Showing papers on "Total external reflection published in 1991"
TL;DR: It is shown that the effect of internal reflection due to index mismatch can be quantitatively accounted for with a single parameter by incorporating a reflection coefficient into the boundary condition for the diffusive light.
Abstract: The consequences of internal reflection of multiply scattered light at the boundaries of disordered media are studied We show that the effect of internal reflection due to index mismatch can be quantitatively accounted for with a single parameter by incorporating a reflection coefficient into the boundary condition for the diffusive light We measure the angular correlation functions in transmission and reflection at different thicknesses for both high- and low-index mismatch By including the effect of internal reflection, we are able to obtain consistent quantitative agreement between experiment and theory Extensions to other experiments including diffusing-wave spectroscopy, coherent backscattering, frequency correlations, and pulse propagation are discussed
305 citations
Patent•
01 Apr 1991
TL;DR: In this article, a method for controlling beams of particles, X-rays and gamma rays including a plurality of channels with total external reflection inner surfaces, input buttends facing a radiation source and output butt-ends aimed at a radiation receiver is taught.
Abstract: A device for controlling beams of particles, X-rays and gamma rays including a plurality of channels with total external reflection inner surfaces, input butt-ends facing a radiation source and output butt-ends aimed at a radiation receiver is taught. Channel-forming elements are in the form of surfaces, tubes, and structures with multiple channels and are rigidly positioned one relative to another with a spacing between supports such that the sagging of the channel-forming elements does not interfere with beam propagation. The device can be used to capture radiation from sources which produce parallel or divergent radiation. The resulting beam or beams can be of a variety of shapes or angular orientations including quasi-parallel, convergent, and split beams. Energy filtering is accomplished by selective absortion of radiation by the channel-forming elements and by selective reflection, by geometrics which cause some energies to be discriminated against because of the angle of total external reflection associated with that energy.
92 citations
TL;DR: X-ray fluorescence and diffraction has been performed on porous silicon samples at incidences near the critical angle for total external reflection, and structure information concerning the mean pore size, correlations between pores positions, the local lattice distortions within the porous silicon in relation to the existence of pore, has been demonstrated as discussed by the authors.
40 citations
TL;DR: In this article, the authors analyzed several approximations for the reflection coefficient of an electric field incident on the interface between two inhomogeneous dielectric media, and showed that realistic waveguides with discontinuous refractive index changes are often more accurately modeled by dividing the incoming electric field into segments coinciding with the intervals over which the interface is continuous, and subsequently superimposing the reflection from each segment.
Abstract: The authors have analyzed several approximations for the reflection coefficient of an electric field incident on the interface between two inhomogeneous dielectric media. While existing expressions agree with exact results in certain limits, realistic waveguides with discontinuous refractive index changes are often more accurately modeled by dividing the incoming electric field into segments coinciding with the intervals over which the interface is continuous, and subsequently superimposing the reflection from each segment. >
27 citations
Patent•
31 Oct 1991
TL;DR: In this paper, a channel-forming element is used to capture radiation from sources which produce parallel or divergent radiation, and the resulting beam or beams can be of a variety of shapes or angular orientations including quasi-parallel, convergent and split beams.
Abstract: A device for controlling beams of particles, X-rays and gamma rays including a plurality of channels with total external reflection inner surfaces, input butt-ends facing a radiation source and output butt-ends aimed at a radiation receiver is taught. Channel-forming elements are in the form of surfaces, tubes, and structures with multiple channels and are rigidly positioned one relative to another with a spacing between suports such that the sagging of the channel-forming elements does not interfere with beam propagation. The device can be used to capture radiation from sources which produce parallel or divergent radiation. The resulting beam or beams can be of a variety of shapes or angular orientations including quasi-parallel, convergent, and split beams. Energy filtering is accomplished by selective absortion of radiation by the channel-forming elements and by selective reflection, by geometrics which cause some energies to be discriminated against because of the angle of total external reflection associated with that energy. Also provided are embodiments which use these devices for improved medical imaging, medical therapy, X-ray lithography, and analytic instruments.
22 citations
TL;DR: In this paper, a series of CEMS spectra at different glancing angles of an evaporated 20 nm 57Fe film on glass substrate are obtained and a theory of propagation of the radiation in the multilayer medium under TER conditions is used for the interpretation of the results taking into account multiple reflections in each layer.
Abstract: Depth selectivity of Mossbauer total external reflection (TER) is demonstrated. A series of CEMS spectra at different glancing angles of an evaporated 20 nm 57Fe film on glass substrate are obtained. A theory of propagation of the radiation in the multilayer medium under TER conditions is used for the interpretation of the results taking into account multiple reflections in each layer. The computer fit gives the three step depth profiles of the distribution of different hyperfine interactions in the film.
[Russian Text Ignored].
13 citations
21 May 1991
TL;DR: In this article, a new x-ray optics has been developed which is capable of focusing, redirecting and collimating x-rays over broad energy and angular ranges, which is expected to have significant medical applications.
Abstract: A new x-ray optics has been developed which is capable of focusing, redirecting and collimating x-rays over broad energy and angular ranges. These optics are small light weight systems of hollow capillary tubes based on the principle of total external reflection at small angles. The transmission efficiency of these lenses is greater than 50% in the energy of 10-100 Kev. These lenses are expected to have significant medical applications.
9 citations
TL;DR: In this article, the reflection of linearly and circularly polarized electromagnetic waves at the boundary between an isotropic non-active medium and a nonactive medium has been investigated.
Abstract: The authors investigate the reflection of linearly and circularly polarized electromagnetic waves both at the boundary between an isotropic non-active medium and an isotropic optically active medium and at the boundary between an optically active medium and a non-active medium. The components of the electric field and the intensity of the reflected and refracted waves are determined. The following differential reflection methods for studying the optical activity are proposed: usual reflection of left and right circularly polarized waves (reflection optical activity); total reflection of circularly polarized waves; total reflection of linearly polarized waves.
