Glass Refractive Index Research Articles

A Method for Determining the Equilibrium Straight Line of the Refractive Index of Glasses by Two Points

A method is devised for determining the equilibrium straight line of the refractive index of glasses by two points in the temperature dependence of the refractive index of thin quenched samples. The time required to obtain data by the proposed method is seven- to tenfold shorter than that required by the standard method.

Luminescence spectra of Eu 3+-doped GeO 2-PbO-Bi 2O 3 glasses

Europium-doped germanium-lead bismuth based glasses in the chemical composition of 62GeO 2-(13-X) PbO-25Bi 2O 3-XEu 2O 3 (where X = 0.1, 0.2, 0.5, 1.0, and 1.5 mol%) have been prepared and carried out in a systematic study on their emission spectra. Upon exposure to the UV source (200–270 nm) these glasses have shown bright reddish orange phosphorescent color that lasted for about half an hour. From the measured glass refractive index (n d = 1.871) and density (5.965 g·cm −3), glass reflectivity, number of luminescent ions (N eu 3+), and inter ionic distance (r eu-eu) values of these europium glasses have been computed. The PL spectra of these glasses have shown emission transitions ( 5D 0→ 7F 1,2,3&4) at 593, 612, 652, and 697 nm. We have examined the dependence of the emission spectra and decay curves on the excitation wavelengths at 228, 246, 259, 361, and 393 nm from a Xe source. Decay curves of the emission transitions have been characterized by a double exponential fitting procedure. From the photoluminescence spectra, concentration quenching at the values of the dopant ion content above 1.0 mol% has been noticed.

Nanosphere Lithography: Effect of Substrate on the Localized Surface Plasmon Resonance Spectrum of Silver Nanoparticles

In this paper, we explore the optical contributions of the substrate to the localized surface plasmon resonance (LSPR) spectrum of surface confined Ag nanoparticles produced by nanosphere lithography (NSL). We present optical extinction spectra of Ag nanoparticles fabricated on the following substrates: fused silica, borosilicate optical glass, mica, and SF-10a high refractive index specialty glass. For all the experiments discussed here, the Ag nanoparticles were approximately 100 nm in in-plane width and 25 nm in out-of-plane height. In a controlled N2 environment, the wavelength corresponding to the extinction maximum, λmax, shifts to the red with increasing refractive index of the substrate, nsubstrate. The sensitivity factor, Δλmax/Δnsubstrate, was measured to be 87 nm per refractive index unit (RIU). Experimental extinction spectra were modeled using the discrete dipole approximation (DDA). The DDA theory qualitatively predicts the experimentally observed trend that λmax is linearly dependent on ns...

An Increase in the Refractive Index of a Multicomponent Silicate Glass by Six-Hundredths upon the Na+glass–Li+meltIon Exchange

An increase in the refractive index of the glass surface by Δn= 0.06 after the Na+glass–Li+meltion exchange is obtained for the first time.

Wavelength-dependent measurements of optical-fiber transit time, material dispersion, and attenuation

A new, to our knowledge, method for measuring the wavelength dependence of the transit time, material dispersion, and attenuation of an optical fiber is described. We inject light from a 4-ns rise-time pulsed broadband flash lamp into fibers of various lengths and record the transmitted signals with a time-resolved spectrograph. Segments of data spanning a range of approximately 3000 A are recorded from a single flash-lamp pulse. Comparison of data acquired with short and long fibers enables the determination of the transit time and the material dispersion as functions of wavelength dependence for the entire recorded spectrum simultaneously. The wavelength-dependent attenuation is also determined from the signal intensities. The method is demonstrated with experiments using a step-index 200-mum-diameter SiO(2) fiber. The results agree with the transit time determined from the bulk glass refractive index to within ?0.035% for the visible (4000-7200-A) spectrum and 0.12% for the UV (2650-4000-A) spectrum and with the attenuation specified by the fiber manufacturer to within ?10%.

Synthesis, characterization and property studies of Pb 2+-containing optical resins

Lead dimethacrylate (Pb(MA) 2) was synthesized and copolymerized with styrene and methacrylic acid, and optical resins containing the heavy-metal ion, Pb 2+, were obtained. The monomer-solubility phase diagrams and polymer-transparency phase diagrams were determined and discussed in detail. This series of metal-containing resins possessed good visible light transparency, high refractive index, and good thermal stability. The relationship between the refractive index ( n D), Abbe number ( ν D), heat resistance, radiation shielding properties, and the content of metal salts in optical resins were investigated. The results indicated that adding of metal Pb 2+ into the optical resins not only exhibited high absorption for X-ray with good visible light transparency, but could also improve the glass transition temperature and refractive index of polymer materials.

