Showing papers on "Total external reflection published in 2002"
TL;DR: The Goos-Hänchen shift is calculated when total internal reflection occurs at an interface between "normal" and negatively refractive media and is negative, consistent with the direction of energy flow in the positively refractive medium.
Abstract: The Goos-Hanchen shift is calculated when total internal reflection occurs at an interface between "normal" and negatively refractive media. The shift is negative, consistent with the direction of energy flow in the negatively refractive medium.
271 citations
TL;DR: Applying Artmann's formula to a light beam in the TM state of wave polarization, it is shown analytically the existence of a large and negative Goos-Hänchen shift near the angle of the Brewster dip on reflection from a weakly absorbing semi-infinite medium.
Abstract: Applying Artmann's formula to a light beam in the TM state of wave polarization, we show analytically the existence of a large and negative Goos-Hanchen shift near the angle of the Brewster dip on reflection from a weakly absorbing semi-infinite medium. The shift is opposite that in the case of total internal reflection, and it can be an order of magnitude larger than a wavelength if the absorption of the reflecting medium is sufficiently weak. Examples are given, and the detectibility of the shift is discussed.
214 citations
TL;DR: In this article, it was shown that a modulated Gaussian beam undergoes negative refraction at the interface between a positive and negative refractive index material, and the interference fronts appear to bend in a manner suggesting positive refraction, such that the true direction of the energy flow associated with the refracted beam is not obvious.
Abstract: We show that a modulated Gaussian beam undergoes negative refraction at the interface between a positive and negative refractive index material. While the refraction of the beam is clearly negative, the modulation interference fronts are not normal to the group velocity, and thus exhibit a sideways motion relative to the beam—an effect due to the inherent frequency dispersion associated with the negative index medium. In particular, the interference fronts appear to bend in a manner suggesting positive refraction, such that for a plane wave, the true direction of the energy flow associated with the refracted beam is not obvious.
137 citations
Patent•
14 Mar 2002
TL;DR: An optical apparatus for total internal reflection spectroscopy comprises: a transparent body having an internally reflective surface; at least one source of electromagnetic radiation for providing at least 1 beam of collimated electromagnetic radiation; optical scanning means for directing the beam or beams to the transparent body so that the radiation is internally reflected at the reflective surface, and sequentially or continuously scanning the incident angle of the radiation over an angular range; a detector for detecting electromagnetic radiation exiting the opaque body, and means for counteracting variation of the irradiance in the illuminated area of the surface during the angular scan,
Abstract: An optical apparatus for total internal reflection spectroscopy comprises: a transparent body having an internally reflective surface; at least one source of electromagnetic radiation for providing at least one beam of collimated electromagnetic radiation; optical scanning means for directing the beam or beams to the transparent body so that the radiation is internally reflected at the reflective surface, and sequentially or continuously scanning the incident angle of the radiation over an angular range; at least one detector for detecting electromagnetic radiation exiting the transparent body, and means for counteracting variation of the irradiance in the illuminated area of the surface during the angular scan, or the effect of such variation on the reflected beam or beams. An optical apparatus for examining thin layer structures on a surface for differences in respect of optical thickness and/or refractive index, and a method for total internal reflection spectroscopy are also disclosed.
42 citations
Patent•
19 Feb 2002
TL;DR: In this paper, a method for testing a surface includes finding respective first and second critical angles for total external reflection of radiation from an area of the surface at first andsecond wavelengths.
Abstract: A method for testing a surface includes finding respective first and second critical angles for total external reflection of radiation from an area of the surface at first and second wavelengths. The first and second critical angles are compared to determine an orientation of a tangent to the surface in the area.
37 citations
TL;DR: Grazing-incidence X-ray methods have been used for a long time as discussed by the authors, but the use of such geometry has only been developed fully with the advent of highly collimated Xray sources, particularly synchrotrons.
