Showing papers on "Total internal reflection published in 1986"

Frustrated total internal reflection: A demonstration and review

Abstract: Frustrated total internal reflection (FTIR) has been studied since the time of Newton and Fresnel. We review its history and applications in modern optics. A simple theoretical description of the phenomenon is presented using Maxwell’s equations. The analogy (often made in textbooks) between FTIR and quantum mechanical tunneling in one dimension is discussed. A simple experimental apparatus, suitable for a laboratory demonstration, is described and a quantitative comparison of the theory with experiment is made at optical wavelengths. A He–Ne laser, power meter, and a simply constructed double‐prism arrangement are used for the demonstration.

Fluorescence of adsorbed protein layers: i. quantitation of total internal reflection fluorescence.

Abstract: A quantitative total internal reflection intrinsic fluorescence (TIRIF) method for determining the adsorption of proteins at optically suitable solid/liquid interface is presented. Intrinsic protein fluorescence is excited by evanescent part of the standing wave produced by total internal reflection. The TIRIF data are quantified using as an internal standard the fluorescence from nonadsorbed proteins which are present in the evanescent region. In order to account for the fraction of fluorescence excited by scattered light which propagates through and beyond the volume sensed by the evanescent wave, a set of nonadsorbing external standards has to be used. The combination of TIRIF and 125I-protein γ-photon detection system is described and applied to bovine serum albumin (BSA) and human immunoglobulin (IgG) adsorption at silica/electrolyte interfaces. The difference between the results obtained with different adsorption detection systems is discussed. An average fluorescence emission efficiency of adsorbed proteins can be evaluated by combining TIRIF adsorption data with the independent in situ quantitation of protein adsorption. It was found that in some cases adsorbed proteins emit fluorescence with significantly lower quantum yield.

Profile-measuring light probe using a change in reflection factor in the proximity of a critical angle of light

Abstract: A profile-measuring light probe includes: an illuminator for irradiating a fine spot of light on a subject to be measured; an objective lens for forming an image of the fine spot on an image plane; and a relay lens for converting the light from the fine spot into a generally parallel ray. Further, the light probe includes a window plate constituted by an entrance prism for taking in the generally parallel ray emitted from the relay lens; a flat glass for subjecting the taken-in ray to multiple internal reflections and transmitting the same, and an exit prism for outputting the ray thus transmitted to the outside. The light probe measures the distribution of light quantity of the light emitted from the window plate to thereby measure a profile of the subject to be measured. With the above-described arrangement, it becomes possible for the light probe to perform the measuring through the utilization of a change in reflection factor of a light inciding in the proximity of a critical angle without using a critical angle prism.

Goos–Hänchen effect around and off the critical angle

Abstract: A general expression for the Goos–Hanchen lateral shift of a Gaussian wave beam, applicable for incident angle θ equal to, near, or larger than the critical angle θc, is obtained It yields finite and smooth results around θc and coincides with Artmann’s classical result otherwise Another expression for the lateral shift of a different beam-field distribution is also obtained and shown to be quite similar to that of the Gaussian beam Comparisons with an existing theoretical expression and with available experimental data (for θ ≃ θc) are made Discussion of a different expression for θ away from θc obtained through an energy method is also presented

Synchrotron x-ray studies of liquid-vapor interfaces

Abstract: The variation of density across the liquid-vapor interface from essentially zero density far out in the vapor phase to a homogeneous density deep in the liquid phase can be determined by X-ray reflectivity measurements1)at grazing angles θ well beyond the critical angle for total reflection, θC. We shall first derive the relation between the density variation, ρ(z), and the reflectivity R(θ). Next we consider as an experimental example the roughness caused by thermal excitations of capillary waves on simple liquids like water and carbon-tetra-chloride2). Then we consider the smectic layering of liquid crystal molecules of the free surface, first in a system with a spontaneous first order phase transition from the isotropic phase to a smectic A phase3), and afterwards in a system with a second order phase transition from the nematic phase to the smectic A phase4–6).

