bluuebunny/crossref_metadata_2025 huggingface dataset:
GaAs Heteroepitaxial Growth on Submicron CMOS Silicon Substrates
Authors: Tewksbury S.K. , Hornak L.A. , Noriman H. , McGinnis S.
Published: February 2023

Preliminary results of our study of the CMOS compatibility of GaAs heteroepitaxial growth on wafers containing twin-tub V CMOS devices (0.9 micron drawn features) are reviewed.
Implementation of a General Purpose Stored Program Digital Optical Computer
Authors: Main P.T. , Feuerstein R.J. , Heuring V.P. , Jordan H.F. , Feehrer J.R. , Love C.E.
Published: February 2023

Optical computing has been a major field of research for a number of years with considerable effort expended on developing appropriate devices.
Field Effect Transistor — Self Electrooptic Effect Device (FET-SEED) Circuits for Optoelectronic Data Processing Systems
Authors: Chirovsky L. M. F. , D’Asaro L. A. , Laskowski E. J. , Pei S. S. , Asom M. T. , Focht M. W. , Freund J. M. , Guth G. D. , Leibenguth R. E. , Livescu G. , Morgan R. A. , Mullaly T. , Smith L. E. , Lentine A. L. , Boyd G. D. , Woodward T. K.
Published: February 2023

Electronic chips have tremendous data processing capabilities but they also have a communications bottleneck. The amount of data that can be processed on electronic chips far exceeds the amount of data that can be brought in and out of these chips.
Design issues for beam array generation gratings
Authors: Morrison Rick L. , Walker Sonya L.
Published: February 2023

Diffractive optical elements play an important role in digital free-space photonic systems. As phase gratings they provide the functionality of holograms that can not be readily achieved using conventional optics.
Design of a microlens based total interconnection for optical neural networks
Authors: Poon P.C.H. , Selviah D.R. , Midwinter J.E. , Daly D. , Robinson M.G.
Published: February 2023

The ability of neural networks to quickly adapt to changing circumstances is important for applications ranging from fast recognition of images to adaptive line equalisation for telecommunication systems.
3-D Optical Memories
Authors: Esener Sadik
Published: February 2023

Summary not available at time of printing.
Content Addressable Network Implementations
Authors: Brodsky Stephen A. , Guest Clark C.
Published: February 2023

Content Addressable Networks are a family of neural networks designed for efficient implementation in optoelectronics and VLSI. Three CAN systems have been constructed for pattern classification, employing the supervised, self-organized, and tutored algorithm variations. The experimental systems use planes of parallel binary optical computations for both learning and recall. Experimental results are presented to demonstrate the fault tolerance of the supervised CAN algorithms. The supervised CAN network was able to learn around optical errors resulting from noise, stuck pixels, and failing pixels, even when these errors caused imperfect application of the learning algorithm.
Random Interconnections with Ground Glass for Optical TAG Neural Networks
Authors: Lee Hyuek-Jae , Lee Soo-Young , Shin Sang-Yung
Published: February 2023

After the first optical implementation of the 1-dimensional Hopfield model had been reported [1], extensive researches have been conducted for 2-dimensional input/out patterns.[2,3] Page-oriented holograms [4] may achieve fairly large fixed interconnections, while volume holograms [5] or lenslet arrays with spatial light modulators (SLMs) [6] achieve adaptive interconnections. However the volume hologram still requires further researches, especially on fixing and copying, and SLM resolution is major limiting factor for large scale implementation for the latter. Recently we had developed an adaptive neural network architecture, TAG (Training by Adaptive Gain), which utilizes fixed global interconnections and adaptive local gains.[7,8] Performance with both random and pre-trained interconnections were investigated. In the previous papers we had used page- oriented holograms for the fixed interconnections. In this paper we show possibility of using ground glass for random interconnections with much higher diffraction efficiency and interconnection density, and report smallscale optical implementation of a classifying neural network.
Fourier Transforms of Fractional Order and their Optical Interpretation
Authors: Mendlovic David , Ozaktas Haldun M. , Lohmann Adolf W.
Published: February 2023

The ath power of x, denoted by x
a
, might be defined as “the number obtained by multiplying unity a times with x”. Thus (2.5)3 = 2.5 x 2.5 x 2.5. This definition makes sense only when a is an integer. However, it is an elementary fact that the definition of the power of a number can be meaningfully and consistently extended to real anil even complex values of a. Likewise, the original definition of the derivative of a function makes sense only for integral orders, i.e. we can speak of the first or second derivative and so on. However, it is possible to extend the definition of the derivative to noninteger orders by using an elementary properly of Fourier transforms. Bracewell shows how fractional derivatives can be used to characterize the discontinuities of certain funct ions [1]. An example from the field of optics is related to the Talbot effect [2], in which self-images of an input object are observed at the 2-D planes z — Nz0 for integer N (z is the axial coordinate and z0 a characteristic distance). Using a self-transformation technique [3], it was shown that N could also take on certain rational values
Simulated Annealing Applied to Placement of Processing Elements in Optoelectronic MultiChip Modules Interconnected by Computer Generated Holograms
Authors: Zaleta D. , Fan J. , Cheng C.K. , Lee S.H.
Published: February 2023