Spectral properties of organic chromophores in fluorophosphate glasses

Rhodamine 6G, Alq 3, quinacridone (QAD) doped lead tin fluorophosphate glass samples (62.3SnF 2, 10.8SnO, 9.5PbF 2, 17.4P 2O 5 wt%) were prepared. Glass samples were melted at 320°C in an electric furnace in a pyrex crucible, then were transferred to a Teflon crucible in another furnace at 280°C. The glass transition temperature, crystallization temperature, melting temperature, refractive index, and chemical durability in water were measured. The absorption spectra and emission spectra of organic chromophores in these samples were measured. The absorption peak shifts from 537.2 (±0.2) to 535.8 (±0.2) nm and the emission peak shifts from 585.0 (±0.5) to 589.0 (±0.5) when the melting time of Rhodamine 6G increased from 15 to 60 min. The energy transfer from Alq 3 to QAD and Rhodamine 6G were investigated by excitation spectra analysis. The results showed that the energy absorbed by Alq 3 from 350 to 450 nm was transferred to QAD, which is important for active devices.

Commentary on Koons, RD, Buscaglia J. The Forensic Significance of Glass Composition and Refractive Index Measurements. J Forensic Sci 1999;44(3):496–503

Abstract Commentary on Koons, RD, Buscaglia J. The forensic significance of glass composition and refractive index measurements. J Forensic Sci 1999;44(3):496–503.

Measurement of physical thicknesses in micromachined structures consisting of glass and c-Si, by Fourier transform infrared reflection

The measurement of thicknesses of micromachined struc- tures consisting of etched glass bonded to c-Si and multilayer structures of both etched c-Si and etched glass is presented. The peaks within the recorded interferograms are identified by inspecting the equation for the reflection coefficient and the corresponding equation for the reflectivity. The amplitudes of the various peaks resulting from the 3-D structure underneath the spot of the beam are evaluated to be able to perform an unambiguous choice of the correct peak when performing automatic pro- cess monitoring. Furthermore, the peaks in the interferogram may be a strong function of wafer position (depending on device layout). In the latter case, it is demonstrated that information obtained directly from the interferogram can be used in wafer imaging. The dielectric dispersion functions for the glass and the c-Si wafer under investigation are evalu- ated from the reflectance measurements. An anomalous shift is ob- served in the interferogram peak corresponding to the glass thickness. The shift is found to be due to the strong dispersion in the refractive index of glass resulting from the SiOSi asymmetric stretching frequency around 1100 cm 21 . Both simulations of the interferogram, and analysis provide a 5% correction for the thickness of the glass under investiga- tion. © 1999 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(99)01109-5)

Some physical chemical properties of α–ω dihydroperfluoropolyethers

This paper describes the physico-chemical characterization and some properties of several α–ω dihydroperfluoropolyethers. Characterization has been carried out on the following properties: vapour pressure, density and viscosity as a function of temperature, glass transition temperature, refractive index and dielectric constant. The boiling point T b and the vaporization enthalpy Δ H v (calculated from vapour pressure data by means of the Clausius–Clapeyron equation) increase with the number of the backbone atoms N; both T b and Δ H v are higher than the corresponding values for compounds with the non-polar chain end CF 3 and the difference decreases, but does not disappear, when the number of chain atoms is as large as 10–15. The cohesive energy density and the solubility parameter δ are also found to be larger. It is shown that the increase with respect to CF 3 terminated homologues has to be attributed, as expected, to the polar component due to the CF 2H end group. The p– V– T properties can be predicted through a modified Peng–Robinson equation, where the critical temperature and pressure are obtained by group contributions. The comparison with the experimental data shows that the best group contribution data are those reported by Joback. The density increases and the expansion coefficient decreases with increasing chain length, as expected; at the same chain length the density is lower for materials with a CF 2H end group; the difference decreases with increasing N. The viscosity also increases with molecular weight; its dependence on temperature is described by the well-known Arrhenius equation. The activation energy is a function of Δ H v, as predicted by the hole theory of Eyring for simple liquids. The glass transition temperatures are very low and depend both on the chain length and on the structure of the compound. While the refractive index is a weak function of chain length and structure, the dielectric constant is a strong function of both variables; a relationship between the dielectric constant and the polar component of the solubility parameter is suggested. Finally the group contributions of the CF 2H group to the molar volume, vaporization energy, molar refractivity and molar polarizability have been determined, so that these data can be used to predict properties of new molecules.