Standing wave pattern of HF radio waves in the ionospheric reflection region: 2. Applications

Abstract: General analytical formulas derived within a uniform approximation in a previous paper by the present authors are utilized for determining the wave pattern of a vertically propagating HF wave that is totally or partially reflected from the ionosphere. The full three-dimensional wave is calculated accurately, also at the reflection point. Parameter values typical of ionospheric modification experiments at Arecibo and Tromso are chosen. The influence of the geomagnetic field and collisions are properly taken into account but nonlinear and coupling effects are excluded. It is shown that the geomagnetic field affects the wave pattern strongly, especially in the Tromso case, and leads to a very high swelling in the first wave maximum below the reflection point.

Transmission type screen

Abstract: PURPOSE: To raise the total reflection effect, and to obtain a transmission type screen having a painting film which scarcely causes optically a defect, by using a transmission type screen in which many lenticular lenses have been formed on the surface of an observation side. CONSTITUTION: Linear total reflection surfaces 5 are formed on both sides of a lens unit for constituting a lenticular lens 2, two total reflection surfaces 5 form a trough part 6, a crest part 7 consisting of three curved surfaces is provided between the total reflection surfaces 5, and a light beam which has been brought to a total reflection once by the total reflection surface 5, and a light beam which has traveled straight to the crest part 7 are diffused and emitted, respectively. In the trough part 6, a low refractive index layer 10 formed by mixing fine particles 9 into a substance 8 whose refractive index is lower than a refractive index of a screen base material 1 is formed closely as the first layer, and also, an arbitrary light absorbing substance 11 having an excellent painting characteristic is buried as the second layer in the trough part 6, and an external light absorbing layer 13 is formed. The fine particles 9 in the first layer 10 fix the low refractive index substance uniformly extending over almost the whole surface of the total reflection surface 5, slimness is prevented, the total reflection effect is raised, and a transmission type having a painting film which scarcely causes optically a defect is obtained. COPYRIGHT: (C)1988,JPO&Japio

Reflection and transmission of beams at a curved interface

Abstract: Gaussian-beam reflection and transmission in the presence of a convex circular boundary separating two different dielectrics is analyzed by the complex ray method whereby rays are traced in a complex coordinate space from the complex source point to the complex extension of the interface and then to the real observation point. The search for the complex parameters describing the ray connecting the source and the observer can be numerically time consuming. Much more efficient are paraxial approximations that express the field as perturbations about its values on the axis of maximum strength. Such paraxial approximations are explored here, using on-axis complex ray and even on-axis real ray solutions with corrections accounting for differences in phase, ray reflection and transmission coefficients, and ray divergence coefficients. Extensive numerical comparisons establish a reasonable range of validity of both paraxial approximations, except in regions characterizing the transition to total reflection, if that can occur.

Recursive numerical solution for nonlinear wave propagation in fibers and cylindrically symmetric systems

Abstract: An efficient and compact recursive numerical solution of the wave equation is developed and applied to cylindrically symmetric optical systems. Numerical results are given for wave propagation through an aperture and in linear and nonlinear optical fibers. This code is most useful for multiwave mixing and wave propagation in nonlinear media.

Goos–Hänchen beam shift at total internal reflection with application to spatially dispersive media

Abstract: In this paper the Goos–Hanchen beam displacement at total internal reflection is reviewed. The basic theory of the beam shift is discussed from a classical approach, and measurement of the shift is discussed. Other experimental results are outlined. The theory of finite beam shift at total internal reflection is summarized. An application to nonlocal media is discussed. Finally, recent developments are outlined with implication for beam shifts in spatially dispersive media.

