bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental comparison of different associative memory techniques implemented optically by the same system architecture
Authors: Weible K.J. , Collings N. , Xue W. , Pedrini G. , Dändliker R.
Published: February 2023

In recent years, much work has been going on in the optical implementation of artificial neural network systems. The parallel and crosstalk free interconnection characteristics of optical systems are well suited to exploit fully the desired parallel characteristics of artificial neural networks. The application of these systems as associative memories has been explored in many cases.1-4 To facilitate optical implementation of these neural systems various modifications to the original Hopfield model have been proposed.5 It has been shown both theoretically and experimentally, that the storage and recall capacity of neural systems based on the Hopfield model are not significantly reduced when only the inhibitory (negative) interconnections are used.6,7
Optical Morphological Image Processing with Acoustooptic Devices
Authors: Athale Ravindra A. , Mait Joseph N. , Prather Dennis W.
Published: February 2023

Morphological image processing based on binary set representation of an image has been receiving increasing attention as a viable alternative to the linear image processing based on Fourier domain filtering [1], The fundamental morphological filtering operations of erosion and dilation are nonlinear operations from which more complex operations (opening, closing, pattern spectra) suitable for shape extraction and analysis can be synthesized. The morphological operations are defined between a working image and a much smaller image called the structuring element. In most cases the structuring element is binary while the working image can be binary, analog with binary threshold decomposition representation or analog with weighted binary representation. For the first two representations, the dilation and erosion operations consist of a superposition of several shifted replicas of the working image followed by a point-wise threshold operation at different levels; 1 for dilation and (m-1) for erosion, where "m" is the number of images superposed. With the third representation, the minimum/maximum value (for dilation/erosion, respectively) for the superposed pixels is detected and assigned as the pixel value in the output image. In either case, the processing operations are of low complexity. The number of shifted replicas of the working image and the amount of shift corresponds to the number and position, respectively, of bright pixels in the structuring element. For large and irregularly shaped structuring elements the morphological processing operation complexity is dominated by data communication.
Demonstration of an All Optical Addressing Circuit
Authors: Chiamlli Donald M. , Levitan Steven P. , Melhem Rami G.
Published: February 2023

This experiment is based on two properties of optical signals, unidirectional propagation and predicatable path delay. Using these properties, logic systems can be devised in which information is encoded as the relative timing of two optical signals. Coincident pulse addressing is an example of such a system. In this case, the address of a detector is encoded as the delay between two optical pulses which traverse independent optical paths to a detector. The delay is encoded to correspond exactly to the difference between the two optical path lengths. Thus, pulse coincidence, a single pulse with power equal to the sum of the two addressing pulses, is seen at the selected detector site. Other detectors along the two optical paths for which the delay did not equal the difference in path length, see both pulses independently, separated in time.
Dual Scale Topology Opto-Electronic Processor (D-STOP): Comparative Analysis and Technological Feasibility
Authors: Krishnamoorthy A. V. , Ford J. E. , Marsden G. C. , Yayla G. , Esener S. C. , Lee S. H.
Published: February 2023

A variety of applications in artificial neural networks, interconnection networks, artificial intelligence, relational databases, and numerical processing require parallel, large scale implementations of matrix-algebraic architectures. Existing VLSI implementations of these architectures are restricted in terms of their parallelism and bandwidth due to their inherent connectivity, pin-out, power dissipation, and crosstalk limitations.[1,2] On the other hand, existing optical matrix-vector architectures suffer from limited SLM throughput and accuracy as well as limited functional flexibility. In the following sections we describe and analyze the Dual-Scale Topology OptoElectronic Processor (D-STOP)[3] which alleviates these limitations, and discuss its feasibility for a near-term implementation.
Ring Array Processor Distribution Topology for Optical Processing and Interconnect
Authors: Li Yao , Ha Berlin
Published: February 2023

In this paper, a study of a ring array processor distribution topology for optical digital processing and interconnect is presented. The work was motivated by the facts that (1) conventional optical imaging elements such as lenses are circularly symmetric about optic axes, and (2) the existing linear/rectangular array distribution topology is sometimes inefficient in terms of optical implementation and synchronization. The proposed new free-space optical ring array topology based processing and interconnect schemes can solve various existing problems in optical processing and interconnects.
Learning in Optical Neural Networks
Authors: Psaltis Demetri
Published: February 2023

In this paper we will review recent advances in training optical neural networks. We will focus on holographic implementations using photorefractive crystals [1]. The vast majority of learning algorithms in neural networks are based on some form of generalized “Hebbian Learning”. With Hebbian learning the strength of the connection between two neurons is modified in proportion to the product (or possibly some other simple function) of the activation functions of the two neurons. These activation functions are typically the neuron response and error signals. The multiplicative Hebbian rule can be implemented if the hologram that connects two neurons is formed as the interference of two light beams generated by the two neurons. This simple and elegant method for training an individual connection can also form the basis for training large optical networks. There are several issues that need to be addressed however before such networks can be constructed. The following is a partial list of these issues, assuming photorefractives are selected as the synapse medium: 1. Architectures for Multiple Holographic Interconnections with 2-D and 3-D Media. 2. Recording Dynamics and Hologram Dynamic Range. 3. Suitable Devices for Neuron Implementation.
Photonics in switching: European systems demonstrators and the long term perspective
Authors: Thylén Lars
Published: February 2023

