Single Prism Research Articles

Incisor Enamel Microstructure of Hystricognathous and Anomaluroid Rodents from the Earliest Oligocene of Dakhla, Atlantic Sahara (Morocco)

Seven hystricognaths and five anomaluroids have been recently described from the earliest Oligocene of the Dakhla (DAK C2) region of Morocco, based primarily on isolated cheek teeth. Here, we analyzed the enamel microstructure of thirty associated isolated fragments of incisors. Among these specimens, only three display an early stage of uniserial Hunter-Schreger bands (HSBs), with mostly a single prism per band, but also occasionally two prisms per band (in two specimens), and a thin interprismatic matrix (IPM) that runs parallel to the prism direction, thereby documenting incisors of anomaluroids. All other sampled incisors display an enamel with multiserial HSBs, thereby documenting hystricognaths. For these latter, we recorded primarily an IPM crystallite arrangement describing the subtype 2 of multiserial HSBs, but with variation including a wide amplitude in the angle (acute) formed between the crystallites of IPM and those of the prisms, some variations in the frequency of the IPM sheet anastomoses, in the number of prisms per HSBs, and variations in the inclination of the HSBs. The absence of the subtypes 2–3 and 3 of multiserial HSBs in DAK C2 suggests that African hystricognathous rodents had still not achieved these most resistant multiserial HSBs at that time. The drier, cooler climatic regime of the early Oligocene, having increased the fragmentation and opening of habitats, might have played a role in the subsequent selection of taxa having acquired a more resistant incisor enamel.

Linear angular dispersion compensation of cleaned self-diffraction light with a single prism

The linear angular dispersion of a self-diffraction (SD) pulse, from a femtosecond laser pulse cleaning device, is compensated for by the use of a single prism. More than $500~\unicode[STIX]{x03BC}\text{J}$ first-order SD pulse has a contrast of $10^{12}$, which is about five orders of magnitude improvement from the input fundamental pulse. The wings of the distribution away from the main pulse in $\pm 1$ ps are cleaned with a contrast improvement of about $10^{7}$, which verifies the pulse cleaning ability of the SD process.

Mathematical modeling of propagation of explosion waves and their effect on various objects

Results of modeling the propagation of a shock wave formed by an explosion of a spherical charge of a high explosive in a semi-infinite space bounded by a flat substrate are reported. Problems of the action of such a wave on objects rigidly fixed on the substrate (a single prism and a set of prisms simulating an urban area) are considered. The computations are performed in a three-dimensional inviscid formulation with the use of the AUTODYN module of the ANSYS commercial software package. These numerical predictions are compared with experimental data on the static pressure measured by sensors mounted on the prism walls. It is demonstrated that an adequate description of the unsteady flow pattern formed around the obstacles mounted on the substrate can be provided. Based on these numerical data, the intensity of the shock wave action on various objects is estimated.

Analysis of four PCR/SNaPshot multiplex assays analyzing 52 SNPforID markers

The SNPforID consortium identified a panel of 52 SNPs for forensic analysis that has been used by several laboratories worldwide. The original analysis of the 52 SNPs was based on a single multiplex reaction followed by two single-base-extension (SBE) reactions each of which was analyzed using capillary electrophoresis. The SBE assays were designed for high throughput genetic analyzers and were difficult to use on the single capillary ABI PRISM 310 Genetic Analyzer and the latest generation 3500 Genetic Analyzer, as sensitivity on the 310 was low and separation of products on the 3500 with POP-7™ was poor. We have modified the original assay and split it into four multiplex reactions, each followed by an SBE assay. These multiplex assays were analyzed using polymer POP-4™ on ABI 310 PRISM® and polymers POP-4™, POP-6™ and POP-7™ on the 3500 Genetic Analyzer. The assays were sensitive and reproducible with input DNA as low as 60 pg using both the ABI 310 and 3500. In addition, we found that POP-6™ was most effective with the 3500, based on the parameters that we assessed, achieving better separation of the small SBE products; this conflicted with the recommended use of POP-7™ by the instrument manufacturer. To support the use of the SNP panel in casework in Malaysia we have created an allele frequency database from 325 individuals, representing the major population groups within Malaysia. Population and forensic parameters were estimated for all populations and its efficacy evaluated using 51 forensic samples from challenging casework.

