bluuebunny/crossref_metadata_2025 huggingface dataset:
Particle image velocimetry for flow analysis in mechanical artificial heart valves
Authors: Castellini P. , Pinotti M. , Scalise L.
Published: February 2023

Red blood cell damage (hemolysis) and thromboemblism are the main complications associated to the implantation of mechanical artificial heart valves.

In the last decades a great number of in vitro studies have been conducted to improve the design and to understand the transvalvular flow patterns under steady state and pulsatile conditions. Steady state tests are useful to study the flow established upstream and downstream the valve prosthesis in the moment of the peak flow rate.

In the present study, Particle Image Velocimetry (PIV) technique was employed to visualise the flow patterns in a precommercial model of bi-leaflet mechanical heart valve prosthesis in a steady state flow. PIV technique and a convenient test rig have provided good conditions to investigate the whole flowfield upstream and downstream the valve.
Enhancement of optoacoustic tissue contrast with absorbing nanoparticles
Authors: Oraevsky Alexander A. , Karabutov Alexander A. , Savateeva Elena V.
Published: February 2023

Laser induced phase transition in the water surrounding absorbing nanoparticle results in dramatic enhancement of the thermoacoustic efficiency and excitation of high-amplitude pressure waves. Feasibility study was performed in tissue phantoms. Experiments supported with theoretical model demonstrated possibility to increase the efficiency of optoacoustic generation in tissue up to two orders of magnitude by application of absorbing carbon and gold nanoparticles.
A dedicated acoustic / acousto-optic imaging system
Authors: Selb Juliette , Pottier Lionel , Lévêque-Fort Sandrine , Boccara Albert-Claude
Published: February 2023

Acousto-optic imaging in strongly light-scattering tissues seeks to reveal optical contrasts in these turbid media. Nevertheless, this technique happens to be also sensitive to their acoustic contrasts. We have built a new setup combining a dedicated echograph and an acousto-optic imager in a single apparatus. Thanks to this setup, we have studied ultrasound absorbent and light absorbent features embedded in several centimeter thick biological tissues, and we have compared for the first time the acoustic and acousto-optic signals recorded in the same configuration. We show that even though optical contrast is the ultimate goal of this technique, preliminary acoustic investigation of the tissue is necessary to interpret correctly acousto-optical signals.
Coating Strategy for Enhancing Illumination Uniformity in a Lithographic Condenser
Authors: Gaines David P. , Vernon Stephen P. , Sommargren Gary E. , Kania Donald R.
Published: February 2023

A three-element Köhler condenser system has been fabricated, characterized, and integrated into an EUV lithographic system. The multilayer coatings deposited on the optics were designed to provide optimal radiation transport efficiency and illumination uniformity. Extensive EUV characterization measurements performed on the individual optics and follow-on system measurements indicated that the condenser was operating close to design goals. Multilayer d-spacings were within 0.05 nm of specifications, and reflectances were approximately 60%. Illumination uniformity was better than ±10%. The broadband transport efficiency was 11%.
The Elusive Diffraction Limit
Authors: Williamson David M.
Published: February 2023

Aberrations smaller than the classical diffraction limit of Rayleigh or Marechal are shown to cause significant losses in depth of focus and critical dimension control.
Specification of the Figure and Finish of EUV Mirrors in Terms of Performance Requirements
Authors: Church E. L. , Takacs P. Z.
Published: February 2023

This paper describes the diffraction-theory relationships between mirror errors and their imaging performance. Results are illustrated for the practical case of fractal-like topographic errors.
Quartz Substrates for EUV Lithography Reticles
Authors: Kania D. R. , Weber F. J. , Vernon S. P. , Hawryluk A. , Baker S. L. , Golub A. M. , Shikata A. , Grady E. C.
Published: February 2023

A EUVL reticle blank was fabricated on a specially polished quartz blank. The stress-induced distortion of the multilayer coating was unacceptably large. The distortion can be effectively eliminated by coating the backside of the reticle blank with an identical coating. This strategy has the potential to eliminate multilayer induced stress distortion for the reticle blank in a manner which is compatible with the existing reticle fabrication infrastructure.
Discussion of Mask Alignment Accuracy for EUV Lithography
Authors: Saito Yasuyuki
Published: February 2023

The shorter lithography printing light source wavelength is, the more accurate alignment is required for resist printing of high packing density integrated circuits (ICs). As to longer wavelength light source than extremely ultraviolet, view systems of alignment mark are sophisticated by using video camera system. However, it seems that it is difficult to sophisticate EUV mask-aligner alignment view system due to shorter light wavelength. Actually, old mask aligner systems such as contact aligners of Cobilt, projection aligners of Perkin Elmer, and direct steppers of GCA have alignment process visualisation for human eye by using cut off filters of UV light. However, EUV use also requires alignment system accuracy in order to increase EUV use value for high packing density on a IC chip. Since, EUV can not be visible for human naked eyes and detection of EUV is relatively difficult, the author thinks that implement of direct view alignment system by using EUV light source is difficult. However, since only use of printing of mask pattern such as printing of grating do not need accurate alignment or alignment itself, EUV lithography printing without alignment process is relatively easily applicable to grating photolithography. Since energy of EUV light is higher than that of UV, it may be necessay to treat or consider prevention against resonant turbulence of edges of photomask metal thin film patterns and photoresist small-size contact hole resonance interferences due to nuclear body resonance vibrations, by intentionally additions of heavy nuclei such as heavy impurites of metals. Through discussion on various kinds of mask aligner alignment processes, EUV lithography processes will be discussed.
Conversion Efficiency and Debris Studies of Ice Targets for EUV Projection Lithography
Authors: Jin F. , Richardson M.
Published: February 2023

