bluuebunny/crossref_metadata_2025 huggingface dataset:
Testing the Agreement Between a Traditional and UAV-Based Method for Quantifying Skips in Suboptimal Cotton Stands
Authors: Pena Martinez Enrique Eduardo , Ward Jason K. , Collins Guy , Nelson Natalie
Published: February 2023

Highlights

Agreement in the mean difference between the traditional and the UAV-based method only occurred in poor stands.

Effects of different sampling sizes between methods were evident in mediocre-to-good stand assessments.

Abstract. When suboptimal cotton stands occur, growers face the decision to accept or reject the stand. The replanting decision is difficult because the tradeoffs associated with replanting expenditures and reduced yields are difficult to objectively assess. Traditional methods like visual assessments and manual counts of cotton stands are commonly used to support a replanting decision. Typically, manual counts of skip size and frequency will provide more accurate assessments of the stand than visual assessments, but they are cumbersome to conduct and may not provide clear evidence that a replant is needed. Still, manual counts are popular among cotton farmers and the scientific community. Skip counts generated with the help of unmanned aerial vehicles (UAV) are less popular among cotton growers but provide more coverage and a larger sampling size across a given field. Therefore, UAVs have the potential to overcome the limitations associated with traditional methods. The motivation behind this study is to inform readers if manual methods can still be used for accurate decision-making regarding the replanting decision. More specifically, we study the interchangeability, or agreement, between a manual and a UAV-based method using Bland-Altman plots. Each method quantified skips greater than or equal to 0.91 m at different sampling sizes. Treatment plots varied in their stand counts, skip size, and skip frequency. Agreement between both methods was only found in the lowest stand treatment, where skips of large sizes were predominant. Conversely, methods disagreed in the higher stand where skips greater than or equal to 0.91 m were scarce. Keywords: Agriculture, Altman, Bland, Drone, Gaps, Precision, Remote, Sensing, UAS.
FRAGMENTO: UM CORPO SEM ÓRGÃOS DE FOTOPOEMADANÇA
Authors: Souza Josiclei de
Published: February 2023

A mistura de gêneros literários é uma realidade na literatura desde o século XIX. Essas experiências de mistura aconteceram entre linguagens artísticas. O presente trabalho se inscreve no campo dos estudos interartes e faz uma análise do fotolivropoema Fragmento (2003), de João de Jesus Paes Loureiro, resultado de um agenciamento com a dançarina Ana Unger e o fotógrafo Luiz Braga, percebendo o referido livro como um Corpo sem Órgãos (CsO), a partir de Deleuze e Guattari, pelo fato de o livro representar uma quebra nas barreiras que separaram a linguagem da poesia e da dança, sendo estas aproximadas e recriadas a partir da linguagem fotográfica. Em termos de poesia o livro recupera experimentações visuais e propõe outras novas, em diálogo com o corpo dançante. O olhar e o registro do fotógrafo é fundamente na mediação e costura desse diálogo. O resultado é corpo poético que escapa às estratificações da hiperexposição da era digital, fazendo com que o corpo entre em um devir dançante com a poesia a fotografia. Além de Deleuze e Guattari, também é trabalhado neste estudo o conceito de corpo narcísico na hiperexposição digital a partir de Byung-Chul Han, e também os estudos de Walter Benjamin sobre a arte na modernidade.
POESIA INSUBMISSA IMERSA NO JARDIM FECHADO DE RAQUEL NAVEIRA
Authors: Leitão Mary , Dias Martins Elizabeth
Published: February 2023

A obra poética de Raquel Naveira, desde a primeira publicação em 1989, apresenta traços de uma produção literária insubmissa. Misturando temas religiosos, históricos, literários e filosóficos, a autora sul-mato-grossense vem se destacando na literatura brasileira por apresentar um novo olhar acerca das narrativas tradicionalmente difundidas segundo uma perspectiva dominante. Apresentamos a leitura de poemas de três de suas obras: Guerra entre irmãos (1993), Caraguatá (1996) e Stella Maia (2001). Os textos eleitos foram publicados em Jardim Fechado (2015), fato destacado por se tratar de uma seleção feita pela própria poeta. No intuito de demonstrar o modo como a autora delineia uma perspectiva diferenciada dos momentos históricos que tematizam as obras, ao analisar os versos, realizamos um resgate dos fatos históricos, bem como identificamos os aspectos que ilustram uma poesia insubmissa, segundo a perspectiva de Roberto Pontes (1999), em Poesia insubmissa afrobrasilusa. É intrínseca a relação entre literatura e história, construindo um percurso que se encontra no âmbito dos estudos da literatura comparada.  A partir das referidas leituras, observamos o constructo de uma identidade literária híbrida que deixa transparecer as diversas influências e os inúmeros resíduos com os quais se edificam, na poética de Raquel Naveira, os traços da literatura brasileira contemporânea. Trata-se de uma voz que nasce individual e cresce coletiva, comprovando a superação do ensimesmamento e o alcance de um modo de ser insubmisso.
EM BUSCA DA FONTE SECRETA
Authors: Vieira de Lima Ricardo
Published: February 2023

