Abbe Number Research Articles

Optical Dispersion Characteristics of Polyvinyl Alcohol Reinforced with a Nanoceramic Filler

Polymer films with high refractive index are suitable for a wide range of applications, such as optical fibers, lens and other components for optoelectronic devices. In this work, polyvinyl alcohol films were prepared from aqueous solutions, which were homogenized by ultrasonication. In order to increase the refractive index, the polymer was reinforced with barium titanate nanoparticles, which are previously ultrasonicated for an adequate dispersion inside the host polymer. The dispersion of the refractive index in visible domain was analyzed as a function of filler percent introduced in polymer, showing that an increase in sample s polarizability determined an increase in the refractive index values. The reinforcement caused a decrease of Abbe number indicating a higher light dispersion in the samples. Optical dispersion parameters were extracted from dispersion curves, revealing a reduction of band gap from 3.448 eV for pure polymer to 2.605 eV for the sample containing 2% barium titanate. Doping with the ceramic nanofiller determined a increase in optical conductivity and real part of dielectric constant as a result of appearance of new level states in the band gap. The increase of third order nonlinear optical susceptibility and nonlinear refractive index indicates the suitability of the analyzed nanocomposites for nonlinear optics applications.

Achromatic Deep Ultraviolet Lens Using Novel Optical Materials

The development of an achromatic lens in the deep ultraviolet (DUV) region is reported. The dispersion and Abbe numbers of lithium calcium aluminum fluoride (LiCaAlF6), magnesium fluoride (MgF2), lithium fluoride (LiF), calcium fluoride (CaF2), and fused silica (SiO2) are investigated in the wavelength range from 200 to 300 nm to determine appropriate material combinations for minimizing chromatic aberration in a doublet. Based on the results of these investigations, a prototype DUV objective lens is fabricated using a LiCaAlF6 (convex lens)SiO2 (concave lens) doublet. The objective lens has a focal length of 10 mm, working distance of 2 mm, and numerical aperture (NA) of 0.2. The objective lens is evaluated to have a chromatic aberration of about 2.8% and resolution of at least 2 μm. It is also evaluated to have a smaller spherical aberration compared with a reflective objective lens with a similar NA.

On the Chromatic Dispersion of Hydrophobic and Hydrophilic Intraocular Lenses.

There is a high variation of chromatic dispersion with contemporary intraocular lens (IOL) materials. It is well known that chromatic aberration limits the optical performance especially with high-power lenses. Lens manufacturers, however, rarely provide data on the chromatic dispersion of their materials, limiting the comparability of available materials. This study aimed to analyze chromatic dispersion of hydrophobic and hydrophilic IOLs without prior knowledge of the IOLs' geometries. We adapted Bessel's method for measuring focal length by placing the IOL in a wet cell. The chromatic dispersion of several hydrophobic and hydrophilic IOLs was characterized by measuring their focal lengths at multiple wavelengths. From the measured focal lengths, the refractive indices and the Abbe numbers were obtained. We measured four hydrophobic and two hydrophilic IOL models with a nominal power of 21 to 29.5 D. The hydrophobic IOLs had lower Abbe numbers (Abbe numbers <41) than did the hydrophilic IOLs (Abbe numbers >50). Most Abbe numbers were in agreement with the values provided by the IOL manufacturers, and the measurements were independent from IOL power. The repeatability for the Abbe number was better than ±3.5% for all lenses and better than ±2% for lenses between 21 and 26.5 D. The dispersion could be described by a Conrady model (R > 0.997). The hydrophobic materials showed larger dispersion than did the hydrophilic IOL materials resulting in increased chromatic aberration. The method allowed for an estimation of the IOL's Abbe number without prior knowledge of IOL geometry.

An inspection of the dispersive properties of imidazolium-based ionic liquids in the Vis-NIR

In this work, the refractive index dependence on the wavelength of 20 ionic liquids is characterised by spectrally resolved white-light interferometry in a spectral interval comprising a range of wavelengths from 400 to 1000 nm at different temperatures between 298.15 and 323.15 K. With these data and using a refractive index model based on a single resonance Sellmeier equation, we calculate the Abbe number, group index, group velocity dispersion, and dispersion of the thermo-optic coefficient for each liquid. Using the Lorentz–Lorenz approach and density data, we demonstrate (from the empirical results) the linear variation of the molar volume and molar refraction with the number of carbons in the alkyl chain. Further, we confirm that this linear relation can be used to predict the refractive index of liquids of the same family provided the addition of CH2 groups does not lead to anisotropies in the refractive index.