The Forensic Significance of Glass Composition and Refractive Index Measurements

Abstract The frequency distributions of refractive index and the concentrations of ten elements in 204 glass specimens received as evidence in casework were evaluated. These data were used to estimate the probability of randomly selecting, from a general population, a glass specimen that is indistinguishable in all measured characteristics from a given glass specimen. The probability of two unrelated glass specimens having indistinguishable elemental compositions and refractive indices is calculated and lies between the extremes of 10−5 and 10−13. For each of the 20,706 pairwise comparisons of the 204 specimens in this study, the two specimens are analytically distinguishable. The use of highly discriminating analytical methods for the comparison of trace evidence and the corresponding low probability of two unrelated glass specimens being indistinguishable eliminates the need to collect extensive databases for the purpose of making exact probability calculations. The approach used here can be applied to other highly discriminating parameters and trace evidence sample types.

Optimization in Polymer Design Using Connectivity Indices

This work addresses the design of polymers with optimal levels of macroscopic properties through the use of topological indices. Specifically, two zeroth-order and two first-order connectivity indices are for the first time employed as descriptors in structure-property correlations in an optimization study. Based on these descriptors, a set of new correlations for heat capacity, cohesive energy, glass transition temperature, refractive index, and dielectric constant are proposed. These correlations are incorporated into an optimization framework. The proposed mathematical description, utilizing the concept of a basic group, accounts fully for molecular interconnectivity. When the nonconvex terms are appropriately recast in the formulation as convex inequalities, a convex mixed-integer nonlinear (MINLP) representation is obtained. Three example problems highlight the proposed molecular description, structure-property correlations, convex MINLP optimization formulation, and solution technique.

北海道白滝遺跡と周辺地域のテフラ

Eleven marker tephras were found at and around a famous paleolithic site in the Shirataki Basin, eastern Hokkaido. The following conclusions are the result mainly of a petrographic analysis, i.e., ratio of glass and minerals, composition of heavy minerals, shape of volcanic glass, and refractive indices of glass, orthopyroxene and hornblende.1) Three widespread tephras were identified in the Shirataki Basin; Tarumae-a pumice (Ta-a) that erupted from Tarumae volcano, western Hokkaido at 1739AD, Kussharo-Shoro ash (Kc-Sr) that erupted from the Kussharo caldera, eastern Hokkaido at ca. 32ka, and Shikotsu-1 pumice (Spfa-1) that erupted from the Shikotsu caldera, western Hokkaido at ca. 40 ka.2) Shirataki-1 pumice (Sit1) is identified with Daisetsu-Ohachidaira pumice (Ds-Oh). Ds-Oh erupted from Daisetsu volcano, central Hokkaido, prior to the eruption of a large pyroclastic flow associated with the formation of the Ohachidaira caldera at ca. 30 ka. Sit1 =Ds-Oh spread widely in the Shirataki Basin and shows a horizon just below the Shirataki stone implements. Thus Ds-Oh must be an important key bed for correlating and chronologically arranging paleolithic cultures in the eastern Hokkaido.3) Shirataki-5 pumice (Sit5) overlies the middle terrace surface in the Shirataki Basin. Sit5 is identified with Toetoko ash (TT) distributed around Lake Saroma. On the basis of stratigraphy by means of pyroclastic flow deposits from the Kussharo caldera and palynological evidence, Sit5=TT seems to be dated back to 150-200 ka. Sit5 is probably distributed in the wide area of the Okhotsk region of Hokkaido. Although the source vent has not been determined yet, Sit5 should be a valuable marker tephra indicating the Middle Pleistocene.

Advanced Techniques in Physical Forensic Science

The techniques and tools of modern physics have long been profitably applied to forensic science. Since the 1900s, forensic scientists have analyzed gunshot residues, examined fired munitions, determined the refractive indices of glass—to name a few of their diverse activities.

Optical characteristics of sodium-zinc-phosphate glasses

Optical-absorption spectra recorded in the UV-visible range for sodium-zinc-phosphate glasses are presented and the estimated values of the optical band gap energy are found to lie in the range 3.0–3.7 eV. The glass density and refractive index for the present samples have also been measured. Some other parameters such as molar volume, ion concentration, width of band tailing, and constantB (related to the Mott-Davis equation) have been worked out to characterize these glasses.

