Showing papers on "Total internal reflection published in 1972"

Calculation and Experimental Proof of the Transverse Shift Induced by Total Internal Reflection of a Circularly Polarized Light Beam

Abstract: Wiegrefe, Fedorov, Costa de Beauregard, and Schilling have discussed the transverse energy flux existing in total reflection of an elliptically polarized light beam, the latter two proposing formulas for the transverse shift of the reflected beam. We have calculated the transverse shift by an energy-flux-conservation argument similar to Kristoffel's and to Renard's in their deduction of the longitudinal Goos-H\"anchen shift, thus obtaining a formula different from those of the previous authors. We have also tested experimentally the existence of the transverse shift, in the optimal case of circular polarization and quasilimit total reflection, by using two slightly different multiplying procedures. Our measurements definitely vindicate our own formula for the transverse shift against both Costa de Beauregard's and Schilling's. The relevance of our results in connection with noncollinearity of velocity and momentum of the spinning photon inside the evanescent wave is very briefly discussed.

Reflection‐Refraction of a Stress Wave at a Plane Boundary between Anisotropic Media

Abstract: A review is given of the pertinent equations necessary to describe the reflected and refracted waves at a plane boundary between anisotropic media and the utility of the wave surface in discussing this problem. The critical angle phenomenon in anisotropic media is discussed in terms of the energy flux vector associated with the reflected and refracted modes. The critical angle is shown to occur generally at that angle of incidence for which the energy flux vector of the reflected or refracted mode is parallel to the boundary and not when the wave vector is parallel to the boundary. The possibility of not needing a nonhomogeneous surface wave to satisfy the boundary conditions at angles of incidence greater than the critical angle is discussed for certain particular regions in some anisotropic materials.

Influence of Material Properties on Rayleigh Critical‐Angle Reflectivity

Abstract: This paper extends the investigation of critical‐angle phenomena and investigates the relationships between material properties and the condition (F0) for which zero reflectivity occurs. It was found that material attenuation, density, and velocity all influence F0. Graphs are presented for several materials from which the reader may determine F0 for a particular sample. Measurements which further verify the accuracy of the model, which we have used in these calculations, are also presented.

Quantized Longitudinal and Transverse Shifts Associated with Total Internal Reflection

Abstract: A recent experiment has shown us that the Goos-H\"anchen shift is quantized, the eigen-functions being the transverse electric and magnetic modes. We give here a straightforward theory of this phenomenon, together with the prediction that our new transverse shift is also quantized, with the circularly polarized modes inside the evanescent wave as eigenfunctions. An experimental test of the latter point is being considered.

Measurement of the angular distribution of light scattered from a glass fiber optical waveguide.

Abstract: This paper reports the measurement of the angular distribution of light scattered from a low-loss fiber at 1.06 μm and 0.633 μm. In addition to Rayleigh scattering, a previously undetected, near-forward scattering peak was observed. The new peak is shown to be consistent with scattering by narrow dielectric filaments aligned with the axis. The total scattering loss rate at 0.633 μm is ~10 dB/km, about 14 of which is due to the near-forward peak. The total scattering loss rate at 1.06 μm is ~1 dB/km.

Shifts of Electron Beam Position Due to Total Reflection at a Barrier

Abstract: Just as light beams can undergo position shifts when totally internally reflected, it is found that analogous shifts of an electron beam can occur upon total reflection at a potential barrier. A given shift corresponds to a spin polarization normal to the shift, and thus an initially unpolarized beam will be separated into two polarized beams. These shifts are comparable to the electron Compton wavelength times the number of multiple reflections.

Opto-electronic apparatus for measuring and controlling the concentration of solutions

Abstract: An improved opto-electronic apparatus for determining the concentration of solutions includes a probe having a prismatic immersion tip with at least two internally reflecting surfaces. A light-emitting means in the probe body directs a collimated beam of light through the prism toward a first reflecting surface of the probe tip, the incident beam making an angle with the first reflecting surface approximately equal to a critical angle of total reflection corresponding to the nominal index of refraction of the solution being examined. The included angle between subsequent reflecting surfaces is preferably approximately at least twice this critical angle. The light beam is reflected from a last reflecting surface toward an adjacent light receiving surface optically connected with a light-sensitive means in the probe body. Variations in the concentration of the solution in which the probe tip is immersed affect the intensity of the light beam finally reflected to the light-sensitive means, and the amplified output of the light-sensitive means provides a voltage suitable for use in measuring and controlling the concentration of the solution.