Poly(methyl methacrylate)/polyphosphate blends with tunable refractive indices for optical applications

Tuning the refractive index of the transparent materials is essential for optical applications. Herein, we report novel materials with a tunable refractive index that are prepared by blending poly(methyl methacrylate) (PMMA) with different concentrations of two polyphosphate hybrid polymers (P1 and P2), having phosphorus in the main chain. The refractive indices and associated optical parameters of these polymers and hybrid materials (PB1 and PB2 series) are investigated using ellipsometry and optical modelling method to find their applicability in optics. Refractive indices of these materials are fine-tuned by altering the ratio of PMMA to P1 or P2. This approach is simple and ideal for obtaining homogeneous blends. Refractive index tunability of 0.05 and 0.1 are achieved for PB1 and PB2 series, respectively, by this approach. Abbe numbers of these blends are reasonable for PB1 series compared to the conventional lens materials, with a maximum value of 56 achieved in the case of PB120 blend. In addition, the trend in variation of extinction coefficient with wavelength for blends PB250, PB260 and PB280 seem promising for optical filter kind of applications. These results show that the synthesized polymer blends are promising as optical materials with refractive index tunability.

TeO2-Ga2O3-ZnO ternary tellurite glass doped with Tm3+ and Ho3+ for 2 µm fiber lasers

The glass-forming region of TeO2-Ga2O3-ZnO (TGZ) ternary tellurite glass was predicted via a thermodynamic method and then confirmed by a few experiments. Upon cooling the melts at a rate of ~20 K/s, the glass formation was observed within the range of 60–97 TeO2, 0–20 Ga2O3, and 0–40 ZnO (in mol%). For a better understanding of their fundamental physical, thermal and optical properties, the density, characteristic temperatures, Abbe number, linear and nonlinear refractive indices were comprehensively investigated. The possibility of TGZ glass host for 2 µm fiber lasers was studied through Tm3+ and Ho3+ doping and rare-earth sensitization. The results show such newly developed TGZ glass owns high thermal stability, low phonon energy and efficient 2 µm fluorescence, which enriches the tellurite glass system and may contribute to the research of high gain fiber lasers.

Optical properties of photoresists for femtosecond 3D printing: refractive index, extinction, luminescence-dose dependence, aging, heat treatment and comparison between 1-photon and 2-photon exposure

Femtosecond 3D printing has emerged as an important technology for manufacturing nano- and microscopic optical devices and elements. Detailed knowledge of the dispersion in the visible and near-infrared spectral range is crucial for the design of these optical elements. Here we provide refractive index measurements for different UV-doses, aging times, heat treatment and 2-photon exposed structures for the photoresists IP-S, IP-Dip, IP-L, OrmoComp, IP-Visio, and PO4. We use a modified and automized Pulfrich refractometer setup, utilizing critical angles of total internal reflection with an accuracy of 5·10−4 in the visible and near-infrared spectral range. We compare Cauchy and Sellmeier fits to the dispersion curves. We also give Abbe numbers and Schott Catalog numbers of the almost entirely polymerized resists. Additionally, we provide quantitative extinction and luminescence measurements for all photoresists.

Optical materials for lens concentrators of solar radiation

“Solar” Abbe number is proposed to operate in assessing the suitability of optical materials at sunlight concentrators manufacture. Comparative results are presented for materials practically used in concentrator photovoltaics from the point of view of designing Fresnel lenses from them with a high average concentration in the focal spot of the minimum size and at the same time with minimum focal length.

