bluuebunny/crossref_metadata_2025 huggingface dataset:
High Energy VUV Pulse Generation by Frequency Conversion
Authors: Dlabal M. L. , Reintjes J. , Tankersly L. L.
Published: February 2023

The efficiency with which VUV radiation can be generated by frequency conversion has been limited by various competing processes to values that are typically of the order of 0.1 - 0.3%. As a result, increases in available VUV pulse energy will have to be made through increases in the pump laser energy. However, the use of higher pump laser power can be accompanied by additional limitations associated with various experimental parameters, especially in the VUV where tight focusing and short interaction lengths are usually used. For example the larger focal spots that must be used with stronger pump lasers to avoid breakdown are necessarily accompanied by longer interaction paths that can make absorption in the nonlinear medium and damage to cell windows more important. We have conducted a series of experiments in third harmonic conversion of XeF laser radiation in Xe to determine the extent to which the additional problems associated with high pump power can be overcome. Our initial experiments, done at a pump energy of 20 to 30 mJ (2 MW peak power) have indicated that the conversion efficiency, which was measured to be of the order of 5 x 10−4, was limited by a combination of breakdown in the focus and absorption of the VUV radiation in the Xe downstream from the nonlinear interaction. The corresponding pulse energy was measured to be of the order of 10 μJ without phase matching. Further increases in VUV pulse energy can be accomplished with a combination of phase matching and increased pump energy. Our initial measurements with phase matched mixtures of Xe and Ar indicate that the conversion efficiency increases by a factor of about 2 when a 5:1 Xe:Ar mixture is used. Further improvements in phase matching, the use of various gas combinations and their effects on breakdown and absorption limitations will be discussed. Scaling of our current results indicate that the conversion efficiency can be raised from 2 x 10−4 to 10−3 with a corresponding increase in VUV energy to 1 mJ if the pump energy is raised to 250 mJ and the nonlinear medium can be confined to the region of the nonlinear interaction. The usefulness of various gas confinement techniques for the conditions required by our high pump laser power (large apertures, long interaction paths) will be described and the results of conversion efficiency measurements at high pump energy will be reported.
Frequency Conversion Processes in Hydrogen
Authors: Gontier Y. , Trahin M.
Published: February 2023

Multiphoton Raman-like transitions taking place above and below the ionization threshold of an atom can be useful for generating energetic photons of well-defined energies. In these processes, the atomic electron makes a bound-bound transition. It first absorbs N photons of the incoming light and then reemits a photon whose energy depends on N and on the discrete final state.
Laser Induced Energy Transfer in Highly Excited States in Molecules
Authors: Lukasik Jacques , Wallace Stephen C. , Green William R.
Published: February 2023

Processes involving high-energy molecular states are experimentally demonstrated using multiphoton excitation techniques.
Recombination Lasers in the Vacuum Ultraviolet
Authors: Silfvast W. T. , Wood O. R.
Published: February 2023

Isoelectronic scaling of known laser transitions to higher ion stages1 has recently been shown to be a useful technique for scaling electron-ion recombination lasers, produced in expanding plasmas, to shorter wave-lengths2. The observation of laser action on a sequence based upon the 4f-5d transition in Ag I (1832 nm), Cd II (537.8 nm) and In III (298.3 nm) is perhaps the clearest example of this technique to date.2 Another sequence, based upon the 4f-3d transition in Li I (1870 nm) (recently observed in laser action in a segmented plasma arc3 device) and Be II (457.4 nm) (reported earlier4) suggests possible new recombination lasers in B III (207.7 nm) and C IV (116.8 nm).
Transform-Limited Bandwidth Injection Locking of an XeF Laser
Authors: Bigio Irving J. , Slatkine Michael
Published: February 2023

Injection locking of excimer lasers has been shown1 to be the most efficient way to control the spectral and spatial output of these high-gain systems. We have previously reported injection locking of a KrF system with very lower reference oscillator power, and in this paper we report the injection locking of an XeF laser to transform-limited bandwidth(~ 50 MHz for a 20-ns pulse). Injection locking of XeF has been previously reported,3 but the reference oscillator used was another XeF laser yielding a relatively broadband output linewidth of 0.2 Å (~ 100 GHz).
Resonantly-Pumped Soft X-ray Lasers Using ICF Drivers
Authors: Hagelstein Peter. L.
Published: February 2023

Simulations of soft X-ray laser targets irradiated with 100 psec pulse of 1.06μ light at 2−4 × 1014 W/cm2 indicate that small signal laser gain between 10 and 50 cm−1 may be obtained on 4-3 transitions in helium-like F and Ne (42.3 eV and 53.6 eV) as well as on 3-2 transitions in helium-like and hydrogenic F and Ne (119 eV-153 eV). Resonances include the Na X/Ne IX resonance near 11.000 Å as well as several L-shell/K-shell resonances (for example, Be-like Cr (13.779 Å)/He-like F (13.782 Å)).
Generation of Vacuum Ultraviolet Radiation by Plasma Nonlinearities
Authors: Carman R. L.
Published: February 2023