A prism-based non-linear optical readout method for MEMS cantilever arrays

This paper demonstrates the use of a single right-angle prism for the optical readout of micro-electro-mechanical systems (MEMS) cantilever arrays. The non-linear reflectivity arisen from the internal reflection at the right-angle prism’s hypotenuse plane enables the measurement of cantilever deflections. The cantilever arrays used in the experiments are made of electroplated nickel structures and actuated at resonance by an external electro-coil. A laser beam illuminates multiple cantilevers, and then it is partially reflected by the prism. The prism reflectivity changes with the cantilever deflection and modulates the laser intensity at the photodetector. The detection sensitivity of the optical readout system is determined by the initial angle of incidence at the prism’s hypotenuse plane, numerical aperture of the illumination system and the polarization of the laser beam. In this paper, we showed both theoretically and experimentally that self-sustained oscillations of two MEMS cantilevers with simple rectangular geometry is achievable using only one actuator and one photodetector. The gain saturation mechanism for the oscillators was provided by the optical non-linearity in the prism readout, which eliminates the requirement for separate sensing electronics for each cantilever. Based on our analytical and experimental data, we found that the prism incident angle around 41.2° is desirable in the closed-loop system due to high responsivity. Finally, we demonstrated simultaneous self-sustained oscillations of two cantilevers in closed-loop with resonant frequencies in the range 25–30kHz. It was shown that multiple oscillations are obtainable if the cantilever resonant frequencies are separated from each other by at least 3dB bandwidth.

A Prism-Based Optical Readout Method for MEMS Bimaterial Infrared Sensors

This letter demonstrates a novel prism-based optical-readout, which uses a single prism to detect the incoming TM polarized wave just below the critical angle. The method is used with a 35- $\mu \text{m}$ -pixel pitch MEMS thermal sensor, whose inclination angle changes with the absorbed infrared (IR) radiation that results in an increase in the reflectivity at the prism’s glass–air interface. We compared this approach with the conventional knife-edge method. Noise equivalent temperature difference for a single sensor was measured as 200 mK for knife-edge method, and 154 mK for the proposed critical angle approach. Our approach shows a significant improvement for the sensitivity of the IR sensor. Both methods utilize an AC-coupled readout method for a single MEMS pixel using a photodetector, which responds only to changes in the scene. This method can be scaled to achieve smart pixel cameras for read sensor arrays with low-noise and high-dynamic range.

Two-prism crystal structures for far-field imaging of subwavelength features at terahertz frequencies

We investigate how a system of two single crystals can be used for far field imaging of subwavelength features. We make use of the phonon response to induce canalization of narrow collimated beams in crystals with suitably high anisotropy at the appropriate transverse optical phonon frequency. By cutting the crystals into suitably designed prisms, we show that an magnified image can be obtained and projected into the far field by a two-prism structure, noting that a single prism does not give a faithful reproduction of the object and will usually result in total internal reflection of most of the radiation. We show simulations using triglycine sulphate, which is both highly anisotropic and has very low absorption, at low temperature.