New computer-aided tools are needed for the development of OptoElectronic MultiChip Modules (OE-MCMs) utilizing free-space optical interconnects.
Direct optical implementation of lateral inhibition and excitation
Authors: Horan Paul
Published: February 2023

Networks utilising lateral inhibitory and excitatory interconnections have a number of interesting properties, particularly for unsupervised learning and self-organisation.
Neural Algorithms that Exploit Optical Hardware Characteristics
Authors: Snowdon John F.
Published: February 2023

Since the beginning of the respective subjects of neural nets and optical processing, groups in both disciplines have believed that the fusion of neural processing ideas with optical technology will produce the most powerful computers of the future.
Optoelectronics Technology for Real World Computing
Authors: Yajima Hiroyoshi
Published: February 2023

Light is expected to be a new information medium, beause of its extended transmission capacity and massively parallel processing capability. Optics provides new device technology as well as new architectures and algorithms in the Real World Computing Program, which aims at flexible information processing using massively parallel and massively distributed processing.
Intelligent Optical Backplanes
Authors: Szymanski Ted H.
Published: February 2023

Intelligent Optical Backplanes can enhance computing and communications architectures by simultaneously transporting and processing digital data at terabit aggregate rates, thereby enabling new paradigms. Prospects for Intelligent Optical Backplanes and their smart pixel arrays will be described.
A Two Layer Image Processing Architecture Incorporating Integrated Focal Plane Detectors and Through-Wafer Optical Interconnect
Authors: Wills D. Scott , Jokerst Nan Marie , Brooke Martin , Brown April
Published: February 2023

This paper presents an extremely high density and lightweight image processing system being designed at Georgia Tech. The system consists of two layers. The upper layer includes a focal plane array of thin-film GaAs detectors that are integrated directly on top of an array of Si-based SIMD processors. The lower layer consists of an array of more powerful MIMD processors connected in a wormhole routed two dimensional mesh. The two layers are interconnected via though-wafer optical interconnects using integrated InGaAsP devices.
Multiprocessor Architectures using Partitioned Optical Passive Star Interconnection Networks
Authors: Teza James P. , Chiarulli Donald M. , Levitan Steven P. , Melhem Rami G.
Published: February 2023

The primary requirements for a tightly coupled multiprocessor interconnection network are high bandwidth, low latency, and a high degree of connectivity among the processors. Multiple passive star networks are attractive for multiprocessor interconnection networks because they offer maximum connectivity with a constant optical power budget, and are simple, relatively low cost yet robust structures [BLM93]. Using multiple passive stars, it is possible to design completely reconfigurable networks without the use of active photonic switches [GLZ91].
The suitability of GRIN rod lenses for imaging arrays of PnpN optical thyristors in optoelectronic computer architectures
Authors: Kirk Andrew , Praet Kristel , Thienpont Hugo , McArdle Neil , Brenner Karl-Heinz
Published: February 2023

Recently differential pairs of PnpN optical thyristors have been developed for use within optical computing architectures [1]. These emitter-receiver elements have a fast turn-on and turn-off time (10 nsec) together with high sensitivity (50 fJ absorbed optical switching energy). A relatively simple fabrication process allows large arrays (16 x 16) of these devices to be constructed with a pitch of 50 μm.
Robust Light Bullet Dragging Logic
Authors: McLeod Robert , Wagner Kelvin , Blair Steve
Published: February 2023

The existence of three-dimensional optical solitons, which feature simultaneous radially-symmetric 2D spatial self-focusing and temporal pulse compression, has recently been suggested1. Unlike one- or two-dimensional solitons, light-bullets are completely localized and are confined purely by nonlinear effects; they do not require any static dielectric waveguide, but as a result can not take advantage of the interplay of dielectric confinement and material dispersion to yield a region of anomalous GVD. AGVD can be created with linear gratings2, by pumping the media to invert the dispersion relation3, and via parametric gain4. Like lower-dimensional solitons, the spatial profile of a light-bullet is created by the balance of Kerr self-focusing and diffraction, while its temporal pulse-shape is determined by the balance of Kerr pulse-compression and group-velocity dispersion.
Critical issues in smart pixel design
Authors: Desmulliez Marc P.Y. , Snowdon John F. , Waddie Andrew J. , Wherrett Brian S.
Published: February 2023

Over the last few years, micron-size opto-electronic devices have become key components in optically interconnected electronic chips. The possibility of integrating these components in conventional electronic families (ECL,CMOS,FET) has allowed the design of various hybrid processing units [1] whose common feature is the optical reception, modulation or emission and the electronic treatment of information. The use of this hybrid technology, defined as smart pixel technology, has provoked recent studies on whether the performance of a smart pixel array [2, 3], its cost and reliability [4, 5] can be regarded as a viable solution in optical information processing. This paper focusses on the current issues involved in increasing the complexity of individual processing nodes in order to optimize the performance of the opto-electronic processor array. The optimum smartness of the pixel, that is, its optimum degree of complexity is quantified on algorithmic, electronic and optical grounds. Having in mind a particular task, such as data sorting, performance metrics of the system are analyzed in terms of its throughtput rate, power consumption, real-estate and laser source power requirements. The use of a particular example, such as the bitonic sorter [6], allows us to quantify exactly the power dissipated and the layout area occupied by the smart pixel in each of the different electronic families examined. Finally optically-induced electronic power dissipation necessitates to decrease the optical power at each photodetector for a given operating frequency and bit-error rate (BER). This issue is analysed in the context of global optimization of the emitter (or modulator) and detector associated with each pixel.
Design of Electro-Photonic Computer-Networks with Non-Blocking and Self-Routing Functions
Authors: Kawai Shigeru , Kurita Hisakazu , Kubota Keiichi
Published: February 2023