Early experimental work1 and numerical studies2 have examined the production of more than fifty harmonics (212 nm) of the CO2 laser in laser matter interaction studies carried out at Los Alamos within the laser fusion program. Initially it was believed that pressure balance between hydrodynamic plasma expansion and radiation pressure was responsible for a substantial density jump near critical, leading to the limitation on the number of harmonics produced.2 While still believed to be important, more recent CO2 laser studies3 have revealed that early-time hydrodynamics when combined with the laser skin depth can play a very significant role in the producton of high harmonics for CO2 laser matter interaction experiments conducted at high irradiances.
Optical Techniques for Use with Soft X-ray and XUV Radiation
Authors: Attwood D. T. , Ceglio N. M.
Published: February 2023

The application of x-ray and XUV radiation to a wide range of interesting biological and physical phenomena will require not only sources of radiation, but also the availability of appropriate "optical" components and techniques for manipulation, transport and detection. Recent technological advances, driven by widely differing scientific requirements, primarily in the areas of micro-electronics and hot, dense plasma studies, have led to broad based and rapidly emerging capabilities in this area. The fabrication of structures with characteristic dimensions on the scale of soft x-ray wavelengths (10 to 100's Å) is now possible. These diffractive elements are opening new opportunities with laboratory and astrophysical x-ray sources, as x-ray interference mirrors and splitters, x-ray lenses, transmission gratings and microscopes. Their use with quasi-coherent radiation sources in x-ray interference and holographic experiments will provide exciting new possibilities. In addition, parallel efforts have led to improved detectors, including picosecond soft x-ray streak cameras.
Pulsed Hollow Cathode Discharge for XUV Lasers and Radiation Sources
Authors: Falcone R. W. , Holmgren D. E. , Pedrotti K. D.
Published: February 2023

Recent proposals for short wavelength (< 1000 Å) lasers1 have indicated a need for new types of electric discharge devices which produce significant densities of highly excited atoms and ions. In particular, the proposal of Harris1 for a laser at 200 Å using the doubly excited states of lithium requires the production of excited atoms in states with ~ 60 eV energy at densities ≥ 1012 atoms/cm3. This Letter reports the operation of a pulsed hollow cathode discharge (HCD) which creates population densities of 4 × 1012 ions/cm3in the lithium ion 1s2s 3s level at 59 eV above the ion ground state, Li+ (1s2 1S). Population densities of other relevant levels as well as electrical characteristics of the HCD have been measured.
Vacuum Ultraviolet Spectroscopy of Molecules Using Third-Harmonic Generation in Rare Gases
Authors: Miller John C. , Cooper C. D. , Compton R. N.
Published: February 2023

We describe a simple apparatus for spectroscopic studies in the vacuum ultraviolet (VUV) spectral region which is based on third-harmonic generation (THG) in rare gases. The apparatus, shown in Fig. 1, consists of three chambers, each of which functions as a proportional counter. Light from an N2-pumped dye laser is focused into the first chamber containing the tripling gas. The VUV radiation is then collimated and passed through a sample cell containing flat-plate electrodes and into the third chamber. This last cell acts as a VUV photon detector via the photoelectric effect. In all three chambers electrons, produced by ionization, are amplified in a counter gas and detected at the electrodes.
FEL Generation of Extreme Ultraviolet Coherent Radiation: Theoretical Aspects
Authors: Renieri A.
Published: February 2023

The main features of the interaction between free-electrons and electromagnetic (e.m.) waves have been deeply investigated in these last years, in connection with FEL dynamics. The first approach to the FEL topics was done in a quantum mechanical framework. In spite of this fact, the most interesting results were obtained by using completely classical approaches. This kind of treatment, which is well justified for the up to now developed FEL sources (infrared and visible radiation), can become no more adequate in the extreme UV spectral region. In this paper the validity limits of the classical approach are investigated. It is found that low electron energy operation with small wavelength pump wave may require the quantization of the electron motion, while the high energy and long pass undulator devices can be treated satisfactorily with classical mechanics. Furthermore, the coherence properties of the emitted radiation are studied. For these topics too, the classical or quantum character of the electron motion plays a crucial role. In particular, it is possible to show that, when a "semi-classical" treatment can be done (i.e., quantized radiation and classical electron) the e.m. field coherent states preserved by the FEL interaction are the same as the ones of standard lasers, i.e. the harmonic oscillator coherent states (Glauber states). Finally, the very short wavelength FEL operation is investigated by accounting for the limitation coming from electron beam energy spread and emittance. It comes out that recirculated FEL devices (i.e., Storage Ring FELs) may have, under this point of view, performances better than the single pass ones.
Proposal for a Free Electron Laser in the X-Ray Region
Authors: Colella R. , Luccio A.
Published: February 2023

The purpose of this paper is to show that a Free Electron Laser (FEL) can be operated in x-ray region (2-3 Ångstroms) provided that suitable machine parameters can be realized. The main problem appears to be in the optics of the system. Are there mirrors that can reflect x-rays with reflectivities greater than 90%? We have investigated the reflectivity properties of silicon perfect crystals Bragg diffracting x-rays at θ = 90°, using dynamical theory of x-ray diffraction. Our analyses show that, for example, the (422) reflection has a reflectivity greater than 91% at 90°, over an angular range of 5.0 minutes of arc, at λ = 2.217 Å. The mirrors can be bent into spherical shapes without loss of reflectivity. For a FEL oscillator to work in the 2 - 3 Å region, the undulator should have a period of 2 cm., a magnetic field of 0.2 T, an electron energy between 3.0 and 3.5 GeV, with a spread ΔE/E less than 10−3, for an undulator 6 m long, with 300 periods. The emittance ε should be kept below 2 × 10−9 m-rad. A gain go = 0.215 can be obtained1-2 at λ = 2.5 Å with a current IO = 0.5 Å in one bunch, and an accelerating voltage of 4 MV, with a harmonic number equal to 1000. The power available from such x-ray FEL should be 250 watts,2 on average, with a peak value of 4 × 106 watts. Alternate schemes based on ring geometry will also be discussed.
A Linac-Driven XUV Free-Electron Laser
Authors: Newnam Brian E. , Goldstein John C.
Published: February 2023

