Total Refraction Research Articles

Polarization-sensitive propagation in an anisotropic metamaterial with double-sheeted hyperboloid dispersion relation

The polarization-sensitive propagation in the anisotropic metamaterial (AMM) with double-sheeted hyperboloid dispersion relation is investigated from a purely wave propagation point of view. We show that TE and TM polarized waves present significantly different characteristics which depend on the polarization. The omnidirectional total reflection and oblique total transmission can occur in the interface associated with the AMM. If appropriate conditions are satisfied, one polarized wave exhibits the total refraction, while the other presents the total reflection. We find that the opposite amphoteric refractions can be realized by rotating the principle axis of AMM, such that one polarized wave performs the negative refraction, while the other undergoes positive refraction. The polarization-sensitive characteristics allow us to construct two types of efficient polarizing beam splitters under certain achievable conditions.

Reswelling transition of poly(sodium acrylate) gels due to destruction of hydrogen bonds observed by ATR FTIR spectroscopy

AbstractWe report the reswelling transition of a physically crosslinked polyelectrolyte hydrogel in water, which was prepared using poly(sodium acrylate) as the main constituent and Al ions as the crosslinker. The nonmonotonic swelling behavior was observed at room temperature (25°C) under the continuous exchange of water; an as‐prepared gel swelled at the first stage (the swelling process) and then shrunk very slowly at the second stage (deswelling process). In the deswelling process, the water exchange was stopped and the diameter of the gel in a limited amount of water was measured as a function of the temperature. The gels reswelled at different transition temperatures in the heating processes, which depended on the initial diameter at 25°C (resulting from the different numbers of water exchange). The reswollen state was stable at 25°C and could shrink again as a result of successive water exchanges at 25°C. In the following temperature increase in the closed system, the reswelling phenomenon was observed again. The destruction of the hydrogen bonds introduced by the water exchange was confirmed by the attenuated total refraction Fourier transform infrared measurements. The reversible transition behavior between the deswollen and the reswollen states is discussed in terms of the formation and destruction of the hydrogen bonds. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Interface properties and refraction of light in twin-layered organic semiconductors

Polytypism associated with periodic twinning with mirror-like orientation of the unit cell in successive layers is often found in crystals of conjugated molecules. The negative and total refraction of light at the interface between the twinned layers is discussed in the case of monoclinic molecular solids of quaterthiophene.

On the Determination of Partial Molar Volumes, Partial Molar Refractions, Mean Electronic Polarizabilities and Effective Molecular Radii from Dilute Multi-component Data alone using Response Surface Models

A quaternary system consisting of three solutes, namely ethanol, diethylene glycol (DEG) and triethylene glycol (TEG) in benzene at 298.15 K and 1.0125 × 105 Pa was studied. An experimental design in the range of concentration 0.006 < xsolute−i < 0.023 was explored, optimizing the metric distance among the solutes to avoid clustering. On-line simultaneous experimental measurements using a densitometer and a refractometer were utilized to measure bulk solution density and bulk refractive index, respectively. Response surface models describing the total molar volume and total molar refraction were employed to determine the partial molar volumes and the partial molar refractions of each solute from the dilute multi-component data alone. Neither densities nor refractive indices of any of the pure components were used and no binary information was required for the analysis. Definitions for the mean electronic polarizability and the effective molecular radius of a solute based on the partial molar refraction were introduced. Subsequently, the mean electronic polarizabilities and the effective molecular radii for each solute in multi-component solutions, as well as the solvent were determined. The results obtained for the partial molar volumes, partial molar refractions, electronic polarizabilities and the effective molecular radii were in good agreement with those obtained from independent binary experiments as well as those from literature binary data.