In massively parallel computers, electrical networks have the serious problems regarding pin bottle-necks in switches, and the number of pathways between processor elements (PEs). In electrical networks, the number of pins for a chip decides the channel size for electrical crossbar switches, and network size. The number of pins for 16 ch crossbar switches exceeds more than IK (1,024), when the 32 ch external-buses are used. The 16 ch size may be limited in a chip for an electrical switch. By using the 16 ch switches, a maximum 128 ch Clos network[l], with only a strictly non-blocking function, may be accomplished. Photonic technologies may serve larger size crossbar switches, and they achieve more than 1K ch networks. Free-space optics may also overcome pathway problems, because light beams can cross each other with no mutual interference. Various data multiplexing technologies may be used in optical networks.
Applications of Fiber Image Guides to Bit-parallel Optical Interconnections
Authors: Li Yao , Kosaka Hideo , Wang Ting , Kawai Shigeru , Kasahara Kenichi
Published: February 2023

A fiber image guide, whether being a coherent fiber bundle or a single gradientindex fiber, has been known useful to transmit image signals. Such a fiber image guide has been successfully used in various medical endoscopic and industrial inspection applications [1,2]. High resolution analog images can be obtained for transmission distances ranging several meters or longer. Depending on used fiber materials, relative low loss transmission can be achieved at certain transmission wavelengths.
Photonic Implementations of Neural Networks
Authors: Kyriakakis C. , Karim Z. , Tanguay A. R. , Cartland R. F. , Madhukar A. , Piazzolla S. , Jenkins B. K. , Kuznia C. B. , Sawchuk A. A. , von der Malsburg C.
Published: February 2023

Several broad classes of neural networks comprise distributed, nonlinear, dynamical systems in which large numbers of relatively simple processing elements (neuron units) are densely interconnected. The interconnections are often configured such that the interconnection weights are adaptive and contain the learned memories and behaviors of the system. Advanced optical interconnection techniques are being developed that can potentially be used in conjunction with optoelectronic neuron units to implement photonic neural-like computational modules (e.g., Fig. 1) with relatively large array sizes (105 to 106 neuron units) and a high degree of connectivity (fan-outs and fan-ins of 104 to 106, with 109 to 1012 total interconnections). A key open question is whether the high bandwidths (potentially 100 MHz or more) available from hybrid optoelectronic spatial light modulators (SLMs) can be effectively combined with such high density volume holographic optical interconnections (dynamically recorded in photorefractive materials) to provide enhanced computational throughput capacity as well as complex neural network simulation capability. A second key open question is whether advanced electronic/photonic packaging technologies can provide capability for system-level integration of highly compact multichip modules that exhibit both local (multi-plane) and global interconnections (Fig. 2).
Convergence of Backward Error Propagation Learning in Photorefractive Crystals
Authors: Petrisor Gregory C. , Goldstein Adam A. , Herbulock Edward J. , Jenkins B. Keith , Tanguay Armand R.
Published: February 2023

Although backward error propagation learning in photorefractive crystals has been previously investigated by simulation and experiment, theoretical results governing convergence have been lacking. In this paper we prove analytically that such learning in multilayer neural networks implemented using photorefractive crystals can have similar convergence properties to those of an ideal backward error propagation network. Further, we derive relationships between two learning parameters that will ensure these convergence properties are satisfied under the assumption of small weight-update sizes, and we relate these parameters to spatial light modulator gain and holographic grating update exposure energy.
A Photorefractive Optical Fuzzy Logic Processor
Authors: Wu Weishu , Yang Changxi , Campbell Scott , Yeh Pochi
Published: February 2023

Fuzzy logic 1 has potential application in fields such as pattern recognition and process control. Since Liu first introduced an optical fuzzy logic processor utilizing a lens-array-based multiple imaging system, 2 many other systems have also been proposed and demonstrated. Most of early implementations were based on the principle of shadow-casting, with spatially encoded patterns being superimposed on each other by use of either light source array 3 or lens-array. 2 To obtain correct output of the fuzzy logic maximization (or minimization) operations, thresholding devices were needed in some systems. These thresholding devices, as well as the complex encoding patterns, make the systems complicated. Other systems utilized a complex encoding scheme which resulted in an output pattern different from the input patterns. Thus, the encoding scheme proposed for two-input fuzzy logic operations was difficult to be extended to multiple-input operations. 3,4, In this paper, we propose and demonstrate a novel optical fuzzy logic processor based on four-wave mixing in photorefractive crystals. Specifically, the recording of light-induced gratings is utilized to achieve minimization operations, while the readout of degenerated gratings is utilized to achieve maximization operations. Our system has several advantages including simple data encoding scheme, full parallelism, high speed, high accuracy, and simple architecture (no thresholding devices).
A custom optoelectronic smart pixel test station
Authors: Wakelin Suzanne , Derstine Matthew W. , Chau Kelvin K.
Published: February 2023