An XUV free-electron laser (FEL) driven by a linear accelerator appears to be feasible for wavelengths as short as 50 nm. This projection is based upon the anticipated successful use of high peak-current (~100 A) linacs in forthcoming FEL oscillator experiments at infrared and visible wavelengths at Los Alamos and Boeing/Mathematical Sciences Northwest. As an alternative to schemes involving storage rings, a linac provides a train of individual electron bunches separated by 10-100 ns and duration of 10-30 ps. Further, electrons pass through the undulator magnet only once, but their remaining energy may be recovered in a separate decelerating structure and fed back into the primary accelerator.
Free-Electron Lasers in the X-Ray Region: General Design Considerations
Authors: Gea-Banacloche Julio , Moore Gerald T. , Scully Marlan O.
Published: February 2023

We consider possibilities for operating a free-electron laser at a wavelength of about 5 Å. At this wavelength a Bragg crystal ring resonator can provide feedback, but since the losses are large, large gain per pass is needed. We calculate the regimes of wiggler wavelength, wiggler length, and electron energy where large gain is obtainable.
High Resolution Fourier Transform Infrared Spectroscopy of small gaseous Molecules and solid Hydrogen
Authors: Winnewisser Manfred
Published: February 2023

The high resolution Fourier Transform Interferometer of the Giessen laboratory has been equipped in recent years by extensive auxiliary technology. This technology includes a setup for a molecular jet, a large multipass cell with base length of 4 m which is capable of producing an absorption path length of 350 m.
Fourier Transform Spectroscopy of Minor Atmospheric Constituents
Authors: Temsamani M. Abbouti , Bach M. , Carleer M. , Clerbaux C. , Colin R. , El Youssoufi Y. , Errera Q. , Guilmot J.-M. , Herman M. , Hurtmans D. , Reniers B. , Vandaele A.-C. , Vander Auwera J.
Published: February 2023

This paper presents an overview of the work performed in our laboratory and aimed at providing information concerning minor constituents of the earth atmosphere by means of Fourier transform spectroscopy in absorption. It involves the laboratory study of minor atmospheric constituents in the spectral region extending from the far infrared to the visible as well as the in situ measurement of the abundance of such species in the atmosphere through their visible/UV absorption.
FTS into the VUV: Progress up the wavenumber scale
Authors: Thorne Anne
Published: February 2023

The main demand for high quality spectral data in the VUV region comes from astrophysicists working on spectra produced by high resolution satellite-borne spectrometers - notably the GHRS on Hubble Space Telescope. The existing laboratory data base has proved both inaccurate and inadequate for the analysis of these spectra - e.g. ref.1. Requirements for wavelengths and energy levels accurate to about 1 part in 106 (0.3 km/sec) and for isotope splittings comparable with Doppler widths can be met only by the high resolution offered by FTS. There is also a demand from atmospheric physicists for fully resolved molecular absorption spectra yielding accurate wavelengths and cross-sections that can be used in line-by-line modelling of the penetration of VUV radiation into the upper atmosphere.
Fourier Transform Absorption Spectroscopy in UV and VUV Regions
Authors: Yoshino K. , Murray J.E. , Esmond J.R. , Parkinson W.H. , Thorne A.P. , Cox G. , Learner R.C.M.
Published: February 2023

In the region 250-175 nm the penetration of solar radiation into the atmosphere is controlled by the absorption cross sections of O2bands. Part of the radiation transmitted in this vacuum ultraviolet wavelength region is available to photodissociate minor species including NO. The molecular absorption processes and parameters related to the absorption of ultraviolet solar radiation in the terrestrial middle atmosphere have been discussed by a number of authors. For accurate modelling of this important process, the computations involving O2and minor species must be performed on a line-by-line basis; laboratory-measured photoabsorption cross sections, with resolution sufficient to yield true cross sections(i.e.undegraded by instrumental effects), are required for both molecules. For most of the Schumann-Runge (S-R) bands of16O2and its important isotopic variants, such measurements have been successfully completed [Yoshinoet al. ,1983; 1987; 1990].
A New Airborne Fourier Transform Spectrometer for Meteorological Applications
Authors: Giroux Jean , Villemaire André , Saunders Roger W.
Published: February 2023

Bomem is currently integrating ARIES (Airborne Radiometer Interferometer Evaluation System), a Fourier transform (FT) interferometer to be installed in a pod of the UK Meteorological Office Hercules C-130 aircraft. This new infrared (IR) instrument has numerous science goals. First it will provide invaluable data to help refine IR radiative transfer models such as FASCODE. It will also help characterize the emissivity and the surface temperature of sea and ground under various conditions (snow, ice, etc.). The IR spectral signature holds a wealth of information so that other physical properties of the atmosphere such as clouds and aerosol effect can also be studied. Retrieval of total column amount of some of the atmosphere minor constituents will be possible as well. Data from the ARIES instrument is also foreseen to be used to support the development of advanced atmospheric sounders such as IASI (IR Atmospheric Sounding Interferometer, a Franco-Italian project) and AIRS (Advanced IR Sounder, a NASA project).
Application of Doppler Michelson imaging to upper atmospheric wind measurement: WINDII and beyond
Authors: Shepherd Gordon G.
Published: February 2023

