bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of FT Spectrometers in optical coating measurements
Authors: Giroux Jean
Published: February 2023

The Fourier Transform Spectrometer consists of a Michelson interferometer, a source and a detector. The sample is placed between the interferometer and detector. A mirror moving at constant speed creates an optical path difference. The measured signal is called the interferogram. After mathematical treatment, including the Fourier transform, the spectrum is retrieved. This spectrum contains information about the sample, but also on the instrumental response. This spectrum is usually ratioed to an open beam or background spectrum which eliminates the instrumental function. Such an instrument can be constructed for operation in any spectral region, but shorter wavelengths dictate more stringent requirements on the optical parts and motion accuracy. Evidently, suitable detectors and sources must be selected. High-end research grade instruments can be easily be re-configured for operation from 1000μm to 250nm.
Nonlinear Optical Coating Indices and Thickness Measured by Spectroscopic Ellipsometry
Authors: Stehle J. L. , Toussaere A. , Ziss J.
Published: February 2023

Nonlinear optical coatings, oriented doped polymers, can be used in guided optics multiplexer devices. Ordinary and extraordinary indices are characterized by spectroscopic ellipsometry.
Graded Rugate Filters for Head up Displays
Authors: Allen J , Herrington B D , Jansen S , Blomfield J C
Published: February 2023

The concept of rugate filters has been known for almost a decade, where a rugate is a medium with a periodically varying refractive index. The spectral performance of a rugate is the Fourier Transform of its refractive index profile. A sinusoidal refractive index profile results in a single rejection band whose wavelength is determined by the modulation frequency and whose bandwidth and rejection level by the peak to peak refractive index modulation and the number of periods.
Parametric Dispersion Models for the Index of Refraction of Transparent Materials
Authors: McGahan William A. , Woollam John A.
Published: February 2023

Parametric dispersion models for the optical constants of materials are often used when fitting optical data in order to reduce the required number of fit parameters and to eliminate the incorporation of random noise in the experimental data into the resulting optical constants. Such models are particularly useful when fitting data for transparent materials, where the absorption (or extinction coefficient or imaginary part of the dielectric function) can be assumed to be zero and only the index of refraction (or real part of the dielectric function) must be parameterized. Several parametric models for the dispersion of the index of refraction are reviewed. These models are fit to literature optical constants for a number of transparent materials (both dielectrics and semiconductor materials at energies below the bandgap). The relative usefulness of the various models is discussed as are internal correlations among the model parameters. Values of the parameters within the models are tabulated for a large number of dielectric and semiconductor materials.
Linear Variable Filter Coatings for Multispectral FPAs
Authors: West R.A. , Walter G.A. , Dahlin M.J.
Published: February 2023

The Thin Film Engineering Laboratory at Santa Barbara Research Center (SBRC) has recently developed a multispectral Focal Plane Array (FPA) for the 3.0-5.5µm region using a Linear Variable Filter (LVF) mounted directly onto a linear or two-dimensional indium antimonide (InSb) detector array. This technology involves depositing a "wedged" thickness interference filter coating on a single filter substrate and then mounting it directly to the detector assembly using a new proximal mounting technique (patent pending) currently under development at SBRC. Each layer in the coating is wedged by use of a mechanically varying shutter on the substrate tooling during the deposition. The purpose of the wedged coating is to provide a spectral bandpass which varies linearly with position along the length of the substrate such that each element of the detector array responds to a different spectral band.
Interference coatings for the ultraviolet spectral region
Authors: Kaiser N.
Published: February 2023

Dielectric coatings for high power excimer laser components and other UV applications have been investigated. Objective was the enhancement of reliability and availability of complex UV photon machining and measuring configurations. It has been shown that it is possible to adapt the UV photon beam shape with high efficiency to specific applications by properly designed interference coatings.
Ion-Aided Thin Film Deposition Processes: An Overview
Authors: Al-Jumaily Ghanim
Published: February 2023

It has been demonstrated that ion bombardment causes significant changes in the optical, physical and chemical properties of thin films. As a result, various ion beam-based thin film deposition processes have been introduced. Significant advances in our understanding of thin film growth have been achieved, especially in establishing a relationship between coating’s microstructure and optical properties. The most important feature of applying ion beam-base processes has been the ability to control film properties and therefore better predict the performance of interference coatings. Ion beam-based deposition processes will be reviewed with special emphasis on their impact on the optical properties of coatings.
Nonconventional Coating Processes—Sol-gel and CUP
Authors: Aitchison Kenneth
Published: February 2023

CVD and sol-gel have seen increasing use in optical coating fabrication. Their relative merits are discussed in terms of microstructure, optical performance, and robustness.
Precision Liquid-Derived Thin Films on Large-Area Optical Substrates Applied by Meniscus Coating
Authors: Britten Jerald A.
Published: February 2023

The emergence of new optical coating materials and new laser technologies in recent years has engendered a need to apply uniform, ultrathin coatings from liquid solutions onto large, heavy substrates. Examples of importance to LLNL's inertial confinement fusion program are sol-gel anti reflective coatings and multilayer high reflectors (HR's) made with sol-gel suspensions, large aperture diffraction gratings, and beam smoothing optics. Manufacture of each of these optics requires deposition of submicron-thickness coatings uniform to within a few percent across the entire clear aperture, which can be on the order of a square meter in size.
Combination of surface characterization techniques for proper investigation of optical thin film morphology
Authors: Duparré Angela
Published: February 2023

When investigating the surface morphology of thin films and substrates the following problems have to be taken into account:

- The microtopography as a two-dimensional roughness profile consists of various structural features the form, size, and distribution of which depend on the substrate and film material, polishing process, deposition procedure, and environmental conditions.