Recent developments in smart pixel device fabrication has enabled researchers to design and develop optoelectronic systems that utilize the parallelism and connectivity of optics with electronic control and processing. It is necessary for users of these devices to have the capability of testing the components at various stages of the development. In particular, the AT&T/ARPA CO-OP FET-SEED platform has enabled groups in the community such as ourselves to work on our own smart pixel device designs in a co-operative workshop [1,2]. We have developed and are using a custom optical and electronic probe station for the testing of smart pixel devices. The test station allows us to input and extract optical and electronic signals from the various parts of the smart pixels in order to characterize their behavior and performance. This feedback is essential for device and system development.
Optimal Intensity Coding for Digital Images Pixelated into Super-Gaussian Beams
Authors: Karpushko Fedor V.
Published: February 2023

It was shown recently [1] that optics allows, in principle, up to 1019 bits/cm2s data transmission rates with no fundamental restrictions in the information channel. This is due to the optical degrees of freedom which are of a 3D-nature. In this paper we discuss how to utilise these optical degrees of freedom with respect to the well-known advantages of the digital approach to general purpose information processing.
Shift Multiplexed Holographic 3-D Disk
Authors: Pu Allen , Barbastathis George , Levene Michael , Psaltis Demetri
Published: February 2023

A holographic 3-D disk consists of a disk-shaped holographic medium and a recording/read-out head. The head moves in the radial direction while the disk rotates to allow access to any location on its surface. Multiple holograms are stored at each location using a plane wave reference and either angle or wavelength multiplexing [1]. Disks can also be constructed using peristrophic [2] or phase-code multiplexing [3]. No matter which of the above methods is used, the multiplexing mechanism must be incorporated in the head along with the CCD, SLM, and passive optical components. In this paper we present a multiplexing method, shift multiplexing[4], which allows holograms to be superimposed at one location using only the rotation of the disk. Since the mechanical system to rotate the disk is already in place, this multiplexing method is well suited for the disk configuration. In addition, access to the data, is more natural in the shift mode because the continuous disk motion is easily combined with successive hologram read-out.
High-Speed Storage of Wavelength-Multiplexed Volume Spectral Holograms
Authors: Shen X. A. , Bai Y. S. , Kachru R.
Published: February 2023

One of the most attractive features of an optical memory is its ability to write and read data in a bit-parallel format, giving rise to theoretically very high (in excess of 1 Gbps) data transfer rates. However, such a potential has not been demonstrated experimentally because of various inherent technical difficulties associated with existing optical storage techniques. In a photorefractive or a persistent spectral hole-burning (PSHB) memory, for example, the time required to record one page varies from a fraction of a second to several seconds.1-3 For a page containing 1000 × 1000 bits of data, it translates to a bandwidth of approximately 1 Mbps, substantially slower than any existing semiconductor memories.
Reconfigurable Space-Variant Optical Interconnection Using Binary CGH
Authors: Ishida Takayuki , Ishikawa Masatoshi
Published: February 2023

A reconfigurable optical interconnection which implements space-variant connections by using a phase modulation type SLM is proposed. The proposed method allows easier alignment compared with conventional crossbar switch. System configuration and experimental results are shown.
Implementation of a Photonic Page Buffer Based on GaAs MQW Modulators Bonded Directly over Active Silicon VLSI Circuits
Authors: Krishnamoorthy A. V. , Ford J. E. , Goossen K. W. , Walker J. A. , Lentine A. L. , D’Asaro L. A. , Hui S. P. , Tseng B. , Leibenguth R. , Kossives D. , Dahringer D. , Chirovsky L. M. F. , Kiamilev F. E. , Aplin G. F. , Rozier R. G. , Miller D. A. B.
Published: February 2023

The tremendous progress in high performance Very-Large Scale Integrated circuit (VLSI) technology has made possible the incorporation of several million transistors onto a single silicon chip with on-chip clock rates of 200 MegaHertz (MHz). By the end of decade, the integration density for silicon Complementary Metal Oxide Semiconductor (CMOS) is expected to be over 20 million transistors and the projected on-chip clock rate is 500 MHz. This enormous bandwidth that will be available for computation and switching on a silicon integrated circuit will create a huge bottleneck for Input and Output (I/O) to the VLSI circuit. Technologies that are being developed at AT&T Bell Laboratories, now exist for attaching GaAs Multiple Quantum Well (MQW) photodetectors and light-modulators onto a prefabricated silicon integrated circuit using a well-established hybrid flip-chip bonding technique followed by substrate removal of the GaAs chip to allow surface-normal operation of the optical modulators at 850nm [1]. From a systems point of view, the demands made of optoelectronic integration method are (i) that the silicon integrated circuit be state-of-the-art, (ii) the circuit be unaffected by the integration process, (iii) that the design and optimization of the circuit proceed independently of the placement and bonding to the optical I/O. The first two goals have been achieved in reference 1, and this technique has been effectively applied to simple switching nodes for a smart-pixel based photonic switch in reference 2. In this paper we further achieve the third goal by demonstrating for the first time that modulators can be bonded directly above active submicron CMOS transistors (figure 1), and by applying the technique to the demonstration of a high-density 2Kbit first-in first-out (Fifo) page buffer circuit.
Airborne Doppler Lidar Wind Field Measurements
Authors: Bilbro James W.
Published: February 2023