Laser produced plasmas from solid metal targets have been shown to produce bright EUV radiation with conversion efficiencies of up to 1.8%1 within the bandwidth of 0.3 nm at the wavelength of 13 nm, a favored wavelength choice for projection lithography2. However, a severe heretofore problem associated with laser plasma has been the presence of debris particles. These debris particles form deleterious thin coatings on any surface with direct line of sight to the plasma at rates which would quickly destroy the reflectivity of multilayer collector optics in envisioned lithography system. This problem has been recognized for some time3 and measures, such as low pressure gas interdiction4 and the use of a fast shutter system5, have been devised to counteract this deposition effect. In addition, special target designs, such as thin tape targets5,6 and a cryogenic Xe target7, are also under investigation in attempts to reduce the yield of debris production from laser plasmas.
Extreme Ultraviolet Moiré Interferometry
Authors: La Fontaine B. , White D. L. , MacDowell A. A. , Tan Z. , Tennant D. M. , Wood O. R.
Published: February 2023

One of the major challenges facing the extreme ultraviolet (EUV) projection lithography program is realizing high resolution, diffraction limited imaging. Even though near diffraction-limited images have been obtained with different systems, at λ =14 nm1 and λ =42 nm2, a precise, quantitative characterization of the imaging capabilities of these cameras is still lacking. In this paper, we present a new test done at λ = 139Å that should provide very precise measurement of the aberrations and alignment errors of a multi-layer coated EUV camera.
Mass-producible microtags
Authors: Sweatt William C. , Descou Michael R. , Ray-Chaudhuri Avijit K. , Krenz Kevin D. , Tichenor Daniel A. , Stulen Richard H. , Warren Mial E. , Kravitz Stan H.
Published: February 2023

The microtag concept has been developed for security purposes. Microtags can be mass-produced using an advanced extreme-ultraviolet lithography (EUVL) tool currently under development at Sandia National Laboratories in Livermore. This method of fabrication results in features small enough (down to 100 nm) to deter most attempts at counterfeiting. Microtags may therefore be used to protect integrated circuits, currency, credit cards, and smart cards.
Image Degradation from Surface Scatter in EUV Optics
Authors: Gaines D. P. , Daly T.P. , Stearns D.G. , LaFontaine B. , Sweeney D.W. , Chapman H.C. , Fuchs D.
Published: February 2023

Synchrotron-based 13 nm measurements of scatter from individual mirrors and an assembled imaging system for Extreme Ultraviolet Lithography have been compared to a model of image formation in the presence of scatter. The theory uses a Power Spectral Density description of the constituent optics to describe modifications to the image due to scatter. Reasonable agreement between measurements and theory was obtained for both individual mirrors and the assembled system.
An Advanced EUV source from water droplet laser plasma
Authors: Jin F. , Richardson M. , Shimkaveg G. , Torres D.
Published: February 2023

We describe the operation of a laser-plasma EUV source that satisfies
all the requirements for projection lithography at 13 nm or 11.6 nm.
We demonstrate that this source, based on mass-limited water droplets
as a laser plasma target is essentially debris-free, produces
narrow-line EUV emission, is continuous in operation and is
practically cost less.
Optical Technology for EUV Lithography
Authors: Ito Masaaki , Katagiri Souichi , Yamanashi Hiromasa , Seya Eiichi , Ogawa Taro , Oizumi Hiroaki , Terasawa Tsuneo
Published: February 2023

A high-throughput optical system that has a bouncing number of only four, including a reflective mask, was designed. The illumination system is comprised of a single tilted-ellipsoidal mirror, that is suitable for a two-aspherical-mirror ring-field imaging system. A prototype optical system was evaluated using synchrotron radiation at the Photon Factory. The experimental results combined with calculations have indicated that a throughput of 15 to 20 wafers/h can be obtained by using the optical system in combination with a compact storage ring. In addition, 0.12-μm line-and-space patterns were delineated in parts of the ring field. The use of alternating and attenuated reflective phase-shifting masks is also discussed to enhance the resolution of EUV lithography.
Lithography for Manufacturing Integrated Circuits Beyond 180 nm
Authors: Gleason R. E.
Published: February 2023

The integrated circuit industry will continue to rely on optical lithography to print patterns as small as 130 nm, and will try to extend its capability to even smaller dimensions. This will require improved mask technology, whose development has lagged the other elements of optical lithography. Potential successors to optical lithography need significantly more complicated masks, and those with large reduction ratios have an advantage. The most difficult technical challenges they face are to make masks without defects, and to keep them clean.
Surface characterization of optics for EUV lithography
Authors: Gaines D. P. , Sweeney D.W. , DeLong K.W. , Vernon S.P. , Baker S.L. , Tichenor D. A. , Kestner R.
Published: February 2023