- Anisotropy and local variations of the roughness profile are likely to occur.

- The characterization techniques should be applicable to quite a large variety of different surface structures such as superpolished substrates, columnar film morphology, corroded surfaces with pronounced roughness etc.

- All techniques of surface roughness measurement are subject to bandwidth limitation. Hence, the information available depends on both the method applied and the particular properties of the sample.
Optical Constants of Electrochromic WO3 Determined by Variable Angle Spectroscopic Ellipsometry
Authors: Hale Jeffrey S. , Hilfiker James N. , Woollam John A.
Published: February 2023

Variable angle spectroscopic ellipsometry (VASE) was used to measure the optical constants and thickness of electrochromic WO3 films with various intercalation levels. The films were deposited by RF magnetron sputtering to thickness between 800nm and 2000nm. The substrates were quartz with electrode layers of optically thin Al or ITO. Li+ ions were inserted into the films by applying a negative voltage to the substrate electrode (Al or ITO) relative to a counter electrode, a gold wire, in a Li+ containing electrolyte. This electrolyte was a 0.5 molar solution of LiClo4 in propylene carbonate. Additionally, in-situ experiments were done in a electrochemical chamber mounted on a VASE. Ellipsometry and transmission data were taken at several angles of incidence with several different amounts of Li+ inserted and the optical constants and thickness were solved for at each level of intercalation. Additional characterization included AFM, interference microscopy, and x-ray diffraction. Figure 1 and 2 attached show the ellipsometric and Ψ and Δ before and after intercalation of the WO3 with Li+. Figure 3 shows the transmissional data. By combining these data simultaneously in the regression fit, we are able to unambiguously determine the index of refraction and extinction coefficient during all stage of “coloring”.
A Single Pass Laser Reflectometer: Conceptual Goals and Physical Results
Authors: Sczupak Robert , Smith Douglas
Published: February 2023

A device capable of measuring optical coating performance over a range of angles was required for the completion of the University of Rochester's Omega Upgrade laser system. The laser system employs several different types of optical coatings including antireflection, high reflectors, beamsplitters, and polarizers. Coating evaluation needed to be accurate to ±0.1%, but flexible enough to accomodate all different sizes and shapes of optics. The current configuration includes three laser sources; Argon, HeNe, and YEOLF. When used in transmission mode, the instrument is capable of measuring contrast ratios (Tp/Ts) over a four decade range.
Materials for the deposition of thin films
Authors: Kirilenko V.
Published: February 2023

Development of the modern optics call forth to create new optical elements with new properties. As the result of fundamental investigations in chemistry and technology of oxides, fluorides and chalcogenides of some elements, it was developed a creation of new high purity materials for the deposition of thin films for various applications.
Characteristics of composite CaF2-SiO2 films as a low-index coating material in UV region
Authors: Chu C. W. , Wei C. T. , Tsai R. Y. , Ho F. C.
Published: February 2023

Calcium floride films have been widely used as coating materials in UV regions with wavelengths > 190nm, particularly for ArF and KrF excimer laser components1-2. However films prepared by average industrical coating technologies are found exhibiting disadvantages such as softness of film, high porosity, and poor adhesion to substrates. Based on our previous studies on the characterization of composite films of CaF2-TiO23-4and also the possible chemical interactions between the adjacent layers of CaF2 & SiO2 in multilayer stack reported in literature5, we believe that a study on the optical and mechanical properties of the films with CaF2 and SiO2 mixed at different composition ratios is of great interest.
Varying the optical properties of Silicon Carbide films produced by Ion Assisted Deposition in a reactive atmosphere
Authors: Scrase Daniel , Reid Ian
Published: February 2023

This paper addresses the optical properties of Silicon Carbide in thin film form produced by Ion assisted deposition. A bulk index of approximately 2.55 [1] is attractive for a range of optoelectronic applications including semiconductor anti-reflection coatings and optical filters. Its optical properties were investigated using thin films formed using conventional PVD techniques with an End-Hall effect Ion Source. Various gases were introduced into the ion source during deposition, and the optical properties of the films measured. Best indices, approaching bulk indices, were found using Methane. The optical properties were measured in the visible and near infrared spectral regions. As a demonstration of the viability of the processing technique a simple SiC based two layer anti-reflexion coating on glass was created using Methane and Oxygen as the ion source gases.
Performance of Thin-Film Structures in the Presence of Random Interlayer Roughness
Authors: DeSandre Lewis , Elson J. Merle
Published: February 2023