Polarized light source for underwater use

Abstract: A circularly polarized underwater light source comprising: a conventional unpolarized light source with a well-collimated output; an efficient optical polarizer, which employs multilayer interference polarization, total internal reflection, birefringent quarter-wave plates; and anti-reflection coatings; a lens to control the extent of the divergence of the illuminating beam; and an underwater housing with a dome-shaped window designed to withstand external hydrostatic pressures, part of the winding forming the lens.

Optical device with means for reducing internal reflections

Abstract: The outer surface of a transparent optical mass is directly coated with an internal reflection suppressing coating having an index of refraction smaller than that of the optical mass for suppressing internal reflections of light passing through the mass at angles of incidence to the surface greater than the critical angle. The coating includes a dispersing medium and a material in the form of light absorbing particles having dimensions smaller than one-fifth of the wavelength of visible light dispersed in the medium. The particles have a sufficient density near the surface to absorb a major portion of visible light at all wavelengths incident upon the surface through the mass at angles of incidence greater than the critical angle.

Method of making totally internally reflected holograms

Abstract: A method is described for making holograms by means of linearly polarized object and reference beams, the reference beam being reflected inside the photosensitive emulsion. The plane of polarization of a linearly polarized reference beam includes an angle of 45 DEG with its plane of incidence. The beam is reflected under the critical angle of total internal reflection at the lower face of a photographic emulsion. The reflected beam is linearly polarized, too, its plane of polarization being turned by 90 DEG , so that no interference between these two beams is possible. An object beam passes a mask and is linearly polarized vertically either to the reference beam or to the reflected beam so that only one hologram can be formed and no undesired interaction between two holograms is possible when the mask is reproduced for exposure of a photoresist-covered semiconductor wafer.

Monte-carlo calculations of the back-scattering of high-energy heavy ions from metal surfaces

Abstract: Random numbers are used to describe the plural scattering of fast heavy ions by amorphous metal films. Rather simple expressions for the single interactions are derived employing a screened Coulomb potential and with regard to the important energy losses of the particles in the foils. As a first result the computer program yields qualitatively the shape of the particle trajectories in accordance with observed fission fragment tracks in thin metal films. Furthermore the spatial distribution of the reflected particles together with the total reflection rate is studied as a function of the entrance angle. It is seen that the portion of the reflected particles decreases rapidly with increasing angle. Similarly the penetration depths and the energy spectra are strongly influenced by the angle of the incident beam. The results are in satisfactory agreement with known experiments.

X-ray scattering study

Abstract: A soft X-ray glancing incidence telescope mirror and a group of twelve optical flat samples were used to study the scattering of X-rays. The mirror was made of Kanigen coated beryllium and the images produced were severely limited by scattering of X-rays. The best resolution attained was about fifteen arc seconds. The telescope efficiency was found to be 0.0006. The X-ray beam reflected from the twelve optical flat samples was analyzed by means of a long vacuum system of special design for these tests. The scattering then decreased with increasing angle of incidence until a critical angle was passed. At larger angles the scattering increased again. The samples all scattered more at 44 A than at 8 A. Metal samples were found to have about the same scattering at 44 A but greater scattering at 8 A than glass samples.

Totally reflecting laser refractometer

Abstract: A laser having isotropic polarization characteristics, is operated with a confocal mirror cavity and is adjusted in terms of mirror reflectivity, spacing, and laser active medium to operate at a particular wavelength. A total internal reflection prism is contained inside the laser optical cavity and is rotated to produce an optical path angle slightly greater than the critical angle. For this condition the prism will constrain the laser to oscillate in such a way that adjacent modes have orthogonal polarizations. In the case of two mode operation one mode will be polarized parallel to the plane of incidence at the prism reflecting surface and the other will be perpendicular to the first. The phase shifts produced upon total reflection are different for light polarized parallel and perpendicular to the plane of incidence. Futhermore the difference in the phase shifts for these two polarization directions is a function of the refractive indices of the prism and its facing material as well as the angle of incidence. Since the difference in phase shift is equivalent to a difference in optical cavity length for the two orthogonally polarized modes the frequency of one of the modes is slightly displaced with respect to the other. Measurement of the beat frequency difference between the orthogonal modes will therefore yield information on the refractive index of the facing material provided that prism index and angle of incidence are known. In one embodiment the prism is provided with a calibrating sample of known refractive index placed in close contact with its reflecting face. The prism and laser cavity are then adjusted to produce a stable mode difference beat frequency. Very small changes in refractive index of the material in contact with the prism face can be correlated with changes in beat frequency thereby giving a very sensitive measure of refractive index. If the comparison sample is a fluid confined inside a chamber sealed to the prism face, extremely slight differences in composition of the fluid can be detected. Since the output is read immediately as a frequency, the system is useful in monitoring flowing fluids.

