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Showing papers on "Total internal reflection published in 1976"


Journal ArticleDOI
TL;DR: In this article, the authors used the binary collision cascade simulation program MARLOWE to study the reflection of 10 eV to 20 keV H, T and He atoms from amorphous Al, Cu, Nb and Au.

581 citations


Journal ArticleDOI
TL;DR: The novel suggestion in this communication is the observation that for certain values of parameters, the interface between the CPC and the surround becomes a perfect total internal reflec­ tion mirror that permits no leakage of radiation.
Abstract: where θm a x is the angular acceptance (half-angle) and n is the index refraction of the collector relative to the sur­ rounding medium. This concentration is the maximum permissable by physical principles. The CPC is a nonimaging light funnel that derives its characteristic optical properties from the specific shape of the external wall, which is made specularly reflecting. The diameters of these structures are generally large relative to the wavelength of light. We have also investigated models of certain visual receptors, which strikingly resemble the compound parabolic shape and wherein the specularity was achieved by total internal reflection. In these examples, chosen to simulate the conditions found in nature, a frac­ tion of the light rays leaks out because they fail to satisfy the condition for total internal reflection. The novel suggestion in this communication is the obser­ vation that for certain values of parameters (of consider­ able practical importance), the interface between the CPC and the surround becomes a perfect total internal reflec­ tion mirror that permits no leakage of radiation. This re­ sult is unexpected because the condition for maximal con­ centration [Eqs. (1) and (2)], which determines the shape of the external wall, and the condition for total internal re­ flection (angle of incidence exceeds the critical angle) have no a priori connection. Incident rays that lie within the angular acceptance (θmax) of the trough CPC are refracted into an elliptic cone of semiminor angle θmg' and semimajor angle θc, where

106 citations


Journal ArticleDOI
TL;DR: An extremely simple derivation of the Goos-Hänchen shift is presented for total internal reflection at a plane interface between two semiinfinite dielectric media, as well as for optical waveguides of plane arid circular cross section.
Abstract: An extremely simple derivation of the Goos-Hanchen shift is presented for total internal reflection at a plane interface between two semiinfinite dielectric media, as well as for optical waveguides of plane arid circular cross section. The derivation is based on energy considerations, requires knowledge of Fresnel's equation only, and shows explicitly that the shift is due to the flow of energy across the dielectric boundary.

89 citations


Journal ArticleDOI
TL;DR: In this article, the stability of a Helmholtz velocity profile in a stably stratified fluid when a lower boundary is present is investigated and it is shown that the gravity wave instabilities result from the ability of an unstable shear layer to overreflect such waves (reflected amplitudes are greater than incident amplitudes).
Abstract: We investigate the stability of a Helmholtz velocity profile in a stably stratified fluid when a lower boundary is present. In addition to the traditional Kelvin-Helmholtz interfacial instability we find an infinitude of unstable internal gravity waves, the most unstable of which bear a close resemblance to disturbances observed in connection with clear air turbulence. It is shown that the gravity wave instabilities result from the ability of an unstable shear layer to overreflect such waves (reflected amplitudes are greater than incident amplitudes). Overreflection at the shear layer is constantly fed by total reflection from the lower boundary. The growth rate of gravity wave instabilities depends markedly on the distance between the shear layer and the ground. A mechanism is suggested whereby gravity wave instability can lead to long-lived almost neutral shear layers.

60 citations


Patent
01 Apr 1976
TL;DR: In this paper, a system for detecting ice on exterior surfaces of aircraft by transmitting a relatively low power microwave electromagnetic signal into a dielectric layer functioning as a surface waveguide, and monitoring the signals transmitted into and reflected from the waveguide is presented.
Abstract: A system for detecting ice on exterior surfaces of aircraft by transmitting a relatively low power microwave electromagnetic signal into a dielectric layer functioning as a surface waveguide, and monitoring the signals transmitted into and reflected from the waveguide. The waveguide includes a termination element which is mismatched with the waveguide impedance, resulting in partial or total reflection of the microwave energy from the remote end of the waveguide. As ice builds up on the surface waveguide, the impedance or reflection characteristics of the composite waveguide comprising the ice layer and the permanent surface waveguide give a reliable indication of the presence and location of the ice. The reflection characteristics are conventionally monitored utilizing a dual directional coupler and a reflectometer.