Status in the area of photonics in switching in Europe, highlighted by systems demonstrators, is reviewed, and the long term perspective for photonics in switching is discussed.
Smart Pixel Optical Computing Architectures
Authors: Sawchuk A.A. , Cheng L. , Forrest S.R. , Prucnal P.R.
Published: February 2023

We describe five classes of smart pixel devices with increasing complexity and present an optoelectronic integrated circuit (OEIC) smart pixel array having programmable amplifier, inverter, logic element, bistable switch or latch functions. These devices are used in transmissive and reflective architectures to implement reconfigurable processors, multiplexed shuffle networks, cellular hypercube processors or sorting networks.
The Application of Self-Similar Patterns to Opto-electronic Shuffle/Exchange Network Design
Authors: Haney Michael W.
Published: February 2023

Multistage Interconnection Networks (MINs), based on free-space optical interconnects, were proposed to overcome the communications bottlenecks, skew, and crosstalk associated with long electronic interconnects.1Versions based on 2-D arrays of processing elements (PEs) were suggested that more fully utilize the third dimension for higher density and efficient use of optical space bandwidth product (SBWP).2,3,4Several of these concepts are based on off-axis imaging techniques which perform shuffle5based permutations by optically interleaving equal sized sectors (such as quadrants) of the source array and overlaying the result on an identical array of detectors. The detected signals are then subjected to local exchange/bypass switching elements which operate on small groups of the array and route the signals to the next stage's source array. The various schemes offer trade-offs between the number of stages necessary for an arbitrary permutation and the complexity of the local switching elements. Examples of proposed optical networks include the 2-D separable perfect shuffle,2the folded perfect shuffle,3and higher order k-shuffles.4Figure 1 is an example of a 1-D perfect shuffle, based on off-axis imaging and interleaving of two halves of the array. The figure is also a side view of the 2-D folded perfect shuffle or 2-D separable shuffle, based on the off-axis imaging and interleaving of the four quadrants of the array. Figure 1 depicts the input and output arrays to be identical, as required for cascadability. The optical efficiency for those emitters located at the outer regions of a quadrant can be increased by adding a lens over each quadrant, as shown in the figure, to capture the cone of light from each pixel's emitter and center it on the associated shuffling lens.
Packaging considerations for planar optical systems
Authors: Acklin Bruno , Jahns Jürgen
Published: February 2023

Various integration techniques have been suggested in order to build compact opto-electronic systems [1-3]. For an actual implementation, several topics have to be addressed:
Packaged optical interconnection system based on photorefractive correlation
Authors: Takahashi Hidemi , Zaleta David , Ma Jian , Ford Joseph E. , Fainman Yeshaiahu , Lee Sing H.
Published: February 2023

An opto-electronic multiprocessor system consisting of a large number of electronic processing elements with optical inputs and outputs is promising for future parallel processing because this architecture removes the limitations of the VLSI technology by providing the interconnects in three dimensions.
Cellular Two-Layer Logic Array and Optoelectronic Implementation
Authors: Liu Liren , Zhang Zibei , Zhang Xuejun , Zheng Jun
Published: February 2023

One of the strong candidates of the parallel architectures for optical computing is cellular array1.
"Smart" Optical Interconnects for High Speed Photonic Computing
Authors: Guilfoyle Peter S. , Zeise Frederick F. , Hessenbruch John M.
Published: February 2023

High speed, low power, "smart" DANE pixels are being developed to implement 2-D arrays of N-bit Boolean multiplications by DeMorgan’s operation on wide-word FAN-INs coupled with N4 global free space optical interconnects.
Comparison of Wavelength and Angle Multiplexed Holographic Memories
Authors: Burr Geoffrey W. , Psaltis Demetri , Curtis Kevin
Published: February 2023

Multiple holograms can be recorded in a material by changing either the reference beam angle [1,2,3] (θ multiplexing) or the recording wavelength [4,5] (λ multiplexing).
Holographic Neural Networks: A Systems Perspective
Authors: Owechko Yuri
Published: February 2023

Many important problems in pattern recognition have no known algorithmic solution. These are problems at which biological organisms excel compared to machine-based approaches in which the rules are assumed a priori.
Optical Matrix Multiplication using Grating Degeneracy in Photorefractive Media
Authors: Gu Claire , Campbell Scott , Yeh Pochi
Published: February 2023

Matrix-matrix multiplication is an important operation in many computational and processing applications including correlation, convolution, Fourier transform of temporal signals and 2-dimensional images.
Model of Lossless Bus Structure Using Erbium Fiber Amplifiers Pumped near 820nm
Authors: Bidnurkar Manoj M. , Levitan Steven P. , Melhem Rami G. , Chiarulli Donald M.
Published: February 2023

In this paper we present a model and simulation results for a lossless tapped fiber bus using Erbium fiber amplifier segments at a pump wavelength near 820nm.
Decomposition Method for Matrix Addressable Microlaser Arrays
Authors: Nahata Hans Raj , Murdocca Miles
Published: February 2023