Pulsed and continous-wave coherent lidar are being used in airborne measurements to determine mesoscale wind fields and atmospheric backscatter. This paper describes recent measurements as well as future plans.
Remote Sensing of Clouds and Boundary Layer Structure Using Airborne Lidar
Authors: Spinhirne James D.
Published: February 2023

Since lidar offers the advantage over passive remote sensing of unambiguously realizing the vertical structure of the atmosphere, there has been a strong interest in the development of lidar for atmospheric measurements. For the past several years a lidar system has been flown as an automated sensor on board high altitude experimental aircraft. The primary application for the lidar system has been cloud studies. Both experimental measurements related to the structure and development of severe storms and to the radiation characterization of clouds are important. The requirement for a lidar measurement from a high altitude aircraft stems from the necessity to operate above the highest clouds such as cumulonimbus.
Remote DIAL Measurements of Methane in Coal Mines
Authors: DeFreez Richard K.
Published: February 2023

Nearly two-thirds of all underground U.S. coal tonnage is extracted using continuous mining machines in room-and-pillar mining operations1. As a result of the Mine and Safety act of 19602 and various state laws, present practice in the room-and-pillar mine is to stop mining every twenty minutes to measure the concentration of methane gas within one foot of the working face. After the mining machine is withdrawn, temporary roof supports are installed to the working face so that a miner can approach the face and measure the methane concentration with a hand-held catalytic combustion methane detector and/or flame safety lamp3. When the measurement is completed, the temporary roof supports are removed and the mining machine begins working again. Obviously, this procedure reduces productivity and is in itself a safety hazard as temporary roof supports can well be dangerous.
On the very long serve life problems of the internal blackbodies of HIRS at TIROS-N satellites in space
Authors: Zhao-xien (Dchang Dchao-shien) Zhang
Published: February 2023

Two computation methods retrieving the radiant powers of the internal blackbodies after performance degradation to the values possesing the accuracy during ground calibration are presented.
Real-Time Measurements of Selected Meso-scale Wind Fields
Authors: Post Madison J. , Richter Ronald A. , Hardesty R. Michael , Lawrence T. Rhidian , Hall Freeman F. , Weber Bonnie F.
Published: February 2023

Recent upgrading of NOAA’s coherent lidar with a real-time data processor, color display, and computer-controlled scanner have increased its utility greatly. We are now able to monitor in real time minute features of the clear air wind field to ranges of 20 km and altitudes of 10 km, in general. It is possible, for instance, to track individual convective plumes and to pinpoint their topographic points of origin, to locate areas of convergence and divergence, and to quantitatively measure Ekman spirals, horizontal wind shears, and localized wind jets.
The Optical Heterodyne Detection in a Turbulent Atmosphere
Authors: Zhengfang Song , Weiyu Gu , Xiachun Liu
Published: February 2023

It is well-known that atmospheric turbulence has a serious effect on optical heterodyne detection. However, the effect of the turbulent outer scale up to date has not an acknowledged view yet. Lutomirski and Yura [1] considered that the presence of a definite outer scale could increase the signal-to-noise ratio of heterodyne detection slightly. Clifford and Wandzura [2] indicated that the performance of a heterodyne lidar could be deteriorated with the outer scale. So it is still intrested to clarify the real action of the outer scale.
IR Laser Stand-Off Detection
Authors: Carrico John P. , Dick Kenneth A. , Webb Ernest N. , van der Laan Jan , Uthe Edward , Hawley James G. , Murray Edward R.
Published: February 2023

A field experimental program utilizing the SRI developed laser stand-off detection systems was completed during the summer of 1984 at Dugway Proving Ground, UT. The systems were exercised against dimethylmethylphosphonate (DMMP) and sulphur hexafluoride (SF6) vapors. Both atmospheric backscatter and topographical reflectors were used. Also, surface contamination with silicone oil (SF-96) was viewed on both natural and artificial surfaces. SRI provided two systems: one ground based (van mounted); the other aircraft mounted. Data analysis, currently in a very preliminary stage, will be presented.
Fluorescence Techniques for the In Situ Detection of Free Radicals in the Stratosphere
Authors: Anderson James G.
Published: February 2023

In the last three years a new generation of free radical detection techniques have been developed which will revolutionize the measurement of trace reactive species in the stratosphere. These techniques include mm-wave emission, laser heterodyne radiometry, LIDAR and eximer lasers and copper vapor lasers. A review of recent results from the techniques will be interpreted within the framework of current theoretical predictions of ozone depletion into the next century.
Active Monitoring of Ozone Vertical Distribution and Related Parameters in the Troposphere and Stratosphere
Authors: Megie G. , Pelon J.
Published: February 2023