The surface topography of optics fabricated for Extreme Ultraviolet Lithography has been measured using a combination of phase-measuring interferometery and atomic force microscopy. Power Spectral Densities were computed over spatial frequencies extending from 2.0×10-8 nm-1 to 7.7×10-2 nm-1. Roughness values for frequencies greater than 1.0×10-6 nm-1 were 0.64 nm rms for a spherical optic and 0.95 nm rms for an aspheric optic. These values are significantly larger than 0.088 nm rms, which as obtained using a spherical optic representative of current limits in surface polishing technology.
Initial Experiments on Direct Aerial Image Measurements in the Extreme Ultraviolet
Authors: Fields C.H. , Oldham W.G. , Ray-Chaudhuri A. K. , Krenz K. D. , Stulen R. H.
Published: February 2023

We report the current status of research to apply the technique of direct aerial image monitoring (AIM) to measure the performance of an Extreme Ultraviolet Lithography (EUVL) test bed. There are several issues which might limit the possibility of performing image monitoring experiments on EUVL systems. These issues include: Source flux, signal to noise ratios, and EUV scanning aperture fabrication.
Development of extreme ultraviolet interferometry for laser plasma source operation
Authors: Ray-Chaudhuri A. K. , Krenz K. D. , Nissen R.P. , Haney S.J. , Fields C.H. , Sweatt W. C. , MacDowell A.A.
Published: February 2023

When characterizing an extreme ultraviolet (EUV) lithographic optical system, visible light interferometry is limited to measuring wavefront aberration caused by surface figure error while failing to measure wavefront errors induced by the multilayer coatings. This fact has generated interest in developing interferometry at an EUV camera's operational wavelength (at-wavelength testing), which is typically around 13 nm. While a laser plasma source (LPS) is being developed as a lithography production source, it has generally been considered that only an undulator located at a synchrotron facility can provide the necessary laser-like point source for EUV interferometry. Although an undulator-based approach has been successfully demonstrated, it would be advantageous to test a camera in its operational configuration. We are developing the latter approach by utilizing extended source size schemes to provide usable flux throughput. A slit or a grating mounted at the source plane can provide the necessary spatial coherence for lateral shearing interferometry. The usable source size is limited only by the well-corrected field of view of the camera under test. The development of this interferometer will be presented.
A 3-D Numerical Study of Pinhole Diffraction to Predict the Accuracy of EUV Point Diffraction Interferometry
Authors: Goldberg K. A. , Tejnil E. , Bokor J.
Published: February 2023

A three-dimensional (3-D) electromagnetic field simulation is used to model the propagation of extreme ultraviolet (EUV), 13 nm wavelength, light through sub-1500 Å diameter pinholes in a highly absorptive medium. Deviations of the diffracted wavefront phase from an ideal sphere are studied within 0.1 numerical aperture, to predict the accuracy of EUV point diffraction interferometers used in at-wavelength testing of nearly diffraction-limited EUV optical systems. Aberration magnitudes are studied for various 3-D pinhole models, including cylindrical and conical pinhole bores.
Surface Imaging Resists: Promises, Practices and Prospects
Authors: Hanratty Maureen
Published: February 2023

Surface imaging technology has the potential of providing enhanced
resolution, larger process latitude and extending the capabilities of
optical lithography tools. Surface imaging resist (SIR) processing in
the form of the DESIRE process has been used at Texas Instruments for
some time. Originally developed for g-line exposure tools (436 nm), it
is now being used to push the capabilities of a 248 nm DUV stepper. In
this paper the advantages of SIR are reviewed, the current practices
described, and prospects for the future applications discussed.
Multiply Charged Ions Produced by Multiphoton Absorption
Authors: L'Huillier A. , Lompre L.A. , Mainfray G. , Manus C.
Published: February 2023

The production of multiply charged ions induced by collisionless multiphoton absorption in rare gas atoms has been investigated using an intense 50 p sec laser pulse. Doubly charged ions are produced in helium and neon with a 1064 nm laser pulse in the 1014 - 1015 Wcm-2 range. Up to Ar3+ ions are produced in Ar, Kr4+ ions in Kr and Xe5+ ions in Xe with a 1064nm laser pulse in the 1013 - 1014 Wcm-2 range. The laser intensity dependence of the production of multiply charged ions has been investigated for the five rare gases /1/. At least 146 photons, a value equivalent to 170 eV, have to be absorbed by a Xe atom at 1064 nm to explain the production of Xe5+ ions. The basic absorption mechanism of so many photons by such multi-electron atoms is not yet well understood.
Planetrary Atoms
Authors: Cooke William E. , Freeman Richard R. , Jopson Robert M. , Bokor J.
Published: February 2023

Planetary atoms1, which have two highly excited electrons, are expected to exhibit new phenomena because the interelectron interaction can be as great as the central force which binds either electron. Angular correlations are expected to be particularly significant as the available phase space increases and as the e-e interaction becomes more anisotropic. We have used a four photon excitation technique2 in conjunction with mass specific ionic detection to populate and identify msns, 1So states of barium having energies between 105,000cm-1 and 114,000cm-1.
Grotrian Diagram of Core-Excited Quartets in Na I
Authors: Holmgren D. E. , Walker D. J. , King D. A. , Harris S. E.
Published: February 2023

Using Hartree-Fock calculations and laser enhanced fluorescence experiments, we have identified 28 visible and near-UV Na emission lines as radiative transitions between core-excited states of Na I 2p53s3p, 3s4s, and 3s3d configurations. The resulting energy level diagram is consistent with these lines and two previously identified Na quartet lines at 3882 Å and 5071 Å.1,2
Use of Synchrotron and Laser Radiations for Present and Future Ionization Studies in Excited Atoms and Ions
Authors: Wuilleumier F.J.
Published: February 2023