Two-dimensional (2D) arrays of microlasers are manufactured in two primary configurations: individually addressable [1], and matrix addressable [2], as illustrated in Figure 1. Each microlaser in the individually addressable array has a ground (n) terminal and a positive (p) terminal. All of the microlasers share the same ground, but a separate p contact is provided for each microlaser. An 8×8 array thus requires 64 p contacts, as indicated by the numbered bonding pads at the edges of the array. For small arrays individual addressing works well, but the complexity becomes unmanageable as the arrays scale to large sizes, and so an alternative configuration is needed that scales more gracefully.
Analysis and optimization of off–axis imaging in planar optical microsystems
Authors: Eckert Werner
Published: February 2023

Free-space optical systems provide parallel access to 2D–dataplanes for data routing and processing purposes. For the construction of complex optical data processing systems microintegration is necessary to get compact setups at acceptable costs. These systems should be modular and self aligning and should allow to cascade an arbitrary number of stages to construct feedback loops. These requirements are met both by planar and by stacked microintegration. Using these techniques optical structures can be produced with lithographic precission on one substrate, thus allowing smart pixel arrays to be aligned to the optical system.
Processing Unit for Stacked Optical Computing System: Discrete Digital Correlator
Authors: Kawai Hideo , Takeuchi Yoshinori
Published: February 2023

We have proposed the stacked optical computing system (STOCS)1 which has advantages of mechanical stability and miniaturization compared to conventional optical systems using lenses and beam splitters. The system has many processing units (STOCS-PUs) which consist of planar optical devices such as a functional interconnection device (FIC), an optical addressable spatial light modulator (SLM), and a reading light supplier (RLS)1,2. Functions of FICs are image splitting, image combining and space invariant/variant other interconnections. Output images from the FIC are written on the writing side of the SLM. The RLS is placed on the SLM, and it supplies reading light to the reading side of the SLM and transmits reading images from the SLM. We demonstrated reading out function of the RLS, and images directly written on the SLM were successfully read out2.
A Collisionless Wavelength-Division Multiple Access Protocol for Free-Space Cellular Hypercube Parallel Computer Systems
Authors: Li Kuang-Yu J. , Jenkins B. Keith
Published: February 2023

The performance of a MIMD parallel computer is critically impacted by the interconnection network performance, which in turn is determined by the network topology, implementation hardware, and communication protocol. Cellular hypercube (CH) interconnection networks, with emphasis on a symmetric cellular hypercube (SCH) network, were studied for the system discussed in this paper because they can exploit the communication locality observed in parallel applications [1], are reasonably scalable due to their O(logN) connectivities, and can be implemented with moderate requirements on the number of wavelength channels needed. While free-space optics can realize highly parallel CH networks [2], little progress has been made in designing an efficient protocol for optical data communication. In this paper a CH interconnection system based on a collisionless wavelength-division multiple access with reroute (WDMA-R) protocol is proposed. This system incorporates space-, time-, and wavelength-multiplexing to achieve dense communication, simple control, and multiple access. Analytic models based on semi-Markov processes were employed to analyze this protocol. The performance of the protocol in terms of network throughput and data packet delay is evaluated and compared to other protocols.
Optoelectronic morphological processor for cervical cancer screening
Authors: Narayanswamy Ramkumar , Sharpe John P. , Turner Richard M. , Johnson Kristina M.
Published: February 2023

Pap-smears are slides of cellular material used to screen for cervical cancer. Currently pap-smears are examined manually, a repetitive and tedious task which leads to about 18 % false negative rate (% of abnormal slides going undetected) [1]. Automated pap-smear examination is desirable as both a quality control mechanism for detecting abnormal slides missed by human inspection and as a primary diagnostic cytology screen. Automated screening is challenging since it is a typical example of the “needle-in-a-haystack” problem, where the features of interest are hidden in a vast search area. In a pap-smear one in 10,000 cells screened may be abnormal. Detecting this cell requires high computation power and throughput. Each slide is 2.5 cm x 5.0 cm on a side. Features of interest (the cell nuclei) are on average 10 microns in diameter and sampling at 0.8 μm/pixel, (equivalent to screening the slide with a 20x objective) therefore requires at least 37,000 images of 256x256 pixels to be processed for each slide screened. In this paper we present an optoelectronic implementation of the morphological hit-or-miss transform which can scan each pap-smear slide and detect the regions of interest (ROI) in that slide in under five minutes.
Demonstration of a dense, high-speed optoelectronic technology integrated with silicon CMOS via flip-chip bonding and substrate removal
Authors: Goossen K.W. , Lentine A.L. , Walker J.A. , D'Asaro L.A. , Hui S.P. , Tseng B. , Leibenguth R. , Kossives D. , Dahringer D. , Chirovsky L.M.F. , Miller D.A.B.
Published: February 2023