Garatujas selvagens, nono livro de poemas de José Inácio Vieira de Melo, é o cume máximo, a síntese extraordinária de uma obra que, ao longo de mais de 20 anos, se impôs aos leitores de poesia, em razão de suas qualidades intrínsecas, as quais, sobretudo a partir deste novo volume de versos, alçam seu autor ao seleto grupo dos maiores poetas brasileiros contemporâneos.
Pump-probe phase spectroscopy with submilliradian sensitivity and nanosecond time delay using Michelson interferometers
Authors: Cruz C. D. , Stephenson J. C. , Engmann S. , Bittle E. G. , Wahlstrand J. K.
Published: February 2023

Using two Michelson interferometers, we describe an experimental scheme for sensitive pump-probe spectral interferometry measurements at long time delays. It has practical advantages over the Sagnac interferometer method typically used when long-time delays are required. First, with the Sagnac interferometer, achieving many nanosecond delays requires expanding the size of the interferometer so that the reference pulse arrives before the probe pulse. Because the two pulses still pass through the same region of the sample, long-lived effects can still affect the measurement. In our scheme, the probe and reference pulses are spatially separated at the sample, alleviating the need for a large interferometer. Second, in our scheme, a fixed delay between probe and reference pulses is straightforward to produce and is continuously adjustable while maintaining alignment. Two applications are demonstrated. First, transient phase spectra are presented in a thin tetracene film with up to 5 ns probe delay. Second, impulsive stimulated Raman measurements are presented in Bi4Ge3O12. The signal-to-noise using the double Michelson technique is comparable to previously described methods with the added advantage of arbitrarily long pump-probe time delays.
Cascade weak-value amplification for optic-fiber-based Sagnac interferometers
Authors: Jing-Hui Huang , Xiang-Yun Hu , Xue-Ying Duan , Guang-Gun Wang
Published: February 2023

In this paper, we propose our advantageous research leading to a new scheme for angular rotation $\Omega$ measurement in an optic-fiber-based Sagnac interferometer based on cascade weak-value amplification (CWVA). CWVA is a modified standard weak-value amplification (SWVA) technique for further enhancing the temporal shifts based on the principle of the Vernier effect. By choosing the appropriate CWVA parameters and the repetition time intervals of the Vernier scale, the temporal shifts in SWVA can be further amplified by measuring the envelope shifts in CWVA. Our simulation results indicated that CWVA can demonstrate the detection of tiny rotations at the range of 1.0 $\times$ $10^{-9}$ rad/s $\leq$ $\Omega$ $\leq$ 10 $\times$ $10^{-9}$ rad/s with higher sensitivity and larger signal-to-noise ratios than SWVA. The enhancement with a larger detection band may have a high influence on physics and related sciences, like rotational seismology and gravitational sensing.
Continuous roller transfer-printing and automated metrology of >75,000 micro-LED pixels in a single shot
Authors: Margariti Eleni , Quinn Gemma , Jevtics Dimitars , Guilhabert Benoit , Dawson Martin D. , Strain Michael
Published: February 2023

A continuous, single shot roller transfer printing process is presented for the large-scale hybrid integration of semiconductor devices. Transfer of a 320 x 240 pixel micro-LED array, representing >75,000 individual devices is demonstrated. The transfer printing process preserves the array geometry with pixel spatial location error less than 1 μm deviation from the as-designed layout. An automated microscopy-based metrology system was developed to assess such large device populations with sub-micron accuracy and allow the assessment of yield.
Tunnel-Injection Laser Based on Type II Broken-Gap p-GaInAsSb/p-InAs Single Heterojunction
Authors: Yakovlev Yu. P. , Moiseev K.D. , Mikhailova M.P. , Ershov O.G.
Published: February 2023

We present a new physical approach to design of III-V middle-infrared diode lasers which can lead to increasing operating temperature of InAs-based lasers. Main pecularity of proposed method is using interface radiative recombination of spatially-separated carriers in type II broken-gap p-p heterojunctions (HJs). Lattice-machted nondoped and doped GaIn0.17As0.22Sb layers with high quality interface were grown on p-InAs (100). It was established that GaIn0.17As0.22Sb/InAs HJ is type II with broken-gap alignment.
Theoretical Analysis of Gain in Compressive Strained Quantum Well InAlAsSb/GaSb Structures for 3-4 μm Lasers
Authors: Nabiev R.F. , Chang-Hasnain C.J. , Choi H.K.
Published: February 2023

Mid-infrared laser diodes are important sources for laser radar systems, molecular spectroscopy, and remote sensing of pollution and gases. InGaSbAs/GaAlSbAs lasers emitting at 2 μm are explored in detail since first room-temperature (RT) lasers [1-3] were demonstrated. However, a breakthrough in 3-4 μm lasers was made only recently [4-6]. Long wavelength lasers exhibit low characteristic temperature (T0 ≤ 30 K [6]), preventing them from operation at RT. One of the possible reasons of high threshold current at RT is Auger-recombination, which is proportional to cube of carrier density. Therefore, for long-wavelength lasers, it is especially important to decrease the carrier density at threshold.
Strained-Layer InGaAs-GaAs-AIGaAs Buried-Heterostructure Lasers with Nonabsorbing Mirrors by Selective-Area MOCVD
Authors: Lammert R.M. , Smith G.M. , Forbes D.V. , Osowski M.L. , Coleman J.J.
Published: February 2023