The study of photoionization processes in excited atoms requires the use of two different photon sources: the one to prepare the atoms in specific initial states and the other one to photoionize these excited states. With the advent of high-power frequency-tunable lasers, it has been possible to prepare a sizable stationary fraction of valence excited atoms and to laser-ionize these laser excited states. However, available laser energies and tunability ranges have restricted these experiments to outer electrons of alkali- and alkaline-earth atoms.1 In some atoms placed into excited states by means of a pulsed laser, inner-shell photoabsorption has been studied by using ultraviolet continuum radiation from a BRV source.2
Efficient Generation of Tunable Radiation below 100 nm in Krypton
Authors: Bonin Keith D. , Morris Mark B. , McIlrath T. J.
Published: February 2023

Tunable, narrowband (< .3 cm−1) coherent radiation below 100 nm will be reported. The vacuum ultraviolet photons were generated by making use of the first available two-photon resonance in Krypton [the 4p6 1S0 - 5p(2-1/2)2 two photon resonance at 216.7 nm] to resonantly enhance the process.
Photoionization Lasers Pumped by Broadband Soft-X-Ray Radiation from Laser-Produced Plasmas
Authors: Silfvast W. T. , Wood O. R. , Macklin J. J. , Lundberg H.
Published: February 2023

Large population inversions have been obtained in Cd1 and Zn ions by using broadband soft-x-ray radiation from laser-produced plasmas to photoionize and thereby remove inner-shell d electrons from the atoms. This technique has presently produced lasers in the ultraviolet, visible and near infrared. The use of optical pumping techniques to transfer the population to higher lying levels may produce VUV and XUV lasers in the same and other species. Gains as high as 40 cm-1 and inversions as high as 1015 cm-3 have been produced in the present lasers. These large inversions suggest extraction energies approaching one mJ/cm3 may be possible for both the visible lasers and also for the transfer lasers operating at shorter wavelengths.
Dynamical Aspects of the Picosecond X-ray Generation from Laser-Produced Plasmas
Authors: Kuroda Hiroto
Published: February 2023

Systematic studies of the generation of picosecond x-ray pulses from laser-produced plasmas are performed experimentally and theoretically. The present understanding of dynamical aspects of transient x-ray generations are reviewed.
Laser-Induced Ionization of Na Vapor: A new Mechanism for Producing Na2+
Authors: Robert Wu C. Y. , Judge D. L. , Roussel F. , Carré B. , Breger P. , Spiess G.
Published: February 2023

The production of Na2+ ions by off-resonant laser excitation in the 5800-6200 Å region mainly results from two-photon absorption by the Na2 molecule to highly excited gerade states followed by (a) direct ionization by absorbing a third proton or (b) coupling to the molecular Na2 D1πu Rydberg state which is subsequently ionized by absorbing a third photon. This mechanism, i.e., a two-photon resonance three photon ionization process, explains a recent experimental observation of Roussel et al.[1] It is suggested that the very same mechanism is also responsible for a similar observation reported by Polak-Dingels et al.[2] in their work using two crossed Na beams. In the latter two studies the laser-induced associative ionization processes were reported to be responsible for producing the Na2+ ion. From the ratio of molecular to atomic concentration in the crossed beam experiment [2] we estimate that the cross section for producing Na2+ through laser-induced associative ionization is at least four orders of magnitude smaller than ionization through the two-photon resonance three photon ionization process in Na2 molecules.
Laser-Induced Continuum Structure in Multiphoton Ionization Spectroscopy
Authors: Coleman P E , Elgin J N , Knight P L , Burnett K
Published: February 2023

Multiphoton processes with significant continuum contributions are enhanced by exploiting autoionizing resonances embedded in the continuum by configuration interaction (1). Tunable "embedding" can be induced by radiative coupling from an initially empty discrete state; such "pseudoautoionizing” states can be shifted and broadened at will.
Space resolved spectra of 2p-3d multiplets of Al XI and Al X....
Authors: Khan M.A. , Tallents G. J.
Published: February 2023

The spectra of 2p-3d multiplets of Al XI and Al X emitted from plasmas produced from 9 μm thick Al foils were recorded with spatial resolution ≃30 μm. The measurements are of interest in plasma diagnostics as well as in our search for suitable lasing transitions in the XUV {1}.
A Soft X-Ray Source Based on the Magnetic Confinement and Compression of a Laser Produced Plasma
Authors: Crawford E.A. , Hoffman A.L. , Quimby D.C.
Published: February 2023

The physics of laser heating of dense plasmas produced by irradiation of solid targets, and of underdense (Ne < critical density) plasmas has attracted considerable interest in recent years. Experiments at MIT1 and at MSNW have recently demonstrated radial magnetic confinement of a solid target plasma plume produced by radiation from a 10.6μ CO2 laser. Presently generated plumes of moderate Z ions are at 100 eV temperatures, 1018 cm−3 densities, and last about 100 nsec. The addition of a simple z-pinch could compress the plume to 1019 cm−3 densities and 600 eV temperatures where it would be an extremely efficient generator of K or L-shell x-rays in the 1-2 keV range. The efficiency and simplicity of such a device, plus the proven physics of the laser plume generation hold great promise for commercial microlithography applications.
Population Density and VUV Gain Measurements in Laser-Produced Plasmas
Authors: Dixon R. H. , Seely J. F. , Elton R. C.
Published: February 2023

