For three years we have used synthetic and field data to investigate the effectiveness of commercial refraction tomography codes on both simple and complex subsurface velocity structures, with the ultimate goal of determining the suitability of the method for karst problems. The results of these studies indicate that refraction tomography is able to resolve karst features under some conditions....

Hyperbolic metamaterials are materials in which at least one principal dielectric constant is negative. We describe the refractive index surface, and the resulting refraction effects, for a biaxial hyperbolic metamaterial, with principal dielectric constants 1 < 0, 0 < 2 = 3. In this general case the two sheets of the index surface intersect, forming conical singularities. We derive the ray des...

Optical coherence tomography (OCT) has been increasingly used for imaging pulmonary alveoli. Only a few studies, however, have quantified individual alveolar areas, and the validity of alveolar volumes represented within OCT images has not been shown. To validate quantitative measurements of alveoli from OCT images, we compared the cross-sectional area, perimeter, volume, and surface area of ma...

Optical index of refraction n is studied by spectroscopic ellipsometry in epitaxial nanofilms of NaNbO3 with thickness ∼10 nm grown on different single-crystal substrates. The index n in the transparency spectral range (n ≈ 2.1 - 2.2) exhibits a strong sensitivity to atmospheric-pressure gas ambience. The index n in air exceeds that in an oxygen ambience by δn ≈ 0.05 - 0.2. The thermo-optical b...

First-arrival seismic traveltime tomography (FAST) is a well-established technique to estimate subsurface velocity structures. Although several existing open-source packages are available for first-arrival tomography, most were written in compiled languages and lack sufficient extendibility new algorithms functionalities. In this work, we develop an open-source, self-contained FAST package base...

A computer model of wave refraction is desirable, in the context of landscape modeling, to generate the familiar wave patterns seen near coastlines. In this article, we present a new method for the calculation of shallow water wave refraction. The method is more accurate than previously existing methods and provides realistic wave refraction effects. We resort to Fermat’s principle of the short...

Abstract. The influence of the observed relict vacuum energy on the fluctuations of CMBR going through cosmological matter condensations is studied in the framework of the Einstein-Strauss-de Sitter vakuola model. It is shown that refraction of light at the matching surface of the vakuola and the expanding Friedman universe can be very important during accelerated expansion of the universe, whe...

Synchrotron radiation has (partly unique) properties promoting the investigation of solids and interfaces on a broad scale. This can support the development of new materials among them certified reference materials (CRMs). Due to the high intensity and the minute size of the light source the radiation can be filtered (monochromatized) and/or focussed onto the sample. Samples can be scanned at h...

The complex index of refraction of aqueous methanesulfonic acid (MSA) at room temperature and at concentrations of 1-70 wt. % is presented. The complex index of refraction is obtained in the entire wave-number region from the mid infrared to the ultraviolet-visible regions. An analysis of the infrared spectra reveals a single absorption band, which makes it possible to identify MSA in aqueous H...