Methods are available to design highly specialized waveguide structures and multilayer-coated optical components that may be a critical element in the performance of optical systems. Since the performance of all optical systems is jeopardized by interface roughness, differences between ideal and actual performance could be severe. Even though a component may perform within system requirements, scattering and absorption may contribute to less than fully capable operation.
Characterizing UV-optical surfaces by scattering measurements using excimer laser radiation
Authors: Apel Oliver , Mann Klaus
Published: February 2023

Scattering measurements represent a standard method for an assessment of the surface quality of optical components [1]. In order to measure the Total-Integrated-Scattering (TIS) of a sample, usually a He-Ne laser (633nm) in combination with an Ulbricht-sphere as integrating element is employed. However, since the intensity of scattered radiation increases with decreasing wavelength [2], the use of wavelengths in the deep ultraviolet (DUV) spectral range opens a way to increase the sensitivity of a TIS measurement.
Space optics sensor requirements: past & future missions
Authors: Breckinridge James B.
Published: February 2023

The performance of space-based remote sensing scientific instrumentation is limited by the performance of optical thin films to select wavelength, control unwanted radiation and perform thermal balance roles within the instrument. Past missions and future missions are presented, and optical thin film performance is discussed.
Photonics crystals
Authors: Sherer Axel
Published: February 2023

Summary not available.
Optical interference effects in semiconducting multilayer systems
Authors: Kalem Seref
Published: February 2023

This paper presents the results of an investigation of optical interference effects in several semiconducting thin film multilayer systems. The multilayers were formed on Si and GaAs substrates with different doping levels and the crystal orientation. The layers are composed of both the group IV such as SiGe and group III-V compound semiconductors such as AlGaAs. The optical interference effects in both the infrared and the visible regions are reported in an attempt to evaluate the performance of these layers for use as possible narrow bandstop (notch) filters on semiconductor substrates. The effects of nanostructuring on optical interference are also reported in these multilayer systems.
A Short History of Optical Coatings
Authors: Abelès Florin
Published: February 2023

The history of optical coatings is an interesting one that spans hundreds of years. The modem phase could be said to begin as long ago as the 17th Century with careful observations of colors and angular effects in thin films, but it was in the middle of the 20th Century that the subject was rapidly propelled from what had been largely peripheral to what became immediately a mainstream subject of critical importance to the development of the entire field of optics. In 1950, Florin Abelès published the text of his doctoral thesis and in it defined and demonstrated the matrix calculation techniques that we still use even in our most advanced computer programs. Until then, laborious iterative techniques had been the norm. Although the use of matrices in applying these iterative techniques had been suggested, it was Florin Abelès who developed the modem matrix method and enabled us to focus our attention in coating design on the layers of the structure rather than the interfaces. This, of course, is well understood today, because it is the method that all of us use, but at that time it was revolutionary. Since then, Florin Abelès has had a constant and major influence on the field both in terms of scientific and technical advances and in terms of the numerous students that he has educated at the University of Paris. He has been recognized in many ways and I mention particularly the award of the 1991 C. E. K. Mees Medal of the Optical Society of America. We are fortunate indeed to have someone to talk to us about the history of optical coatings who has played such an important part in creating it.
Low level absorptance measurements and scans of high performance optical coatings for atomic vapor isotope separation applications
Authors: Chow Robert , Taylor John R. , Wu Z. L. , Krupka Rene , Yang Tianli
Published: February 2023

An uranium enrichment plant utilizing atomic vapor laser isotope separation (AVLIS) technology is currently being planned. Deployment of this plant requires tens of thousands of commercial and custom optical components. The custom optical components are expected to perform at a high level of optical efficiency and reliability in a high average power laser production environment. The custom optical coatings for the AVLIS plant must meet simultaneous performance of numerous material properties, one of which is extremely low levels of absorptance. Low absorptance level minimizes thermal-induced distortion of the optic when exposed to high irradiance laser beams. Distortions are not desired because they cause light loss and subsequent degradation of plant efficiency. Low absorptance also reduces the incidence of laser-induced damage.
Design Method of Reflection Filter
Authors: Tan Manqing , Lin Yongchang , Zhao Dazun
Published: February 2023

This paper proposes three methods to design reflection filter. The first method is to design a reflection filter being composed of ultrathin mettallic film of Cr, F-P filter of all-dielectric and a high reflectivity film of Ag. The general structure can be expressed as A/CrXL(HL)
N
(LH)
N
ZLAg/G where N is the number of periods and is an integer, X and Z are phase accommodation coefficients for maximum reflectivity at central wavelength λ0, H is high refractive-index dielectric layer, its optical thickness is λ0/4; L is a low refractive index dielectric layer, its optical thickness is λ0/4, and the geometric thickness of Ag film is 100nm its design example is A/Cr0.93LH2LH0.76LAg/G, where n
H
=2.35, n
L
=1.35, n
g
=1.52, n
A
=1.52, N=1, d
Cr
=7nm the spectral refectance Curve shows in Fig.1.
Parallel synthetic aperture transport-of-intensity diffraction tomography with annular illumination
Authors: Ullah Habib , Li Jiaji , Zhou Shun , Bai Zhidong , Ye Ran , Chen Qian , Zuo Chao
Published: February 2023