Population density inversions in laser-produced plasmas between hydrogenic and helium-like carbon ion energy levels were obtained from measured resonance line comparisons1,2. Such measurements have been extended to absolute flux from which the densities of potential lasing transitions are deduced. From this and the line width the gain coefficient can be derived. This becomes a vital gauge diagnostic in increasing the gain towards significant amplification by parameter variation for increased ion density and increased pumping. Calibration of the vacuum spectrograph for absolute intensity determinations is performed in the near-uv against a standard D2 lamp and transferred to the 4 nm wavelength region by an in-situ branching ration technique involving resonance as well as high-lying transitions. Gains measured in electron-capture pumped plasmas are in agreement with a simple physical model from which parameter scaling is readily conceptualized. Expansion of the parameter space available for significant gain is predicted for higher-Z targets and for supplementary photon pumping.
Generation of Narrow-Band Tunable Radiation in the 1200A Spectral Region
Authors: Tomkins F. S. , Mahon R.
Published: February 2023

In an extension of previous work1,2 on the efficient (up to 1%) generation of vacuum ultraviolet radiation in mercury vapor, we now report the generation of continuously tuneable, narrow-band (0.02 cm−1) radiation in the spectral region of 1218Å to 1197Å. The mechanism is a resonantly enhanced 4-wave sum-mixing process

6

s

21

s
o

2

ω
1

→

6

s7s

1

s
o

ω
2

→

6

snp

1

P
1

ω
3

→

6

s

21

s
o

where the ω3 radiation is generated about the 12p through the 16p1P1 transitions of Hg. The ω2 coumarin 520 dye laser is pumped by the third harmonic of a Nd:Yag laser, currently producing only 0.2 mJ of laser light which is tuneable from 5000 to 5500Å. The ω1 laser at 6250Å is pumped by the remaining second harmonic of the Nd:Yag giving 0.8 mJ when frequency doubled to 3125Å. We are confident that these input energies will he increased substantially when the appropriately coated optics are acquired. Using a 25 cm focal length achromat to focus the beams into a Hg cell at 140°C (2 Torr), with 10 Torr of helium as buffer gas, we measure the generated photons in an NO ionisation chamber. The generated power peaks up substantially in the immediate vicinity of the np 1P1 transition frequencies and, even though hydrogen Lyman α is almost exactly midway between the 11p and the 12p transition, we measure 2×109 photons per pulse in this 10 pps system. At the nearby 12p 1P1 frequency (1212.65Å) we see 2×1011 photons per pulse. We will show absorption profiles scanned through hydrogen Ly α (1215.67Å), deuterium Ly α (1215.34Å) and also through the resonance triplet of atomic nitrogen at 1199.55Å, 1200.22Å, and 1200.71Å. A careful examination of the wavelengths involved lead to the conclusion that the transition line frequencies listed in the Moore tables for the 15p and the 16p1P1 levels of Hg are off. We measure the 15p level to be at 83273.5 cm−1 whereas the Moore tables give 83280.5 cm−1. Similarly, the 16p is measured at 83407.7 cm−1 in comparison with the tabulated frequency of 83420.3 cm−1.
Fourier Transform Emission Spectroscopy
Authors: Bernath Peter F.
Published: February 2023

We have found Fourier transform infrared emission spectroscopy to be a powerful technique. Many transient molecules have infrared electronic transitions. For example we observed a new metal nitride, YN1, by detection of the A1Σ+- X1Σ+ electronic transition near 3900 cm-1. The YN molecules were made in a yttrium hollow cathode lamp with a trace of N2 added.
Time-resolved Fourier-transform Infrared Emission Study of the 193-nm Photolysis of 3-Pentanone
Authors: Preses J.M. , Hall G.E. , Muckerman J.T. , Weston R.E.
Published: February 2023

Small and medium-sized ketones are of interest due to their rich chemistry and involvement in practical combustion mechanisms. Further, the primary products of their dissociation, such as ethyl radicals and carbon monoxide in the present case, are themselves important combustion species. The photochemistry of ketones has been extensively investigated both by classical photochemical techniques, and more recently by methods that provide detailed information about the dissociation process and the disposition of energy in the fragments.1 Acetone is the simplest ketone and serves as an excellent model for extending these studies to higher ketones. Recently, a number of investigations of acetone photodissociation have been carried out using pulsed UV radiation at 193 nm from an excimer laser. The next higher symmetrical analogue of acetone is 3-pentanone (diethylketone), and its photochemistry has also been investigated using classical techniques.2 No investigations of 3-pentanone photolysis at shorter wavelengths or attempts to determine energy disposal among the fragments have been reported. A comparison of the photodissociation dynamics with those of the smaller ketone acetone should be illuminating. With this goal in mind, we have examined the photodissociation of diethylketone using our time-resolved FTIR apparatus, a commercial interferometer combined with a CAMAC-transient-digitizer-based data acquisition and storage system.3 One hundred interferograms were collected at 1-µs intervals; the laser was fired at the twentieth interval. The signal-to-noise ratio was further enhanced by combining our data into nonoverlapping 5 µs time bins before transformation.
Light Element Impurity Annalysis by Spectroscopy Annalysis for Semiinsulating Semiconductor Materials
Authors: Saito Yasuyuki
Published: February 2023