Topography and longitudinal chromatic aberration characterizations of refractive–diffractive multifocal intraocular lenses

Most optical systems present chromatic aberration quantified along the optical axis by the longitudinal chromatic aberration (LCA). LCA is controlled by the biomaterial Abbe number combined with diffractive effects, driven by the intraocular lens (IOL) topography. This study experimentally aimed at describing the effect invitro of LCA in diffractive multifocal IOLs, with the help of dedicated optical benches and topographic characterization. Centre Spatial de Liège, Belgium. Optical and topology analysis of various multifocal diffractive IOLs. Seven diffractive multifocal IOLs, available on the market and exhibiting different diffractive profiles, made from various biomaterials, were characterized under different wavelengths. Through-focus modulation transfer function (MTF) curves and IOL diffraction efficiency depends on the incident light wavelength. In this study, the topology properties of various multifocal IOLs were investigated and their characteristics were correlated to their optical behavior for various wavelengths. Chromatic properties and their origins were then compared. As expected, diffractive and refractive effects were found to act in opposite ways, and could be partially or completely compensated. The LCA of each of the IOLs was evaluated invitro. In most of the multifocal IOLs studied, some of the foci were found to be refractive, whereas others were diffractive. Although the results were not extrapolated to clinical relevance, it was shown, in some of the cases, that LCA could be fully compensated.

Imidazole derivatives as thermal latent catalyst for thiol-michael reaction thermosetting resins

Imidazole is an excellent nucleophilic initiator in thiol-Michael addition reaction of thiol and vinyl sulfone at room temperature. To delay the gelation of the monomer mixture, thermal latent curing agents based on imidazole are designed and the latency and curing efficiency towards thiol-vinyl sulfone system are evaluated. N-carbonylated imidazole derivatives are non-nucleophilic towards Michael reaction with vinyl sulfone. However, during curing at elevated temperature (>80 °C), thiol monomer thiolyze imidazole derivative and the released imidazole acts as a nucleophilic initiator. It is found that the viscosity at room temperature of thiol-vinyl sulfone system with 2b or 2d imidazole derivatives increases slowly up to over 10 h, which permits sufficient time for processing such as mixing, degassing and injection into the mold. In the application of 2b or 2d in network polymerization of polythiol and divinyl sulfone, both catalysts have excellent curing ability with a 98% and 95% thiol conversion, respectively within 7 h at 100 °C. Using 2b or 2d, transparent thiol-vinyl sulfone resins with a refractive index of 1.57 and an Abbe number of 47.78 are successfully produced.

High refractive index polythiourethane networks with high mechanical property via thiol-isocyanate click reaction

High refractive index polymers (HRIPs), especially sulfur-containing HRIPs, play an important role in optical materials; particularly the thermosetting sulfur-containing polyurethane is widely used in optical lenses. To understand the effect of thiol and isocyanate structures on thermosetting polythiourethane properties, a comprehensive study of the basic thermal, optical and mechanical properties of the obtained polythiourethane network structure was conducted, which results indicated that in addition to functionality and the presence of rigid groups affect the glass transition temperature, the conjugation effect and steric hindrance effect in the structure can also cause more changes in the glass transition temperature. All polythiourethane materials formed uniform and densely crosslinked network structures. Due to the introduction of highly polarizable sulfur atoms in 2,3-bis((2-mercaptoethyl)thio)-1-propanethiol (GST) and benzene rings in bis(isocyanatomethyl)benzene (XDI), the resulting polythiourethanes exhibited a high refractive index of 1.6559 (589 nm) and a tensile strength of 95.64 MPa while the Abbe's number was 33.24, fully meeting the lens requirements. The important structure-property relationships of polythiourethane will be helpful for the rational design of HRIPs.

Direct introduction of elemental sulfur into polystyrene: A new method of preparing polymeric materials with both high refractive index and Abbe number

The present work proposes a facile but effective method for the design and synthesis of optical polymers with both high refractive index (RI) and Abbe number (AN) by the direct introduction and dispersal of elemental sulfur in polystyrene (PS). The excellent dispersal of the reaction products of elemental sulfur with styrene (St-S) in the PS result in the highest RI of 1.6220 and AN of 27.3. The acceptable uniform dispersal of elemental sulfur in the PS is verified by photographic analysis, optical transmission spectra, scanning electron microscopy, and energy dispersive spectroscopy analyses. The thermal properties of polymeric materials were investigated using thermogravimetric analysis and differential scanning calorimeter. The proposed strategy not only provides a new high RI material for optical applications, but also offers new opportunities for the dispersal of substances into polymeric materials.

