published: February 2023

High electric fields of the order of several V/nm influence the adsorption-and desorption-processes of molecules [1]. Because photons are not effected by an electric field, they are suitable for investigating the underlying excitation mechanisms in the presence of such high electric fields. The effect of the external field on the adsorption and desorption processes should be particularly distinct if a polar adsorbate (e.g. water) is used. Therefore, experiments with synchrotron light were carried out with field emitters exposed to water vapor.
Reflection Electron Energy Loss Spectroscopy during Molecular Beam Epitaxy
Authors: Atwater H.A. , Ahn C.C. , Nikzad S.
Published: February 2023

Modern epitaxial crystal growth techniques have made it possible to tailor compositionally modulated thin films on an atomic level. However, further progress in control of epitaxial growth is limited by a relative lack of useful in situ techniques for surface analysis during growth. The most widely used in situ structural analysis technique for molecular beam epitaxial (MBE) growth is reflection high energy electron diffraction (RHEED). Its long working distance and high data rate have prompted investigations of RHEED oscillations and other RHEED dynamic features by many groups. However, there is currently no widely employed in situ chemical analysis technique that has the advantages of RHEED[1]. Hence, for example, the ability to perform real-time control of alloy composition in epitaxial films is limited.
Optical Diagnostics during Film Processing of Micro- and Nanostructures
Authors: Herman Irving P.
Published: February 2023

The importance of real-time in situ sensors during the fabrication of electron and photon devices is increasing in light of tighter device tolerances, the trends toward larger wafer sizes and in situ, cluster and flexible processing, and the need for submonolayer composition control in heterostructure fabrication and surface passivation. Optical spectroscopies are often excellent diagnostics for practical control of these film processes, as well as for related fundamental and process development studies. They can be sensitive to crucial material and process parameters, and are usually noninvasive and nondestructive. The range of optical spectroscopies of the gas phase, the surface and the substrate that can be used to monitor gas-surface processes are surveyed. Of particular interest in micro- and nanoprocessing are optical probes that can determine the composition in regions near a surface or interface with submonolayer resolution and those that can measure temperature. The fundamental physical mechanisms underlying these applications are discussed.
Single Nanocrystal Spectroscopy by Two Photon Excitation
Authors: Blanton Sean. A. , Dehestani Ahmad , Lin Peter C. , Guyot-Sionnest Philippe
Published: February 2023

Current methods of semiconductor nanocrystal synthesis produce samples which are nearly monodisperse in size. The remaining polydispersity in size, along with possible variations in surface configuration, still introduce an inhomogeneous broadening to most spectroscopic studies. In an effort to eliminate this broadening, we perform spectroscopy on single nanocrystals.
Correlation of Size and Photoluminescence for GE Nanocrystals in SIO2 Matrices
Authors: Yang C.M , Shcheglov K.V. , Vahala K.J. , Atwater H.A.
Published: February 2023

Thermally-grown silicon dioxide films 100 nm thick were implanted with 70 keV Ge ions at a dose of 2 x 1016/cm2. These samples were subsequently annealed for 40 min. at 600 °C, 800 °C, 1000 °C and 1200 °C. Plan-view transmission electron microscopy (TEM) was performed to obtain crystal size distributions. Photoluminescence spectra were measured at room-temperature, excited by 50 mW of 457 nm radiation from an Ar ion laser and spectra were acquired by a charged-coupled-device optical multichannel analyzer (OMA) spectrometer with optical fiber input. The system response of the OMA spectrometer was calibrated using a black body radiation source, and all spectra are corrected for the system response of the spectrometer.
Nanoscale Characterization of InP Islands on InGaP(001)
Authors: Bressler-Hill V. , Reaves C. M. , Varma S. , DenBaars S. P. , Weinberg W. H.
Published: February 2023

Indium phosphide and its related alloys are widely used in optoelectronic materials and devices. Using InP in strained-layer material systems presents a way of producing nanostructures. From growth simulations of InAs/GaAs(001), Ghaisas and Madhukar [1] proposed that islands in registry with the substrate occur before defect formation. In addition, they predicted a critical volume for an island to be coherently strained to the substrate. After this critical volume is exceeded, dislocations or other defects can result. Recently, the existence of strain-induced coherent islands has been verified experimentally in other systems, i.e., Ge/Si(001)[2] and InGaAs/GaAs(001)[3-6], InP/InGaP(001)[7], and InP/GaAs(001)[8] and have all been shown to produce a single type of coherently strained island during growth.
Surface Plasmon Enhanced Raman Scattering at Gratings: Optimization and Stimulated Regime
Authors: Baltog I. , Primeau N. , Reinisch R. , Coutaz J. L.
Published: February 2023