The electro optical revolution that began at the Laboratoire de Bellevue in France led aeronomers to realize the potential of the Fabry-Perot spectrometer for measurement of upper atmospheric temperature from Doppler line widths of atomic oxygen emission in airglow. An alternative offering much greater responsivity is the field-widened Michelson interferometer; for reviews see Ring and Schofield (1972) and Baker (1977).
MIPAS, a Balloon- and Satellite-Borne Limb Emission Experiment
Authors: Fischer Herbert
Published: February 2023

The balloon-borne MIPAS (Michelson Interferometer for passive atmospheric sounding) yielded already ozone-relevant information on stratospheric trace gas profiles while the corresponding satellite instrument is still being constructed.
Atmospheric Measurements of Transient Species Using the Fourier Transform Ultraviolet Spectrometer (FTUVS)
Authors: Sander Stanley P. , Cageao Richard P. , Blavier Jean-Francois , McGuire James P. , Chave Robert L. , Al-Jumaily Ghanim , Natzic David
Published: February 2023

A new, compact Fourier Transform Michelson interferometer (FTUVS) with an unapodized spectral resolution of 0.07 cm-1 has been developed for field and laboratory measurements of trace gas-phase species in the UV through visible region (200-800 nm). The instrument uses a flex pivot swing carriage mechanism driven by a voice coil actuator with a maximum translation of 5 cm. Essentially frictionless motion is achieved with high mirror velocity stability (rms velocity error less than 0.01%). Residual alighment errors are corrected dynamically to 0.1 μrad using a servo-controlled piezoelectric mirror tilt mechanism. The mirror moves at a constant velocity controlled by a commercial HP Laser Positioning System servo-axis driver which uses a 2.1 MHz Zeeman split, linearly polarized two-frequency He-Ne laser. The Doppoer shifted beam from the arm with the moving mirror is compared to the laser reference frequency for measurement and control of the mirror velocity.
Asymmetric Fourier Transform Spectrometer Line Shapes: Review of Possible Causes
Authors: Blavier Jean-François
Published: February 2023

Observed spectroscopic features can exhibit a natural asymmetry if they result from the superposition of lines from the same atom or molecule at different pressures [1] or with different Doppler shifts. Examples of varying Doppler shifts are given by winds in planetary atmospheres [1] or by convection in stars [2]. In the absence of these effects, for example when one is measuring the absorption spectrum of a gas in a cell, the resulting line shape should be symmetrical.
Laboratory FTS Measurements in Support of Space Programs
Authors: Varanasi Prasad
Published: February 2023

Anthropogenic trace gases such as chloro-fluoro-carbons (CFCs) CFC-11 (CFCl3) and CFC-12 (CF2Cl2),1,2the hydro-chloro-fluoro-carbon HCFC-22 (CHFCl2),3and sulfur hexaflouride (SF6),3having been in extensive worldwide use in many industrial applications and possessing either a strong ozone-depletion potential4or a global-warming potential,5-7or both, have posed a threat to the welfare of our planet. Recognition of this fact has led to significant curtailment, if not total banishment, of their use globally. However, as recent satellite observations8have shown, decline in their atmospheric concentrations is not immediate. The marked depletion of ozone which has been observed in recent years at high latitudes has made infrared remote sensing of the atmosphere an activity of high priority.8-11The success of any infrared remote-sensing experiment conducted in the atmosphere depends upon the availability of accurate, high-resolution, spectroscopic data that are applicable to that experiment. This paper presents a preliminary phase of a multi-faceted work using a Fourier-transform spectrometer (FTS) which is in progress in our laboratory. The concept of how laboratory-borne measurements can be geared toward obtaining a database that is directly applicable to sattelie-borne remote sensing missions is the main thrust of this paper which addresses itself to ongoing or planned international space missions.
Accuracy of FT-Measurements of Spectral Intensities - an Issue Relevant for Remote Sensing
Authors: Birk Manfred
Published: February 2023

In the last decade high resolution FT-IR spectrometers have become increasingly important for remote sensing of the stratosphere. While the number of observations from space and stratospheric balloons is still small there is already a large number of ground based instruments measuring ozone and a variety of important trace gases. Most of the ground based instruments work in solar occultation (transmittance measurement) within the Network for Detection of Stratospheric Change whereas instruments measuring thermal emission of radiation are rare. For source photon noise limited observation the sensitivity of an emission measurement is better if the optical band width is larger than about 1-10 cm-1. Furthermore, emission measurements have a larger versatility since they are independent from the time of day.
Long Path Tropospheric Absorption Measurements using the NOAA Fritz Peak FTS
Authors: Brault James W. , Harder Jerald W.
Published: February 2023