Nd3+-doped mixed-anion fluoro-sulfo-phosphate glass for 1.06 μm solid-state laser

Fluoro-sulfo-phosphate poly-anionic glasses KPO3–AlF3–K2SO4 (KPFS) and Nd3+-doped samples (Nd–KPFS) were prepared by conventional melt-quenching method and their physical properties were comprehensively analyzed. Their actual glass compositions were carefully checked by different methods. These glasses exhibit typically low linear refractive index nd (~ 1.482) and nonlinear refractive index n2 (~ 0.86 × 10−13 esu), high Abbe's number (~ 72.0) and moderate elasticity modulus E⁎ (~ 50.2 GPa). The spectroscopic properties of Nd–KPFS specimens are further evaluated by the Judd-Ofelt theory, and the results suggest that the stimulated radiative parameters can be enhanced by tuning sulfate contents. Besides, Nd–KPFS glasses present relatively long lifetime τexp (~ 428 μs) and large figure of merit FOM (~ 9.29 × 10−24 cm2 s). All of the results imply that such fluoro-sulfo-phosphate glass would be a promising candidate for solid-state laser.

Novel gallate‐based oxide and oxyfluoride glasses with wide transparency, high refractive indices, and low dispersions

AbstractThe glass‐forming region of a BaO‐La2O3‐Ga2O3 ternary system was confirmed and BaF2‐BaO‐La2O3‐Ga2O3 new oxyfluoride glasses were prepared by a containerless processing. We also analyzed the physical, thermal, and optical properties of new oxide and oxyfluoride glasses. The direct effects of the substitution of oxygen by fluorine and the effect of BaO and La2O3 on the refractive index and Abbe number were discussed on the basis of electronic polarizability and resonance wavelength of oscillator. The refractive indices increased with increasing La2O3 concentration because La2O3 increased the electronic polarizabilities. Abbe number increased with increasing BaO and fluorine concentration because of the decrease in resonance wavelength of oscillator. By the combination of the BaO, La2O3, and fluorine in the gallate glass system, we could obtain novel oxide and oxyfluoride glasses with high refractive index (1.81‐1.95) and high Abbe number (31‐55). The absorption edge in UV region shifted to the shorter wavelength and IR cut‐off wavelength shifted to the longer wavelength with increasing fluorine. Therefore, wide transparent glass was obtained from 262 nm to 11.3 μm.

Demulsification‐Induced Fast Solidification: A Novel Strategy for the Preparation of Polymer Films Based on Inorganic Salt Solutions and Organic Solvents

AbstractThe development of a novel film fabrication strategy, named demulsification‐induced fast solidification (DIFS), for the rapid fabrication of large‐area polymer films is reported in this study. The polymer films are fabricated through dialysis and dipping processes using emulsions and a demulsifier based on the DIFS method. Furthermore, robust and flexible free‐standing films with controllable thicknesses and functionalities, such as tunable mechanical properties (elongation at break of 350–980% and ultimate tensile strength of 0.21–1.88 MPa); excellent optical properties (optical transmittance greater than 52.03% in the visible region, refractive index of 1.4888 ± 0.0001, and Abbe number of 52.1 ± 1.1); and luminescence properties, are rapidly and easily prepared by mechanical exfoliation based on the DIFS method. The results show that this academic concept and fabrication method will provide support for the design and preparation of functional polymer films that are highly desirable for optical, flexible device, and wearable material applications.

Study on the optical properties and broad infrared luminescence of Tm3+/Yb3+ co-doped Nb2O5-based glasses

Raman spectra of Tm3+/Yb3+ co-doped Nb2O5-based glasses with different Yb3+ concentrations have been studied. The results reveal that Yb3+ ions have no effect on the maximum phonon energy. Moreover, this heavy-metal oxide glass has low phonon energy with a value of ∼ 800 cm−1, which is very helpful to obtain strong infrared luminescence. The absorption coefficient of OH- group is small, which is helpful for infrared luminescence. Nb2O5-based glasses have a high refractive index with the nd value over 2. Yb3+ is not good for the refractive properties on the whole. The abbe number can be calculated by using characteristic values. All the glasses with different Yb3+ concentrations show high a Abbe number with the value over 16. Nb2O5-based glasses perform excellent optical properties that satisfy well the requirements of commercial glasses. The amorphous phase is confirmed by XRD and SEM images. Additionally, EDS results indicate the homogeneous distribution of compositions in the glass. A broad and strong near infrared emission centered at ∼ 1850nm ascribed to 3F4→3H6 is obtained from Tm3+/Yb3+ co-doped Nb2O5-based glasses at 980 nm excitation. The emission intensity first increases and then decreases with Yb3+. When y = 0.03, the emission is the strongest. The luminescence process is the energy transfer from Yb3+ to Tm3+. The lifetime of the excited state for Tm3+/Yb3+ co-doped Nb2O5-based glasses (y = 0.03) is calculated to be 2.292 ms. Such long lifetime is very favorable to get strong luminescence.