This work passes an important milestone in the history of optoelectronic and perhaps even electronic technology in general, the demonstration of a VLSI-scalable electronic technology integrated with a high-speed, dense optoelectronic technology. With optoelectronic integration to silicon VLSI, one hopes to augment state-of-the-art silicon density and processing power with fast, highdensity optical I/O. This is the first integration of dense silicon circuitry (120,000 transistors/cm2) and dense optoelectronics (28,000 devices/cm2) on a chip, all operating at a clock of 250 Mbits/sec. Of course, we only produced a small operating area (480x480 μm), but the indications of our research are that chips on the order of 1 cm2 are reasonable. This development potentially has the most impact in the field of photonics since the semiconductor laser and optical fiber transformed the telecommunications industry. The reason for this is first that it ameliorates the development of higher throughput (~ terabit/sec) switches,1 impacting the multi-ten billion dollar/year switching equipment market and allowing telephony traffic at projected levels in the next century. Second, it alleviates the integrated circuit I/O communication bottleneck, thus potentially affecting the entire computing industry.
InGaAs Transceivers for Smart Pixels
Authors: Neilson D.T. , Goodwill D.J. , Wilkinson L.C. , Tooley F.A.P. , Walker A.C. , Stanley C.R. , McElhinney M. , Pottier F.
Published: February 2023

A promising route for the construction of smart pixels is to flip-chip bond III-V semiconductor devices as detectors[1] and modulators onto silicon circuitry. InGaAs quantum well devices grown on GaAs substrates and operating at around 1 μm provide a good option for the III-V devices since there are high power lasers available including Nd:YLF at 1047nm and substrate removal is not necessary. Silicon CMOS is attractive for the electronics since it is a mature technology, allows very high packing density and has the low power consumption necessary for systems based on many channels each with a high degree of smartness. In our work we have so far used 1 μm double metal n-well CMOS and future devices will be fabricated using 0.7/0.8 μm CMOS. The CMOS process limits the available voltage swing for driving the InGaAs modulators to 5 V.
Design and Demonstration of Projection and Selection Modules for a VCSEL/HPT-Based Database Filter
Authors: Snyder R. D. , Lurkins J. W. , Stanko P. J. , Beyette F. R. , Feld S. A. , Irakliotis L. J. , Mitkas P. A. , Wilmsen C. W.
Published: February 2023

The development of high capacity parallel optical memories has opened up the possibility for very high data transfer rates from secondary storage devices [1]. Current electronic interfaces may not have sufficient bandwidth to utilize these high data rates, and thus a bottleneck can be created between the secondary storage and main memory. A primary use of these large capacity memories is storage of records in a database environment, where the majority of transactions comprise searches for data that match a given search argument [2]. Electronic database processors have made good use of preprocessing units to filter the data being transferred to main memory in an effort to reduce the data flow rates to usable levels. A similar filtering unit that can operate on the parallel optical data output from an optical memory would provide even greater benefits. We have presented in an earlier paper a filtering unit consisting of cascaded arrays of optoelectronic logic elements [3]. The major components in this filtering unit are optoelectronic XOR and AND gates arrays. Previously we reported the demonstration of the XOR array using standard table-top optics [4]. In this paper we present a complete optical system redesign using a slotted plate platform, developed elsewhere [5]. The system uses AND and XOR arrays in the demonstration of the projection and selection modules of the database filter.
Considerations of the Optical and Opto-electronic Hardware Requirements for Implementation of Stochastic Bit-stream Neural Nets
Authors: Hall T.J. , Peiffer W. , Hands M. , Thienpont H. , Crossland W.A. , Shawe-Taylor J.S. , van Daalen M.
Published: February 2023

The complexities of implementing neural network systems stem from the requirement that each neuron can receive excitation from many inputs (1-1000, or more) and each input must be multiplied by a weight Conventional analog and digital electronic hardware implementations of neural architectures often use much of the available hardware to implement the calculation of the product of the weights and inputs, and have to resort to a time-multiplexing scheme (which allows sharing of the multiplier hardware) to implement networks with more than a few thousand neurons in the system. This problem can be overcome by using stochastic computing techniques. Therefore, this paper details the results of an investigation of the implementation of the functional components of a stochastic bit stream neuron in optic/optoelectronic hardware. This approach offers several advantages.
Optoelectronic Fuzzy ARTMAP Processor
Authors: Blume Matthias , Esener Sadik C.
Published: February 2023

The realization of practical optical or optoelectronic computers has been hampered by the lack of algorithms suited to optoelectronic implementation. We have chosen an algorithm that is particularly compatible with optoelectronic processors and parallel access optical memory, mapped it onto an architecture which satisfies the constraints of the hardware, and suggest an implementation which is an appropriate combination of optical and electronic technology. The proposed parallel optoelectronic implementation increases throughput by several orders of magnitude over serial implementations, facilitating the real-time solution of large problems.
An Optical Flash Analog to Digital Converter
Authors: Prusten Mark J. , Gmitro Arthur F.
Published: February 2023

Fast analog-to-digital (A/D) converters are important in a number of applications. Several systems have been proposed for fast A/D converters using optical technology1-4. The most common types of converters are the successive approximation and Flash converters. In a Flash converter there is a separate comparator for each possible output bit code. Each comparator is biased with a reference level that is a specific increment of the full scale value. Since comparators in a Flash converter operate in parallel, this architecture is intrinsically fast. However, as the accuracy requirements increase, the number of comparators increases as 2N where N is the number of bits. In the case of an 8 bit Flash ADC, there are 256 comparators. The 256 comparator output signals are routed to a decoder circuit that produces and 8 bit digital word. The schematic for a Flash converter is shown in Fig. 1. The focus of this paper is on a new implementation of an 8 bit Flash converter utilizing optical technologies.
Variations of the hybrid imaging concept for optical computing applications
Authors: Sinzinger Stefan , Jahns Jürgen
Published: February 2023