In 1993, a high resolution (.0034 cm-1) FTS was developed at Fritz Peak Observatory (18 km west of Boulder, CO) to provide CO abundance measurements for an OH intercomparison campaign. These measurements made use of a 121-element retroreflector array situated near Caribou Mine 10.3 km away, giving a total optical path of 20.6 km at a mean height of about 2.8 km above sea level (see Figure). Recently, the instrument has been used for a general survey of tropospheric absorbance in this mountain airmass, which is relatively clean during times of westerly airflow but may show significant pollution during times of easterly upslope flow from the Front Range urban corridor. These measurements were primarily in the 4000-6700 cm-1 region. The new principles involved in the design of this instrument have already been published1, and more details will appear later; here we will discuss some preliminary results.
A Fourier Transform Cavity Ring Down Spectrometer
Authors: Engeln Richard , Meijer Gerard
Published: February 2023

A novel multiplex absorption spectrometer is presented, in which the sensitivity of the cavity ring down absorption technique is combined with the multiplex advantage of a FT-spectrometer.
Time-Resolved Fourier Transform Emission Spectroscopy of Transient and Excited Molecules
Authors: Dai Hai-Lung
Published: February 2023

A combination of fast detectors and a step-scan FT spectrometer allows emission spectra from a low density sample be recorded with 10 ns and sub-cm-1 resolution. This ability enables the characterization of rovibronic spectroscopy and collisional kinetics of transient and excited molecules.
Sounding Retrieval from Upwelling and Downwelling Infrared Interferometer Radiance Measurements
Authors: Ho S.-P. , Smith W. L. , Huang H.-L.
Published: February 2023

During the past thirty years considerable progress has been made in passive infrared remote sensing of vertical temperature and moisture profiles. Unfortunately, passive soundings have not processed the accuracy required for forecast models (Bengtsson, 1979).
Fourier-transform Emission Spectroscopy of Molecular Transitions in the Near-Infrared
Authors: Fink Ewald H. , Chemie Fachbereich
Published: February 2023

Emission spectra of transitions from low-lying metastable electronic states of diatomic radicals have been studied in the NIR region with high-resolution BOMEM or BRUKER Fourier- transform spectrometers. Different groups of radicals and types of transitions have been studied, - a1Δ(g)→X3Σ-(g) and b1Σ+(g)→X3Σ-(g) transitions of radicals of the O2/NH/NF family, - a3Σ-(u)(a11(u))→X1Σ+(g)(X0+(g)) transitions of group VA diatomics (BiN, BiP, BiAs, BiSb, Bi2, Sb2), - transitions between the fine structure components of widely split X2Π or x3ς ground states of metal hydrides, halides and chalcogenides (BiH, BiX, BiY, TeH, TeX, PbX; X=F,Cl,Br,I; Y=O,S,Se).
High Performance Fourier Transform IR Ellipsometer
Authors: Luttmann Michel , Stehle Jean-Louis , Piel Jean-Philippe , Boher Pierre
Published: February 2023

Spectroscopic ellipsometry is a well established technique for the optical characterization of bulk materials, deposited thin films and surface layers [1]. It is based on the measurement of the change of the polarization state of light after reflection on a sample. This change is directly related to the complex ratio ρ defined by : ρ = r
p
/ r
s
= tanψe
j
Δ , where r
p
and r
s
are respectively the reflection coefficients of the waves parallel and perpendicular to the plane of incidence. A. Rosëler has been the first to combine Fourier transform spectrometer (FTS) to a classical rotating polariser or analyser ellipsometer [2]. The optical set-up of such an apparatus consists of a light source, an Michelson interferometer, a polariser, a sample, an analyser and a detector set. The accuracy of this ellipsometer is affected by polarization defects of the different components, particulary those of the wire grid used as polariser and analyser. Many procedures have been proposed recently to take into account imperfect components [2,3,4] such as interferometric residual polarization, polariser and analyser non nul attenuation coefficients and detector set dichroism. However, those procedures have some limitations and do not take in consideration the detector set non linearity. Our new ellipsometer is based on SOPRA’s compagny rotating analyser ellipsometer VASE-FTIR model 3 [5]. The use of special polariser and analyser allowed us to get an accuracy better than 1% in straight line without sample on the sample holder. We have observed however a slight shift on the cosΔ spectrum. This behaviour is induced by the detector set non linearity. Assuming a quadratic non linearity we have been able to correct the ellipsometric spectrum in real time. The accuracy in straight line reaches a few 1/1000 over the whole spectral range, which is very good in the IR.
High Index Gradient in Glass by Ionic Exchange
Authors: Coutaz J.L. , Jaussaud P.C.
Published: February 2023

Gradient index of 0.2 has been obtained in a TiF6 Schott Glass by ion exchange technique. High diffusion rate was observed. Index profiles and ionic concentrations will be presented.
Diffusion Behavior of Doped Polarizable Ions in Glass During Ion-exchange Process
Authors: Kitano I. , Nishizawa K. , Momokita A.
Published: February 2023

It is well-established that by applying ion-exchange technique, the gradient refractive index distribution is produced in a glass rod due to the diffusion of doped electro-polarizable ions. In this paper, the dopant concentration profiles were deduced by computer simulation under the various diffusion constants which depend differently on the dopant concentration. The refractive index distribution converted from the dopant concentration profile was compared with the index profile measured by differential interference microscope and the diffusion behavior of doped ions was investigated.
Development of Fiber Array with Wider View Angle
Authors: Akazawa Noboru , Toyama Minoru , Matsushita Kazuo
Published: February 2023