Breaking the resolution limit in light microscopy

Fluorescent imaging microscopy has been an essential tool for biologists over many years, especially after the discovery of the green fluorescent protein and the possibility of tagging virtually every protein with it. In recent years dramatic enhancement of the level of detail at which a fluorescing structure of interest can be imaged have been achieved. We review classical and new developments in high-resolution microscopy, and describe how these methods have been used in biological research. Classical methods include widefield and confocal microscopy whereas novel approaches range from linear methods such as 4Pi, I(5) and structured illumination microscopy to non-linear schemes such as stimulated emission depletion and saturated structured illumination. Localization based approaches (e.g. PALM and STORM), near-field methods and total internal refraction microscopy are also discussed. As the terms 'resolution', 'sensitivity', 'sampling' and 'precision' are sometimes confused, we explain their clear distinction. Key concepts such as the point spread function and the Abbe limit, which are necessary for an in depth understanding of the presented methods, are described without requiring extensive mathematical training.

A Dataset of Human Cornea Proteins Identified by Peptide Mass Fingerprinting and Tandem Mass Spectrometry

Diseases of the cornea are extremely common and cause severe visual impairment worldwide. To explore the basic molecular mechanisms involved in corneal health and disease, the present study characterizes the proteome of the normal human cornea. All proteins were extracted from the central 7-mm region of 12 normal human donor corneas containing all layers: epithelium, Bowman's layer, stroma, Descemet's membrane, and endothelium. Proteins were fractionated and identified using two different procedures: (i) two-dimensional gel electrophoresis and protein identification by MALDI-MS and (ii) strong cation exchange or one-dimensional SDS gel electrophoresis followed by LC-MS/MS. All together, 141 distinct proteins were identified of which 99 had not previously been identified in any mammalian corneas by direct protein identification methods. The characterized proteins are involved in many processes including antiangiogenesis, antimicrobial defense, protection from and transport of heme and iron, tissue protection against UV radiation and oxidative stress, cell metabolism, and maintenance of intracellular and extracellular structures and stability. This proteome study of the healthy human cornea provides a basis for further analysis of corneal diseases and the design of bioengineered corneas.

TOTAL AND NEGATIVE REFRACTION OF ELECTROMAGNETIC WAVES

Recently there has been a great deal of interest in an unusual category of material, that is, a material that exhibits negative refractive index or more generally negative group velocity. Perhaps the most immediate application of this type of material is in an area known as total and negative refraction, which may potentially lead to many novel optical devices. The reason that the phenomenon of total and negative refraction has become so interesting to the physics community is also due largely to the notion that this phenomenon would never occur in conventional materials with positive refractive index. It turns out that total and negative refraction can be realized even in natural crystalline materials or in artificial materials (e.g. photonic crystals) without negative (effective) refractive index. In this brief review, after providing a brief historic account for the research related to finding materials with negative group velocity and achieving negative refraction, we discuss the three primary approaches that have yielded experimental demonstrations of negative refraction, in an effort to clarify the underlying physics involved with each approach. A brief discussion on the subwavelength resolution application of the negative (effective) refractive index material is also given.

Rapid Measurement of Phytate in Soy Products by Mid-infrared Spectroscopy

ABSTRACT: The rapid measurement of phytate from soybean and its products, such as soy flour, defatted meal, soymilk, and tofu, was investigated using Fourier transfer infrared spectroscopy (FT-IR) with an attenuated total refraction accessory. The phytate, separated from protein by trichloroacetic acid (TCA), was precipitated completely by the addition of calcium, pH > 7.0, even in the presence of TCA. The precipitate was dissolved in citrate buffer (pH 6.0) and then used for infrared measurement. The absorbance at 1070 cm−1 correlated well the phytate content of the each sample. The measurement of phytate can be done rapidly by FT-IR with an ATR accessory and gives reproducible values.