Transport-of-intensity diffraction tomography (TIDT) is a recently developed label-free computational microscopy technique that retrieves high-resolution three-dimensional (3D) refractive index (RI) distribution of biological specimens from 3D intensity-only measurements. However, the non-interferometric synthetic aperture in TIDT is generally achieved sequentially through the acquisition of a large number of through-focus intensity stacks captured at different illumination angles, resulting in a very cumbersome and redundant data acquisition process. To this end, we present a parallel implementation of a synthetic aperture in TIDT (PSA-TIDT) with annular illumination. We found that the matched annular illumination provides a mirror-symmetric 3D optical transfer function, indicating the analyticity in the upper half-plane of the complex phase function, which allows for recovery of the 3D RI from a single intensity stack. We experimentally validated PSA-TIDT by conducting high-resolution tomographic imaging of various unlabeled biological samples, including human breast cancer cell lines (MCF-7), human hepatocyte carcinoma cell lines (HepG2), Henrietta Lacks (HeLa) cells, and red blood cells (RBCs).
Digital filtering of ghost signal in phase measuring deflectometry
Authors: Jeong Byeongjoon , Ordones Sotero , Quach Henry , Kim Daewook , Choi Heejoo
Published: February 2023

We introduce a method of geometric screen modification to remove ghost reflections commonly observed in deflectometry optical testing. The proposed method modifies the optical layout and illumination source area to bypass the generation of reflected rays from the undesired surface. The layout flexibility of deflectometry allows us to design specific system layouts that avoid the generation of interrupting secondary rays. The proposed method is supported by optical raytrace simulations, and experimental results are demonstrated with convex and concave lens case studies. Finally, the limitations of the digital masking method are discussed.
Potential and Limitations of VLSI
Authors: Mead Carver
Published: February 2023

The VLSI Technology, as we know it, has the potential of creating systems with 1010 interconnected active devices on a single silicon wafer. Each device can evaluate an interesting function every 10−10 seconds. The awesome functional capability of such an arrangement is not matched by a corresponding communication bandwidth. Even at present complexity, designs are severely restricted by wiring congestion and delays due to wiring capacitance. The technology is complementary to optical systems, in which communication is fast and abundant, but non-linear functions are slower and more costly. A hybrid technology organized to take advantage of the strengths of both VLSI and optics could have a revolutionary impact on system design.
Special Architectures for the Fifth Generation Computers
Authors: Moto-oka Tohru
Published: February 2023

Inference machines, knowledge base machines and intelligent man-machine interface machines are typical core processors which constitute the fifth generation computer systems for knowledge systems.
Computing Applications of Optical Guided-Wave Devices
Authors: Leonberger F. J.
Published: February 2023

The status of a variety of integrated optical switches, modulators and couplers, both as discrete devices and in arrays, are reviewed for applications in optical computing.
Asynchronous Integrated Optical Multiply Accumulate Unit
Authors: Israel Scott , Gustafson Steve
Published: February 2023

Current bulk acousto-optic processors calculate products very rapidly yet they suffer the following limitations: 1) the data is clocked into the processor thereby limiting the ultimate speed of the processor to that of the clock, 2) the processor is limited to matrix calculations, 3) an extremely stable, large platform is needed for the apparatus, and 4) a long time is needed to convert the mixed binary output to useable (at least to the rest of the computer world) pure binary.
Systolic array machines can be both fast and programmable
Authors: Kung H.T.
Published: February 2023

Warp is a programmable systolic array machine developed by Carnegie Mellon. Currently two 10-cell machines are operational at Carnegie Mellon, with each cell being a 10 MFLOPS programmable processor. These machines have been used in a diverse range of applications, including navigation for robot vehicles, signal processing, and medical image processing, and as a tool for vision research. For these applications, Warp is typically several hundred times faster than the VAX 11/780. General Electric, which is Carnegie Mellon's industrial partner for the Warp project, is building at least eight additional Warp machines.
Optical Computer Architecture: What is the Ideal?
Authors: Hillis W. Daniel
Published: February 2023

We shall define the ideal computer as one which can execute any calculation as fast as any other computer, within a multiplicative constant.
Advances in Brain-Style Computation
Authors: Rumelhart David E.
Published: February 2023

A sketch of current work on brain-style computation is provided. Emphasis is on applications for building content-addressable memories and learning machines.
An Optical, Cross-Bar Arithmetic/Logic Unit
Authors: Falk R. Aaron , Capps C. David , Houk Theodore L.
Published: February 2023