Grazing incidence X-ray fluorescence analysis

Abstract: The X-ray external total reflection method was applied to the analysis of the concentration profile of As atoms near the Si surface. Si wafers were implanted with As ions and then annealed at a high temperature. The intensity of the As Kα fluorescence signal excited by monochromated synchrotron radiation was measured as a function of the glancing angle of the incident X-rays. The effect of annealing on the concentration profile was analyzed non-destructively. The results obtained are in good agreement with those using depth profiling by secondary ion mass spectrometry. The limit of detection by this method was estimated as 1013 As atoms/cm2.

Characterization of surface-breaking defects in metals with the use of laser-generated ultrasound

Abstract: The interaction of ultrasound with surface-breaking slots has been used to characterize the slots, with laser generation of ultrasound providing the short-duration Rayleigh pulses used as the probe. Defect depth has been measured in the range 0.3-5.0 mm. Analysis has shown that surface echoes reflected from the defect have two major components. The first arises from direct reflection of a Rayleigh pulse from the top of the defect, whereas the second arises from a shear pulse originating from the bottom of the defect which mode-converts to a Rayleigh pulse on reaching the metal’s surface at the critical angle. This interpretation offers a diagnostic technique for measuring defect depths.

Diffraction d'un faisceau de rayons X en incidence très rasante

Abstract: The penetration depth τ of an X-ray beam (λ ≃ 1 A) incident on a surface with an angle α decreases rapidly when α goes below αc, the critical angle of total reflexion. It is shown experimentally that at the same time the Bragg peaks have a stick-like shape perpendicular to the sample surface. The variation of the depth τ as a function of α has been determined by measuring the length of the stick. The variation of the Bragg intensity and the position of the peak as well as the depth are calculated precisely using the simple Fresnel formulae.

New Quantitative Technique for Attenuated Total Reflection (ATR) Spectrophotometry; Calibration of the "CIRCLE" ATR Device in the Infrared

Abstract: A general method for spectroscopic determination of the incidence angle and number of reflections in ATR devices is described. This technique extends the inherent advantages of ATR by simplifying general quantitative spectroscopic measurements. Effects of polarization, beam focusing, errors of alignment, indices of refraction, handling of the optical elements, and surface activity of internal standard are discussed. Measured ATR absorbances are fitted mathematically with the use of incidence angle as a parameter. A standardizing solution, molar absorptivities for that solution, and knowledge of the dimensions of the internal reflection optical element are required. Application of the method to a cylindrical internal reflection (CIR) device gives the averaged incidence angle in the CIR with greater accuracy than is otherwise obtainable. With the use of a side-focusing Fourier transform spectrophotometer, the average incidence angle in the Spectra-Tech, Inc. "Micro-cell" "CIRCLE" CIR was 49.68 degrees ± 0.78%, and the number of solution-sensing internal reflections was 7.52 ± 1.95%.

Angled stripe superluminescent diode

Abstract: A semiconductor light-emitting device structured similarly to an index-guided laser, but having waveguide channels that are formed at a selected small angle of inclination with respect to a direction normal to cleaved facets formed in the structure. The angle of inclination should be at least half the critical beam angle above which total internal reflection will not occur within the waveguide channels. The angled condition of the waveguide channels ensures that effective mirror losses at the facets exceed the modal gain of the device, so that lasing will not occur, even when the current and power are increased to high levels. The device produces up to 30 mW or more of output power at a large spectral bandwidth and small coherence length.

Optical constants measurements of strongly absorbing media.

Abstract: An experimental arrangement is described for determination of refractive indices n and extinction coefficients k of strongly absorbing liquids and solids over a wide spectral region. The reflectivity of parallel polarized light vs angle of incidence is measured, and the optical constants are calculated from the minimum parallel reflectivity and the corresponding Brewster angle. The accuracy of n and k determination is analyzed. The refractive indices and extinction coefficients of 0.4-M rhodamine 6G in methanol are presented around the S1 absorption band.