Swelling behavior of poly(sodium acrylate) gels crosslinked by aluminum ions

The cylindrical poly(sodium acrylate) gel (SA gel) was synthesized in the glass capillary using aluminum ions as the crosslinker. The swelling ratio of the gel was measured after the repeated exchange of solvent (distilled deionized water, about pH 5.8). The gel exhibited two relaxation processes; at first the gel swells rapidly as exchange of water (the swelling process), then shrinks very slowly (the shrinking process). In order to reveal the microscopic structural change (especially, the formation of hydrogen bonding) by water exchange, attenuated total refraction (ATR) Fourier transform infrared (FT-IR) spectroscopy was applied to the gels with different swelling ratio. The IR absorption peaks of the gel were assigned based on those of poly(sodium acrylate) aqueous solutions at different pH. On the swelling process, the carboxyl groups were gradually protonated, and the intermolecular hydrogen bonding started to form in the gel with maximum swelling ratio. On the shrinking process, the formation of hydrogen bonding gradually increased with long-time repeated water exchange which resulted in the shrinkage of the gel. Effects of the repeated water exchange on the swelling behavior were discussed in terms of the exchange of counter ions and the formation of hydrogen bonding.

Total Refraction of P-Polarized Light at the Boundary of 90°-Domains in the Ferroelectric Crystal

A 90°-domain structure was fabricated using electrical poling in ferroelectric birefringent KNbO3 crystal. The refraction and reflection characteristics of the light at the boundary of the 90°-domain structure were investigated, and the novel behavior of total refraction (no reflection) has been found for the P-polarized light throughout the entire range of incident angle (0≤θ≤90°). Strong refraction of the light was observed after it exited from the crystal output surface at the incidence parallel to the domain boundary. These behaviors were explained analytically.

Time-Domain Green's Functions for Microstrip Structures Using Cagniard–de Hoop Method

Time-domain Green's functions are required for transient analyzes of many structures using the time-domain integral equation method. In this paper, we express the generalized reflection coefficient of the microstrip structure in terms of a geometric optics series so that by applying the Cagniard-de Hoop method to each term of the series, we can derive the time-domain Green's function. It is demonstrated that this series converges rapidly and there are two contributing waves from each source image if the observation point is beyond the total internal refraction location. The two waves are the direct wave from the image and the head wave from the image to the critical point, and then laterally along the surface to the observer. Each contribution is a definite integral that is evaluated for each point in space and time. Therefore, the derived Green's function is efficient for time-domain simulations compared with conventional approach, in which for each point in space and frequency a Sommerfeld type integral is involved and then the frequency-domain data is converted into time-domain by discrete Fourier transform. This rigorous Green's function can also be used to check the accuracy of other approximate methods such as those using the discrete complex image theory.

Total negative refraction in real crystals for ballistic electrons and light.

It is found that there exists a category of material interfaces, readily available, that not only can provide total refraction (i.e., zero reflection) but can also give rise to amphoteric refraction (i.e., both positive and negative refraction) for electromagnetic waves in any frequency domain as well as for ballistic electron waves. These two unusual phenomena are demonstrated experimentally for the propagation of light through such an interface.

Effect of infusion bottle height on lens power after lens refilling with and without a plug

Purpose To evaluate the influence of intraoperative infusion bottle height on the power of refilled pig lenses. Setting Research Laboratory, Pharmacia Intraocular Lens Manufacturing Plant, Groningen, The Netherlands. Methods This study comprised 2 groups of pig eyes. In 1 group, the lens was refilled with silicone oil using a plug to close the capsulorhexis; in the other group, no plug was used. The anterior chamber depth, lens thickness, and vitreous chamber depth were measured by A-scan ultrasound. The total refraction was measured with a Hartinger refractometer. Measurements were performed with the infusion bottle at 0 cm, 25 cm, 50 cm, 75 cm, and 100 cm above eye level. Calculations using a model eye were performed to evaluate the change in lens power based on empirical data. Results The mean change in the power of refilled lenses caused by varying the height of the infusion bottle was 1.8 diopters. Lenses refilled with a plug had a thickness similar to that of natural lenses. Lenses refilled without a plug were significantly thinner ( P<.05). The power of lenses refilled with a plug was significantly higher that of lenses refilled without a plug ( P<.05). Conclusions During lens refilling, infusion bottle height influenced the resulting lens power. Using a plug to close the capsulorhexis resulted in refilled lens dimensions similar to those of the natural lens.