57 citations


Patent
09 Feb 1976
TL;DR: In this article, a photocoagulating scalpel system including a scalpel having a sharp, transparent blade for forming an incision, and a laser optically coupled to the blade for coagulating blood adjacent the incision is presented.
Abstract: A Photocoagulating scalpel system including a scalpel having a sharp, transparent blade for forming an incision, and a laser optically coupled to the blade for coagulating blood adjacent the incision. Laser radiation is transported to the blade through a low-loss fiberoptic waveguide. The radiation propagates through the waveguide and blade by means of multimode optical waveguide propagation wherein each mode has a discrete angle of incidence with respect to the blade surface. As the radiation reaches the beveled cutting edge of the blade, the angle of the blade surface changes causing the radiation to be emitted from the blade because the incident angles of individual modes fall below the critical internal reflection angle of the blade. Radiation leakage is further increased by the presence of blood on the blade surface which increases the critical internal reflection angle of the blade. Higher order modes having angles of incidence less than the critical internal reflection angles of the waveguide and blade are restricted so that radiation does not leak from the waveguide or blade before reaching the cutting edge. The laser radiation is preferably from an argon laser since its radiation is at a wavelength which is readily absorbed by red hemoglobin while being reflected by white tissue so that the radiation coagulates blood without causing extensive necrosis of the incised tissue. A power control on the handle of the scalpel allows the surgeon to adjust the intensity of the radiation as required depending upon the quantity of blood to be coagulated.

51 citations


Patent
15 Oct 1976
TL;DR: In this paper, a light curtain for scanning rectangular openings with an oscillating light beam originating in a corner of the opening is placed in the same corner, and a photo-detector, such as triple reflectors, are placed on adjacent sides of the camera, opposite the light source for reflecting light back to the photo-sensor.
Abstract: A light curtain for scanning rectangular openings with an oscillating light beam originating in a corner of the opening. A photo-detector is placed in the same corner. Retroreflectors, such as triple reflectors are placed on adjacent sides of the opening which are opposite the light source for reflecting light back to the photo-sensor. Above a critical reflection angle for the retroreflector, a plane mirror is provided which directs light from the source to the retroreflector on the adjacent side so that light impinging on the mirror at an angle exceeding the critical angle is received by the adjacent retroreflector at an angle that is within the critical angle. Consequently, such light is reflected via the plane mirror back to the photo-sensor. The light can be modulated to facilitate the monitoring of the area encompassed by the opening.

42 citations


Patent
16 Dec 1976
TL;DR: In this article, the authors proposed to eliminate the image distorsion by making plane waves incident at an angle upon the surface of a photosensitive material while fixing the angle between the plane waves and spherical waves.
Abstract: PURPOSE: To eliminate astigmatism and image distorsion, even if the wave fronts are made different upon formation and reproduction of FZP (Fresnel Zone Plate), by making plane waves incident at an angle upon the surface of a photosensitive material while fixing the angle between the plane waves and spherical waves COPYRIGHT: (C)1978,JPO&Japio

41 citations


Journal ArticleDOI
TL;DR: In this paper, the authors obtained the first one or two terms in the asymptotic expansion of the fields valid as the point of observation moves away from the interface a distance large compared to the wavelength in any fixed direction apart from certain specified critical angles.
Abstract: Asymptotic approximations are obtained for the reflected and refracted fields that result when an arbitrary monochromatic electromagnetic wave is incident on a plane interface separating two linear, homogeneous, isotropic dielectrics. The results are the first one or two terms in the asymptotic expansion of the fields valid as the point of observation moves away from the interface a distance large compared to the wavelength in any fixed direction apart from certain specified critical angles. The approximations are obtained from the exact solutions by applying the method of stationary phase extended to allow for the nonstandard form of the integrands in the integral representations of the fields. Although the method is applicable only when the medium containing the point of observation is nonabsorbing, the results probably have more general applicability.

39 citations


Journal ArticleDOI
Abstract: The reflectance of a homogeneous amplifying layer between two transparent regions is determined theoretically with the help of the Fresnel formulas. The transparent region containing the incident beam has a higher refractive index, corresponding to an internal reflection configuration. In the limit of infinite layer thickness, the reflectance is a continuous monotonic function of incident angle, greater than unity for all angles. For certain finite values of layer thickness, the reflectance has a singular point. The results explain the reported observation of a reflectance of 1000 from an excited laser dye in contact with a quartz prism.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the back bending of the reflection minimum as a function of θ at constant λ was studied and the influence of the interband absorption determined the R (θ,λ) dependence.