Optical interconnections for smart pixel arrays [1] require the use of an imaging optics that can handle large fields at high resolution. For that purpose, the use of "hybrid" imaging systems has been proposed and demonstrated [2-4]. The basic setup of a hybrid imaging system that combines conventional 4-f imaging with microoptic lenslet arrays is shown in Figure 1.
System issues in 2-photon absorption based 3-D optical memories
Authors: Çokgör I. , McCormick F. B. , Dvornikov A. S. , Coblentz K. , Esener S. C. , Rentzepis P. M.
Published: February 2023

The 2-photon absorption based three dimensional memory1 is an optical storage device where the bits of information are stored throughout the volume of a material. The use of optical beams for write/read operations allows the data to be densely packed inside the material, hence increasing the memory density. The third dimension allows the information to be accessed in parallel providing a high data transfer rate.
Optical Wavelet Processor for Target Detection
Authors: Chao Tien-Hsin , Yacoubian Araz , Lau Brian , Miceli William J.
Published: February 2023

Wavelet transform has been widely applied to time-frequency signal analysis, image processing (enhancement, feature extraction, etc.), and target detection. Since wavelet transform is a convolution process between an input and a large number of wavelet bases, the computation load increases nonlinearly with the sizes of the input and the wavelet. Near real-time optical wavelet transform [1-3] could be accomplished by using an optical correlator architecture. The processing speed of optical wavelet transform is independent of the size of the wavelet filter and is only limited to the updating speed of the spatial light modulator.
Pulse-to-pulse field characterization at x-ray free-electron lasers using a speckle-correlation scattering matrix
Authors: Lee KyeoReh , Lim Jun , Park YongKeun
Published: February 2023

In coherent diffraction experiments, knowledge of the incident field is important to extract pure sample-induced data from measured diffraction patterns. However, this becomes challenging in x-ray free-electron lasers (XFELs), as incident fields vary from pulse to pulse due to the stochastic nature of self-amplified stimulated emission. Despite various proposed field retrieval methods, single-shot characterization of each pulse remains elusive. To address this, we propose the speckle-correlation scattering matrix as a solution. Our method directly reconstructs the complex field without sample constraints or multiple acquisitions by introducing a designed diffuser before the detector. We demonstrate the robustness of our approach through successful field reconstructions in various experimental configurations. Based on the retrieved field results, pulse-to-pulse variations in pulse intensity, position, illumination angle, and shape were analyzed. We believe our method can readily serve as an on-field and real-time pulse diagnostic tool at XFELs and improve the overall quality of all experiments performed at XFELs.
Air Pollution Monitoring with CO2 Lasers
Authors: Lundqvist Stefan
Published: February 2023

The presently most widely used methods for detecting and obtaining quantitative measurements of air pollutants require fixed monitoring stations using wet chemical methods with inherently long integration times. The rapidly maturing laser-electrooptical techniques for remote sensing of the atmosphere are a promising answer to the need for sensitive, instantaneous detection methods with the capability to measure atmospheric gaseous pollutants over large areas [1].
Polarization Anisotropy in Lidar Multiple Scattering from Atmospheric Clouds
Authors: Carswell A.I. , Pal S.R.
Published: February 2023

The use of polarization information in lidar measurements of the atmosphere, has proven to be a very useful technique, particularly for cloud diagnostics.1 The backscattering of liquid water droplets has very different polarization characteristics from the backscattering of ice crystals, and in many situations it is possible to use the polarization signatures to discriminate between ice and water in atmospheric clouds. Also of considerable importance is the utilization of lidar polarization information for separating the contributions of single and multiple scattering in water droplet clouds. When such clouds of perfectly spherical scatterers are illuminated by linearly polarized radiation, the single scattering in the backward direction, retains the linear polarization of the incident beam, while the multiple scattering introduces a cross-polarized component. (We designate the parallel and cross-polarized components as I‖ and I⊥ respectively). Because the I⊥ component can only arise from the multiple scattering process, observation of the polization components provides a direct measure of the multiple scattering taking place in the cloud. Since most lidar analyses assume that only single scattering is occurring, the ability to quantitatively detect the presence of multiple scattering is extremely valuable in most cloud lidar investigations. As a result lidar systems have been designed to permit such measurements. In the lidar systems, the polarization measurement is performed on the backscattered laser radiation which falls within the field of view of the lidar receiver. Implicit in the polarization measurement is the assumption that the polarization state is uniform within the field of view and that the measured properties reflect the polarization state of the entire scattering volume viewed by the receiver.
Target Calibration, Parameter Modeling, and Data Processing Considerations for Accurate Lidar Aerosol Backscatter Measurements
Authors: Kavaya Michael J. , Menzies Robert T.
Published: February 2023