A comparative study of the anisotropic dynamic and static elastic moduli of unconventional reservoir shales: Implication for geomechanical investigations

We obtained the complete set of dynamic elastic stiffnesses for a suite of “shales” representative of unconventional reservoirs from simultaneously measured P- and S-wave speeds on single prisms specially machined from cores. Static linear compressibilities were concurrently obtained using strain gauges attached to the prism. Regardless of being from static or dynamic measurements, the pressure sensitivity varies strongly with the direction of measurement. Furthermore, the static and dynamic linear compressibilities measured parallel to the bedding are nearly the same whereas those perpendicular to the bedding can differ by as much as 100%. Compliant cracklike porosity, seen in scanning electron microscope images, controls the elastic properties measured perpendicular to the rock’s bedding plane and results in highly nonlinear pressure sensitivity. In contrast, those properties measured parallel to the bedding are nearly insensitive to stress. This anisotropy to the pressure dependency of the strains and moduli further complicates the study of the overall anisotropy of such rocks. This horizontal stress insensitivity has implications for the use of advanced sonic logging techniques for stress direction indication. Finally, we tested the validity of the practice of estimating the fracture pressure gradient (i.e., horizontal stress) using our observed elastic engineering moduli and found that ignoring anisotropy would lead to underestimates of the minimum stress by as much as 90%. Although one could ostensibly obtain better values or the minimum stress if the rock anisotropy is included, we would hope that these results will instead discourage this method of estimating horizontal stress in favor of more reliable techniques.

A Study on the Improvement of Performance Testing System of Domestic Surveying Equipment

In this paper, we proposed the improvements for performance test and surveying equipment regulations, standards, methods and procedures, depending on the need of improving the legal system for surveying equipment in a diverse and sophisticated surveying industry. This research was performed first investigating the existing legal systems(Act on the establishment and management of spatial data, Framework act on national standards, ISO 17123, JIS B 7912) with respect to the surveying equipment performance testing and the research for IOS and KOLAS suggested the improvements on the application for the surveying equipment performance testing standard. More exactly, first, two years were presented for the surveying equipment performance testing cycle considering the precise accuracy of the instrument stability, purpose and frequency of use, etc. Second, the abolition of the measurement distance by grade and the upward or cross-grade adjustment of the single prism standards about the light wave rangefinder and total station were suggested for the improvement on survey equipment performance criteria. Third, since the main function of total station is focused on a three-dimensional coordinate measurement due to the improvement of surveying equipment performance testing, it was proposed to use the precision(repeatability) of the coordinate measuring method as an evaluation method.

Design and optical analyses of an arrayed microfluidic tunable prism panel for enhancing solar energy collection

We present the design and optical analyses of an arrayed microfluidic tunable prism panel that enables wide solar tracking and high solar concentration while minimizing energy loss. Each of the liquid prism modules is implemented by a microfluidic (i.e. non-mechanical) technology based on electrowetting for adaptive solar beam steering. Therefore the proposed platform offers a low-cost, lightweight and precise solar tracking system while obviating the need for bulky and heavy mechanical moving parts essentially required for a conventional motor-driven solar tracker. In this paper, various liquid prism configurations in terms of design (single, double, triple and quad-stacked prism arrays) as well as optical materials are considered and their impact on optical performance aspects such as solar beam steering, reflection losses and beam concentration is studied. Our system is able to achieve a wide solar tracking covering the whole-day movement of the Sun and a reflection loss below 4.4% with a Rayleigh’s film for a quad-stacked prism configuration. Furthermore, an arrayed prism panel is proposed to increase the aperture area and thus allows for the collection of large amounts of sunlight. Our simulation study based on the optical design software, ZEMAX, indicates that the prism panel is capable of high solar concentration up to 2032× factor even without conventional solar tracking devices. We also deal with dispersion characteristics of the materials and their corresponding effect on concentration factor. The proposed microfluidic platform has a potential for high solar energy harvesting and is not only economically viable, but also reliable and practical for various solar power applications.

Dispersion-based Color Projection using Masked Prisms

We present a method for projecting arbitrary color images using a white light source and an optical device with no colored components - consisting solely of one or two prisms and two transparent masks. When illuminated, the first mask creates structured white light that is then dispersed in the prism and attenuated by the second mask to create the color projection. We derive analytical expressions for the mask parameters from the physical components and validate our approach both in simulation and also demonstrate it on a wide variety of images using two different physical setups one consisting of two inexpensive triangular prisms, and the other using a single rhombic prism. Furthermore, we show that optimizing the masks simultaneously enables obfuscating the image content, and provides a tradeoff between increased light throughput by up to a factor of three and maximum color saturation.