We have developed the graded index fiber (known as SELFOC lens, trade name) with Cs as dopant constituting graded refractive index. Graded index fiber array with the SELFOC lenses arranged linearly (known as SELFOC lens array or SLA) is widely used in the optical system of copying machines. The half view angle of SLA (θ) is 6°.
Recent Developments in Gradient Index Guided Wave Optics
Authors: Nutt Alan C.G. , Nishizawa Koichi
Published: February 2023

The development of multi-mode fibre systems has been largely limited by insertion loss and fabrication difficulties when realising even the simplest of components using optical fibres. An alternative technique is to make use of guided wave optics to realise these components. Since these components can be mass produced the main points to be considered in component evaluation are insertion loss and operational capability.
Comparison of Two Interferometric Methods for Wave Aberration Measurement in Distributed-Index Microlens
Authors: Batubara John E. , Iga Kenichi
Published: February 2023

Since the performance of every optical component is directly influenced by the existence of aberration, the measurement of wave aberration is essential in characterizing such components. Interferometry is one of the effective methods to obtain a clear information on the performance of such lenses.
Modelling, Design Optimization and Fabrication of Guided-Wave Photonic Devices in Glass
Authors: Yip Gar Lam
Published: February 2023

Design optimization is very important to achieve high performance of integrated optical devices. For accurate designs, detailed information on the characteristics of slab and channel guides made in glass substrates must be known in relation to their fabrication conditions since these waveguides often form the basic units in more complicated waveguide structures used in devices. This paper will outline the characterization and modelling procedures of such waveguides, and present the methodology of design optimization of waveguide devices. In particular, the beam propagation method (BPM) combined with the effective index method (EIM) will be discussed. Illustrative examples will be given on power dividers, wavelength multi/demultiplexers and vertical directional couplers made by K+-ion exchange in glass. Comparisons between the measured performance figures of fabricated devices and design predictions will be presented.
Use of a Prism Coupler for the Determination of the Index Profiles of Ion-Exchanged Channel Waveguides
Authors: Weiss Martin N. , Srivastava Ramakant
Published: February 2023

The K+-Na+ ion-exchange process (IEP) has long been recognized as an attractive technique for producing high-quality, low loss, graded refractive index (GRIN) optical waveguides in glass substrates. Devices produced by this technique are index compatible with silica fibers, and as a result, this technology has received considerable attention as a means of producing low-insertion loss integrated optic devices for use in fiber communications networks.1 Accurate design of such devices, generally comprised of one or more channel waveguides, requires a thorough characterization of the waveguide-forming process. Although planar K+-Na+ IEP waveguides have been studied extensively2, to date however, only limited characterization of channel waveguides has been performed.
New method for measuring the distribution of refractive index in blanks for GRIN optical elements
Authors: Gerasimova L.A.
Published: February 2023

Characterization of refractive index distribution in optical materials is an important problem in the fabrication of glass blanks for GRIN optical elements. Most of the existing methods for such characterization have different disadvantages. For example, all methods of deviated beam depend on the accuracy of the distance measurements which are always limited by the radius of the laser beam scanning along the sample. Interference methods based on using a Mach-Zehnder interferometer can be used only for optical materials with small gradients of refractive index because of resolution limitations. Their disadvantage is also sensitivity to vibrations and temperature variations decreasing the accuracy of measurements.
The Large Dimensional Radial Grin Polymer
Authors: Wu Shang Pin , Nihei Eisuke , Koike Yasuhiro
Published: February 2023

Recently, the optical technology has progressed with various kinds of materials. The graded index optical materials are expected as rod lens, low chromatic aberration lens, and high bandwidth optical fibers1)-3) etc. Nowadays, most of practically used GRIN material are made by inorganic materials. On the other hand, it has been reported that the GRIN material can be synthesized by organic material more easily and mildly than inorganic materials4). Regardless of the inorganic or organic materials, the GRIN materials so far have only the small size in diameter as ϕ =10 mm, which is too small to be used as eyeglasses or camera lenses.
Spherical Aberration of a Schematic Eye with a Grin Crystalline Lens in Several Accommodation States
Authors: Melgosa M. , Poza A. , Hita E. , Gómez-Reino C.
Published: February 2023

In a previous work1 we analyzed the spherical aberration of LeGrand’s unaccommodated theoretical eye2 modified by several GRIN crystalline-lens models. That effort has been complemented by the present work, in which we consider several theoretical eyes, with different states of accommodation, in a search for a more detailed analysis of the influence in the spherical aberration of both a homogeous/GRIN crystalline model and a spherical/aspherical corneal surface.
A New Put-in Micro-connector-II Using GRIN Microlenses
Authors: Kato T. , Baba T. , Iga K.
Published: February 2023

For the realization of future large-scale optical fiber communication systems, one of the most important issues is the light coupling between optical fibers and optical components, e.g., semiconductor lasers, OEIC’s, optical waveguides, and optical couplers. However, the individual alignment of optical components for high efficiency optical coupling needs precise adjustment, and several authors have reported on integrated couplers [1] [2]. However, most of them still require some level of precise alignment.
Numerical Investigation of Spherical Gradient Index Microlenses with the Wave Propagation Method
Authors: Singer W. , Brenner K.-H. , Testorf M.
Published: February 2023