Optical absorption in the active region near the facets of semiconductor lasers during high-power operation may result in catastrophic optical damage (COD). Several schemes to increase the COD limited optical power have been reported. One scheme entails forming non-injection regions near the facets to reduce the nonradiative recombination at the facets [1], [2]. A disadvantage of this scheme is that the non-injection region acts as a saturable absorber which may effect the L-I curve near threshold. Another scheme to increase the output power at which COD occurs involves forming a region at the laser facets which has a higher band gap energy than the energy of the emitted laser light. One method to produce these nonabsorbing mirrors (NAMs) utilizes bent-waveguides fabricated using nonplanar substrates [3], [4]. Although this method produces NAMs with broad near-fields, the coupling of the optical field between the window region and the light-emitting region is low due to the optical beam diffracting freely in the window region. In addition, accurate cleaving is necessary to achieve the relatively short window regions needed (<15 µm). Another method to produce NAMs uses an etch and regrowth technique, but this method also allows the optical beam to diffract freely in the window region and accurate cleaving is again needed [5].
Optical Bistability and NOR-Gate Operation In Intracavity-Coupled In-Plane and Vertical Cavity Surface Emitting Lasers
Authors: Shire D. B. , Tang C. L. , Parker M. A.
Published: February 2023

Gain-controlled, intracavity-coupled in-plane and vertical cavity surface emitting lasers (VCSELs) fabricated from the same epitaxial material have recently been reported1-2. Earlier work on gain quenching and bistability in intracavity coupled lasers involved in-plane devices only3-5. It has been pointed out that the conditions for bistability in cross coupled lasers depend on the individual lasers' self- and cross-saturation coefficients6-7. The cross saturation terms are highest when the overlap of the two lasers' gain sections is maximized. Consequently, the hysteresis in the power output vs. power input characteristic of cross-coupled VCSEL and in-plane lasers is expected to be larger and more easily realized than that observed in cross-coupled in-plane lasers alone. We report the first observation of optical bistability in cross-coupled VCSEL and in-plane lasers, and we present an all-optical two-input NOR gate which was fabricated to demonstrate the flexibility of this switching technology.
Miniature Lidar using Diode Lasers Modulated with PN Codes
Authors: Abshire James B. , Rall Jonathan A.R.
Published: February 2023

Takeuchi et al. [1,2] first reported aerosol lidar measurements using an AlGaAs laser modulated with a pseudo-noise (PN) code in 1986. Recently, we have reported the design, theory and measurements [3-5] made with our breadboard PN aerosol lidar, which uses a photon counting detector and histogram-correlate receiver processor.
A Monolithic Stable-Resonator Semiconductor Laser
Authors: Biellak S. A. , Sun Y. , Wong S. , Siegman A. E.
Published: February 2023

Semiconductor lasers with a variety of cavity geometries have been studied for nearly three decades. For wide stripe monolithic lasers (width > 20 μm), nearly all the resonators fabricated so far can be divided into two types: cleaved flat-mirror structures generally employing some form of gain or index guiding [1], and unstable-resonator diode lasers [2,3]. The stable-resonator geometries widely employed in ordinary gas and solid-state lasers [4] have not to date been realized in monolithic semiconductor lasers for a number of reasons. First, the technology to fabricate precisely curved end mirrors has not been widely available until recently. Second, nonlinear saturation and waveguiding effects are strong in semiconductor lasers, and hence lateral gain and index guiding can be expected to deform the modes of stable-resonator lasers at high power levels. Third, the rather weak transverse mode discrimination of stable resonators may not lead to good mode selection in diode lasers having high gain and large output coupling.
Operating Characteristic Simulation of High-Power Broad-Stripe Quantum-Well Semiconductor Traveling Wave Amplifiers
Authors: Dai Zheng , Michalzik Rainer , Unger Peter
Published: February 2023

To design an optimized high-power semiconductor traveling wave amplifier (TWA), it is important to study the parameter dependencies of a TWA on its waveguide structure, material properties, and operating conditions. Since the degradation of the output beam profile in a broad-stripe TWA is often observed in practice, two-dimensional models employing the beam propagation method (BPM) and the effective index method have been widely used [1-2]. These models are usually based on a linearization of basic material properties. For high-power TWAs, the operating current is several times larger than the threshold current of a corresponding laser diode. Linear approximations are under these conditions no longer valid. In this paper, we consider nonlinear material properties in a self-consistent BPM model. Nonlinear gain and residual facet reflectivities are found to greatly influence the operating characteristics of the devices.
1.5 μm Vertical-Cavity Surface-Emitting Lasers
Authors: Fisher M.A. , Huang Y.-Z. , Dann A.J. , Elton D.J. , Harlow M.J. , Perrin S.D. , Reed J. , Reid I. , Wickes H.J. , Adams M.J.
Published: February 2023

VCSELs emitting in the 1.3 and 1.55 μm regions could be particularly useful as low cost sources for optical fibre telecommunications applications because mode-matched devices can be coupled to single-mode fibres with high efficiency and good alignment tolerance. The absence of cleaved facets also permits on-wafer characterisation of devices.
Impurity Induced Disordering for Improved Vertical Cavity Lasers
Authors: Floyd P. D. , Peters M. G. , Coldren L. A. , Merz J. L.
Published: February 2023

Vertical cavity surface emitting lasers (VCSELs) are interesting due to their single longitudinal mode operation, a circularly symmetric optical mode profile, and surface normal light emission. These characteristics make them ideal light sources in both free space optical communication systems and in short haul optical fiber communication systems.
A CW External Cavity Surface Emitting Laser
Authors: Sandusky J. V. , Mukherjee A. , Brueck S. R. J.
Published: February 2023