In semiinsulatling (SI) semiconductor materials, light-elements such as carbon act as important role to sustain semiinsulating of electric conduction. They also make electric conduction in SI semiconductor materials. Since there are at least a few elements related to SI electric conduction mechanism, it is difficult for electric conduction measuremenr to reveal the element states in SI semiconductor materials. Therefore, other methods for electric conduction analyses, such as optical method of infrared (IR) absorbance spectroscopy, are required. Since IR spectroscopy can yield different informations from those of electric conduction measurements, gaseous substances of electric conduction in glass ampules and internal states of colligated substances were investigated with optical spectroscopy. [1] Optical spectroscopy can give informations on motions of very small fragment substances in the colligated substances. [2] For example, spectra of impurities such as carbon in solids such as polyethylene film are in a IR range are [3], as well as gas such as ammonia in a KRS-5-window gas-cell or liquid such as ethylalcohol in a KRS-5-window liquid-cell [4] with a Perkin-Elmer double-beam IR spectrometer Model 21 of a sodium chloride crystal prism, a thermocouple IR detector, a Nernst lamp IR source and a synchronized detection amplifier. However, as impurity concentrations in semiinsulating semiconductors are usually not so high, therefore, optical spectroscopy of absorbance as to them requires sensitivity of spectroscopy apparatuses. Moreover, observation range of carbon-related phenomena is in a far IR range. It is difficult to obtain far–IR light sources of high luminosity and high resoultion wavelength dispersion system of far IR. Therefore, cooling of samples is adopted to reduce background noise. Since wavelength of far IR is long (~10 µm—several tens µm) and also it is prefer to eliminate bulk far–IR absorbance in a prism, wavelength dispersion system with a interferometor of resonator frequency-variable mirrors of position scanning is adopted. The author will present examples of relationships between electric parameters and carbon concentartions in SI Gallium Arsenide (GaAs) crystals by Fourier-transform IR (FT–IR) spectroscopy and memos on the way to considering the results.
Evaluation of the Hg Pencil Lamp as a Wavelength Calibration Standard
Authors: Sansonetti Craig J. , Salit Marc L. , Reader Joseph
Published: February 2023

Hg pencil-type discharge lamps are widely used for alignment and calibration of instruments in analytical spectroscopy laboratories. Their wide availability, easy operation, and simple spectrum make them an attractive source for wavelength calibration; however, no precise measurements of the Hg lines as emitted by these lamps have previously been published. As one component of a Cooperative Research and Development Agreement (CRADA) with Oriel Corporation, we have observed several Hg pencil lamps with a high-resolution Fourier transform spectrometer (FTS) and have evaluated their suitability as a source of wavelength standards.
Numerical analysis of partially-resolved line structures from FT spectra
Authors: Engleman R. , Brault J. W.
Published: February 2023

Even with the great resolution of modern spectrometers, it often happens that the Doppler width (or other causes of line broadening) is large enough that close lying lines are only partially separated. This is common in atomic spectra where many hyperfine components may occur within an interval only a small fraction of a wavenumber wide. It is also a common occurrence in spectra from elements with several isotopes, or can be due to chance coincidence of transitions from the same or different elements. Similar situations also often arise in molecular spectra that could be treated by similar techniques, but they are beyond the scope of the present discussion. We will limit our consideration to structures in atomic transitions due to hyperfine splitting and/or isotope shifts.
FTS Measurements of Solar Magnetic Fields Using the MgI Zeeman Line at 12.3 Microns
Authors: Jennings D. E.
Published: February 2023

Since their discovery over a decade ago (Murcray et al., 1981; Brault and Noyes, 1983), the neutral Magnesium emission lines at 12 microns wavelength have proven to be valuable probes of the Sun's magnetic field. These infrared lines are the most Zeeman-sensitive lines observed in the solar spectrum. These lines arise in the upper photosphere, at around 400 km above the continuum. Our group at Goddard Space Flight Center has used the McMath-Pierce telescope and Fourier transform spectrometer, in combination with two cryogenic infrared postdispersers, developed at Goddard Space Flight Center and Kitt Peak National Observatory, to observe the 12.32-micron line. This program has produced an extensive study of the magnitude and structure of magnetic fields in sunspots and other active regions, as well as in quiet regions.
Atmospheric Profile Retrievals Using Grating and Interferometer Infrared and Microwave Measurements
Authors: Huang H.-L. , Smith William L. , Whipple Mark S.
Published: February 2023

Infrared radiance spectra measured by grating and interferometer devices will be widely available in the EOS (Earth Observing System) and NPOESS (National Polar Orbiting Environmental Satellite System) era. The future European polar satellite system, METOP, is scheduled to carry an interferometer to obtain infrared spectra. The Japanese satellite ADEOS (Advanced Earth Observing Satellite) launched on August 16, 1996 is also carrying an interferometer capable of measuring infrared spectra. These future infrared measurements will all possess spectral resolutions of better than 1 cm-1 and have quasi-continuous spectral coverage in the 3 μm ~ 15 μm region. With nearly thousands of spectra measurements at any single field of view, it is important to develop an innovative retrieval algorithm which cannot only handle a large volume of measurements but can also yield high precision sounding profiles.
Ground Based FTS and Infrared Array Spectroscopy
Authors: Hinkle Kenneth
Published: February 2023