The ion exchange process in glass is an important fabrication method for waveguides as well as for gradient index microlenses [1]. The diffusion response and therefore the shape of the gradient index distribution is variable due to many exchange parameters. Different glass-types and different exchange pairs, showing different degree of non-linearity of the exchange process influence the steepness of the profiles, whereas the symmetry of the index-distribution is changeable by mask-design [2]. For the user of microlenses as well as for the manufacturer, it is important to know the imaging properties of the different index profiles.
Reduction and Enlargement using Unity Magnification Gradient-Index Lens Arrays
Authors: Rees James , Loce Robert
Published: February 2023

Arrays of gradient-index lenses are commercially available as Selfoc® lens arrays from the Nippon Sheet Glass Co. The lenses are radial gradient cylinders that are arrayed in a parallel fashion, and thus are necessarily confined to unity magnification (1×) imaging. A primary application of Selfoc lens arrays has been in personal and engineering drawing photocopiers copiers that operate at only unity magnification. For other light-lens photocopiers, in addition to unity magnification, reduction and enlargement copying has become a universal customer requirement that is now generally considered a standard feature. In an attempt to broaden the applicability of Selfoc lens to more general office copying needs, a reduction/enlargement gradient-index lens array has been developed and previously described in Ref. 1. This R/E Selfoc has certain short comings; only one value of reduction and its reciprocal for enlargement are possible, and it is limited to relatively small field sizes (original/copy) such as B4/A4 paper combinations with magnifications in the range of 70-140%. Finally, image quality varies across the field, being lower at the edges than at the center.
Mueller matrix polarization imaging and quantitative parameters analysis method
Authors: Yin Qiyuan , Gao Wanrong , Chang Ying
Published: February 2023

Mueller matrix polarization imaging is a new biomedical optical imaging method that can generate both polarization and isotropic intensity images of structures of the biological tissue sample surface. In this paper, a Mueller polarization imaging system in the reflection mode is described for obtaining the Mueller matrix of the specimens. Diattenuation, phase retardation, and depolarization of the specimens are derived by using the conventional Mueller matrix polarization decomposition method and a newly proposed direct method. The results show that the direct method is more convenient and faster than the conventional decomposition method. The polarization parameter combination method is then presented in which any two of the diattenuation, phase retardation, and depolarization parameters are combined, and three new quantitative parameters are defined in order to reveal more detailed anisotropic structures. The images of in vitro samples are presented to demonstrate the capability of the parameters introduced.
Phase-assisted Bessel-metasurface: a single-sized approach for simultaneous printing and holography
Authors: Chen Kuixian , Li Zile , Guan Zhiqiang , Li Jiaxin , Dai Qi , Fu Rao , Deng Liangui , Cui Hao , Zheng Guoxing
Published: February 2023

Due to the unprecedented wavefront shaping capability, the metasurface has demonstrated state-of-the-art performances in various applications, especially in printing and holography. Recently, these two functions have been combined into a single metasurface chip to achieve a capability expansion. Despite the progress, current dual-mode metasurfaces are realized at the expense of an increase in the difficulty of the fabrication, reduction of the pixel resolution, or strict limitation in the illumination conditions. Inspired by the Jacobi-Anger expansion, a phase-assisted paradigm, called Bessel metasurface, has been proposed for simultaneous printing and holography. By elaborately arranging the orientations of the single-sized nanostructures with geometric phase modulation, the Bessel metasurface can not only encode a greyscale printing image in real space but can reconstruct a holographic image in k-space. With the merits of compactness, easy fabrication, convenient observation, and liberation of the illumination conditions, the design paradigm of the Bessel metasurface would have promising prospects in practical applications, including optical information storage, 3D stereoscopic displays, multifunctional optical devices, etc.
New model of glucose-insulin regulation characterizes effects of physical activity and facilitates personalized treatment evaluation in children and adults with type 1 diabetes
Authors: Deichmann Julia , Bachmann Sara , Burckhardt Marie-Anne , Pfister Marc , Szinnai Gabor , Kaltenbach Hans-Michael
Published: February 2023

Accurate treatment adjustment to physical activity (PA) remains a challenging problem in type 1 diabetes (T1D) management. Exercise-driven effects on glucose metabolism depend strongly on duration and intensity of the activity, and are highly variable between patients. In-silico evaluation can support the development of improved treatment strategies, and can facilitate personalized treatment optimization. This requires models of the glucose-insulin system that capture relevant exercise-related processes. We developed a model of glucose-insulin regulation that describes changes in glucose metabolism for aerobic moderate- to high-intensity PA of short and prolonged duration. In particular, we incorporated the insulin-independent increase in glucose uptake and production, including glycogen depletion, and the prolonged rise in insulin sensitivity. The model further includes meal absorption and insulin kinetics, allowing simulation of everyday scenarios. The model accurately predicts glucose dynamics for varying PA scenarios in a range of independent validation data sets, and full-day simulations with PA of different timing, duration and intensity agree with clinical observations. We personalized the model on data from a multi-day free-living study of children with T1D by adjusting a small number of model parameters to each child. To assess the use of the personalized models for individual treatment evaluation, we compared subject-specific treatment options for PA management in replay simulations of the recorded data with altered meal, insulin and PA inputs.
Preliminary effectiveness and implementation outcomes of the IMARA-South Africa sexual health intervention on adolescent girls and young women: A pilot randomized trial
Authors: Merrill Katherine G. , Atujuna Millicent , Emerson Erin , Blachman-Demner Dara , Bray Bethany C. , Bekker Linda-Gail , Donenberg Geri R.
Published: February 2023