We report the first continuous wave, external cavity, optically pumped surface emitting laser. The device is a resonant periodic gain (RPG) vertical cavity surface emitting laser (VCSEL) with the top mirror stack replaced by an epitaxially grown antireflection (AR) coating, as shown in Fig. 1.
Oscillation wavelength shift characteristics of a semiconductor laser in a magnetic field -Observation using a beat note-
Authors: Sato Takashi , Matsuda Shin’ya , Shibata Kazunori , Yamamoto Shigeki , Ohkawa Masashi , Maruyama Takeo , Shimba Minoru
Published: February 2023

Since the development of the first semiconductor lasers, we know that the oscillation wavelength of a semiconductor laser depends on injection current, laser temperature and magnetic field. Among these factors, injection current and laser temperature are the principal means by which to control the wavelength of laser diodes, in many practical applications. The wavelength shift of laser diodes subjected to strong magnetic fields in low temperature was reported from a physical point of view in the early 60’s[1]. Even after such work was further progressed, little time was spent actually testing semiconductor lasers in a magnetic field except for the spin-flip Raman[2] and quantum well[3] lasers.
Selected Multi-Wavelength Oscillation of a Semiconductor Laser in an External Cavity
Authors: Lin Ching-Fuh
Published: February 2023

A multi-wavelength laser source is important for applications in areas such as wavelength-division multiplexing (WDM), interferometry, lidar and optical data storage. Simultaneous oscillation of multipe wavelengths have been demonstrated in several methods including spatially chirped Bragg reflector vertical cavity surface emitting laser (VCSEL) arrays,1 multichannel grating cavity (MGC) laser,2 multistripe array grating integrated (MAGIC) laser,3 and multi-wavelength DFB laser array by control selective area MOVPE.4 In those devices, arrays are required for the generation of multi-wavelength oscillation. Each array element is responsible for its individual wavelength oscillation. In this work, it is demonstrated that a single-stripe Fabry-Perot laser diode is able to oscillate at selected multiple wavelengths with a wavelength separation ≥1.3 nm, several times larger than the Fabry-Perot longitudinal mode spacing.
Optical Matrix-Vector Multiplication Using a Spatial Light Modulator and a Phase Conjugator
Authors: Chiou Arthur E. , Yeh Pochi , Khoshnevisan Monte
Published: February 2023

A variety of optical matrix processing schemes [1, 2] use two-dimensional spatial modulation of optical intensity to represent a matrix to exploit the inherent parallel nature of optics. Such an approach typically requires the projection of a spatial pattern to match another pattern to perform the element-by-element multiplication. The basic incoherent matrix-vector multiplication scheme [3], for example, requires the use of anamorphic optics to project a linear array of sources (or a one dimensional spatial light modulator) to precisely match a two dimensional matrix masks. In the matrix-vector multiplication scheme using four-wave mixing in nonlinear media [4], simultaneous alignment of all the pixels of the matrix and vector is a major task, particularly for a large number of pixels. Misalignment of the pixels may lead to severe errors. For a given size of matrix mask, the density of elements increases as the dimension (N) of the matrix increases. As a result, the requirement on alignment becomes more and more stringent. In practice, the critical alignment required is likely to impose a practical limit on the optimum dimension of the matrix (N) to be of the order of one hundred or less depending on the specific architecture.
Optical Associative Memory for Word-break Recognition
Authors: Paek Eung Gi , Von Lehmen A
Published: February 2023

In this paper, we describe a novel associative memory based on a coherent optical correlator which is able to identify individual words in a continuous string of letters. The output is readable text: a series of words with spaces inserted between them. The system is shift invariant and has error correction capability.
Real-Time Programmable Joint Transform Correlator with a Threshold Hard-Clipping Microchannel Spatial Light Modulator
Authors: Yu F.T.S. , Song Q.W. , Suzuki Y. , Wu M.
Published: February 2023

A programmable real-time optical joint transform correlator that generates sharper autocorrelation peaks is presented. In the system, a Microchannel spatial light modulator (MSLM) is utilized as the threshold hard-clipping square-law device. A liquid crystal television (LCTV) is used, with a microcomputer, to display input target and reference image at the input plane. By using the feed-back loop, in principle, the system would offer adaptive processing capability. A preliminary experimental result is given.
A Spatially Segmented Design Appraoch to Spatial Light Modulators
Authors: Athale Ravindra A. , Lee Sing H. , Essner Sadik
Published: February 2023

All optically addressed spatial light modulators (SLM) contain the functionalities of detection of input light pattern and corresponding modulation of the readout beam. These two functions are often performed by two physically distinct parts, although in some cases the same material or structure performs these two functions. The isolation between these two functionalities of an SLM is an important feature, which can be achieved using several different approaches: (1) wavelength seperation between read and write signals, (2) seperation along the direction perpendicular to the device plane, (3) seperation along a direction within the device plane.
Real-Time Optical Edge Enhancement Using a Hughes Liquid Crystal Light Valve
Authors: Chao Tien-Hsin , Liu Hua-Kuang
Published: February 2023