Relationship between the p and s Fresnel reflection coefficients of an interface independent of angle of incidence

Abstract: The Fresnel reflection coefficients rp and rs of p- and s-polarized light at the planar interface between two linear isotropic media are found to be interrelated by (rs − rp)/(1 − rsrp) = cos 2β, independent of the angle of incidence ϕ, where tan2β = ∊ and ∊ is the (generally complex) ratio of dielectric constants of the media of refraction and incidence. This complements another relation (found earlier), (rs2 − rp)/(rs − rsrp) = cos 2ϕ, which is valid at a given ϕ independent of ∊ (i.e., for all possible interfaces). Taken together, these two equations specify rp and rs completely and can be used to replace the original Fresnel equations.

The Interpretation Of Glancing Incidence Scattering Measurements

Abstract: The practical testing and specification of x -ray and UV mirrors requires a scattering theory to link topo-graphic finish errors and functional performance. This paper examines various smooth - surface theories thathave been proposed for this purpose, with particular attention to their behavior near the critical angle wherethe surface reflectivity is a rapid function of angle. Of the various diffraction theories considered,Rayleigh -Rice vector perturbation theory is the most realistic; and predicts scattering distributions that arecharacteristically different from those of the canonical model. In some cases these differences or anomaliesare similar to those observed by Yoneda and by Matsushita et al., which have previously been interpreted usinggeometrical-optics models. But there are differences. For exa ple, the Rayleigh -Rice theory predicts anoma-lous scattering near the critical angle above the glancing angle of incidence ( "anti - Yoneda effect "). Resultsare illustrated by calculations for strawman scattering experiments.IntroductionSurface finish is a critical property of high- performance x -ray and UV mirrors. An essential link in thetesting and specification of such mirrors is the ability to predict the performance of surfaces under testfrom laboratory measurements, and conversely, to translate performance requirements into manufacturing speci-

Accurate reconstruction of the refractive-index profile of fibers and preform rods from transverse interferometric data

Abstract: A closed-form strict correlation between the interference fringe shift and the ray deflection function is derived which enables an accurate determination of the refractive-index distribution in fibers, preform rods, and GRIN-rod lenses to be performed by transverse interferometric methods. The refraction of the probing rays as well as the defocusing effect are entirely compensated and the immersion-object index mismatch is also taken into account. The comprehensive analysis presented proves that nondestructive transverse interferometry can be utilized as a reliable tool in the examination of both GRIN and step-index fibers and rods with low as well as with high numerical apertures.

Optical efficiency of far-infrared photoconductors

Abstract: The present optimization of the geometry of far-IR photoconductive detectors with diffraction-limited throughput, on the basis of experimental and theoretical results, gives attention to the internal optical path relative to measured absorption length, photoconductive gain, uniformity of illumination, cosmic ray cross section, and design compatibility with the requirements of one- and two-dimensional arrays. It is demonstrated that a rod-shaped, square cross section detector geometry, having lateral face electrodes and a beveled backface with which to trap the radiation by total internal reflection, exhibits responsivity commensurate with that of the best available detectors in integrating cavities.

Spin-wave spectra of insulating films: Comparison of exact calculations and a single-wave-vector model

Abstract: Spin-wave spectra are usually calculated within the circular-precession approximation which neglects ellipticity of the microwave magnetization. This approximation yields rigorously correct results only for perpendicular resonance and becomes worse for parallel resonance. Even if the ellipticity is accounted for, only single-wave-vector modes are commonly postulated for nonperpendicular resonance. Such modes cannot satisfy the boundary conditions except for zero surface anisotropy energy when the model is exact for any configuration of applied external field. Rigorous results correspond to normal modes made up of waves with two different wave vectors. Calculations with a set of parameters typical for a 1000-A\r{}-thick Permalloy film indicate that the exact results may significantly differ from the single-wave-vector model both in the position of the normal modes and their intensities. The predicted critical angle is also different from the \ensuremath{\pi}/4 observed. It is concluded that the exact procedure is, in principle, required.