In 1978 Kitt Peak National Observatory introduced a FTS of 1.8 m
maximum path difference as a facility instrument for night-time
astronomy at the 4 meter telescope. This instrument was decommissioned
in 1995, after having recorded tens of thousands of spectra. This FTS
is described by Hall et al. (1979). Note that the 4 meter FTS while
similar in function is not the same instrument as the FTS at the Kitt
Peak McMath-Pierce solar telescope. The McMath-Pierce FTS (Brault
1978, 1985) continues to be used extensively for both solar and
laboratory work.
Towards accurate wavenumber standards beyond 5000 cm−1.
Authors: Picqué N. , Guelachvili G.
Published: February 2023

Fourier transform measurements of line positions of the 3-0 band of CO are reported and compared to the corresponding best predicted Dunham estimates.
Design of a Gradient Index Photographic Objective
Authors: Atkinson Leland G. , Houde-Walter Susan N. , Moore Duncan T. , Ryan Danette P.
Published: February 2023

Gradient index lenses require fewer elements yet maintain comparable performance to homogeneous systems. The Gradient Index Laboratory at the University of Rochester has designed a camera objective using two gradient index elements.
Development of an instrument to measure distribution and unevenness of light quantity for gradient index fiber array
Authors: Ogura Yukio , Maeda Ikuo , Suzuki Toshitatu , Sakuma Nobuo , Kawazu Motoaki
Published: February 2023

Fiber array comprising fibers arranged in one or more arrays has been used as an imaging element for copying machine or CRT- printer. Recently such fiber array has found also further application such as an imaging element for CCD sensor. A single fiber of distributed refractive index type presents a spheroidal pattern of light quantity distribution. Accordingly, a fiber array serving as actual size imaging element exhibits its light quantity distribution pattern corresponding to a combination of said spheroidal patterns exhibited by the individual unit fibers, which is a unique pattern of light quantity distribution never exhibited by ordinary lenses. It is the most important thesis to design the fiber array so that a relatively high luminosity is obtained with a negligible unevenness of light quantity, at one side, and to measure the light quantity distribution exhibited by this fiber array with an acceptable precision, on the other side.
Effect of Axial Perturbation on GRIN Lens Performance
Authors: Newhouse M. A. , Keck D. B.
Published: February 2023

The imaging capabilities of graded index materials hold considerable promise for a wide variety of applications. As the technology developes it is likely that several different processing technigues will be developed to provide the range of index profiles desired by lens designers. While these may provide the desired profile they may also exhibit process induced perturbations which will detract from overall imaging performance. One example of such a process and perturbation is the vapor deposition technique (1) used in fabricating optical waveguides in which an index depression (2) is often present in the profile. The subject of this work is to analytically determine the effect which such an axial perturbation can have on imaging performance.
Real-Time Index Profile Measurement During Grin Glass Fabrication
Authors: Houde-Walter Susan N. , Moore Duncan T.
Published: February 2023

Index profile control is essential in the manufacture of GRIN lens blanks. Yet the evolution of the index profile during ion exchange with finite salt melts in some important glass/salt pairs is not well understood at this time. In this paper, we present a technique for monitoring the development of the index profile as it is formed, including the effects arising from concentration dependence, structural changes and time-dependent boundary conditions. The resulting data will contribute to a more precise formulation of the actual conditions that gradient index materials are made in, and lead to better control and repeatability of gradient lens blanks manufactured by ion exchange in glass.
Algorithm to Select the GRIN Lens and Calculate its Length for Variable Magnification Photocoagulating Endoprobe
Authors: Pankratov Michail M.
Published: February 2023

The probe currently available for intraocular photocoagulation consists of a single quartz fiber that delivers a diverging beam. The surgeon must estimate the beam diameter and its irradiance on the target. As the optical medium inside the eye changes during surgery, beam divergence and other related beam parameters (diameter and irradiance) also change. Our goal was to design a probe that: (1) delivers a converging beam with a known waist at a known distance in front of the tip; (2) maintains waist size regardless of changing optical media; (3) has an array of spot sizes; (4) has an unchanged output power at the exit from the probe for all spots in the spot size range (SSR) for any constant-input laser; and (5) has a total diameter of 0.9 mm.
Tracing Path Length on a Skew Ray in a Radial Gradient
Authors: Marchand Erich W.
Published: February 2023

Analytic formulas provide a rapid means of tracing rays in a gradient medium. Streifer and Paxton1,2 derived such formulas for the convergent type of radial gradient. They used a perturbation method to solve the appropriate differential equations, and the resulting formulas are quite accurate if a sufficient number of terms are retained.
Influence of Ag+ - Na+ ion-exchange equilibrium on the index profile of single-mode glass waveguides
Authors: Ramaswamy R.V. , Srivastava R. , Chludzinski P.
Published: February 2023