Edge enhancement is one of the most important preprocessing techniques utilized in optical pattern recognition. In an optical correlator, cross-correlations among similar input objects can be greatly reduced by using the edge enhancement technique. Traditionally, optical edge enhancement is obtained by high-pass filtering at the Fourier plane. However, the system SNR is generally lowered by this filtering process. Recently, two differentiating spatial light modulators, specifically designed to generate edge-enhanced output, have been reported. Casasent et al. have demonstrated real-time edge enhancement using a Priz light modulator [1]. The Priz light modulator is a transverse modification of the Pockel’s Read-out Optical Modulator (PROM) with a [111] BSO crystal cut. Armitage and Thackara have designed a BSO photo-addressed nematic liquid crystal differentiating spatial light modulator [2, 3]. A layer of liquid crystal is tuned in a transverse configuration (i.e. the electro-optic response is optimized for Ex and Ey rather than Ez) to achieve the edge-enhancement. The BSO crystal is used as a photo-addressing medium. This SLM is functionally optimized as an edge-enhancing SLM.
Spatial Light Modulation in GaAs
Authors: Cheng Li-Jen , Gheen Gregory , Liu Tsuen-Hsi
Published: February 2023

Gallium Arsenide (GaAs) is the most technologically-important compound semiconductor for electronics and optoelectronics. Semi-insulating Cr-doped and undoped GaAs crystals are known to be photorefractive.1,2 This provides opportunities to use GaAs for optical processing, including spatial light modulation. In this paper, we will present recent results of our investigation on the feasibility of using GaAs in this area.
Spatial Light Modulators: Fundamental and Technological Issues
Authors: Kyriakakis C. , Asthana P. , Johnson R. V. , Tanguay A. R.
Published: February 2023

Numerous applications have been envisioned for spatial light modulators in optical information processing and computing systems [1, 2]. These applications can be summarized within the context of a generalized optical information processor or computer as shown schematically in Fig. 1 [2]. The principal functional roles of both one- and two-dimensional spatial light modulators include those of format, input, output, CPU, and memory devices. In addition, spatial light modulators can be effectively utilized to provide certain types of feedback interconnections, as for example in the case of optical crossbar switches and holographically encoded weighted interconnections.
Spatial Light Phase Modulators and Fresnel Optical Elements using Liquid Crystals
Authors: Purvis Alan
Published: February 2023

The ability of liquid crystaline material to modulate the phase of a light beam has been exploited in the production of thin-film Fresnel optical components.
Silicon Active Backplane Spatial Light Modulators Using Ferroelectric Liquid Crystals
Authors: Crossland W.A. , Birch M.J. , Vass D.G. , Underwood I. , Reid S.A. , Latham S.G.
Published: February 2023

A thin layer of fast chiral smectic liquid crystals may be placed directly over suitably designed silicon VLSI circuits in order to enable the modulation of light in response to variations in voltage. This hybrid electro-optic technology may enable a number of the key components required for parallel optical systems to be made (1). The simplest of such components are electrically addressed spatial light modulators which consist of arrays of electrically addressed shutters (1,2,3,).
Liquid Crystal Space Time Light Modulators in Associative Holographic Memory
Authors: Vasiliev A.A. , Galavanova E.I. , Kompanets I.N. , Lunyakova G.A.
Published: February 2023

LC SML is used as phase conjugation mirror in holographic associative memory; a complete reconstruction of the images is observed when the input image is even one-fourth itself.
Device Characteristics of Optical Disc Spatial Light Modulators
Authors: Rilum John H. , Tanguay Armand R.
Published: February 2023

Optical memory disc technology has recently matured and penetrated the personal computer industry market with high density and extremely high capacity serial data storage devices. The high resolution (submicron) and long life time (> 10 years) characteristic of the optical disc medium in combination with image-based recording and an appropriate parallel readout scheme also make this advanced technology a very competitive alternative for spatial light modulation.
The Magneto-optic Spatial Light Modulator
Authors: Davis Jeffrey A.
Published: February 2023

The magneto-optic spatial light modulator1-3 (MOSLM), commercially available through Semetex Corporation, consists of a one or two dimensional array of electrically addressable pixels which affect the polarization state of transmitted light. This paper provides an overall background on the device and reports improvements in optical transmission, contrast ratio, and frame rate.
Lowered Temperature MBE Regrowth of LED Structures on High Density GaAs Circuits Fabricated through MOSIS
Authors: Grot Annette C. , Psaltis Demetri , Shenoy Krishna V. , Fonstad Clifton G.
Published: February 2023

We present results on GaAs/AlGaAs LEDs monolithically integrated by Molecular Beam Epitaxy (MBE) regrowth with GaAs MESFET circuits fabricated through the MOSIS service.
Real time displacement measurement with FLC-SLM (Ferroelectric Liquid Crystal Spatial Light Modulator ) by correlation of speckle patterns
Authors: Kobayashi Yuji , Takemori Tamiki , Mukohzaka Naohisa , Yoshida Narihiro , Fukushima Seiji
Published: February 2023

Specklephotography1)2) is effective in the analysis of two-dimensional displacement information.
Optical Memory Elements Based on Hetero-nipi Superlattice Asymmetric Cavity Spatial Light Modulators
Authors: Hibbs-Brenner M.K. , Mukherjee S.D. , Lehman J. , Ruden P.P. , Liu J.J. , Sawchuk A.A. , Hsu W.-F.
Published: February 2023

Hetero-nipi superlattices are semiconductor structures in which both the composition and doping are varied in the direction of epitaxial growth in a periodic fashion.
Optically addressed zero-crossing edge detection spatial light modulator
Authors: Jared David A. , Johnson Kristina M.
Published: February 2023