Fullerenes, endohedral fullerenes, and the prediction of high boiling points

Extrapolation of the experimental vapor–pressure curves of the [60], [70], [76] and [84] fullerenes gives normal, estimated boiling or sublimation temperatures such that half of the boiling points predicted by an earlier semi-empirical theory, based primarily on the total molar refraction for all exposed atoms, of essentially all vaporizable non-metals, organic and inorganic, having limited polarities, differ from these estimated values by less than the calculated uncertainties. These data suggest that the theory is applicable up to ca. 1900 K, even though the original proposal made verified claims up to less than 900 K. This leads to: Tb,est([n]fullerene) ≈ Tb,pred([n]fullerene), supporting the claim that we can predict many boiling points over a wide range of temperatures. Here we also extend the predictions to include endohedral fullerenes.

Observation of light propagation by holography with a picosecond pulsed laser

We demonstrate the propagation of a light pulse undergoing refraction and total refraction inside a glass block as well as diffraction at a grating. Observation of a frameless, continuous motion picture of the light propagation is possible by recording of hologram with a picosecond pulsed laser. It is shown that the direction of the pulse changes as a result of refraction, the pulse's speed decreases inside a glass block, and the pulse travels a zigzag path by total refraction. The pulse fronts of the diffracted light propagating parallel to the grating surface are also demonstrated.

The importance of genes and environment for ocular refraction and its determiners: a population based study among 20–45 year old twins

AIMSTo estimate the heritability for ocular refraction and its determiners in a population based cohort of 20–45 years old twins.METHODS114 twin pairs (53 monozygotic and 61 dizygotic) participated. Refraction was...

Angle of Total Refraction in the Interaction of a Plane Skew Shock Wave with the Interface of Two Media

The solution of practical problems associated with determination of the shock‐wave configuration that results from the interaction of a stationary plane skew shock wave (SSW) with the interface of two media, is invariably related to determination of the critical angles of the interaction. The author suggests a method of analytical calculation of one of these angles within the framework of the applicability of the hydrodynamic theory of shock waves, namely, the angle of total refraction, denoted by ϕt in some of the indicated works.

High-efficiency multilevel zone plates for keV X-rays

The development of high brilliance X-ray sources coupled with advances in manufacturing technologies has led to significant improvements in submicrometre probes for spectroscopy, diffraction and imaging applications. The generation of a small beam spot size is commonly based on three principles1: total reflection (as used in optical elements involving mirrors or capillaries), refraction (such as in refractive lenses2) and diffraction. The latter effect is employed in Bragg–Fresnel or Soret lenses, commonly known as Fresnel zone plate lenses. These lenses currently give the best spatial resolution, but are traditionally limited to rather soft X-rays—at high energies, their use is still limited by their efficiency. Here we report the fabrication of high-efficiency, high-contrast gold and nickel multistep (quaternary) Fresnel zone plates using electron beam lithography. We achieve a maximum efficiency of 55% for the nickel plate at 7 keV. In addition to their high efficiency, the lenses offer the advantages of low background signal and effective reduction of unwanted diffraction orders. We anticipate that these lenses should have a significant impact on techniques such as microscopy3, micro-fluorescence4 and micro-diffraction5, which require medium resolution (500–100 nm) and high flux at fixed energies.