A comparative study of optical quality for different polymeric contact lenses

The comparision between pure organic polymer namely Poly(methyl methacrylate) “PMMA” and impregnated with Titanium dioxide nanoparticles (TiO2 NPs) as contact lenses on image quality of human eye have been investigated. Pure PMMA and TiO2-PMMA materials were considered and applied using ZEMAX software as contact lenses (CLs) basis on Liou & Brennan eye model. Ocular performance was evaluated and analysis by three criteria, namely tangential modulation transfer function (TMTF), wavefront aberration characteristics and root mean square (RMS) of spot diagram. All the criteria showed that contact lens made of TiO2-PMMA when its refractive index (RI) = 1.61 and Abbe number (νd) = 31.8 provided the closest imaging properties to the healthy eye. From the results of our investigation, PMMA doping with TiO2 resulted in balanced RI with νd polymer and it provided the best retinal image when it used in CLs in comparison with image properties of the resulting image using the lens of pure PMMA polymer.

Mesomorphic behavior of methanesulfonate salts of esters of L-Methionine and their optical properties

A set of methanesulfonate salts of esters of (S)-2-Amino-4-(methylthio)butanoic acid [L-Methionine] and fatty alcohols have been synthesized in good yields by a green protocol involving a one-step and solvent-free approach. All derivatives have been evaluated for their liquid crystalline properties using polarizing optical microscopy and differential scanning calorimetry and found to be enantiotropic liquid crystals. Refractive indices were measured for one of the derivatives at different temperatures and wavelengths. It exhibited a high Abbe number and low dispersive power. Synopsis: To be provided by author

Control of thermal, mechanical, and optical properties of three‐component maleimide copolymers by steric bulkiness and hydrogen bonding

ABSTRACT N‐substituted maleimides polymerize in the presence of a radical initiator to give polymers with excellent thermal stabilities and transparency. In this study, we synthesized various maleimide copolymers with styrenes and acrylic monomers to control their thermal and mechanical properties by the introduction of bulky substituents and intermolecular hydrogen bonding. Three‐component copolymers of N‐(2‐ethylhexyl)maleimide in combination with styrene, α‐methylstyrene (MSt), or 1‐methylenebenzocyclopentane (BC5) as the styrene derivatives, and n‐butyl acrylate, 2‐hydroxyethyl acrylate, 4‐hydroxybutyl acrylate, or acrylic acid as the acrylic monomers were prepared by radical copolymerization. These copolymers were revealed to exhibit excellent heat resistance by thermogravimetric analysis. Glass transition temperatures increased by the introduction of bulky MSt and BC5 repeating units. The mechanical properties of the copolymer films were improved by the introduction of intermolecular hydrogen bonding. Optical properties, such as transmittance, refractive index, Abbe number, and birefringence, were determined for the copolymers. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1569–1579

Infrared Glass–Ceramics with Multidispersion and Gradient Refractive Index Attributes

AbstractInfrared (IR) glass–ceramics (GCs) hold the potential to dramatically expand the range of optical material solutions available for use in bulk and planar optical systems in the IR. Current material solutions are limited to single‐ or polycrystalline materials and traditional IR‐transparent optical glasses. GCs that can be processed with spatial control and extent of induced crystallization present the opportunity to realize an effective refractive index variation, enabling arbitrary gradient refractive index elements with tailored optical function. This work discusses the role of the parent glass composition and morphology on nanocrystal phase formation in a multicomponent chalcogenide glass. Through a two‐step heat treatment protocol, a Ge–As–Pb–Se glass is converted to an optical nanocomposite where the type, volume fraction, and refractive index of the precipitated crystalline phase(s) define the resulting nanocomposite's optical properties. This modification results in a giant variation in infrared Abbe number, the magnitude of which can be tuned with control of crystal phase formation. The impact of these attributes on the GCs' refractive index, transmission, dispersion, and thermo‐optic coefficient is discussed. A systematic protocol for engineering homogeneous or gradient changes in optical function is presented and validated through experimental demonstration employing this understanding.