This paper describes an optoelectronic system that performs zero-crossing edge detection using an VLSI, ferroelectric liquid crystal (FLC) spatial light modulator (SLM).
DANE Switching Arrays for High Performance Computing (HPC) Modules
Authors: Guilfoyle Peter S. , Grider David E. , Van Zeghbroeck Bart
Published: February 2023

High performance computing (HPC) modules are being developed which incorporate a 2-D GaAs, high speed, spatial light modulator called a DANE array (Figure 1).
Retina-like Adaptive Thresholding in a Nonlinear Joint Transform Correlator
Authors: Schehrer K. L. , Schirber L. , Handschy M. , Roe M. G.
Published: February 2023

Joint transform correlators, now made practical by the availability of many electrically- and optically- addressed spatial light modulators (SLM) and convenient coherent light sources, have been shown to be effective at both optical pattern recognition (OPR) [1] and tracking [2].
Characterization of a Free-Space Opto-Electronic Interconnect System based on Si/PLZT Smart Pixels.
Authors: Mansoorian B. , Marsden G. , Ozguz V. , Fan C. , Esener S.
Published: February 2023

The characteristics of Si/PLZT smart pixels suggests that they are suited for use in opto-electronic systems requiring moderate speeds and a large dynamic range due to noise and fan-out considerations1,2.
Generalised dynamic holographic interconnects using spatial light modulators
Authors: O’Brien D.C. , Wilkinson T.D. , Mears R.J. , Crossland W.A.
Published: February 2023

Applications such as optical neural networks often require a programmable weighted optical interconnect between ‘neurons’.
Programmable Diffractive Optical Elements
Authors: Davis Jeffrey A. , Cottrell Don M. , Bunch Robert M. , Brandt Werner V. , Schley-Seebold Heidi M. , Guertin Jarod
Published: February 2023

Diffractive optical elements can be written onto spatial light modulators (SLM's) yielding several advantages.
A Self-amplified Beam-Steering Technique for Programmable Optical Interconnections
Authors: Liu Hua-Kuang , Zhou Shaomin , Yeh Pochi
Published: February 2023

A self-amplified angularly multiplexed beam-steering technique for programmable interconnection and optical computing applications is presented.
Photoanisotropic Organic Volume Holograms for Spatial Light Modulation
Authors: Huang Tizhi , Weaver Samuel , Blair Steve , Wagner Kelvin
Published: February 2023

In optical processing it is often required to transform the information to be processed into a coherent modulation carried on a laser beam.
Polarization Rotation Modulator in a Strained [110]-Oriented Multiple Quantum Well
Authors: McCallum D.S. , Huang X.R. , Smirl Arthur L. , Sun D. , Towe E.
Published: February 2023

Optical modulators with a high contrast ratio are desirable for use in optical information processing applications. Devices based on semiconductor multiple quantum wells are of particular interest because of the possibility of combining modulators with detectors and electronic components on a single substrate to make high-speed smart-pixel arrays. However, it is difficult to obtain large contrast ratios in conventional MQW modulators, which function by using the quantum confined Stark effect to modify the absorption coefficient of the MQW. For example, a typical p-i(MQW)-n modulator has a contrast ratio of 3:1 to 5:1, although contrast ratios as high as 10:1 have been obtained. Fabry-Perot cavities have been used to increase the contrast ratio to 100:1, but at the expense of optical bandwidth.
Photorefractive Persistence and Erasure in AlGaAs Spatial Light Modulators
Authors: Bowman S. R. , Rabinovich W. S. , Katzer D. S. , Kyono C. S.
Published: February 2023

Spatial light modulators have been demonstrated by a number of groups using GaAs/AlGaAs quantum well materials. These optical modulators utilize the enhanced electro-absorption and electro-dispersion associated with quantum confined excitons. Many of these devices use pixelated electrodes to apply a spatially varying electric field across the quantum well layer. We have investigated non-pixelated devices in which the applied field is varied through spatially modulated illumination. These optically addressed spatial light modulators (OASLM) are simple to fabricate and have demonstrated higher spatial resolution than pixelated devices. [1-4] Here we present recent experiments designed to determine the lifetime of the transient space charge distributions generated in GaAs/AlGaAs OASLM's.
The History of Optical Computing: A Personal Perspective
Authors: Lohmann Adolf W.
Published: February 2023

For me the history of optical computing can be divided into several phases, which will illustrate by examples. The phase transitions mark changes of my personal attitude towards optics in general and to information optics in particular.
Tunable birefringent filters using liquid crystals
Authors: Miller Peter J.
Published: February 2023

Liquid crystal materials may allow the construction of rapidly tunable filters with a variety of bandwidths. These filters would be built as birefringence filters which use the electro-optic properties of liquid crystals to achieve tunability. The most common liquid crystal device is the twisted-nematic cell, but the device of interest to us is called a 'flat-field' or non-twisted cell.
Effects of Ion Bombardment on the Environmental Durability of Metal Coatings
Authors: Al-Jumaily G.A. , Mooney T.A. , Smajkiewicz A.
Published: February 2023

Metal coatings are widely used as wide band reflectors for astronomical and laser applications. Optical components exposed to the environment such as telescope mirrors suffer from corrosion due to natural elements such as rain and wind. The deloyment of optical elements in space for scientific, military, and commercial applications makes it necessary to improve the lifetime, reliability, and tolerance to radiation of optical coatings. The benefits of improving the properties of optical coatings on the performance of optical telescopes are enormous.
Combining Beams in a Multi-Telescope Interferometer
Authors: Ribak Erez
Published: February 2023