The electromagnetic origin of surface enhanced Raman scattering (SERS) may involve local or delocalized surface plasmons (SP). We consider here grating excited delocalized SP. It is known that these SP may be resonantly excited leading in this way to enhanced Raman scattering. It has been even predicted that there exists an optimum groove depth of the grating for which the Raman efficiency is the greatest [1]. To the best of our knowledge, this effect has only been observed in the case of a prism coupler in the Kretschmann configuration where an optimum Ag-thickness has been found[2]. In this Communication, we report on optimized SERS at a coated grating of variable groove depth. We also show that, when optimization is achieved and SP resonance occurs, the Raman process is no longer a spontaneous one but becomes stimulated.
Time-of-Flight and Internal State Distributions of Photodesorbed Species from N2O Adsorbed on Pt(111) by 193 nm light.
Authors: Masson D.P. , Lanzendorf E.J. , Kummel A.C.
Published: February 2023

Polarized ultraviolet light from an excimer laser (193 nm) was used to photodesorb and photodissociate N2O adsorbed on a cold Pt(111) surface. The desorbed species and their time-of-flight (TOF) were monitored by resonantly enhanced Multi Photon Ionization (MPI) spectroscopy of N2 and atomic oxygen. We have identified three major channels: thermal desorption of molecular N2, photodesorption of ground electronic state N2O, and ejection of ballistic oxygen atoms.
Vacuum Ultraviolet Laser / Time-of-flight Spectroscopy of Cl2.
Authors: Lipson R.H. , Dimov S.S. , Wang P. , Okuda I.V.
Published: February 2023

Vacuum ultraviolet (VUV) spectra of Cl2 are highly irregular due to extensive excited state perturbations, and in the past, have been difficult to interpret1. This situation was offset substantially by the ab initio calculations of Peyerimhoff and Beunker2. They showed that the strongest VUV transition below 145 nm involves a third tier

1

∑
u
+

ion-pair valence state dissociating to Cl+(1Dg) + Cl-(1Sg), which interacts with the near isoenergetic 4pπ

1

∑
u
+

Rydberg state leading to the formation of a double well potential curve, labelled 1

1

∑
u
+

.
An Optimal Frequency Domain Textural Edge Detection Filter
Authors: Frost Victor S. , Shanmugan K. Sam , Townsend J. Keith
Published: February 2023

Edge detection in images is an important first step in extracting information from the image. Many edge detection schemes have been employed to enhance the boundaries between regions of different average gray tone. These tonal edge detectors are inadequate when regions in an image are characterized by textural features.
Morphic analysis of printed circuit images
Authors: Mandeville Jon R.
Published: February 2023

To keep pace with the trend towards increased electronic circuit integration, printed circuit patterns are becoming denser and more complex. During the manufacturing process, visual inspection is often required to detect a variety of printed circuit defects. Interest in automating visual inspection is motivated by the desire to reduce manufacturing costs, improve product reliability, and standardize inspection quality.
Digital Automated Visual Inspection with Darkfield Microscopy
Authors: Sanz Jorge L.C. , Merkle Fritz , Wong Kwan Y.
Published: February 2023

Current research interests in the area of visual inspection include the design of new sensing technologies, high speed digital image processing techniques for scene analysis and efficient architectures for real-time implementation of the inspection tasks.
Phase-Shifting Moiré Interferometry
Authors: Koliopoulos Chris L. , Bell Bernard W.
Published: February 2023

Theory and experimental results are presented for phase-shifting moiré interferometry using a CCD detector array.
Current Industrial Applications of Machine Vision and Future Challenges
Authors: Holland S. W. , Tilove R. B.
Published: February 2023