As indicated in an earlier paper presented at this conference,(1) use of parallel Fourier optical pattern recognition techniques in conjunction with a final non-linear threshold allows rapid computation of sums and products in residue arithmetic. The coherence properties of the architecture reduce the number of non-linear elements to 2n-1 where n is the size of the radix. Incoherent point sources could also be used with the grating filters performing a holographic interconnect function, but, at the expense of requiring n2 non-linear elements. This expense is offset by allowing performance of any multi-level logic function, residue arithmetic being only one example of a multi-level logic function. This paper will describe an alternative technique to performing the desired n2 interconnect pattern which requires no lenses or filters, thereby significantly reducing the fabrication and alignment difficulties.
Correlation Algorithm and Architecture for Optical Complex Discrecte Fourier Transformation
Authors: Huang Hongxin , Liu Liren , Wang Zhijiang
Published: February 2023

It is an important subject in optical computing to perform Fourier transform with innate characteristics of optics such as parallel, high-speed, wideband and no crosstalks. A lot of architectures and algorithms have been developed by using coherent and incoherent optical systems. This paper, we report a new correlator architecture and algorithm for performing complex DFT [1].
Digital Optical Computing with Fibers and Directional Couplers
Authors: Jordan Harry F.
Published: February 2023

The goal of the Digital Optical Computing program of the Center for Optoelectronic Computing Systems is to design and demonstrate a prototype of a stored program optical computer using the knowledge base developed in connection with electronic digital computers. The target architecture is to be all-optical. This means that components with only optical inputs and outputs (except perhaps for power) are the basis of the architecture. The devices making up these components may have significant electronic parts which mediate the optical switching. From the architectural point of view, however, these components are treated as "black boxes" and could be replaced with any optical switching devices yielding the same functionality. The emphasis is thus on optical architecture, which we take to mean the architecture of a machine in which all information is carried between logic elements by optical signals, and in which the role of electronics interior to switching elements is minimized to the extent which is realizable.
Integrated array of self electro-optic effect device logic gates
Authors: Lentine A. L. , Chirovsky L. M. F. , Focht M. W. , Freund J. M. , Guth G. D. , Leibenguth R. E. , Przybylek G. J. , Smith L. E. , D’Asaro L. A. , Miller D. A. B.
Published: February 2023

Arrays of symmetric self electro-optic effect devices (S-SEEDs) have been made with low operating energies and fast switching speeds [1,2]. The device has the characteristics of a set-reset latch, although it can be made to do logic functions such as a NOR gate by presetting the state of the device before the application of the data inputs [3]. Logic gates that can perform more complex functions without preset beams may be realized by using electrically connected detectors configured like transistors in NMOS or CMOS circuits together with an output S-SEED to provide the output beams [4]. In this paper, we describe the first integrated arrays of these logic gates, each of which can perform the four basic logic functions without the use of preset beams. Each logic gate in the array consists of six quantum well p-i-n diodes, four input diodes configured similar to transistors in a CMOS NOR gate, and two output diodes (i. e. a S-SEED) that provide a set of complementary output beams. Like the S-SEEDs, this device has time sequential gain, in which the low power input beams set the state of the device and a set of equal higher power clock beams subsequently read the state. This device retains many desirable qualities of the S-SEED such as signal regeneration and retiming, wavefront restoration, and operation over several decades in power levels due to its differential nature. Because the logic gate contains only quantum well diodes, the same batch fabrication procedures [1] used for S-SEED arrays were used to make the arrays of these devices.
Binary Optics and Applications
Authors: Veldkamp Wilfrid B.
Published: February 2023

In a classic example of technology transfer, binary optics is allowing optical designers to create innovative optical components which promise to solve key problems in optical sensors, communication, and optical processors.
Gray-Scale Controllable Ferroelectric Liquid Crystal Spatial Light Modulator
Authors: Gomes Cleber M. , Tsujikawa Susumu , Maeda Hiroki , Sekine Hiroyuki , Yamazaki Takashi , Sakamoto Mikio , Okumura Fujio , Kobayashi Shunsuke
Published: February 2023

A new optically addressed spatial light modulator (OASLM) with memorized gray-scale capability has been developed, which has potential application in analog optical computing. This OASLM exploits the occurrence of a gray-scale effect in the memory state of surface stabilized ferroelectric liquid crystal (SSFLC) cells when the SSFLC is oriented by ultra-thin polyimide Langmuir-Blodgett (LB) films.1) In the case of LB orientation films, the gray-scale can be attributed to the topography of the substrate ITO films which produces spatial fluctuation in the spontaneous polarization (multidomain).2) The OASLM has many pixels, each corresponding to the smallest unit of the multidomain gray-scale. Because it is possible to add switching devices such as thin film transistors to the pixels, the OASLM has the potential of particularly designed functions.3)
Optical Algorithms in Geometry
Authors: Karasik Y. B. , Sharir M.
Published: February 2023

We consider the application of optical computational operations to problems that arise in various geometric applications, such as computer graphics, image processing, pattern matching. etc. We show how to implement, using only a constant number of basic optical operations, a variety of algorithms that solve fairly complex tasks of this sort. We discuss the methodology that we propose, list the geometric algorithms that we have developed to date, and illustrate the approach in two more detailed applications, motivated by computer graphics and pattern matching: drawing all possible lines connecting pairs in a given set of points, and computing the closest pair (orkclosest pairs) of points in a given set.
Interconnection Theory and Optoelectronic Computing Architectures
Authors: Ozaktas Haldun M.
Published: February 2023