As a consequence of research efforts performed to observed any anthropogenic influence on atmospheric ozone, new systems have been developped to monitor the ozone profile and total content from the ground. As part of it an ultra-violet lidar system was implemented in 1980 at the Observatoire de Haute Provence (OHP), and was involved in different international comparison campaigns. Some results of these campaigns will be presented, with other specific comparisons as they have allowed to validate the lidar measurements performed at the OHP throughout the altitude range from the ground up to 45-50 km. Such high altitudes have been reached by means of a new generation of laser systems, the implication of which on the ozone survey in the upper stratosphere will be emphasized. Lidar systems are also potential instruments for ozone survey in the troposphere and especially their ability to perform high spatial and temporal resolution measurements, below 15 km, allows to describe some aspects of stratosphere-troposphere exchanges as will be presented.
Air Force Geophysics Laboratory’s (AFGL) Mobile CO2 Doppler Lidar
Authors: Alejandro S.B. , Fitzgerald D.R.
Published: February 2023

AFGL is developing a mobile coherent, pulsed, Doppler CO2 lidar system designed to evaluate techniques for the acquisition and real-time interpretation of atmospheric wind field structure as well as aerosol attenuation and concentrations over long path lengths . The system utilizes a low chirp electron beam injection CO2 TEA laser which is mode locked by hole injection from a Littrow grating tuned low pressure flowing gas cw CO2 laser . An identical low pressure laser is used as the local oscillator . The entire optical assembly is mounted upon a 3.7m × 8.3m optical table, with the exception of the scanner which is mounted over the table on an elevator system . The scanner system is raised through a hatch in the trailer roof and is capable of full hemispherical and fixed point scanning. The return signal is detected in the usual superheterodyne technique by a Hg:Cd:Te detector. The system IF amplifier output will be split to allow simultaneous real time analog display of velocity as a function of range and digital conversion for obtaining power, velocity, and variance characteristics of the signal. A schematic of the system is shown in figure 1 and the system design parameters are given in Table 1. The entire lidar system along with field operations support equipment will be housed in a modified 12m semi trailer.
Influence of the Atmosphere on Remotely Sensed Reflection from Vegetation Surfaces
Authors: Simmer C. , Gerstl S.A.W.
Published: February 2023

One purpose of vegetation canopy modelling is to predict the solar radiation reflection distribution produced by the canopy, in order to use it as an identifier in remote sensing. For remote sensing by satellite or aircraft the measured reflectance pattern also contains the signature of the atmosphere, which changes both the radiation distribution of the downwelling solar source before it reaches the canopy, as well as the reflected upwelling signal before it reaches the sensor.
Remote Sensing of Atmospheric Opacity Using Multiple View Angle Imaging
Authors: Diner David J. , Martonchik John V.
Published: February 2023

The Earth’s atmosphere influences spacecraft measurements of surface reflectance in a variety of ways. The dominant effects are (1) extinction, which results in attenuation of both incident and emergent radiation, and (2) the introduction of an additive diffuse path radiance field as a result of atmospheric scattering. Since the magnitude of both of these effects is strongly influenced by the atmospheric opacity, determination of this quantity will be an important component of atmospheric correction algorithms.
Backscatter Measurements in the Atmosphere with a 10-μm Airborne Velocimeter
Authors: Vaughan J. M. , Woodfield A. A.
Published: February 2023

The laser true airspeed system (LATAS) developed by RSRE and RAE Bedford has now been flown in the HS 125 aircraft for nearly four years. The equipment incorporates a 4W waveguide laser and 25 MHz bandwidth surface acoustic wave spectrum analyser and has been described in earlier publications. An extensive flight program has investigated not only the measurement of true airspeed ahead of the aircraft but also pressure error measurement and wind shear and turbulence. From the strength of the doppler return the back scattering strength in the atmosphere at 10.6μm can be obtained. The most recent calibration analysis shows that the limiting sensitivity corresponds to 3 times 10 to the minus 11 per M per SR. During the flight program at altitudes to 13.1 km a body of data over Northern Europe and the UK at different seasons of the year and in different conditions has been accummulated and also in mid summer in Colorado during 1982 JAWS exercise.
Preliminary Results from 1984 Airborne Lidar Wind Measurements
Authors: Fitzjarrald D. E.
Published: February 2023

The 1981 flight test program of the MSFC lidar wind measuring system (Bilbro, et al., 1984) confirmed the soundness of the basic idea, but showed areas in which system improvements could greatly increase the utility of the apparatus. In addition, analysis of the wind data indicated that some of the serious deficiencies could be overcome with a modest amount of revision to the system. The system improvements will be summarized below, along with a description of the experiments that were performed in the 1984 flights and some preliminary results of those flights.
The Study of Atmospheric Transport by the SWIRLS Instrument on Eos
Authors: McCleese Daniel J. , Rider David M.
Published: February 2023