Assessment of various reflectors used with rectangular scintillation detectors

Abstract: The use of various types of reflector with two simulated rectangular scintillation detectors (40.5 cm*15.2 cm*6.3 cm and 60.0 cm*40.5 cm*6.3 cm) has been investigated with respect to the efficiency and uniformity of light collection, by means of optical model experiments. It is shown that good efficiency and uniformity of light collection can be achieved by collecting light from one end of the detector only, through a single light guide, provided that the basic method of light reflection employed is total internal reflection. Various specular or diffuse reflectors placed close to, but not in optical contact with, the surfaces of the detectors increased the collection of light without seriously affecting the uniformity.

Stratified media and total reflection phenomena.

Abstract: General recurrence relations for the deduction of the reflection and transmission coefficients of a stratified medium are derived. These are suitable for numerical computations on such layered systems involving complex indices of refraction and oblique incidence. The results are applied to total reflection phenomena involving the presence of a dielectric, a perfectly reflecting, or a metallic medium in the less dense medium beyond the totally reflecting boundary. Numerical results are given on a total reflection attenuator, on a total reflection phase shifter, and on a total reflection polarizer. These indicate the potential use of such total reflection phenomena for optical components and laser applications.

Reflection of Internal Gravity Waves by small Density Variations

Abstract: The propagation of small-amplitude internal gravity waves through a finite layer of varying Brunt-Vaisala frequency is analyzed. A two-scale analysis is used and it is shown that the amount of reflection a wave undergoes is related to the correlation coefficient between the first harmonic of the wave and the variations of the medium. Therefore, with proper care one can extend the usual WKB technique to account for reflection.

Measurements of the critical angle for channeling of heavy ions in copper using characteristic X-ray generation

Abstract: Measurements are presented of ψ1/2, the width of the dip in the yield of CuL X-rays when Ne+, Ar+, Kr+ and Xe+ of 150–350 keV are channeled in the axis of copper. Absorption of the X-rays and the slowing down of the beam are shown to limit the depth from which the detected X-rays can come. The magnitude of the effect of multiple scattering on the measured values of ψ1/2 is shown to be small for all the projectiles except nech. The data has a dependence on (Z 1/E) which is intermediate between that of the critical angles ψ1 and ψ2. A numerical calculation of critical angle gives good agreement with the data. At low energy the calculation uses a potential which is a sum of screened Coulomb and Born-Mayer terms; at higher energy screened Coulomb alone is adequate. A simple analytical expression for the critical angle, based on a 1/r2 atomic potential, may be used as an approximation to the results.

Internal reflection ellipsometry for metal deposits

Abstract: A method for determining the optical constants of thick absorbing metal deposits on a homogeneous and isotropic substrate is developed by measuring the ellipsometer parameters ψ and Δ at the substrate‐metal interface. The method is advantageous because surface contamination of the metal deposit by the atmosphere is eliminated. It also lends itself to an accurate determination of the thickness and optical constants of oxides formed on the air side of the metal deposit. Results of measurements are compared for gold, platinum, and silver with those obtained from conventional ellipsometry. An example of oxidation of Ni–P deposits is also given. The results demonstrate the validity and versatility of the present technique; apart from being simple and easy to apply, the calculations of refractive indices are exact with no approximation involved.

Totally Internally Reflecting Thin-Film Optical Cavities

Abstract: Thin-film optical cavities formed by optical waveguides in which end faces are parallel, optically smooth, and perpendicular to waveguide surfaces are analyzed for the possibility of total internal reflection of waveguide mode ray components at the end faces. Conditions for the occurrence of this phenomena in various modes are derived and evaluated for GaAs waveguides using dispersion relations. A refractive index difference between waveguide and surrounding media of at least 4% for GaAs is necessary before total reflection at the end faces can occur. For such differences, total reflection in single mode GaAs waveguide is nearly always expected.

On the Wave Formation in Explosive Bonding

Abstract: The interface between explosively bonded metals exhibits a wave-like form, but the theory of formation of wave has not been fully studied. In this paper the relation between wavelength and collision angle was investigated by using the semi-cylinder method and angular method, and an attempt to explain the mechanism of wave formation was made. The results obtained are as follows.1. The wavelength increased continuously with the collision angle until a critical angle, beyond which the wave-like profile vanished and a linear interface was observed. For a given value of collision angle, the wavelength increased with the plate thickness. However the collision velocity at the critical angle was constant independently of plate thickness.In angular method, the wave tended to grow in the direction of bonding and none was observed for the distance of 20-30 mm from starting to bond.2. The wave amplitude increased with the collision angle but the ratio of amplitude to wavelength was constant.3. The material near the interface suffered extreme plastic deformation and the folw configuration, in particular wave-like profile, resembled the stream pattern in a fluid having a Karman vortex street, so the authors considered that a wavy interface resulting from Karman vortex street occurred in the vicinity of collision point and they tried to calculate the wavelength λ. The following equation was used.For a symmetric collision shown in Fig. 12 (a) : collision angle 2γ, λ=20h (1-cosγ)For an asymmetric collision shown in Fig. 12 (b) : collision angle γ, λ=10h (1-cosγ) where h: the thickness of flyer plate.The values calculated by using these equations agreed generally with measured values.4. An increase in hardness at interface, when the collision velocity exceeded 1800 m/sec, was observed in bonding an iron flyer plate to a mild steel semi-cylinder. This fact might be attributed to martensite marking of the pressure-induced tranformation that appeared at a pressure more than 130 Kbar in iron.