Various optically interconnected computer architectures are compared based on a number of considerations including interconnection density and heat removal.
Robot Navigation Using a Peristrophic Holographic Memory
Authors: Pu Allen , Denkewalter Robert , Psaltis Demetri
Published: February 2023

In recent years there has been a resurgence of interest in holographic memories. Most of the recent experiments in holographic storage have been in LiNbO3, in which up to 10,000 holograms have been stored in one location [1], or the DuPont photopolymer in which 1,000 holograms were stored [2], A technique called peristrophic multiplexing was combined with conventional angle multiplexing to store the 1,000 holograms in the polymer which has a thickness of only 100 microns. Most of the development of holographic memories is aimed at digital computer storage. In this paper we focus instead on the application of holographic memories to image processing. Specifically we use the peristrophic system as an optical database to store images to navigate a small car autonomously along specified paths. This experiment suggests that the two best features of holographic storage, capacity and parallel access, can be put to good use in real time machine vision applications.
Application of Fourier Optics for Defect Detection in Microelectronics Fabrications
Authors: Lin Lawrence H.
Published: February 2023

Fourier optics offers a simple and effective means for detecting defects in the fabrication processes of semiconductor devices or flat panel displays. Application to commercial equipment development will be presented.
A Mobile Atmospheric Profiling System (MAPS)
Authors: White Kenneth O. , Gutman William M. , Dowling James A.
Published: February 2023

Atmospheric propagation tests in support of electro optics system development frequently require measurement of the atmospheric transmission at discrete frequencies or the average transmission for a finite spectral bandwidth. The conditions of the test may require that measurements be made over horizontal or slant paths, or even that a moving source be tracked. In many tests it is also necessary to acquire slant path atmospheric turbulence data. A measure of the transverse coherence length (ro), isoplanatic angle (θo), and/or turbulence structure constant
(Cn2) profile, may be required. In order to address these needs, an extremely versatile Mobile Atmospheric Profiling System (MAPS) has been designed and fabricated. Field tests have been under way for several months and a variety of data has been collected.
A Bistatic LIDAR for Mapping of Ionospheric Species and A Precise Locating LIDAR for the Tethered Satellite System
Authors: Karl Robert R. , Horak Henry G. , McComas David J. , Wilkerson Thomas D. , Spence Harlan E.
Published: February 2023

A new ionospheric measurement concept using a bistatic lidar is described for the Tethered Satellite System (TSS) and the Space Shuttle as first suggested by McComas and Spence.1 This technique will utilize low power lasers in the Shuttle bay. Lightweight photometers with small electrical consumption will be placed on the sub-satellite to be deployed on a tether towards the earth. Ranges will be from 20 to 100 kilometers from the Shuttle with a minimum sustainable altitude of approximately 130 km. The long duration of this mission offers unique opportunities for a global mapping of trace species in the 100-150 km altitude region. This technique offers sensitivities not currently available using ground-based or space-based instrumentation and provides opportunities for long-term monitoring at altitudes not accessible to non-tethered satellites. The two main lidar components are the following:
Doppler Lidar Observations in Thunderstorm Environments
Authors: McCaul Eugene W. , Bluestein Howard B. , Doviak Richard J.
Published: February 2023

On 30 June 1981, the wind fields around a variety of convective clouds, ranging from large thunderstorm complexes to isolated cumulus congestus, were observed in some detail using an airborne Doppler lidar operated by the National Aeronautics and Space Administration (NASA) and a reasonably clear picture of the main features of the flow fields near several clouds have been obtained.
Far-Infrared Measurements of Stratospheric Trace Species
Authors: Chance K. V. , Lin F. J. , Traub W. A.
Published: February 2023

This paper presents the current state of results from our program of balloon-borne far-infrared spectroscopy of the stratosphere. The instrumentation used in these observations consists of a two-beam Fourier transform spectrometer, which receives thermal emission radiation from the atmosphere by means of a telescope that is accelerometer- and gyroscope-stabilized to 0.02° in absolute elevation. The spectrometer is operated over the range 80-220 cm-1, with an unapodized resolution of 0.032 cm-1. The field of view on the sky is 0.3°, corresponding to a sampling width of less than 1/3 atmospheric scale height when used in a limb-scanning manner to probe the atmosphere below the altitude of the balloon platform.
Application of Coherent Lidar to Remote Sensing of Atmospheric Species*
Authors: Killinger D. K. , Menyuk N.
Published: February 2023

The use of a pulsed, coherent-detection LIDAR for the remote sensing of atmospheric species is of current interest. Coherent (heterodyne)- detection offers significant advantages, in principle, over direct-detection in expected carrier-to-noise ratios and detection ranges. However, attempts to achieve these predicted advantages have been limited by a variety of experimental problems. This paper will discuss some of these problems, including laser tunability, speckle effects, and tracking of the local oscillator frequency.
Remote and Selective Detection of Natural Gas Leaks Using a Frequency Mixed CO2 Laser
Authors: van der Laan Jan E. , Rosengreen Arne , Altpeter L. L.
Published: February 2023