An interferometer is under study that is comprised of a number of small telescopes mounted in the same structure. Fibre optics or a succession of mirrors lead the light from the foci of the telescopes to the vicinity of the detector, at which point one of the following schemes can be employed:
Interferometric Spectral Imaging in the Visible and Near-Infrared Regions
Authors: Itoh Kazuyoshi , Inoue Takashi , Ichioka Yoshiki
Published: February 2023

We present experimental results of an interferometric method called the Fourier transform spectral imaging[1], The method is based on the alterations[2] of coherence function during propagation in free space. We assume that an incoherent light source (object) illuminates an observing site and that the optical wave field around this site consists of an ensemble of plane waves with uncorrelated amplitudes. This is a reasonable assumption when the observation volume is small or an appropriate transform lens is placed between the object and observation area. The theory predicts that three-dimensional (3-D) Fourier transformation of the 3-D spatial coherence function of the optical wave field gives the 3-D energy density function, a function of a 3-D spatial frequency or a wave vector, associated with the object[1]. Under the assumption stated above, the wave vectors assign particular directions of propagation and wavelengths of the plane waves that emanate from the particular positions in the object. Thus, the density function fully specifies the spectral image information of the object, i.e. the spatial distribution of radiation and the spectral contents comprising the radiation. Since the present method is an extension of Fourier spectroscopy to imaging spectroscopy[1], it inherits the desirable properties of the multiplex and throughput advantages.
Performance comparison of two Wolter Type II telescopes in the vacuum ultraviolet
Authors: Leviton Douglas B. , Wright Geraldine A. , Thomas Roger J. , Davila Joseph M. , Epstein Gabriel L.
Published: February 2023

The SERTS-A and SERTS-C solar telescopes are examples of Wolter Type II glancing incidence telescopes built for flight1,2 on sounding rockets to study active regions on the sun in the extreme ultraviolet wavelength range 24-45 nm. Improvements in computer-controlled polishing technology at GSFC have led to the SERTS-C telescope which has substantially improved throughput and angular resolution in that wavelength range over the earlier SERTS-A. While both telescopes are diffraction-limited in the visible, preventing an obvious selection of the better telescope for flight, laboratory results in the far ultraviolet were used to make the selection and flight data are shown to illuminate these advances.
POINTS Optics: Challenges and Options
Authors: Reasenberg Robert D.
Published: February 2023

It has been widely recognized for several years that interferometric instruments will play a major role in many aspects of space-based optical astronomy. More recently, optical interferometry received very favorable treatment in the AASC (Bahcall Committee) report and the POINTS mission is a close match to the Astrometric Interferometry Mission that the report lists as a moderate space-based program. In the next century, milliarcsecond-and submilliarcsecond-resolution images will likely be obtained from interferometric instruments deployed in space. An important precursor to such imaging instruments is a small astrometric optical interferometer. (Recommendations of the Interferometry Panel of the AASC.)
The Role of Cerium Oxide in Glass Polishing
Authors: Silvernail Walter L.
Published: February 2023

As is well-agreed, the polishing of glass is a complex process involving interactions between the glass surface, the polishing agent, water, and the polishing lap. But because the mechanism of glass polishing still is not clearly understood, determining the optimum conditions of preparation of the polishing agent requires an empirical approach and the following discussion is aimed at describing how various methods of preparing cerium oxide affect the characteristics of the product and how (not necessarily why) these correlate with polishing activity.
Deblurring and Three-Dimensional Reconstruction from Multiple Linear-Tomograms
Authors: Kawata Satoshi , Sklansky Jack
Published: February 2023

The image of the tomogram obtained by a conventional x-ray tomographic machine is degraded by the superposition of motion-blurred images of nonpivotal planes. We introduce a method to eliminate these blurred images from a tomogram. In this method a set of tomograms, each focused on one of a set of parallel planes, are combined to form a three-dimensional reconstruction of blur-free tomograms. This approach is equivalent to the inversion of a linear system. By a mathematical analysis of linear-motion tomography, we found that linear-motion tomography is restricted to angularly-limited frequency information. An iterative matrix inversion algorithm with the constraints of nonnegativity and finite-extent is applied to the reconstruction of the plane of interest from a set of tomograms.
Image Reconstruction and Partial Deconvolution with Support Constraint Separation Angle and Least-Squares Interpolation Procedures
Authors: Lannes A.
Published: February 2023

In image reconstruction from projections [1], and more generally, in any partial deconvolution with support constraint, the central problem is to specify the conditions under which it is possible to interpolate, in a bounded region W, the Fourier transform of an object function with support in a bounded region V [2,3,4]. In particular, it is then essential to understand, in an analytical way, the parts played by the size of V and W, and the geometry of the whole V, W-configuration (cf. for example Fig. 1). The aim of this communication is to summarize the corresponding analysis, and to visualize the main results with the aid of appropriate representations.
Bayesian Approach to Limited-Angle CT Reconstruction*
Authors: Hanson Kenneth M. , Wecksung George W.
Published: February 2023