The remote measurement of atmospheric aerosol backscatter coefficients using lidar is well suited for the present need to expand the statistical data base of backscatter coefficients over broad ranges of latitude, longitude, altitude, time, and weather conditions. Quantitative measurements in the 9-11 μm spectral region, for a variety of atmospheric conditions, are important for the assessment of the feasibility of various CO2 lidar remote sensing goals. These goals include improved understanding of aerosol particles in the atmosphere, use of the DIAL technique to measure atmospheric species concentrations and distributions of pollutant gases, and an Earth-orbiting CO2 lidar which would use aerosol backscatter to globally measure atmospheric winds for better understanding of processes occuring within the troposphere and for greatly enhanced 12 hour - 5 day weather forecasts.
An Intermediate-distance Dual cw CO2 Laser Remote Sensor for Atmospheric Trace Gases
Authors: Grant William B.
Published: February 2023

A dual cw CO2 laser system has been designed and is being assembled for remote long-path measurement of atmospheric trace gases. The components comprise a pair of RF-excited, grating-tunable waveguide CO2 lasers, a beam splitter, a 5X beam expanding telescope with a pinhole aperture, transmit mirrors, a 37-cm diameter collector mirror, a HgCdTe detector, a pyroelectric reference detector, a dual function generator, four phase-sensitive (lock-in) detectors, three ratiometers, a differential meter and a chart recorder.
Finestructure of Elevated Inversions: Implications for Optical Systems
Authors: Gossard Earl E. , Gaynor J. E. , Zamora Robert
Published: February 2023

An experiment is described that combines in situ measurements made with very fast response sensors on a 300 m tower at the Boulder (Colorado) Atmospheric Observatory (Kaimal and Gaynor, 1983), with remote sensing of atmospheric layer structure by acoustic and FM-CW radar sounders (e.g., Little, 1969; Richter, 1969). A finestructure of laminae is often present within elevated inversion layers that is reminiscent of the sheet and layer structure found in the ocean thermocline and in lakes and estuaries (e.g., Gregg, 1982). Figure 1 shows an acoustic record of such a stepped profile event through which a moving carriage on the tower carried temperature, humidity and wind sensors along time-height trajectories shown by the superimposed staight lines. The temperature measurements were made with platinum wires, humidity was measured with a Lyman-α humidiometer, and wind was measured by three-component sonic anemometers. The_data were then digitized at_a 10 Hz rate, and the carriage rose at 0.56 ms-1 and descended at 0.58 ms-1. Figure 2 shows the resulting profiles of temperature, humidity and wind. The transition through the sheets and layers within the inversion is often extremely abrupt with very large gradients. Near_the center of the lower sheet the local gradient of temperature was 6°C m-1. An experiment is described that combines in situ measurements made with very fast response sensors on a 300 m tower at the Boulder (Colorado) Atmospheric Observatory (Kaimal and Gaynor, 1983), with remote sensing of atmospheric layer structure by acoustic and FM-CW radar sounders (e.g., Little, 1969; Richter, 1969). A finestructure of laminae is often present within elevated inversion layers that is reminiscent of the sheet and layer structure found in the ocean thermocline and in lakes and estuaries (e.g., Gregg, 1982). Figure 1 shows an acoustic record of such a stepped profile event through which a moving carriage on the tower carried temperature, humidity and wind sensors along time-height trajectories shown by the superimposed staight lines. The temperature measurements were made with platinum wires, humidity was measured with a Lyman-α humidiometer, and wind was measured by three-component sonic anemometers. The_data were then digitized at_a 10 Hz rate, and the carriage rose at 0.56 ms-1 and descended at 0.58 ms-1. Figure 2 shows the resulting profiles of temperature, humidity and wind. The transition through the sheets and layers within the inversion is often extremely abrupt with very large gradients. Near_the center of the lower sheet the local gradient of temperature was 6°C m-1.
The Experimental Measurement of Total Absorptance by the Ozone 9.6 Micron Band
Authors: Guang-ze Zhu
Published: February 2023

The total absorptance of ozone (O3) 9.6 micron band has been measured at the room temperature. The amount of ozone is from 0.0188 to 0.5 atm-cm and the range of pressure is from 17 to 760 mmHg. In the experiment the cross-shaped absorption cell containing ozone is used; the ultra-violet absorption is recorded through one arm of the absorption cell to determine the amount of ozone and the infrared spectrum is recorded through the other arm to determine the total absorptance of ozone in the cell. Fig.1 shows the measured value. The experimental data have been analysed and proceed according to the theory of the absorption spectrum model. The result of the experiment shows that the experimental data are consistent with the statistical model.
A Simple Spaceborne Lidar for Measurements From Operational Satellites
Authors: Endemann M.
Published: February 2023

The results from a recent ESA study /1/ about applications of lidars for relevant measurements for meteorology and climatology from future earth observation satellites are presented. In the course of the study the conceptual design for a spaceborne lidar for measurements from operational observation satellites (orbit height 800 km) was worked out. It features a modular design that provides a large growth potential: the basic version is a simple backscatter lidar to measure cloud-top heights as well as density and distribution of subvisible clouds and aerosol layers. In later phases, additional equipment can be incoporated to perform the more complex DIAL measurements for humidity /2/, pressure /3/ and temperature profiling /4/.
Changes in Solar Heating Rates and Planetary Albedo Induced by the El Chichon Volcanic Cloud
Authors: Valero Francisco P. J. , Ackerman Thomas P. , Starr Walter L.
Published: February 2023