7 citations
Patent•
03 Oct 1991
TL;DR: In this article, a method and apparatus for increasing the index of refraction, n, by several orders of magnitude is presented, by pumping and probing radiation excite the various atomic levels of a material, and establish coherence between such levels.
Abstract: Method and apparatus for increasing the index of refraction, n, by several orders of magnitude. Pumping and probing radiation excite the various atomic levels of a material, and establish coherence between such levels. Index of refraction can thereby be increased while, concomitantly, absorbence of the material is minimized.
7 citations
TL;DR: In this article, a new scheme for x-ray grazing incidence diffraction (GID) under total external reflection conditions is presented, which allows the grazing angles and the scattering angles to be adjusted independently so that the structural and/or the chemical profiles of materials can be determined at controlled depths.
Abstract: A new scheme for x‐ray grazing incidence diffraction (GID) under total external reflection conditions is presented. This simple scheme allows the grazing angles and the scattering angles to be adjusted independently so that the structural and/or the chemical profiles of materials can be determined at controlled depths. As an example, Si1−xGex/Si superlattice materials were studied. Both commensurate and incommensurate growths between the two quantum wells in the strained‐layer superlattice were observed by the GID technique.
4 citations
01 Jun 1991
TL;DR: In this paper, the reflected polarization angle is determined from the extinction position of the analyzer, which gives the ratio of the reflected p-wave to s-wave, which can be used to determine the index of refraction from Fresnel equations.
Abstract: Linearly polarized light remains linearly polarized after reflection from a transparent material at oblique incidence. The reflected polarization angle is determined from the extinction position of the analyzer. If the incident polarization angle is 45 deg, the reflected polarization angle gives the ratio of the reflected p-wave to s-wave. This value can be used to determine the index of refraction from Fresnel equations. With our instrument, the uncertainty in the deduced refractive index is +/- 0.0004. This method is fast, convenient, and versatile enough to provide accurate results on small laboratory samples. In addition to measuring the refractive index, the method is sufficiently accurate to characterize the homogeneity of transparent materials.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Patent•
31 Oct 1991
TL;DR: In this paper, a device for controlling beams of particles, X-rays and gamma rays including a plurality of channels with total external reflection inner surfaces, input butt-ends facing a radiation source and output buttends aimed at a radiation receiver is taught.
Abstract: not available for EP0555376Abstract of corresponding document: WO9208235A device for controlling beams of particles, X-rays and gamma rays including a plurality of channels with total external reflection inner surfaces, input butt-ends facing a radiation source and output butt-ends aimed at a radiation receiver is taught. Channel-forming elements are in the form of surfaces, tubes, and structures with multiple channels and are rigidly positioned one relative to another with a spacing between suports such that the sagging of the channel-forming elements does not interfere with beam propagation. The device can be used to capture radiation from sources which produce parallel or divergent radiation. The resulting beam or beams can be of a variety of shapes or angular orientations including quasi-parallel, convergent, and split beams. Energy filtering is accomplished by selective absortion of radiation by the channel-forming elements and by selective reflection, by geometrics which cause some energies to be discriminated against because of the angle of total external reflection associated with that energy. Also provided are embodiments which use these devices for improved medical imaging, medical therapy, X-ray lithography, and analytic instruments.
TL;DR: In this paper, the authors applied scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) for fluorescence analysis of 50 A- and 125 A-thick Au thin films on Si(100).
Abstract: Scanning electron microscopy & total-reflection-angle X-ray spectroscopy (SEM-TRAXS) was applied for fluorescence X-ray analysis of 50 A- and 125 A-thick Au thin films on Si(100). The intensity of the AuM line (2.15 keV) emitted from the Au thin films varied as a function of the take-off angle (θt) with respect to the film surface; the intensity of AuM line from the 125 A-thick Au thin film was 1.5 times as large as that of SiKα line (1.74 keV) emitted from the Si substrate when θt=0°-3°, in the vicinity of a critical angle for total external reflection of the AuM line at Si (0.81°). In addition, the intensity of the AuM line emitted from the 50 A-thick Au thin film was also sufficiently strong for chemical analysis.
TL;DR: In this article, standing waves generated above a mirror surface during total external reflection have been used to locate a heavy atom layer which was embedded hundreds of angstroms above the mirror surface in a Langmuir-Blodgett multilayer.
Abstract: X-ray standing waves generated above a mirror surface during total external reflection have been used to locate a heavy atom layer which was embedded hundreds of angstroms above the mirror surface in a Langmuir-Blodgett multilayer. This same method has also been used to map out the ion distribution in the diffuse double layer that forms at the electrolyte/charged surface interface.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
01 Jan 1991
TL;DR: In this paper, standing waves generated above a mirror surface during total external reflection have been used to locate a heavy atom layer which was embedded hundreds of angstroms above the mirror surface in a Langmuir-Blodgett multilayer.
Abstract: X-ray standing waves generated above a mirror surface during total external reflection have been used to locate a heavy atom layer which was embedded hundreds of angstroms above the mirror surface in a Langmuir-Blodgett multilayer. This same method has also been used to map out the ion distribution in the diffuse double layer that forms at the electrolyte/charged surface interface.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
01 Jan 1991
TL;DR: In this article, the authors describe several x-ray diffraction techniques which have been found to be very useful for characterizing the structure of magnetic multilayers and superlattices.
Abstract: In this paper we describe several x-ray diffraction techniques which we have found to be very useful for characterizing the structure of magnetic multilayers and superlattices. Examples are given from several of the magnetic and non-magnetic materials studied recently with these techniques.