Les réseaux de villes baltiques : la dimension spatiale de la recomposition des niveaux

Depuis la fin des années 1980, les acteurs locaux sont confrontés à une recomposition des interactions entre niveaux géographiques. Ils doivent composer plus directement avec un nombre accru de niveaux dans un contexte interterritorial complexe et hybride, régi par une concurrence très forte entre municipalités. Les réseaux de villes apparaissent alors comme des outils d'adaptation, surtout dans le cas des villes baltiques qui s'inscrivent de manière singulière dans les processus d'européanisation politique et de mondialisation économique. Leur étude permet d'identifier différentes traductions spatiales des stratégies interterritoriales trop souvent considérées sous le seul prisme de la gouvernance.

Asymmetric transmission in prisms using structures and materials with isotropic-type dispersion.

It is demonstrated that strong asymmetry in transmission can be obtained at the Gaussian beam illumination for a single prism based on a photonic crystal (PhC) with isotropic-type dispersion, as well as for its analog made of a homogeneous material. Asymmetric transmission can be realized with the aid of refraction at a proper orientation of the interfaces and wedges of the prism, whereas neither contribution of higher diffraction orders nor anisotropic-type dispersion is required. Furthermore, incidence toward a prism wedge can be used for one of two opposite directions in order to obtain asymmetry. Thus, asymmetric transmission is a general property of the prism configurations, which can be obtained by using simple geometries and quite conventional materials. The obtained results show that strong asymmetry can be achieved in PhC prisms with (nearly) circular shape of equifrequency dispersion contours, in both cases associated with the index of refraction 0<n<1 and n>1. For the comparison purposes, results are also presented for solid uniform non-magnetic prisms made of a material with the same value of n. It is shown in zero-loss approximation that the PhC prism and the ultralow-index material prism (0<n<1) can replace each other in some cases without affecting the scenario of asymmetric transmission. Moreover, the PhC prism and the solid dielectric prism can show the same scenario at n>1. Possible contributions of scattering on the individual rods and diffraction on the wedge to the resulting mechanism are discussed. Analogs of unidirectional splitting and unidirectional deflection regimes, which are known from the studies of PhC gratings, are obtained in PhC prisms and solid uniform prisms, i.e. without higher diffraction orders.

Polarization manipulation in single refractive prism based holography lithography

We propose theoretically and demonstrate experimentally a simple but effective strategy for polarization manipulation in single refractive prism based holographic lithography. By tuning the polarization of a single laser beam, we can obtain the pill shape interference pattern with a high-contrast where a complex optical setup and multiple polarizers are needed in the conventional holography lithography. Fabrication of pill shape two-dimensional polymer photonic crystals using one beam and one shoot holography lithography is shown as an example to support our theoretical results. This integrated polarization manipulation technique can release the crucial stability restrictions imposed on the multiple beams holography lithography.

Continuous-wave broadly tunable high-power Cr:CdS laser.

We report spectroscopic characteristics and laser properties of the mid-infrared active laser medium Cr2+:CdS. Temperature-dependent absorption, luminescence and lifetime measurements of the 5E exited state allow determination of peak emission cross section value of 1.35 × 10−18 cm2 in σ-polarization at room temperature. Lifetime values vary from 7.6 µs at 8 K to 0.48 µs at 320 K, corresponding to 22 % quantum yield at 285 K. Under Tm-fiber laser pumping, the continuous-wave output reached 1.8 W at 2.5 μm with 35.5 % slope efficiency. With a single CaF2 prism, the CW Cr2+:CdS laser could be tuned from 2.240 to 3.285 µm.