Consider the function f(x,y) to belong to the set of all integrable functions with compact support. The projections of f(x,y) may generally be written as where the hi are strip-like response functions corresponding to each of the N available projection measurements. The objective of computed tomography (CT) is to reconstruct the source function f(x,y) from these N measurements. Clearly a limited number of such measurements cannot completely specify an arbitrary f(x,y). Since Eq. 1 may be viewed as an inner product between hi and f in the Hilbert space of all acceptable functions, each measurement consists of a projection of the unknown vector f onto the basis vector hi. The available measurements can only provide Information about those components off that lie in the subspace spanned by the response functions called the measurement subspace. The components off that lie in the orthogonal (null) subspace do not contribute to the measurements and, hence, cannot be determined from the measurements alone. Without prior information about f(x,y) it is at least necessary to restrict the solution to the measurement space in order to make it unique, i.e., have minimum norm. The null-space components of such a solution are obviously zero. It is known that this leads to identifiable, objectionable artifacts when the projections span a limited range of angles.1,2 In its generality, Eq. 1 is representative of any discretely sampled, linear-imaging process. Thus, the above statements and the approach that follows are applicable to many other problems such as restoration of blurred images and coded-aperture imaging.
The Use of A Priori Information In Image Reconstruction From Limited Data
Authors: Medoff B.P. , Brody W.B. , Macovski A.
Published: February 2023

Image reconstruction algorithms implemented on existing CT scanners require the collection of line integrals that are evenly spaced over 360 degrees.1 In many practical situations, requirements for high temporal resolution or the presence of an x-ray opaque structure prevent the measurement of all the line integrals. Attempts to use existing algorithms in this "limited data" situation result in images with severe streak artifacts.2
Averaging the Fourier Phase Information in a Signal Ensemble without Calculating Phase
Authors: Swan Herbert W. , Goodman Joseph W.
Published: February 2023

A length-M discrete stochastic process, s(k), and a length-N deterministic sequence, h(k), are convolved to yield the discrete stochastic process, x(k). If we take the length-L discrete Fourier transform of s(k), h(k), and x(k), where L is some integer greater than N+M−2, and pad with zeros as necessary, then (1) for 0 ≤ n < L. Here H(n) is deterministic while X(n) and S(n) are stochastic. Given an ensemble of the process x(k), and sufficient knowledge of the self-statistics of s(k), we wish to recover h(k). Problems such as this arise in the fields of geophysics, radar signal processing, and space object imaging. Although it is easy to estimate the Fourier magnitude of h(k) from (2) estimating the phase of H(n) can be difficult, due to the phase unwrapping problem[1]. The difficulty is worsened by observational noise and by extending the problem to 2-dimensional images.
Maximum Entropy Image Reconstruction from Phaseless Fourier Data
Authors: Skilling John
Published: February 2023

We investigate the reconstruction of a real and positive spatial pattern or "image" (1) from incomplete phaseless Fourier data Dkwith noise σk, (2) The first step is to define the set of "feasible" images, any of which is consistent with the data. This involves comparing the actualdata Dkwith the simulated data |Fk|2which wouldbe observed (apart from noise) from a trial image f. The simplest comparison measure is chisquared (3) Any trial image f for which
χ2>M+3⋅3M (M = number of data) is rejected with 99% confidence: the surviving images are feasible and only these need be considered further. In N-dimensional image-space, the feasible set forms a 2M-dimensional toroid, projected linearly to infinity in any unmeasured Fourier planes. Much of the difficulty encountered with phaseless data stems from the connected topology of this constraint.
On Some Explicit Deconvolution formulas
Authors: Berenstein C. A. , Taylor B. A. , Yger A.
Published: February 2023

Given several measuring devices defined by convolution with distributions μ1,…,μm of compact support in ℝn one would like to construct explicitly deconvolutors, i.e. distributions v1,…,vm, also of compact support, such that This would allow us to reconstruct exactly an arbitrary signal ϕ ∈ C∞(ℝn) which was measured as g1 = μ1 * ϕ,…,gm = μm * ϕ by.
Factorizing Entire Functions of Exponential Type
Authors: Lawton Wayne , Morrison John
Published: February 2023

The nonlinear problem of factorizing a distribution having compact planar support as a convolution product given possible a priori information about the factors includes the problems of blind deconvolution and signal recovery from magnitude. By the Paley-Wiener-Schwartz theorem [1, p. 390] this problem is equivalent to factorizing entire functions of exponential type. Moreover, typical a priori information about the convolution factors can be equivalently specified in terms of the corresponding entire function. For example, Bochner’s theorem [1, p. 715] implies the correspondence between positive measures and positive definite functions and the Plancherel-Polya theorem [2, p. 353] together with the result in [3, p. 7] implies that the convex closure of the support of a distribution having compact planar support is completely characterized by the growth rate, in various directions, of the corresponding entire function.
Spatially Constrained 3-D Reconstruction from Limited-Angle Projections in Optical Microscope Tomography
Authors: Kawata S. , Nakamura O. , Minami S.
Published: February 2023

In earlier work, we invented a principle of optical microscope tomography and developed a prototype system to achieve tomographic microscope imaging of three-dimensional specimens [1,2]. In this paper we describe the principle of optical microscope tomography and the algorithm to reconstruct the 3-D distribution of the sample from the obtained images. Since the system is angularly band-limited, we have to constrain the inverse equation of the system by some a priori information to lead to a unique solution. We use the information of the knowledge of the spatial outer boundary of the object to truncate the projection system function. The outer boundary of the object is easily measured. Since this constraining preserves the linearity of the system, reconstruction can be simply performed by a linear-system solving method.