The eruption of the Mexican volcano El Chichon (17.33°N, 93.20°W) on March 28, April 3, and April 4, 1982 injected particulate and gaseous matter into the stratosphere. This volcanic cloud ranked as one of the most massive of this century. DeLuisi et al, (1983) reported that "the atmospheric radiative effects of the El Chichon cloud far exceed the effects of all other volcanic clouds observed at Mauna Loa since observations were began in 1958". Very large optical depths were reported for this volcanic cloud in the northern tropics during the first few months since its formation.
Quantitative Concentration Measurements with Differential Absorption Lidar (DIAL)
Authors: Leonard Donald A. , Wilkerson Thomas D. , Johnson Douglas w.
Published: February 2023

This paper treats the dependence of concentration accuracy, dynamic range and the product of concentration and path length on the measurement accuracy of the lidar instrument. Limiting noise sources are investigated for the measurement of DMMP vapor at a test range. Atmospheric turbulence combined with speckle from hard targets and interference from various dusts and smokes are the noise sources that are considered.
The Eos Microwave Limb Sounder Experiment
Authors: Waters J.W. , Barath F.T. , Cofield R.E. , Flower D.A. , Froidevaux L. , Harwood R.S. , Jarnot R.F. , Kerridge B.J. , Lau G.K. , Matheson D.N. , Peckham G.E. , Pickett H.M. , Read W.G. , Siegel P.H. , Stachnik R.A. , Wilson W.J.
Published: February 2023

The Eos Microwave Limb Sounder (MLS) experiment is an enhanced version of the UARS MLS described in a separate paper presented at this meeting. Most of the Eos MLS measurements will be from the submillimeter spectral region around 600 GHz (20 cm-1). This region is very rich in spectral lines of atmospheric interest, and includes the first rotational line of HC1, and the strongest emission lines of ClO and many other molecules. Figure 1 shows emission spectra for a small portion of the spectral region to be covered. Figure 2 summarizes the measurement capability of the instrument (vibrationally excited states of O3, O2, and possibly of other molecules, will also be measured). All measurements are made simultaneously and continuously, at all times of day and night, with ~3 km vertical resolution. Latitude coverage is 82°S-82°N on each orbit. The altitude range shown in Figure 2 is where the expected atmospheric volume mixing ratio exceeds by 2× the predicted ‘noise-equivalent volume mixing ratio’ of the instrument, and where, based on data in the JPL Submillimeter, Millimeter, and Microwave Catalog [1], the targeted spectral lines are expected to be sufficiently free from other interfering lines. Figure 3 shows one day’s measurement pattern.
Design of Improved Limb Atmospheric Spectrometer (ILAS) aboard ADEOS
Authors: Takeuchi N. , Suzuki M. , Yokota T. , Matsuzaki A. , Akimoto H.
Published: February 2023

Impact of the global environmental issues has been rapidly increasing nowadays. The depletion of the ozone layer and the greenhouse effect are typical topics among them. The satellite remote sensing is a powerful method for monitoring the global environment. On this occasion, the Improved Limb Atmospheric Spectrometer (ILAS) was planned to monitor the stratospheric ozone layers and the polar ozone holes, and was applied to the ADEOS (Advanced Earth Observing Satellite), to be launched in February, 1995, by NASDA, Japan. ILAS was selected as an AO instruments, with two core sensors; AVNIR(Advanced Visible and Near Infrared Radiometer), OCTS(Ocean Color and Temperature Spectrometer), and other five AO sensors; NSCATT(NASA-Scatterometer), TOMS(Total Ozone Mapping Spectrometer, NASA), POLDER(Polarization & Bidirectionality of Earth’s Surface, CNES), IMG(Infrared Mapper for Greenhouse Gases) and RIS(Retroreflector in Space). ILAS is a solar occultation sensor (Fig. 1), which measures high latitude stratospheric constituents in both hemispheres. ADEOS is an experimental polar platform spacecraft, to be launched to a sun-synchronous orbit by a H-II rocket. The equatorial crossing time will be 10:30 a.m. (descending). The inclination angle is 98.6 deg., the orbit altitude is 800 km, and the period of one cycle is 101 min. ADEOS is an international satellite, which offers the opportunity to the sensors from outside Japan. The combination of the ILAS (Japan) and TOMS (NASA) will work to give global coverage and the vertical profile for a global ozone distribution.
A Simple Method of Estimating Photosynthetically Active Radiation at the Earth's Surface from Satellite
Authors: Eck Thomas , Dye Dennis
Published: February 2023

A physically based method of estimating the photosynthetically active radiation (PAR) incident at the earth's surface is described. Ultraviolet reflectivity, inferred from the Total Ozone Monitoring Spectrometer (TOMS) onboard the polar orbiting Nimbus-7 satellite, is used to account for the effect of cloud albedo on the attenuation of PAR incident at the surface. The clear sky incident radiation for the PAR wavelengths (400-700 nm) is computed from the spectral model of Goldberg and Klein (1980). Monthly averages of incident PAR at the surface estimated from the satellite method differed from estimates of PAR from ground pyranometers by less than 6%. This method of PAR estimation can be applied globally over snow and ice free areas.
Vertical Resolution of Atmospheric Profiles Obtained with the Proposed Passive Infrared Sounders
Authors: Huang Hung-Lung , Smith William L.
Published: February 2023