The binary Ag+ - Na+ exchange has been widely used for fabrication of planar and channel waveguides generally using pure Ag NO3 melt. The single-mode waveguides thus obtained [1] have large surface index change (Δ n ~ 0.1) , show large scattering losses, are incompatible with fiber-core dimensions, and their characteristics are not reproducible to desired accuracy. To circumvent these problems, low melt concentrations of silver (NAg ~ 10-2 - 10-3 molar fractions where NAg = CAg /(CAg + CNa) and Ci is the absolute concentration of the cation i) in Na NO3 bath have been used [2-4]. However, at low concentrations, Δn is a very strong function of NAg [4] saturating at ~ 0.1 for pure Ag NO3 melts in most soda-lime glasses. Since for fiber compatible single-mode guides, NAg ~ 10-4 MF, this strong dependence of Δn on NAg calls for a precise control of NAg and its understanding via a detailed study of the transport phenomena and thermodynamical equilibrium between the melt and glass phases. While such a study has been reported [2,3,5] for NAg > 10-2, the results are not applicable to the low concentrations involved in the fabrication of single-mode waveguides. Besides, the results are likely to depend on the processing temperature and the substrate glass. Moreover, since the concentration profile depends on the interdiffusion coefficient which is concentration independent only if the silver concentration in glass is very small, a knowledge of its dependence on NAg will permit the solution of the diffusion equation with concentration-dependent interdiffusion coefficient [2].
Glass waveguides made using ion exchange in a KNO3:AgNO3 equimolar melt
Authors: Jackel Janet Lehr
Published: February 2023

Ion exchange has proved to be one of the simplest and most effective means for making optical waveguides in glasses. Even when only soda-lime glasses are considered, the variety of ions which can be used to replace the sodium in the glass gives this process substantial though not unlimited flexibility. The most commonly used ions for exchange in soda-lime glass are silver, potassium, and thallium. Properties of guides made by exchange in nitrates of these ions are summarized in Table 1.
Gradient-Index Polymer Materials and Application to Optical Devices
Authors: Koike Yasuhiro , Ohtsuka Yasuji
Published: February 2023

One of advantages of polymer GRIN is to obtain large dimensional GRIN, compared with glass materials. In the case of a radial-GRIN, we have succeeded in preparing a GRIN rod with 20-mm diameter. In the case of an axial-GRIN, the maximum depth of GRIN is 40 mm with Δn=0.05. The other advantage is that many geometric GRIN devices, such as spherical GRIN lens or steric GRIN wavequides, are easily prepared by new technologies presented in this paper.
Calculating of optical path length in inhomogeneous media - An alternative method
Authors: Puchalski J.
Published: February 2023

An alternative method for calculating of optical path length in inhomogeneous media is presented. This method may be used with the three component and the four component ray-trace schemes considered ealier2,3.The method is based on a series expansion of the refractive index of the medium for second ray-trace scheme divided by the third optical direction cosine as a function of six suitable ray-trace parameters from a given, three adjacent Runge-Kutta points.

A comparison with previous method which was applied for the three component ray-trace scheme is made.
A New Analytical Profile to Characterize Planar Waveguides
Authors: Montero C. , Prieto X. , Liñares J. , Pelli S. , Righini G. C.
Published: February 2023

Ion-exchange technique has been by far the most popular technique to produce optical waveguides in glass [1]. In order to design, fabricate, and study their properties, it is necessary to have an accurate knowledge of the refractive index profile resulting from this fabrication process. Until a few years ago, the refractive-index profile has been approximated by several functions that, generally, have not provided a satisfactory model. Some ones, for instance the Gaussian one, are only empirical functions that does not fulfil the physical boundary conditions of the process. Other ones, the Erfc and the truncated-parabolic ones, are only valid for determined values of the parameter α = 1 - r, with r the ratio between the self-diffusion coefficient of the incoming (Di) and outgoing (Do) ions. Recently, it has been presented [2,3] new more accurate models, to characterize silver (Ag+) and potassium (K+) waveguides, valid in a wide range of α. Nevertheless, these models do not describe well almost steplike profiles (α → 1) because the approximations used in their derivation are not adequate.
Technology of Ultra-Thin Graded-Index Objective
Authors: Tagantsev D.K. , Kurbatova G. I. , Korolyov Yu. G.
Published: February 2023

It is known1 that the cylindrical glass sample π/2g long with the radial distribution of refractive index works as an objective, where n is the refractive index, no is the refractive index at the objective axis,

g
=

2

n
0

Δ
n

is a constant which characterizes the optical power of the objective, Δn is the refractive index drop between the side surface of the objective and its axis, h
i
are aberration coefficients, r is the current radius. One of the most wide-spread methods of creating the racial refractive index distribution is an ion-exchange diffusion2. The basis of such technology is the ability of alkali cations of glasses to exchange with the alkali cations of salt melts. The exchange is carried out at temperatures near glass transition ones.
GRIN-Optics with High Numerical Aperture by Silver-Exchange
Authors: Possner T. , Messerschmidt B. , Palme M. , Göring R.
Published: February 2023

The ion-exchange process is a well established technology for the generation of gradient-index elements /1/. Because of the high achivable refractive index differences and high transparency of the generated elements Tl-exchange is preferred. But beside the toxicity of Tl-containing salt melts and glasses there is a further disadvantage of Tl-GRIN-elements. This is the high chromatic aberration introduced by the Tl-ion.
New Markets for GRIN Microlenses
Authors: Oikawa Masahiro , Wong Michael
Published: February 2023

Substantial progress in optical fiber communication and optical processing has been made. A new class of optical components based on GRIN technology has led to the creation of innovative optical systems. These systems are characterized by packages which are compact, lightweight, and multifunctional. As a result, high optical performances are achieved by means equivalent to or better than conventional classical optics.