The Stratospheric Wind Infrared Limb Sounder (SWIRLS) investigation which has been selected for the Earth Observing System (Eos) is an investigation of dynamics and transport in the stratosphere that brings together the key measurements needed to develop an understanding of the coupling between chemistry and dynamics in the stratosphere. The investigation focuses on developing a description of the dynamical climatology of the stratosphere with emphasis on winds and temperature, and their variation on time scales ranging from diurnal to interannual. In addition, the the investigation will quantify the physical mechanisms responsible for structure and variations of the stratospheric circulation and temperature fields, including the transport of heat and momentum and will directly investigate the transport of ozone and and other trace atmospheric constituents. Existing measurements lack the combination of accuracy, global and temporal coverage, spatial resolution and simultaneity required to distinguish between dynamics and photochemical processes. Improved instruments are needed to understand why ozone and other trace constituents have their current distribution and how they are evolving.
Overview of Atmos Results from Spacelab 3
Authors: Gunson M.R. , Farmer C.B.
Published: February 2023

The Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment is an investigation of the distribution of neutral constituents in the earth’s atmosphere. The ATMOS instrument is a Michelson interferometer, with a response to radiation in the near- to mid-infrared, designed to make observations from on board the space shuttle in the solar occultation mode.1,2 Its first flight was made as part of the Spacelab 3 (SL-3) payload which flew on the shuttle "Challenger" between April 29 and May 6, 1989. The ATMOS experiment gathered data during 20 occultation events; 13 sunset occultations located between 26° - 34°N latitudes and 7 sunsets around 48°S.1,2 The data returned was composed of over 1000 high resolution infrared spectra containing absorption features of the earth’s atmosphere, spanning tangent heights from the ground up to 150 km, and a like number of high sun reference spectra. The spectra obtained within each occultation have been analyzed for the concentration height profiles of more than 25 different atmospheric species, including the first detection and confirmation of the presence of several gases.
Retrieval of CLAES Filter Shapes from Spectral Calibration Data
Authors: Mergenthaler J.L. , Potter J.F. , Kumer J.B. , James T.C. , Roche A.E.
Published: February 2023

The Cryogenic Limb Array Etalon Spectrometer (CLAES) will derive Stratospheric temperatures and constituent number densities from the measurement of infrared spectral emissions, during its 18 month mission on board the NASA Upper Atmosphere Research Satellite (UARS). Overviews of the CLAES experiment and hardware are given by Roche et al (1) and Burriesci et al. (2). This paper describes the mathematical inversion of system cold test calibration data described by James et al.(3) to retrieve system spectral blocker filter profiles in the pressure and temperature retrieval channel centered at 791.5 cm-1.
An Integrated Interactive Graphic System Including Remote Sensing Data
Authors: Klaes K. Dieter
Published: February 2023

To have the most efficient overview and the most effective use of all available meteorological data GMGO is running an operational realtime Interactive Graphic System (IGS) since 1981, providing the users with all synoptic data.
Remote Sensing of Trace Gases Using the Atmospheric InfraRed Sounder (AIRS) Part 1: Sensitivity Analysis
Authors: Haskins R.D. , Kaplan L.D.
Published: February 2023

The importance of monitoring the trace gases active in the thermal infrared region of the spectrum is becoming more and more critical in light of the recent results regarding climate change and the greenhouse effect. Sources and sinks of anthropogenic gases such as CO, CH4, and CFC’s are important parameters in determining the climatic impact of man’s use of the Earth’s resources. The Atmospheric InfraRed Sounder (AIRS)1 is a moderately high spectral resolution (ν/Δν = 1200) infrared sounder selected as facility instrument on the Earth Observing System (Eos). The primary purpose of AIRS is the extraction of atmospheric and surface temperature useful for weather prediction. However, AIRS complete infrared coverage from 17 to 3.3 microns will also allow the retrieval of many other useful weather and climate parameters such as the ability to monitor certain IR active trace gases. The moderate spectral resolution of AIRS does not permit the sensing of individual molecular lines so that interfering species must be accounted for and retrieved simultaneously. The results of sensitivity simulations in this study indicate that a number of useful measurements of column abundances of trace gases can be made.
Inversion of Fabry-Perot CCD Images: A comparison of techniques
Authors: Skinner Wilbert R. , Abreu Vincent J.
Published: February 2023

The Fabry-Perot interferometer has been used extensively to probe the upper atmosphere of the earth from ground based and satellite observatories. The high spectral resolution and throughput of this device make it ideal for measuring the line shapes and Doppler shifts of absorption and emission spectral features. Detectors for near visible Fabry-Perot interferometers have advanced from photographic film to single channel photomultipliers to multichannel photomultipliers. Further advances in our understanding of the physical processes dominating the upper atmosphere demand observational capability near 1µ. In the red and near-infrared portions of the spectrum, charge-coupled devices (CCD) are very efficient detectors. High quantum efficiency and broad spectral response (UV to near infrared) render CCDs highly desirable as imaging devices for Fabry-Perot interferometer applications. Other important characteristics of CCDs are their high spatial resolution, low noise, large dynamic range and linearity. A major limitation is the read noise, which restricts low light level applications unless special precautions are taken. This paper discusses one way to reduce the effect of read noise when the image is a circularly symmetric pattern such as a Fabry-Perot finge.
Trends in Stratospheric NO2: the Relevance of Ground-based Differential Absorption Spectroscopy
Authors: Keys Gordon , McKenzie Richard , Johnston Paul
Published: February 2023