The utility of current satellite measurements for the retrieval of atmospheric temperature and moisture profiles are seriously compromised by their poor spectral resolution. This limitation in the spectral resolution makes the reconstruction of sounding profiles difficult and does not provide a vertical resolution sufficient to meet the requirements of numerical weather prediction.
HF Curve of Growth in the Fundamental R Branch as Inferred from HALOE Measurements; Retrieval Consequences
Authors: Gordley Larry L. , Mlynczak Pamela E.
Published: February 2023

The Halogen Occultation Experiment is designed to measure HF, HCI, NO, and CH4 in the stratosphere and lower mesosphere using gas correlation spectroscopy. It is found that collisional narrowing effects must be incorporated for accurate HF retrieval using HALOE data.
Wind Imaging Interferometer (WINDII) for the UARS Mission
Authors: Shepherd Gordon G. , Gault William A. , Hersom Charles H. , Solheim Brian H.
Published: February 2023

In 1984, the Centre National d’Etudes Spatiales of France and the National Research Council of Canada agreed to collaborate in providing a Wind Imaging Interferometer (WINDII) for NASA’s Upper Atmosphere Research Satellite, planned for launch in late 1991. A description of the mission is given by Reber in these proceedings.
Non-LTE Emission from CO(v=l) in the Mesosphere and Lower Thermosphere and its Effect on Remote Sensing
Authors: Winick Jeremy R. , Wintersteiner Peter P. , Picard Richard H.
Published: February 2023

An accurate modular computer code has been developed at the Geophysics Laboratory for calculating the non-LTE vibrational temperature of important emitters in the Earth’s upper atmosphere. This code was first developed and applied to CO2 ν2 emission (P.P. Wintersteiner, this meeting). We will describe the application to CO(v=1) which although simpler since it is clearly a two-level problem, is more demanding of an accurate treatment of radiative transfer for a number of reasons.
Atmospheric Changes above ISSJ from Infrared Solar Observations
Authors: Zander R. , Demoulin Ph.
Published: February 2023

Despite the outstanding progress made during the last decade in observational methods such as passive emission spectrometry and active Lidar applications, infrared remote sensors using the sun as source of radiation remain among the most powerful tools for atmospheric investigations. The quality and quantity of such solar observations have reflected the progress made in detector sensitivities, in new instrumental techniques and modes of operation, as well as the power of analytical algorithms based on modern computers. Infrared spectrometers have been adapted and proven suitable for measurements from the ground, aircraft and balloons, even from orbiting platforms with extensive vertical and near-global coverages.
A Transmitting/Receiving Telescope for DOAS-measurements using Retroreflectortechnique.
Authors: Axelsson H. , Galle B. , Gustavsson K. , Ragnarsson P. , Rudin M.
Published: February 2023

DOAS (Differential Optical Absorption Spectroscopy) is a remote sensing technique in which light is transmitted over kilometer distances with a transmitter, then collected by a receiver and analyzed in a special spectrometer. Thus an absorption spectrum of the air between transmitter and receiver is obtained (Platt o Perner 1979). The method has proven to be powerful and a number of substances have been successfully measured in applications ranging from background monitoring to urban air and emission studies (Platt, Perner, Pitts, Biermann). Traditionally light is transmitted by a parabolic mirror with the lamp mounted in its focus, thus emitting a parallel beam of light. In the receiving end, light is collected by a similar mirror and focused into an optical fiber connected to the spectrometer. Alternatively the converging light may be coupled directly to the spectrometer by means of a folding mirror in Newtonian or Cassegrain arrangement.
Lidar and radiometry (LIRAD) Sensing of Cloud Properties
Authors: Platt C.M.R.
Published: February 2023

Clouds are now recognized as one of the major stumbling blocks to the proper understanding of predicted global warming resulting from the increase of anthropogenic gases in the atmosphere.
Atmospheric Temperature and Aerosol Measurement by a Multi-Color Lidar
Authors: Uchino O. , Takashima H. , Tabata I.
Published: February 2023

Atmospheric temperature profiles can be deduced from the molecular density profiles assuming hydrostatic equilibrium for the atmosphere where the density profiles can be obtained from the Rayleigh backscatter lidar signal profiles. This technique have been sucecssfully used to measure temperature above 35-km altitude where aerosol scattering is considered negligible compared with Rayleigh backscattering (Hauchecorne and Chanin, 1980).
Signal Processing and Data Smoothing Influences in Dial Measurements
Authors: Ismail Syed , Browell Edward V. , Hall William M. , Kenimer Robert L.
Published: February 2023

The detection, amplification, and filtering of signals by lidar detector systems and subsequent data processing modify the characteristics of true atmospheric lidar signal returns. These influences can lead to significant changes in the shape of atmospheric concentration profiles calculated using the Differential Absorption Lidar (DIAL) technique in regions of large aerosol gradients. This paper discusses the sensitivity of these influences in the measurement of water vapor (H2O) by an airborne or spaceborne DIAL system operating in a nadir viewing configuration.