Abstract: ### Grazing-incidence X-ray methods
Although the advantages of using grazing incidence (GI) techniques in X-ray scattering and spectroscopy have been known for a long time (Yoneda and Horiuchi 1971), the use of such geometry has only been developed fully with the advent of highly collimated X-ray sources, particularly synchrotrons. It is now possible to place the entire output of a synchrotron insertion device (wiggler or undulator) onto the surface of a flat crystal or analogous sample with minimal angular divergence at the critical angle for total external reflection. This allows the application of unprecedented X-ray intensity in a region confined within a few nm of the surface. Such intensity allows for measurement of the X-ray absorption and emission spectrum with sufficient counting statistics so that extremely small surface coverages of impurities, precipitates or sorbed species can be structurally probed. This is of value to environmental geochemistry, as the majority of toxic pollutants in the environment do not occupy mineral surfaces with anything like monolayer (ML) coverages. Hence the majority of X-ray experiments to date deal with unrealistically high surface loadings, relatively thick surface precipitates, or natural samples with high levels of contaminants. This is of special significance because small quantities of surface complexes may bind to defect or otherwise unrepresentative low density sites on a surface, and hence would not behave like species sorbed at higher densities. In addition, the use of single crystal samples allows the polarization of the synchrotron radiation to be used to probe specific directions with respect to the surface plane (for K and L1 edges), hence potentially obtaining additional crystallographic information about oriented adsorbates, precipitates or epitaxial layers. One can select the type of substrate, the plane (hkl) of the substrate, and the orientation of that plane with respect to the propagation direction and electric vector polarization of …
33 citations
11 Sep 2002
TL;DR: Based on the principle of total internal reflection, a new experimental system, in which the sample is close sandwiched between two prisms, was designed to determine the refractive indices of biotissues and homogeneous medium as discussed by the authors.
Abstract: Based on the principle of total internal reflection, a new experimental system , in which the sample is close sandwiched between two prisms, was designed to determine the refractive indices of biotissues and homogeneous medium. Some mammalian tissues have been determined at laser wavelengths ofO.488, 0.6328, 1.0795 and 1.3414?tm, respectively, and their dispersion equations have been obtained. And the absolute error between the n calculated from the dispersion equation and the measured is within 0.002. By utilizing these dispersion equations, the refractive indices of the tissues can be obtained at any wavelength within the waveband of O.488-1.3414?m. The method has great reliability and accuracy, and it can be used for measuring the refractive indices of biotissues and any other medium.
33 citations
TL;DR: In this article, the authors derived new expressions for the amplitude reflection and transmission coefficients of light, and from these the stationary phase approximation to the Goos-Hanchen shifts is obtained.
Abstract: It is predicted that the Goos–Hanchen effect can be resonantly enhanced by placing a metallic quantum well (ultrathin film) at the dielectric–vacuum (air) interface. We study the enhancement of the phenomenon, as it appears in frustrated total internal reflection with p-polarized light, both theoretically and numerically. Starting from boundary conditions for the electromagnetic field, which in a self-consistent manner take into account the quantum-well dynamics, we derive new expressions for the amplitude reflection and transmission coefficients of light, and from these the stationary phase approximation to the Goos–Hanchen shifts is obtained. It is shown that large peaks appear in the Goos–Hanchen shift below the critical angle in reflection, and these are located at the minima for the energy reflection coefficient. Both positive and negative shifts may occur, and the number of peaks depends on the gap width. To determine the accuracy of the simple stationary phase approximation, we carry out a rigorous stationary energy-transport calculation of the Goos–Hanchen shift. Although the overall agreement between the two approaches is good, the stationary phase approach mostly overestimates the peak heights. For a Gaussian incident beam, the resonance displacement of the reflected beam can be as large as the Gaussian width parameter. It is suggested that the possible relation between the Goos–Hanchen effect and the optical tunneling phenomenon in the two-prism configuration should be reinvestigated by depositing quantum wells on the glass–vacuum interfaces to obtain a better spatial photon localization.
30 citations
TL;DR: In this paper, the local environment of zinc in phospholipid Langmuir-Blodgett films with extended X-ray absorption fine structure spectroscopy in total reflection conditions (reflEXAFS) was studied.