The Influence of Inconsistent Data on Cost-Sensitive Classification Using Prism Algorithms: An Empirical Study

Cost-sensitive classification is one of the hottest research topics in data mining and machine learning. It is prevalent in many applications, such as Automatic Target Recognition (ATR), medical diagnosis, etc. However, the data in practice may be inconsistent due to dimensional reduction operation or other pre-processing, yet it is not clear how the inconsistent data affects cost-sensitive learning. This paper presents an empirical comparative study using four Prism rule-generating algorithms with J-measure pruning, two of which are proposed in this paper. The most important result of our study is that inconsistent data dose often affects the performance of cost-sensitive Prism classifiers, and in the inconsistent data setting, merely a single Prism classifier’s robustness cannot completely satisfy the requirements of cost-sensitive systems.

Numerical investigation into the fragmentation efficiency of one coal prism in a roller pulveriser: Homogeneous approach

The aim of this paper is to numerically model the rolling compression induced breakage process of a single coal prism in a roller pulveriser and to quantify the resultant fragmentation efficiency. A coupling approach of the finite element method (FEM) and the smoothed particle hydrodynamics (SPH) method is adopted to examine the complete deformation and progressive fragmentation process involved. A coupled damage-plastic material model is used to simulate the complex deformation and failure behaviour of coal materials. In order to quantify the geometric properties of main fragments by the rolling compression, a numerical approach is developed based on the union-find algorithm. Parametric studies have been conducted considering various factors, including the geometric factors of prismatic coal specimens and the rotating velocity of the rigid roller. Typical modelling results are provided and the fragmentation efficiency is examined and discussed with respect to the corresponding factors.

Fabrication of two kinds of eight-fold photonic quasi-crystals assisted by a specially designed prism

We demonstrate that two kinds of 2D eight-fold photonic quasi-crystals (PQCs) can be fabricated by a specially designed prism via single-exposure holographic lithography. The prism with five continuous side surfaces out of common eight symmetrical side surfaces, plus a top surface, is well designed for PQC fabrication. Compared with the traditional method of setting up eight free-space beams in the half-space for an eight-fold PQC fabrication, our specially designed prism reduces the number of beams, avoids the differences of beam-to-beam phases, and simplifies the fabrication process. The theory and computer simulation confirm the patterns of two kinds of PQCs by a single prism illumination recording. Further, these quasi-crystal patterns are successfully verified by experimental results under a scanning electron microscope. In addition, these samples show some good properties, such as uniformity over large area, the implementation of a single defect by underexposure, and symmetry break of the eight dots. Our special prism-assisted holographic lithography technique provides a base for further investigating the optical properties of these novel structures.

Electron-Energy Loss Study of Nonlocal Effects in Connected Plasmonic Nanoprisms

We investigate the emergence of nonlocal effects in plasmonic nanostructures through electron-energy loss spectroscopy. To theoretically describe the spatial dispersion in the metal permittivity, we develop a full three-dimensional nonlocal hydrodynamic solution of Maxwell's equations in frequency domain that implements the electron beam as a line current source. We use our numerical approach to perform an exhaustive analysis of the impact of nonlocality in the plasmonic response of single triangular prisms and connected bowtie dimers. Our results demonstrate the complexity of the interplay between nonlocal and geometric effects taking place in these structures. We show the different sensitivities to both effects of the various plasmonic modes supported by these systems. Finally, we present an experimental electron-energy loss study on gold nanoprisms connected by bridges as narrow as 1.6 nm. The comparison with our theoretical predictions enables us to reveal in a phenomenological fashion the enhancement of absorption damping that occurs in these atomistic junctions due to quantum confinement and grain boundary electron scattering.

Diode-pumped passively mode-locked tunable Yb:CALGO solid-state laser

In this paper, we present a simple, compact, and efficient Yb:CALGO laser system that can produce sub-100&#xA0;fs pulses easily tunable over a 38&#xA0;nm wide wavelength range between 1034 and 1072&#xA0;nm. The laser is passively mode locked with a semiconductor saturable absorber and generates up to 90&#xA0;mW output power (for 230&#xA0;mW absorbed pump), using a single prism for both tuning and dispersion compensation.