Although research in machine vision began in the late 1960’s, industrial applications have only recently emerged. Among these, however, are some extremely impressive technical achievements. Most forecasts regarding future growth of commercial machine vision are highly optimistic. In this paper, we discuss some of the critical technologies that have contributed to successful machine vision implementation.
A very compact 3-D camera for robotic application
Authors: Blais François , Rioux Marc , Poussart Lenis
Published: February 2023

A. new 3-D camera which presents very interesting characteristics of size and robustness, making it ideal for robotic applications, is proposed. A very simple modification to a standard video camera produces this low cost 3-D sensor.
3-D Inspection using Multi-Stripe Structured Light
Authors: Case Steven K. , Jalkio Jeffrey A.
Published: February 2023

A number of methods have been demonstrated for 3-D coordinate measurements of an image. These include time of flight, stereo matching, and structured light. Most commercially available systems employ structured light, as this technique affords the resolution and speed required for many industrial tasks. In this paper we discuss a structured light 3-D inspection system with the potential for high speed and no moving parts.
Shape Representation in a Mainpart/Subpart Hierarchy
Authors: Gindi Gene R. , Delorie Donald H.
Published: February 2023

In many applications, objects may be defined and recognized by shape features. To achieve a measure of generality, a shape recognition system must recognize objects despite changes in position, scale, and orientation of the object, have a notion of similarity of objects, and handle occlusion and the presence of multiple objects. We limit the problem here to the case of single, 2-D, unoccluded objects.
Processing of Moving Edges with Pyramid Networks of Programmable Logic Elements
Authors: Vidal Jacques J. , Salas Paul
Published: February 2023

This paper presents a parallel processing network for detecting line segments from moving objects. It is founded on two recent developments from our UCLA research group. The first is a radical approach to dynamic edge detection which is event-driven and based solely on the order of passage over triads of equidistant detectors. Simple operations on traversal order, when a translating edges crosses the triad, yield approximate edge direction and velocity. The second foundation is a novel architecture concept for parallel logical inferences using networks of dynamicaly programmable Boolean logic modules (DPLMs). In this approach, Boolean inference data propagate asynchronously and concurrently through a functionally reconfigurable combinatorial network [Vidal83]. Propagation is wavelike and self-timed, proceeding at the maximum speed allowed by component delays. DPLM networks are made of identical modules with a regular topology, well suited to VLSI.
Determining 3-D Transformation Parameters from Images: Theory
Authors: Aloimonos J. , Ito I.
Published: February 2023

The problem of estimating three dimensional motion from dynamic imagery has several applications in the robotics field and it is by no means a simple one. There are essentially three ways in which the problem has been tackled.
Segmentation of Multiscale Curves by Chain Pyramids
Authors: Meer Peter , Baugher Sam , Rosenfeld Azriel
Published: February 2023

A planar curve may convey information at several levels of detail. Consider the top-left curve in Figure 3. It can be perceived as a sequence of wiggles on a quasi-sinusoidal line slightly drifting downward. Note that three different resolutions are involved. Locating the curve extrema with the best precision, while trivial for human perception, presents considerable difficulties for computer vision.
Review of the Two-Stage Camera Calibration Technique plus some New Implementation Tips and some New Techniques for Center and Scale Calibration
Authors: Tsai Roger Y. , Lenz Reimar
Published: February 2023

Camera calibration is fundamental to 3D Sensing/Measurement with robotics/machine vision. Tsai, 1985, gives a detailed explanation of why camera calibration is important, a comprehensive review of the state of the art, and several reasons why there is a need, for a new technique like the Two-Stage Camera Calibration Technique. It also gives a complete account of the theory and implementation of the Two-Stage Calibration Technique. This talk, however, does the following things: 1. It attempts to review the principle of the Two-Stage Technique very briefly so that the readers can grasp the main ideas quickly. 2. It mentions some new experimental results which indicate that stage 2 of the Two-Stage Calibration Technique only requires one iteration to reach good results. 3. It gives several implementation tips or pointers that are helpful for those who plan to implement the technique on their own. 4. It outlines several new techniques we developed for calibrating the scale and lens center.
Partial Matching in a Hierarchical Pattern Recognition System
Authors: Kim B. F. , Bohandy J.
Published: February 2023