Enhanced scattering voltage sensitive encapsulated liquid crystal with light directing and interference layer features

Abstract: Encapsulated liquid crystal material in a support medium illuminated from the viewing side or through a louvered light guide from the back side will appears bright relative to background when in distorted alignment absent an electric field. Incident light on the liquid crystal material is isotropically scattered into the support medium, and using the principle of total internal reflection and possibly also optical interference a relatively large part of the isotropically scattered light is directed back to illuminate the distorted liquid crystal material tending to brighten the same so that light it scatters back to the viewing direction out of the support medium. Original incident light where there is no liquid crystal material, that light which is isotropically scattered toward the back or non-viewing side of the display within a certain cone or solid angle, and that light passing through aligned (field-on) liquid crystal material will tend not to be totally internally reflected; such light will pass through the support medium and may be absorbed by a remote black or colored material.

Substance detector device

Abstract: The substance detection device comprises a transparent element and a light source for transmitting light through the transparent element onto a polished surface of the element. A pair of photodetectors are positioned for detecting intensity of light reflected from the polished surface and a circuit is provided for determining a difference in detected reflected light intensity on the photodetectors to determine a change in the critical angle of an optical interface at the polished surface.

The determination of optical absorption and scattering in translucent porcelain

Abstract: Reflectance and transmittance theories have been used to calculate the optical absorption and scattering within materials. For these calculations, the incorporation of corrections for interfacial reflections has not been universally applied, and when corrections have been incorporated, the value used for the diffuse internal reflection coefficient has often been based on theoretical considerations. A method of incorporating interfacial-reflection corrections is presented. The importance of the incorporation of such corrections, with the proper value for the internal reflection coefficient, is clearly demonstrated for both reflectance and transmittance theories. The limitation of transmittance theory to materials with a scattering power (SX) of greater than 0.5 is also demonstrated for collimated illumination, unless an independent determination is made of the internal reflection coefficient.

Critical angle in electron capture

Abstract: The simultaneous single electron capture and production of doubley-charged He ions in single collisions between fast protons and He atoms has been studied experimentally as a function of scattering angle (0.3-3.2 mrad) and impact energy (200-500 keV). The angular dependences reveal a critical angle at which the probability for production of He/sup ++/ simultaneously with electron capture peaks sharply. The peak itself as well as the energy dependence of the size and shape of it may be interpreted qualitatively in terms of a capture mechanism proposed already in 1927 by L. H. Thomas on the basis of classical mechanics.

Novel x-ray diffractometer for liquid surface studies

Abstract: An x‐ray diffractometer for studying the structure of the liquid–vapor interface is described. It is designed to permit reflectivity and scattering studies from liquid surfaces for angles varying from grazing incidence, below the critical angle for total external reflection up to angles ∼3° using a rotating anode x‐ray generator. In principle the diffractometer system can be used to study both the density profile normal to the surface and in‐plane structural features. The former is determined by deviations of the measured reflectivity from the Fresnel law of classical optics and the latter from nonspecular scattering. Results obtained using this spectrometer to measure the density profile normal to the surface of water and a liquid crystal are presented.

Dispersion and attenuation of the eigenwaves for light propagation in heiicoidal liquid crystals

Abstract: The dispersion curves and attenuation factors of the Bloch eigenwaves in heiicoidal liquid crystals (chiral smectic C and cholesterics) are calculated using the 4 × 4 characteristic matrix method. Four possible types of eigenmodes are seen to exist in the medium. The reflection peaks, which correspond to odd parts of the full pitch, are total reflection peaks, while those corresponding to even parts of the full pitch are composed of three branches at high incidence angles, where the outer branches are selective reflection and the central one is a total reflection peak. Selective reflection regions occur only at the edges of the Brillouin zones, while total reflections can occur anywhere inside the zones. The former are interpreted according to the coupled mode theory as resonant Bragg reflections, with the latter as exchange Bragg reflections. When the tilt direction exceeds the propagation direction, the central branch of the even sequence of peaks starts to be due to resonant Bragg reflections....