Improved detection of natural gas leaks is of interest to the gas industry. At present, gas survey trucks sample the air at the street surface. The air is then fed through a flame ionization detector (FID) for the detection of methane that may have leaked from a gas line below the street. This method is relatively slow, because the truck can move only a few miles per hour, and is limited in that it cannot make remote measurements of areas that are inaccessible to the truck. Furthermore, the FID reacts to any hydrocarbon in the air, causing false alarms.
High Power CO2 Laser System for Pulsed Lidar Applications
Authors: Moody S.E. , Znotins T.A. , Byron S.R. , DeHart T.E.
Published: February 2023

The utility of carbon dioxide lasers, both cw and pulsed, is now well proven in a variety of remote sensing applications. The remote sensing of atmospheric wind velocity, using Doppler coherent lidar techniques, is one such application. The range and data acquistion rate of such lidars has previously been limited by the pulse energy and average power available from properly frequency stabilized CO2 lasers.
The Upper Atmosphere Research Satellite (UARS)
Authors: Reber Carl A.
Published: February 2023

The Upper Atmosphere Research Satellite (UARS), to be launched in late 1991, will provide a detailed look at the physical and chemical processes controlling ozone in the Earth's upper atmosphere. It will produce comprehensive state-of-the-art measurements of ozone and key members of the nitrogen, hydrogen, and chlorine chemical families, as well as energy inputs, temperature, and wind fields in the stratosphere, mesosphere, and lower thermosphere. The scientific payload includes one microwave and two infrared emission limb sounders for determing vertical profiles of trace species and temperature, an infrared solar occultation sensor for minor species, two high resolution interferometers for doppler wind measurements, two full-disk solar spectrometers, and a high energy particle monitor. The UARS Science Team is composed of the nine investigator groups responsible for instruments, plus ten investigator groups providing additional capability in the areas of data analysis and interpretation. A dedicated distributed data system provides a powerful capability for data processing, storage, scientific analysis, and communications. An extensive effort to utilize correlative measurements, both for instrument data validation and for complementary scientific studies, is expected to foster wide-spread cooperative efforts in the use and analysis of UARS data.
Calibration and Stability Requirements for Trend Detection from Satellites
Authors: Gille John C.
Published: February 2023

The measurement of long term trends from satellite instruments requires careful attention to many details. Examples drawn from the Ozone Trends Panel will be discussed.
Lidar in Space
Authors: McCormick M. P.
Published: February 2023

The use of lidars in space to study the Earth's atmosphere and its surface has been proposed for a number of years, but none have flown to date. These proposals date back to the mid-1970's, with U.S. proposals to fly aboard skylab, shuttle, Air Force meteorological satellites, and most recently, NASA's polar orbiting platform and space station. European and Russian proposals over these years have also been put forth. These efforts have mostly proposed a phased approach where the initial flight or flights would concentrate on aerosol and cloud measurements at single or multiple wavelengths. Subsequent flights would incorporate gaseous measurements, usually H2O, utilizing differential absorption techniques. In parallel with these atmospheric measurement efforts, proposals have been put forth to utilize doppler techniques to measure tropospheric winds, and to use accurate ranging techniques to measure crustal deformations, and ice sheet and land topography.
Lite Laser Design and Architecture
Authors: Storm Mark E. , Barnes Norman P.
Published: February 2023

The LITE instrument is a shuttle-based lidar system that will be used to determine global distributions of aerosols. LITE will make quantitative measurements of cloud tops, tropospheric and stratospheric aerosols, and temperature. The first step in achieving global lidar coverage for measuring atmospheric constitutients important for understanding the earth's biosphere, is to design, build and fly a space-qualified Nd:YAG lidar system1. This paper will discuss the analytical and experimental results of the NASA/Langley LITE laser transmitter design which minimizes parasitic lasing, size, and weight while maximizing efficiency and reliability.
FIRS-2 Measurements of Halogen and Nitrogen Species in the Stratosphere
Authors: Chance K. V. , Traub W. A. , Johnson D. G.
Published: February 2023

The FIRS-2 instrument consists of a Fourier transform spectrometer with 0.004 cm−1 (un-apodized) resolution and 6.8 × 10-3 cm2 sr throughput, a feed telescope, and a ±0.02° stabilized pointing system for measurements of the stratospheric emission spectrum from a balloon platform. Measurements are currently made in the far infrared, from 70-220 cm−1, and in the mid infrared, from 350-700 cm−1. The instrument is flown on a gondola provided and supported by the Jet Propulsion Laboratory. FIRS-2 has had 4 successful flights, taking place in fall 1987, spring 1988, spring 1989, and fall 1989. The mid infrared channel was first operated successfully during the balloon flight of May 15, 1989. The balloon flights which yielded the results presented here are from the flights of May 12-13, 1988 and May 15-16, 1989.
Measurement of Marine Tropospheric Aerosol Backscatter Coefficients with an Airborne Coherent Lidar
Authors: Menzies Robert T. , Tratt David M.
Published: February 2023