Column amounts of stratospheric NO2 have been measured at Lauder, New Zealand since December 1980; and at Arrival Heights, Antarctic, since September 1982. As the data sets grow their usefulness for trend analysis increases, with the time span covered approaching a complete solar cycle. This paper comments on the significance of trends seen in the data, and emphasizes the important "control" role that is exercised by such ground-based measurements. Refinements in retrieval methods have significantly reduced errors since measurements were first initiated.
RASS Observations of an Arctic Front in Colorado
Authors: Neiman P.J. , May P.T. , Shapiro M.A. , Stankov B.B.
Published: February 2023

A technological advance in measuring high-vertical-resolution temperature profiles in the lower and middle troposphere has recently come forth as the result of studies using Radio Acoustic Sounding Systems (RASS). RASS combines radar and acoustic techniques to obtain vertical profiles of the speed of sound, from which virtual temperature profiles are calculated (Marshall et al. 1972; May et al. 1989). RASS measures nearly continuous temperature profiles with the same vertical resolution as the wind profiler. Although RASS cannot yet measure temperatures to heights attained by the 12-hourly rawinsonde (>15 km), it can, with 15 min temporal resolution, resolve the temporal evolution and vertical structure of lower-tropospheric temperature features associated with locally enhanced stable layers, frontal zones, and land-sea breeze circulations.
Design and Preliminary Results from the Cloud Lidar And Radar Exploratory Test (CLARET)
Authors: Eberhard W.L. , Cupp R.E. , Hardesty R.M. , Intrieri J.M. , Willis R.J.
Published: February 2023

Clouds and their radiative effects strongly influence climate (Ramanathan et al., 1989). High priority has been assigned (CES, 1989) to research the role of clouds’ radiative properties in climate change, especially as feedback mechanisms, and on how to incorporate these effects properly in climate models. Measurements of climate-significant properties of clouds, such as height, optical density, and particle size distribution, are needed in intensive process studies and also in extended studies to observe the large variety of cloud conditions that occur.
Inverse Theory for Occultation Measurements
Authors: Kyrölä E. , Korpela S. , Tuomi T. , Kotivuori Y. , Varis J. , Piironen A. , Haario H.
Published: February 2023

The changes in the composition of the atmosphere are predicted to be very fast compared to the usual geological time scales but they are still subtle and slow from the point of view of monitoring. Only long-term monitoring can be hoped to reveal the trends of anthropogenic origin from the natural variations. Moreover, the change may be small in the total amount of a trace gas but can still be seen clearly in the vertical distribution. The case of ozone is a good example. The stratospheric depletion of ozone due to CFC gases is largest at about 40 km altitude whereas the tropospheric ozone is predicted even to increase. It is therefore evident that in the monitoring of the atmosphere we need instruments which have global coverage, stable operation and ability to vertical resolution.
Long Pulse CO2 Lasers/Amplifiers for High-Resolution Laser Radar/Lidar
Authors: Freed C. , Eng R. S. , Greene J. , Parshall E. R. , Marcus S. , Grimm J. G. , O'Donnell R. G.
Published: February 2023

We have designed, constructed, and tested two different versions of long pulse CO2 laser systems which are capable of delivering high-quality laser beam outputs to be used in high-resolution laser radar applications.
Short-Pulse Coherent Doppler Nd:YAG LIDAR at 1.06 μm
Authors: Chan Kinpui , Sugimoto Nobuo , Killinger Dennis K.
Published: February 2023

The merits of using coherent Doppler LIDAR to perform wind velocity and moving target measurements are well recognized. Coherent Doppler LIDARs employing CO2 lasers at 10 μm wavelength have been developed to a point where ground-based and airborne systems have been sucessfully used for wind shear measurements.1 With recent progress in compact and tunable solid state lasers, there is increasing interest in the development of an all solid-state coherent Doppler LIDAR which may offer technological advantages compared with CO2 laser-based LIDAR, and is suitable for future space-borne LIDAR schemes. In this paper, we report the development of a short- pulse (<10ns) coherent Doppler Nd:YAG LIDAR at 1.06 μm. Preliminary coherent LIDAR measurement results will also be presented and discussed.
Multiwavelength CO2 Dial System Designed For Quantitative Concentration Measurement
Authors: Leonelli Joseph , van der Laan Jan , Holland Peter , Fletcher Leland , Warren Russell , McPherrin David , Comeford Jack
Published: February 2023

A multiwavelength CO2 direct-detection differential absorption lidar (DIAL) system has been designed and developed to produce range-resolved vapor concentration contour plots of 1 km x 1 km grid at 20-m spatial resolution in 10-s intervals.
Determining C n 2 From Lidar Beam Wander
Authors: Garner R.C. , Moskowitz W.P. , Davidson G.
Published: February 2023

We are developing a remote sensing technique to determine the atmospheric
C
n
2 profile for ranges of up to 2.5 km using a modified backscatter lidar. Determination is made of the angle of arrival of backscattered laser light in the lidar system.
C
n
2 is calculated from these measurements using the standard weak turbulence model.