Family-based interventions may help reduce the risk of HIV and other sexually transmitted infections (STI) among adolescent girls and young women (AGYW) in sub-Saharan Africa but few have been tested. We examined the preliminary effectiveness and implementation outcomes of Informed, Motivated, Aware, and Responsible Adolescents and Adults—South Africa (IMARA-SA), an evidence-based intervention for South African AGYW (15–19 years) and their female caregivers. We piloted IMARA-SA in the Western Cape using an individually randomized experimental design and average follow-up at 11 months. Primary outcomes were HIV Testing and Counselling (HTC) uptake, STI incidence (gonorrhea, chlamydia), and pre-exposure prophylaxis (PrEP) uptake. Secondary outcomes were self-reported sexual risk behavior (condom use at last sex, consistency of condom use, substance use during sex, and number of sexual partners) and PrEP adherence. We examined four implementation outcomes: reach, feasibility, acceptability, and fidelity. Data from 59 AGYW (mean = 17.2 years) were analyzed at baseline (n = 29 from IMARA-SA, 30 from a health promotion control group). At follow-up, 51 (86%) completed surveys and 39 (66%) presented for HTC, STI testing, and/or PrEP. Compared to controls, fewer IMARA-SA participants tested positive for an STI (22% versus 38%), more IMARA-SA participants took up PrEP (68% versus 45%), and four of five secondary outcomes favored the IMARA-SA group at follow-up. These differences did not reach statistical significance. HTC uptake at follow-up was 100% in both groups. All AGYW-FC dyads agreed to participate in the study (reach). In the IMARA-SA group, 76% of dyads completed the intervention (feasibility), and over 76% of acceptability ratings from AGYW and their FC had the highest Likert rating. Fidelity of intervention delivery was 95%. IMARA-SA is a promising strategy for reducing HIV/STI risk among South African AGYW. We found strong evidence of reach, feasibility, acceptability, and fidelity. A fully powered randomized controlled trial is warranted.

Trial registration: Clinical trials.gov registration number: NCT05504954.
Efficacy of intralesional meglumine antimoniate in the treatment of canine tegumentary leishmaniasis: A Randomized controlled trial
Authors: Lago Jamile , Fraga Deborah , Guimarães Luiz Henrique , Lago Tainã , Santos Yuri , Lago Ednaldo , Werneck Guilherme L. , Bacellar Olívia , Carvalho Edgar M.
Published: February 2023

Dogs living in areas of Leishmania (Viannia) braziliensis transmission may present canine tegumentary leishmaniasis (CTL) characterized by cutaneous or muzzle ulcers as well as asymptomatic L. braziliensis infection. It is not clear if dogs participate in the transmission chain of L. braziliensis to humans. However, dogs may remain with chronic ulcers for a long time, and as there are no public policies about CTL, these animals die or are sacrificed. Here we compare the efficacy of intralesional meglumine antimoniate with intralesional 0.9% NaCl solution in CTL treatment. This randomized control study included 32 dogs with cutaneous or muzzle lesions who had L. braziliensis DNA detected by PCR in tissue biopsied. Group one received 5ml of intralesional Glucantime, and group two received 5ml 0.9% NaCl solution, both applied in the four cardinal points on days 0, 15, and 30. Cure was defined as complete healing of the ulcers in the absence of raised borders on day 90. There was no difference in animals’ demographic and clinical features in the two groups (p >.05). While at the endpoint, the cure rate was 87.5% in the group test, and in those who received 0.9 NaCl the cure rate was only 12.5%. As important as the high cure rate, the healing time was faster in dogs treated with antimony than in those treated with saline (p < .001). Intralesional meglumine antimoniate is effective in the treatment of dogs with L. braziliensis infection and accelerates the healing time of CTL.
Precise language responses versus easy rating scales—Comparing respondents’ views with clinicians’ belief of the respondent’s views
Authors: Sikström Sverker , Pålsson Höök Alfred , Kjell Oscar
Published: February 2023

Background

Closed-ended rating scales are the most used response format for researchers and clinicians to quantify mental states, whereas in natural contexts people communicate with natural language. The reason for using such scales is that they are typically argued to be more precise in measuring mental constructs; however, the respondents’ views as to what best communicates mental states are frequently ignored, which is important for making them comply with assessment.

Methods

We assessed respondents’ (N = 304) degree of depression using rating scales, descriptive words, selected words, and free text responses and probed the respondents for their preferences concerning the response formats across twelve dimensions related to the precision of communicating their mental states and the ease of responding. This was compared with the clinicians’ (N = 40) belief of the respondent’s view.

Results

Respondents found free text to be more precise (e.g., precision d’ = .88, elaboration d’ = 2.0) than rating scales, whereas rating scales were rated as easier to respond to (e.g., easier d’ = –.67, faster d’ = –1.13). Respondents preferred the free text responses to a greater degree than rating scales compared to clinicians’ belief of the respondents’ views.

Conclusions

These findings support previous studies concluding that future assessment of mental health can be aided by computational methods based on text data. Participants prefer an open response format as it allows them to elaborate, be precise, etc., with respect to their mental health issues, although rating scales are viewed as faster and easier.