Since 1984 the Jet Propulsion Laboratory has been developing a heterodyne-detection pulsed CO2 lidar instrument for airborne deployment aboard the NASA DC8 research aircraft during the NASA GLOBE (Global Backscatter Experiment) campaigns scheduled for the Fall of 1989 and Spring of 1990. The GLOBE program essentially comprises a survey of tropospheric aerosol information in remote marine environments, this to assess worst-case background scenarios in support of the Laser Atmospheric Wind Sounder (LAWS) intended for launch in the late 1990s as part of the International Space Station/Earth Observing System concept.
Simultaneous Retrieval of Atmospheric Parameters Using Parallel Processing
Authors: Sparks L. , Patterson J. E. , Fanselow J. L.
Published: February 2023

Remote sensing instruments to be flown on planned NASA missions will generate unprecedented quantities of data. It is essential that these data be processed rapidly and the results conveyed quickly to the scientific community. Such considerations mandate substantial advances in current techniques for analyzing data. In particular major improvements in both computation technology and numerical analysis methods are necessary. We examine the extent to which sequential parameter estimation can be used to automate and expedite the retrieval of atmospheric parameters from remote sensing data.

Our algorithm utilizes a square root information filter to retrieve the vertical profiles of trace gases from spectroscopic data. The algorithm permits simultaneous retrieval of many atmospheric parameters such as species abundance, atmospheric temperature, atmospheric pressure, and water vapor profiles. Implementation of this algorithm in a parallel processing environment should result in dramatic increases in the rate at which data can be analyzed.
Total Ozone Trends using Internally Calibrated TOMS Data
Authors: Stolarski R.S. , Herman J.R. , Hudson R.D. , Krueger A.J. , McPeters R.D. , Wellemeyer C.G. , Taylor S.L.
Published: February 2023

For the past two decades much concern has been focussed on the question of possible changes in the stratospheric ozone layer induced by human activity. The primary long-term record of the amount of stratospheric ozone has been obtained via ground-based measurements by Dobson spectrophotometers based at a few tens of stations located mostly at northern mid latitudes. In addition to the sparseness of this network f or, global coverage, these Instruments show drifts relative to one another which are minimized by comparison to a world standard instrument which is calibrated each year at Mauna Loa. The solution to the problem of obtaining truly global trends is to couple this ground-based system with satellite-based remote sensing.
Aspects of the SAGE III/Eos Water Vapor Retrieval
Authors: Larsen J.C. , Chu W.P. , McCormick M.P. , Rind D.
Published: February 2023

The utility of the solar occultation remote sensing technique for providing accurate, high vertical resolution, global distributions of aerosols and atmospheric gases is now well established following a number of space flight experiments; SAM II (McCormick et al., 1979), SAGE (McCormick et al., 1979), and SAGE II (McMaster, 1986). The Stratospheric Aerosol and Gas Experiment (SAGE III) will continue these measurements through the Eos era. SAGE III has been chosen for definition phase study(phase B) for both the NASA Polar Orbiting Platform (NPOP) and the Space Station Freedom Attached Payload (SSF/AP) of Eos. Like SAGE II, SAGE III will measure aerosols, ozone, nitrogen dioxide, and water vapor. Enhanced measurement capabilities include coverage of the oxygen-A band from which pressure and temperature profiles will be inferred (Chu et al., 1990), additional aerosol channels, and an additional channel for mesospheric ozone. Spectral coverage of the water vapor band will be expanded to most of the band at higher resolution. Twenty radiometric channels, each with 2 nm spectral resolution, provide contiguous coverage from 920 nm to 960 nm. This paper examines how the multiple channel measurements may be best used to minimize uncertainties in the retrieved water vapor and to optimize vertical coverage.
High Precision Cavity Detector Performance
Authors: Hoffman James W.
Published: February 2023

A new cavity detector has been developed for high precision earth radiation monitoring from space. The detector has a flat spectral response from 0.2 to 100 microns with 100% linearity over the full dynamic range. The detector features a sensitivity improvement of more than an order of magnitude over previous similar detectors. Several detector modules and a complete set of breadboard electronics were built and tested by Space Instruments, Inc. as part of a NASA funded development program. A photograph of one of the detector modules with an integral preamplifier is shown in Figure 1.
Edge Technique for Lidar Wind Measurement with Incoherent Detection
Authors: Korb C. Laurence , Gentry Bruce M.
Published: February 2023

The edge technique is a powerful new method for the detection and measurement of small frequency shifts. It can be used with a pulsed laser to measure the Doppler shift of an atmospheric backscattered signal and to thus obtain range resolved measurements of winds with high accuracy and high vertical resolution. The technique can be used at near-infrared or visible wavelengths using well developed solid state lasers and detectors.
Lidar Research in the Antarctic
Authors: Stefanutti L.
Published: February 2023

Lidar Research in the Antarctic goes back to the second part of the seventies. Two applications have immediately appeared: 1) study of the structure of tropospheric clouds 2) study of the aerosol loading of the Polar Stratosphere Both ground based lidar and airborne lidars have been operated.