Abstract: We have studied the local environment of zinc in phospholipid Langmuir-Blodgett films with extended X-ray absorption fine structure spectroscopy in total reflection conditions (reflEXAFS). Mono- and multilayer films made of dilauroyl-phosphatidic acid (DLPA) and monolayer films made of dimyristoyl-phosphatidylcholine (DMPC) were deposited on quartz slides from ZnCl2 solutions, and their molecular order was checked by means of X-ray reflectivity measurements. A very good signal-to-noise ratio in the reflEXAFS spectra of both multi- and monomolecular films was obtained. The theoretical fits to the experimental data show that zinc coordinates four atoms about 0.20 nm distant in both acidic DLPA and neutral DMPC films, while in water solutions, zinc coordinates six atoms about 0.21 nm distant.
27 citations
Patent•
01 Nov 2002
TL;DR: In this paper, a total internal reflection illumination (TIMI) is applied to a microscope which illuminates a sample through an objective having a numerical aperture enabling total internal reflections illumination, consisting of a first total internal reflect mirror which is arranged in the vicinity of an outermost peripheral part of an observation optical path of the microscope to reflect an incident illumination light in a direction of the objective, a second total internal mirror that is arranged at a symmetrical position with the first total reflection mirror to sandwich an observation orientation and reflects return light reflected on a surface of the sample in
Abstract: A total internal reflection illumination apparatus applied to a microscope which illuminates a sample through an objective having a numerical aperture enabling total internal reflection illumination, comprises a first total internal reflection mirror which is arranged in the vicinity of an outermost peripheral part of an observation optical path of the microscope to reflect an incident illumination light in a direction of the objective, a second total internal reflection mirror which is arranged at a symmetrical position with the first total internal reflection mirror to sandwich an observation optical axis and reflects return light reflected on a surface of the sample in a direction different from the illumination optical path, and a return light dimming part configured to dim the return light reflected by the second total internal reflection mirror.
27 citations
Patent•
28 Aug 2002
TL;DR: In this article, an arrangement for optical communication consisting of an optical coupler, an opto-electronic board, and an optical fiber is presented, where an optical signal enters the first refraction surface, couples from the first to the second surface via the internal reflector, and exits the second to define a light path.
Abstract: An arrangement for optical communication comprises an optical coupler, an opto-electronic board, and an optical fiber. The optical fiber comprises a first refraction surface, a second refraction surface, and an internal reflector. The first refraction surface has a first finite focal length. The second refraction surface has a second finite focal length. In operation, an optical signal enters the first refraction surface, couples from the first refraction surface to the second refraction surface via the internal reflector, and exits the second refraction surface, where the optical signal defines a light path. The light path optically couples the opto-electronic board to the optical fiber.
Patent•
18 Mar 2002
TL;DR: In this article, an optical switching element, comprising a light transmitting element, a reflection substrate, and index variable material, was proposed to change the direction of the reflected light by varying the index of refraction of the reflection substrate.
Abstract: An optical switching element, comprising a light transmitting element, a reflection substrate, and index variable material. The light transmitting element has a first light incident surface, a second light incident surface not parallel to the first light incident surface, and a light outgoing surface. The reflection substrate is arranged opposite to the second light incident surface and has a reflection surface with an angle that is not parallel to the second light incident surface, wherein a reflected light passes through the light transmitting element and the reflection substrate and then is reflected by the reflection surface. The index variable material is sandwiched between the light transmitting element and the reflection substrate and has an index of refraction varied according to an external signal. By varying the index of refraction of the index variable material, an angle formed by the reflected light and a normal line of the light outgoing surface is changed such that the emitting direction of the reflected light is changed.
TL;DR: In this article, a particular approach of kinematic x-ray scattering theory is developed to interpret experimental scattering curves, and simulations demonstrate the particular sensitivity of X-ray reflectivity for very small grating amplitudes.