Journal ArticleDOI
TL;DR: In this article, the authors focus on adsorption and transport across surfaces at or below monolayer coverages, using mostly examples from the author's laboratory, and emphasize that IRS is complementary to and, in general, not a substitute for conventional transmission IR spectroscopy.
Abstract: Infrared internal reflection spectroscopy (IRS) has in recent years found wide use in the analysis of surfaces. Often times these have been novel applications as, for example, in the identification of stamp adhesives [l] or the observation of the spectrum of bee wings [2]. We will not attempt a review of this diverse literature but, using mostly examples from the author's laboratory, focus attention on adsorption and transport across surfaces at or below monolayer coverages. We emphasize again [31 that IRS is complementary to and, in general, not a substitute for conventional transmission IR spectroscopy [4, 51 in situations where a high area, transparent sample is available. Only for the cases of adsorption on transparent single crystals or thin films are the two techniques in direct competition. In this case multiple internal reflection provides a higher signal-to-noise ratio than would transmission because it avoids reflection and scattering losses at the film interface. Internal reflection al...

Journal ArticleDOI
TL;DR: In this paper, a pulsed source (radar) and continuously recording echoes reflected from within dielectric earth materials as a function of angle of incidence are used to identify the lateral wave.
Abstract: Electromagnetic waves refracted at the critical angle according to Snell's law give rise to the lateral wave. The low amplitude lateral wave is usually obscured by other waves when continuous wave sources are used. Using a pulsed source (radar) and continuously recording echoes reflected from within dielectric earth materials as a function of angle of incidence, records are produced which clearly show the lateral wave. In some earth‐probing applications, the lateral wave may predominate and proper identification of its characteristics is important.

Journal ArticleDOI
TL;DR: In this paper, total reflection coefficients (R), backscattered energy fractions (γ), and energy spectra were evaluated using a binary collision Monte Carlo technique for a variety of light ions (H, D, T, He) in the energy range 0.25-8 keV, incident on amorphous targets (C, Fe, Nb).


Journal ArticleDOI
TL;DR: In this article, the general condition for the critical angle in anisotropic media is discussed, and it is shown that for some planes in quartz, major errors may arise if one employs the usual statement of Snell's law for definition of critical angle.
Abstract: Recent investigations have utilized the measurement of the critical angle for reflection from a liquid‐solid interface for determination of the elastic constants of the solid. For anisotropic media, this technique is appropriate only for certain special cases of the incident plane and reflecting surface. We discuss here the general condition for the critical angel in anisotropic media and show that for some planes in quartz, major errors may arise if one employs the usual statement of Snell’s law for definition of the critical angle.Subject Classification: [43]20.30; [43]35.26.

Patent
18 Nov 1976
TL;DR: In this paper, a method of non-destructively testing materials comprises directing an incident beam of ultrasonic waves onto the surface of a material and detecting the beam reflected by the surface, the angle of incidence and the wavelength of the ultrasonic wave being detected, and the critical angle at which the energy of the reflected beam passes through a minimum being determined for at least two different wavelengths.
Abstract: A method of non-destructively testing materials comprises directing an incident beam of ultrasonic waves onto the surface of a material and detecting the beam reflected by the surface, the angle of incidence and the wavelength of the ultrasonic waves being detected, and the critical angle of incidence at which the energy of the reflected beam passes through a minimum being determined for at least two different wavelengths. A curve is then prepared showing how the critical angle or a quantity dependent thereon varies with the wavelength or a quantity dependent thereon. Apparatus for carrying out the method comprises a goniometer for transmitting the incident ultrasonic beam and detecting the reflected beam, means for varying the angle of incidence of the beam, means for varying the wavelength of the waves, and means for determining the critical angles of incidence. The invention is applicable inter alia to the testing of tempered steel components.