Pervaporation separation and pervaporation-esterification coupling using crosslinked PVA composite catalytic membranes on porous ceramic plate

A composite catalytic membrane with a crosslinked PVA dense active layer coated on a porous ceramic plate support was prepared using a novel method and evaluated with a pervaporation setup for the separation of several organic aqueous mixtures. Several key problems occurred during the preparation procedure are discussed. SEM (scanning electron microscopy), IR (infra-red) (ATR) (attenuated total refraction) and XPS (X-ray photoelectron spectrometry) were used to characterize the catalytic membrane natures. N-Butyl alcohol-acetic acid esterification was used as a model system for investigating into the coupling of reaction with pervaporation in a batch reactor. Different reaction parameters, temperatures, catalyst concentrations and initial reactant molar ratios were studied experimentally.

Optical Fiber Communication Systems

The Communications Toolbox: Introduction. Probability and Random Variables. Some Important Probability Distributions. Signals and Systems. Random Processes. Spectral Analysis. Narrowband Signals and Systems. Elements of Detection Theory. From Light to Signals. Basic Optical Fiber Communications Components: Introduction. The Refractive Index and the Laws of Reflection and Refraction. Total Internal Refraction. Step Index Fibers and Slab Waveguides. Maxwell's Equations in the Slab Waveguide. Even Propagation Modes. Odd Propagation Modes. Number of Modes and Single-Mode Fibers. Phase Velocity. Group Velocity. Attenuation and Dispersion. Dispersion-Shifted and Dispersion-Flattened Fibers. Polarization-Maintaining and Single-Polarization Fibers. The P-N Junction. Single Heterostructure. Double Heterostructure. LED Physical Structure. The LED Rate Equation. LED Output Spectrum. LED Modulation Response. The Fabry-Perot Resonator. Semiconductor Laser Physical Structure. Laser Output Spectrum--Spectral Width and Linewidth. Bragg Reflections. Distributed Feedback (DFB) and Distributed Bragg Reflection (DBR) Lasers. Rate Equations. The Steady-State Solution to the Rate Equations. Laser Modulation--Step Response. Laser Modulation--Sinusoidal Frequency Response. Relative Intensity Noise (RIN), Phase and Frequency Noise, Chirp. Laser Package. The PIN Photodiode. The Avalanche Photodiode, ADP. Basic Binary Optical Communication System: Introduction. System Description. Performance Evaluation. Coherent Systems: Motivations and Basics. Fundamental Receiver Sensitivity--Homodyne Systems. Heterodyne Systems--Synchronous Detection. Heterodyne Systems--Asynchronous Detection. Heterodyne Systems--Weakly Synchronous Detection. Summary and Comparison of Fundamental Sensitivities. Optical Hybrids. Phase Noise and Linewidth. Synchronous Systems. Asynchronous Systems. Weakly Synchronous Systems. How to Deal with Phase Noise--Summary. Polarization Fluctuations. Appendix A--Statistics of Phase Noise to Amplitude Conversion. Appendix B--Evaluation of Averages by Quadrature Rules. Optical Amplifiers: Introduction. Semiconductor Amplifiers. Erbium-Doped Fiber Amplifier. Comparison of Major SOA and EDFA Characteristics. Other Fiber Amplifiers. Soliton Systems: Intuitive Explanation of Solitons. Advantages of Solitons for Long Distance Transmission. Derivation of Solitons. Amplitude, Duration, Energy, and Power. Higher-Order Solitons. Qualitative Physical Explanation of Solitons. Estimation of Peak Pulse Power Required for Solitons. Fiber Loss and its Compensation. Lumped Amplifiers in Soliton Systems. Polarization Dispersion. Amplified Spontaneous Emission Noise in Soliton Systems. Error Rates in Soliton Systems. Soliton Experiments. Using Recirculating Loops. Wavelength Division Multiplexing with Solitons. Bidirectional Soliton Systems. Sources of Soliton Pulses. Beyond the Gordon-Haus Limit. Multichannel Systems: Introduction. Time-Division Multiplexing (TDM). Wavelength-Division Multiplexing. Subcarrier Multiplexing. Code-Division Multiplexing. Space-Division Multiplexing. Network Issues.