A pattern recognition system has recently been described,(1) in which images are represented by a hierarchical sequence of patterns of decreasing size, forming a type of pyramid structure (similar in some respects to resolution pyramids). Pattern recognition occurs by comparison of sub-patterns of images in each level with array patterns stored in a memory associated with each level. In these comparisons, a matching criterion determines, at each level, the degree to which the patterns being compared must match in order to be considered equivalent. The purpose of this report is to present some results on how the matching criteria affect the performance of this type of system.
Comparison of Reflectometric and Psychophysical Measures of Cone Orientation
Authors: Burns Stephen A. , Elsner A. E. , Gorrand Jean-Marie , Kreitz Mark R. , Delori Francois C.
Published: February 2023

The intensity and color of a light determined psychophysically depends on where the light enters the eyes pupil, (the Stiles-Crawford effect10). This effect occurs due to the physical orientation and waveguide properties of the cone photoreceptors. In principle the measurement of cone alignment and orientation is a powerful clinical technique, providing direct information on the status of the outer retina. The outer retina is very sensitive to retinal and systemic disease, due in part to its high metabolic activity. Healthy photoreceptors are well oriented, and the orientation is maintained by an active process, with cones recovering their orientation following insult or disease4,5,8,9. In practice it has proven to be dificult to obtain a full map of cone orientation in a naive subject, and this has limited the use of the Stiles-Crawford effect for clinical research.
Solvable Models of Optical Resonators
Authors: Malev A.V.
Published: February 2023

Transverse effects in optical systems have been intensively studied in last years/1,2/. But it is rather difficult to analyze resonator diffraction effects and especially to take into account the influence of space inhomogeneities on laser generation in the framework of standard approach. However one can solve this problems in a mathematically sound way using the self-adjoint extension theory. The extension theory technique provides almost analytically describing of different physical processes (see /3,4/ for details and examples). This technique was used in /5/ for chaotic behavior studies of quantum systems.
Phase Quasi Integral for Stimulated Raman Scattering Initiated by Quantum Fluctuations and Statistics of Soliton-Like Random Pulses in Depleted Pump
Authors: Kilin S. Ya.
Published: February 2023

Stimulated Raman scattering is a quantum macroscopic process starting from unstable state. Any fluctuations, initial or boundary, classical or quantum in nature, lead to the macroscopic output fluctuations of the Stokes amplitude. Manifestation of these fluctuations in the statistics of the Stokes pulse energy and its spectrum have been studied extensively for the linear stage of the SRS [1]. Another fluctuation phenomena arises in nonlinear stage of the SRS - the random spikes, usually called soliton-like, are observed in the depleted pump [2]. Here we shown that the reason for these soliton-like spikes is the conservation of the relative phase Δϕ=ϕL−ϕS+ϕQ of the laser, Stokes and the polarization wanes [3].
The Dynamics of Transverse Field Structure in Unidirectional Ring Laser with Fast-Relaxed Active Medium
Authors: Veshneva I.V. , Mel’nikov L.A. , Sokolov A.A. , Tatarkov G.N.
Published: February 2023

We considered the unidirectional ring cavity formed by mirrors M1-M4, lens L and Gaussian aperture D (Fig.1) and filled with the active medium with homogeneously broadened gain line. We suppose that the relaxation rates of medium polarization γ and inversion γ
L
obey the conditions γL/c, γ
L
L/c ≫1, where L is cavity length.
Asymmetric Behaviour and Kink Shaping by Optical Feedback
Authors: Brivio F. , Mazzoleni S. , Milani M.
Published: February 2023

A systematic investigation of optical feedback induced effects on semiconductor laser diodes shows a variety of phenomena; some of them are linked to (left-right) symmetry properties of the system (symmetric solitary device plus optical feedback source). Attention is devoted to the appearance of feedback induced nonlinearities (kinks) in the P-I curves just above threshold [1]. Such nonlinearities are present in the characteristic curves taken from both facets, depend on the feedback ratio, and are reproducible. Kink formation and shaping are not substantially affected by the path between the laser facet and the reflecting surface; in particular they are not dependent on the presence of splices or connectors when a typical transmission line is the subject of investigation. Furthermore the role of optical feedback in destroying the symmetry between light outputs from the (equal reflectivity) front and rear facet of the devices is examined in detail, and a connection is established with the feedback adversely affecting the differential quantum efficiency of the device, in a selected range of values of the feedback ratio.