Journal ArticleDOI
TL;DR: In this paper, a matrix method for calculating the effective refractive index of guided modes on multilayer dielectric waveguides is developed and employed to calculate the effective electrooptic coefficient of such waveguide structures when one of the media composing them is electro-optic.
Abstract: A matrix method for calculating the effective refractive index of guided modes on multilayer dielectric waveguides is developed and employed to calculate the effective electro-optic coefficient of such waveguide structures when one of the media composing them is electro-optic. In properly specified three-layer waveguides, enhancement of the effective electro-optic coefficient above the bulk value by as much as a factor equal to the square of the highest refractive index in the structure is possible. The maximum modulation enhancement for the three-layer guide is attainable with loosely, as well as with tightly, confined waveguide modes.

Journal ArticleDOI
TL;DR: In this paper, a total reflecting mirror of 120 cm length was designed and built to focus synchrotron radiation emanating from the electron-positron storage ring at the Stanford Linear Accelerator Center (SPEAR).
Abstract: A total‐reflecting mirror of 120‐cm length was designed and built to focus synchrotron radiation emanating from the electron–positron storage ring at the Stanford Linear Accelerator Center (SPEAR). The reflecting surface is of unpolished float glass. The bending and tilt mechanism allows very fine control of the curvature and selectability of the critical angle for wavelengths ranging from 0.5 to 3.0 A. Elliptical curvature is used to minimize aberrations. The mirror is placed asymmetrically onto the ellipse so as to achieve a tenfold demagnification of the source. The bending mechanism reduces nonelastic deformation (flow) and minimizes strains and stresses in the glass despite its length. Special design features assure stability of the focused image. The mirror reduces the intensity of shorter wavelength harmonics by a factor of approximately 100.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated soft apertures whose action is based on the dependence of the transmission of light by a three-layer medium on the thickness of the layer separating the surfaces on which light is incident at an angle exceeding the angle of total internal reflection.
Abstract: The results are given of theoretical and experimental investigations of "soft" apertures whose action is based on the dependence of the transmission of light by a three-layer medium on the thickness of the layer separating the surfaces on which light is incident at an angle exceeding the angle of total internal reflection. It is shown that such apertures can be used to form a beam with a specified radial intensity profile from beams with Gaussian and uniform profiles. The high optical strength of such apertures and the possibility of formation of a radial profile with a high spatial fill factor without formation of diffraction rings makes them suitable for use in high-power laser systems.

Journal ArticleDOI
TL;DR: In this article, a fiber optics refractometer was developed based on a simple low volume cell, which confines the liquid to be measured around a waveguide whose multiple reflections can enhance the contrast at the critical angle.
Abstract: A fiber optics refractometer has been developed based on a simple low‐volume cell (5–7 μl) which confines the liquid to be measured around a waveguide whose multiple reflections can enhance the contrast at the critical angle. The electromechanical and electrooptical design allows the fiber optics refractometer to measure absolute refractive index with manual or automatic readout, and differential operation with automatic tracking that permits its use as a universal detector for gradient elution chromatography. Present sensitivity is approximately 1×10−5 refractive index units in the static mode and 7×10−5 refractive index units in the scanning beam mode. These sensitivities can probably be improved by a factor of 5 by appropriate system changes.

Patent
Daniel L. Rode1
23 Feb 1976
TL;DR: In this article, a process for improving the smoothness of semiconductor layers grown by epitaxy is described, which is achieved by misorienting the growth surface of the substrate from a major crystallographic plane by a small critical angle approximately equal to the tread-to-riser angle of terraces.
Abstract: A process for improving the smoothness of semiconductor layers grown by epitaxy is described. Smooth epitaxial layers, free of crystal terraces, are attained by misorienting the growth surface of the substrate from a major crystallographic plane by a small critical angle approximately equal to the tread-to-riser angle of terraces which would be formed if the epitaxial layer were deposited on a growth surface nominally parallel to the major plane. The critical angle is a function of both the growth temperature and the crystal composition. Specific examples for the growth of LPE Al x Ga 1-x As at various growth temperatures and values of x on GaAs substrates misoriented from the (100) and (111)B major planes are given. Also described are examples of silicon layers grown by CVD on (111) substrates to measure the critical angle in the (112) direction.

Journal ArticleDOI
TL;DR: In this article, a classic effect of "reflection" and catching of electrons by opposite electromagnetic waves, similar to the one experienced by Cherenkov wave, has been found in vacuum and in a medium with an arbitrary index of refraction n(ω) ≶ 1.