Spectral properties of Tb3+: B2O3–P2O5–R2SO4 glasses

Here, we bring out the studies made on the production and optical characterization of certain terbium glasses in the following composition: 44.5B2O3+44.5P2O5+10R2SO4 (where R=Li, Na, K). From the glass density (d) and refractive index (nf, nd, nc) values obtained at three different wavelengths (486.1 nm, 589.3 nm, 656.3 nm), physical and spectral properties have been computed. On excitation with the λexc=487 nm, these Tb3+ glasses are found to be green fluorescent and it is stronger in the Li+ containing Tb3+-glass than in Na+ and K+ glass systems.

Influence of rare-earth ions on fluorogallate glass formation and properties

Various rare earths have been incorporated in a lead fluorogallate glass with the following chemical composition: 30PbF2–20GaF3–15InF3–20CdF2–15ZnF2 (PGICZ). Selected rare earths are La, Ce, Pr, Nd, Gd, Er, Yb and Lu, and the doping level varies between 1 and 10 mol%. The influence of rare earth fluorides on glass forming ability and on physical properties is investigated. At low concentration (<3 mol%) lanthanide incorporation increases glass stability. While large amounts of rare earths may enter glass composition, thick samples are difficult to obtain with this glass composition. Larger samples containing 9 mol% NdF3 in a modified PGCIZ glass have been cast. Experimental results suggest that rare earths act as modifiers rather than vitrifiers in this fluorogallate system. The effect of rare earths on the values of glass transition temperature, refractive index, density and thermal expansion is reported.

Grating-assisted coupling of light between semiconductor and glass waveguides

Floquet-Bloch theory is used to calculate the electromagnetic fields in a leaky-mode grating-assisted directional coupler (LM-GADC) fabricated with semiconductor and glass materials. One waveguide is made from semiconductor materials (refractive index /spl ap/3.2) while the second is made from glass (refractive index /spl ap/1.45). The coupling of light between the two waveguides is assisted by a grating fabricated at the interface of the glass and semiconductor materials. Unlike typical GADC structures where power is exchanged between two waveguides using bound modes, this semiconductor/glass combination couples power between two waveguides using a bound mode (confined to the semiconductor) and a leaky mode (associated with the glass). The characteristics of the LM-GADC are discussed. Such LM-GADC couplers are expected to have numerous applications in areas such as laser-fiber coupling, photonic integrated circuits, and on-chip optical clock distribution. Analyses indicate that simple LM-GADC's can couple over 40% of the optical power from one waveguide to another in distances less than 1.25 mm.

Radiation effects of low refractive index, fluorinated methacrylate polymers for fiber cladding

AbstractThe gamma radiation stability, optical properties, and mechanical properties of 1H, 1H, 3H‐hexafluorobutyl and 1H, 1H‐heptafluorobutyl methacrylate homopolymers and copolymers were determined and compared to poly(methyl methacrylate), PMMA. The aim of this study was to identify polymers for fiber cladding materials that exhibit improved optical radiation resistance and physical properties. Using 60Co source, the samples absorbed 10 Mrads of gamma radiation at 0.04 Mrads/hr in an air environment. UV/Vis transmission spectra were obtained before irradiation, just after 10 Mrads, and regularly thereafter, to track recovery in transmittance. The glass transition temperatures, decomposition temperatures, refractive indices and flexural moduli were also obtained. Poly(heptafluorobutyl methacrylate) exhibited the greatest resistance to radiation induced discoloration and the lowest refractive index of the compositions tested. As the composition of the copolymers increased in hexafluorobutyl methacrylate concentration, both the radiation induced discoloration and the refractive index increased.

高純度Ｇｅ‐Ｇａ‐Ｓ系ガラスの作製法とＮｄ｀３＋´イオンの溶解性

The preparation process of Ge-Ga-S glasses is studied and its glass-forming region is presented. The effects of Ga and S contents on properties：glass transition temperature, density, and refractive index are investigated. The S content dependence of glass transition temperature and refractive index are divided into three regions relating to three bond types：1)the cation excess region with the contribution of Ge-Ge bonds, 2)an anion excess region with the dominant contributions of GeS2 tetrahedra connected by the S-S bonds, and 3)the other anion excess region with the contributions of S-S bonds and S8 rings. The solubilities of rare earth ion, Nd3+ in Ge-Ga-S, Ge-In-S and Ge-Sb-S glass systems are discussed using ionicity parameter, which based on the electronegativity between cation and sulfide anion.