Abstract: The sinusoidal shape of light-induced surface relief gratings of polymers can be probed by x-ray scattering techniques. A particular approach of kinematic x-ray scattering theory is developed to interpret experimental scattering curves. The simulations demonstrate the particular sensitivity of x-ray reflectivity for very small grating amplitudes. At angles of incidence close to the critical angle of total external reflection a grating amplitude h < 2 nm already provides measurable grating peaks. In general the grating amplitude h can be measured from the envelope function over the grating peak maxima. The capability of the approach is demonstrated by simulation of the reflection curve recorded from a polymer sample with non uniform grating height.
01 Jan 2002
TL;DR: In this article, two low power systems using polycapillary focusing optics designed to collect Cu Ka radiation from Oxford ultra-bright micro-focus sources to produce a convergent beam for X-ray powder diffraction and protein diffraction measurements were described.
Abstract: In this paper, we describe two low power systems using polycapillary focusing optics designed to collect Cu Ka radiation from Oxford ultra-bright micro-focus sources to produce a convergent beam for X-ray powder diffraction and protein diffraction measurements. A collimator with two apertures was used to block high-energy X-rays. A still data set for chicken egg-white lysozyme was collected with the low power source focusing optic combination. This data exhibits high quality when processed with a special software program. Several powder samples were also measured and compared with measurements taken with an Enraf-Nonius FR590 sealed-tube source based system. 1. INTRODUCTIONoptics are made of thousands of bundled bent hollow glass capillaries to focus and control X-rays or neutrons over broad capture angles (up to 30o) and energy ranges (200 eV - 80 keV) with high efficiency (10-50%). These tiny hollow glass tubes typically have diameters ranging between 5 and 50 micrometers 1 . X-ray beams are deflected by total external reflection from the capillary inner surface at very small angles 2 . Total external reflection for small angle scattering at the capillary walls occurs because the index of reflection n of glass is slightly less than the index of refraction from air. X-rays incident at angle less than a critical angle θc are totally reflected. Polycapillary optics have been successfully applied for protein diffraction applications recently. 3-7
Journal Article•
TL;DR: In this article, a simple three term nonlinear model was derived from the one developed for the visible region for the index of refraction of water was reviewed and reduced to wavelength dependent formulas.
Abstract: Models for the index of refraction of water are reviewed and reduced to wavelength dependent formulas.A simple three term nonlinear model was derived from the one developed for the visible region.The available data will over an extended range covering the UV to the near-IR(200-1100nm).
TL;DR: Grazing Incidence X-ray Photoelectron Spectroscopy (GIXPS) as discussed by the authors is a non-destructive technique to measure the thickness and chemistry of ultrathin gate dielectric films.
Abstract: Grazing Incidence X-ray Photoelectron Spectroscopy (GIXPS) is a method that offers promise as a nondestructive technique to measure the thickness and chemistry of ultrathin gate dielectric films. It combines aspects of x-ray reflectivity and conventional x-ray photoelectron spectroscopy (XPS). Collimated x-rays are incident on the sample at a grazing angle. A series of photoemission spectra are obtained over a range of incidence angles in the vicinity of the critical angle for total external reflection. The advantage of this method is the incorporation of the optical constants of the layers, as well as the photoemission cross sections of the elements and the inelastic attenuation lengths of the escaping photoelectrons, to fit the nonlinear variation of the photoemission spectra as a function of angle. The x-ray field variation with angle within individual layers provides additional constraints beyond standard angle-resolved XPS for interpreting the densities and thicknesses of multiple layers. The application of this method to the analysis of oxide on Si is described.
TL;DR: In this article, an analysis of reflection and transmission of acoustic waves from an imperfectly reflecting, rough fluid-fluid interface within the Kirchhoff approximation is presented. But the results of the analysis are restricted to the case where the surface reflection coefficient depends upon the local angle between the incident wave and the rough surface.
Patent•
21 Nov 2002TL;DR: In this article, a converging air lens structure includes a first refractive medium that has a first index of refraction, and a second medium that is less than the first one.