Proceedings ArticleDOI
01 Jan 1976
TL;DR: In this article, a mesa-shaped pin-photodiodes with high internal quantum efficiency at a lifetime below 100 ps using a grated highly reflecting back contact and total reflection at the top was presented.
Abstract: Thin-silicon-film mesa-shaped pin-photodiodes are presented, which exhibit high internal quantum efficiency at risetimes below 100 ps using a grated highly reflecting back contact and total reflection at the top. Theoretical and typical experimental data are given. Transparent photodiodes fabricated in a similar way are introduced, which can be inserted into an optical transmission path to take out a fraction of power without the need of an optical coupler.

Journal ArticleDOI
TL;DR: The fluorescence emission from the quantum counter cell was found to be significantly less polarized and also less dependent on excitation wavelength.
Abstract: A new design for quantum counter cells is described that uses total internal reflection to minimize depth-of-penetration and polarization effects. This new cell is compared to a standard 1-cm thick quantum counter cylindrical cell. Solutions of 5 g/liter of rhodamine B chloride in ethylene glycol were used in both cells. The fluorescence emission from the cell was found to be significantly less polarized and also less dependent on excitation wavelength.

Patent
27 Jan 1976
TL;DR: In this article, a scanning light beam is focussed across the material track by a cylindrical lens, and reflected light is directed to a light conducting bar with a photosensitive device at its end(s).
Abstract: A scanning light beam is focussed across the material track by a cylindrical lens, and reflected light is directed to a light conducting bar with a photosensitive device at its end(s). The re-emitted light is collected in the opposte direction to the incident light. The incident and re-emitted light pass through apertures in the same cylindrical lens, and the returned light is directed to the surface of the light conducting bar (14) which has a stepped mirror system (53) in its reception area (24). It reflects the light falling at about a right angle to the bar (14) so that the reflected light falls on the bar surfaces at total reflection angles.

Journal ArticleDOI
TL;DR: In this article, the problem of optical design is formulated as follows: given a principal surface r(α) and a maximum focal angle αm, find the pair of optical surfaces for which diffraction limited focusing is achieved.
Abstract: For many laser applications, it is desired to focus a collimated beam with a specified transformation of the intensity distribution. The transformation properties of a lens or mirror system can be specified in terms of the principal surface r(α), which maps the height of the incident ray parallel to the optic axis onto a given angle at the focus. The intensity distribution at the focus is then given by the relation I(α) = I(r)r(dr/dα)/sinα. One aspheric surface in an optical system is sufficient to yield diffraction limited focusing. By means of two aspheric surfaces, diffraction limited performance with a specified principal surface can be achieved. The problem of optical design is stated as follows: Given a principal surface r(α) and a maximum focal angle αm, find the pair of optical surfaces for which diffraction limited focusing is achieved. It is shown that specification of r(α) and αm uniquely determines the lens design to within a scale factor, given the refractive index of the lens. It is further shown that one straightforward Runge-Kutta integration routine generates both surfaces for either a lens or a pair of mirror surfaces. The complete family of aplanatic lenses will be described. Deviation from sphericity will be discussed, as will the possibility of realizing the specified lens designs. The family of lenses that map uniform incident intensity into uniform illumination about the focus will also be described. Extension of the method to off-axis aberrations will be considered.


Journal ArticleDOI
TL;DR: In this article, the longitudinal shift of a microwave beam at total internal reflection is measured and good agreement with the prediction of classical electromagnetic theory is provided, and the magnitude of the effect at microwave frequencies is conveniently large and the experimental setup used is sufficiently straightforward to allow this experiment to be repeated in an undergraduate laboratory program.
Abstract: We have measured the longitudinal shift of a microwave beam at total internal reflection. Good agreement with the prediction of classical electromagnetic theory is provided. The magnitude of the effect at microwave frequencies is conveniently large and the experimental setup used is sufficiently straightforward to allow this experiment to be repeated in an undergraduate laboratory program.

Patent
28 Jul 1976
TL;DR: A light mixing device of optically clear light transmitting material where the various color components of light introduced in the input end of the device are efficiently mixed by internal reflection through the length of the mixer is described in this article.
Abstract: A light mixing device of optically clear light transmitting material where the various color components of light introduced in the input end of the device are efficiently mixed by internal reflection through the length of the mixer. The mixer may be either linear or curved and includes axially extending reflective surfaces internal of its outer periphery.