Abstract: Converging air lens structure includes a first refractive medium that has a first index of refraction. A second refractive medium that has a second index of refraction is immersed in the first refractive medium. The second refractive index is less than the first index of refraction. The lens structure features converging lens properties. An aperture stop is disposed in the second refractive medium, which is preferably air.
03 Jun 2002
TL;DR: In this paper, analytical and numerical models predict total external reflection at optical wavelengths for a metal-dielectric composite material at the interface between vacuum and a medium with refractive index less than unity.
Abstract: Total external reflection can occur at the interface between vacuum and a medium with refractive index less than unity. Here, analytical and numerical models predict such reflection at optical wavelengths for a metal-dielectric composite material.
01 Jan 2002
TL;DR: The ability of polycapillary optics to reject radiation incident outside the critical angle for total external reflection while efficiently transmitting radiation within a critical angle make them ideal two-dimensional angular filters for X-rays and neutrons as discussed by the authors.
Abstract: The ability of polycapillary optics to reject radiation incident outside the critical angle for total external reflection while efficiently transmitting radiation within the critical angle make them ideal two-dimensional angular filters for X-rays and neutrons. The use of such angular filters is shown to be important for medical imaging to give contrast and resolution improvement, for improved spatial resolution and contrast for radiological in-raging, as two-dimensional collimators for diffraction measurements, for X-ray source size and shape measurements, and for x-ray and neutron angular distribution measurements.
01 Jan 2002
TL;DR: In this article, the authors used a sample cell with a water delivery system that has been custom designed, where silicon samples can be analyzed directly beneath a water layer (in situ TXRF).
Abstract: Synchrotron radiation based total external reflection x-ray fluorescence spectroscopy (TXRF) is now being routinely used at the Stanford Synchr otron Radiation Laboratory (SSRL) to carry out industrially relevant measurements. For transition elements on Si wafer surfaces, detection limits of 8x10 7 atoms/cm 2 that correspond to 1 impurity atom among 30 million substrate atoms have proven more than adequate for the studies undertaken to date. New studies, which aim to develop a better understanding of the kinetics of metal deposition during Si wafer cleaning processes, are being pursued. By using a sample cell with a water delivery system that has been custom designed, silicon samples can be analyzed directly beneath a water layer (in situ TXRF). Initial results measuring silicon samples with known Cu concentrations are presented. Due to the increased scatter and background from the water layer along with the attenuation of fluorescence signals, minimum detection limits for the in situ TXRF setup increased to 8x10 10 atoms/cm 2 , in close agreement to predicted values extracted from modeling calculations.
TL;DR: In this paper, the amount of back reflected light at one of the output ports of a 2 × 2 single-mode optical-fiber coupler due to Fresnel reflection was monitored by means of a high sensitivity sensor.
Abstract: In accordance with the principle of the technique based on Fresnel reflection, reflectivity of a dielectric surface depends on the difference of refractive indices of the surface and the surrounding medium, and the reflection coefficient is defined as the ratio of the reflected light power to the incident light power. In the investigations reported, the amount of back reflected light at one of the output ports of a 2 × 2 single-mode optical-fiber coupler due to Fresnel reflection was monitored by means of a high sensitivity …
Journal Article•
TL;DR: In this paper, the authors analyzed the angle of refraction at total optical reflection and showed that the real part is equal to π/2, and the imaginary part determines the decaying constant of evanescent wave in the optically thinner medium.
Abstract: The angle of refraction at total optical reflection is analyzed. It is shown that this angle is a complex. The real part is equal to π/2, and the imaginary part determines the decaying constant of evanescent wave in the optically thinner medium. The Snell's law is expressed in terms of the imaginary part of the refraction angle. The dual form of Snell's law is then given for the incidence angle less than the critical angle.
17 Jul 2002
TL;DR: In this paper, analytical and numerical models predict total external reflection at optical wavelengths for a metal-dielectric composite material at the interface between vacuum and a medium with refractive index less than unity.
Abstract: Total external reflection can occur at the interface between vacuum and a medium with refractive index less than unity. Here, analytical and numerical models predict such reflection at optical wavelengths for a metal-dielectric composite material.