Microwave Phase Measurements Associated with the Goos–Hänchen Shift

Abstract: Microwave phase measurements, using the Robertson homodyne detection method, have been made in the field outside a dielectric prism after microwave energy has experienced total internal reflection. The phase changes that occur in this case are explained by extending Artmann's theory of the Goos-Hanchen effect to microwave optics. Satisfactory agreement between the theory and measurements has been obtained for angles of incidence from 40 to 50° on a dielectric boundary for which the critical angle is 36.4°.

Specific gravity and refractive index measurements

Abstract: 1301082 Measuring refractive index photo-electrically; measuring state of charge of a battery RICHMOND ELECTRONICS (MARKYATE) Ltd 13 Feb 1970 [14 Nov 1968] 54169/68 Headings G1A and G1U [Also in Divisions G2 and G4] The refractive index of a fluid is measured, in order to determine the specific gravity thereof, by means of a probe comprising a translucent block 1, means 4 for directing light towards a surface 2 of the block which forms an interface with the fluid, and means for receiving light distributed along a line 6 reached by the light after internal reflection at the interface, the extent of illumination along the line being dependent on the refractive index of the fluid. The probe may monitor flowing fluids or designed for use in testing inaccessible fluids, for example, in a battery, the state of charge of which is to be checked by determination of the specific gravity, Fig. 4. The light source which may be a permanent emitter of the type employing a beta source and which may be monochromatic may be mounted at one corner of block 1, which may be of plastics or glass, a shield member 5 being provided internally of the block, to prevent light passing direct to detection surface 6. One or more photo-cells or photodiodes may be mounted adjacent face 6 to provide an analog or digital measure of the illuminated part y of face 6. Alternatively, Fig. 2 (not shown), light may be conducted to the corner by a fibre optic guide (7) and a row (8) of fibres be mounted at face 6, these being associated with an equal number of photo-cells at a remote location for digital measurement or with a single photo-cell sensing the total intensity issuing from the fibres of Y. A single fibre or cluster of fibres may be used to determine refractive index changes in a very narrow range and may be associated with a further single fibre to sense the direction of change. In an alternative form of block, Fig. 3 (not shown) face 6 is at an obtuse angle to the interface, for greater sensitivity. Circuit Fig. 5 for a multi-cell battery monitor, has probes for each cell of the battery producing refractive index and temperature indications. Various summing circuits and a comparator are used to produce a temperature compensated measure of mean charge which is indicated and/ or used to control charging.

Light collection in rectangular scintillation counters

Abstract: An expression is derived which can be used to calculate the quantity of light available for collection at one surface of a rectangular scintillation counter in which the total internal reflection method of light collection is used, and under conditions in which there is no loss of light by absorption. Methods of correcting the expression to allow for light absorption are applied in order to derive the theoretical response to scintillations at any position along the central axis and an extreme axis of a rectangular block (61 cm*40.5 cm*6.3 cm) of refractive index 1.5. Results obtained using an experimental model of the same dimensions are in good agreement with the theory. The value of the expression in counter design is discussed.

Depolarization of Singly Scattered Radiation in a Turbulent Plasma

Abstract: Single scattering in a weakly inhomogeneous turbulent plasma is examined for angles of incidence greater than the critical angle of the medium. A possible mode for depolarization of backscattered radiation is discussed with the help of the radiative transport equation.

Improvements in or relating to optical couplers

Abstract: 1287035 Optical couplers WESTERN ELECTRIC CO Inc 22 Jan 1970 [24 Jan 1969 21 April 1969] 3078/70 Heading G2J [Also in Division H3] An optical coupler comprises a thin film 12, 13 of optical material the major surfaces of which are plane parallel and the index of refraction n 2 , and a prism 16 having an index of refraction n 3 , the prism being adapted for internal reflection of light at a first surface 18 disposed parallel to the major surfaces of the thin film 13 and separated therefrom by a gap of refractive index n 1 to partially frustrate the internal reflection, the major surface remote from the gap being in contact with an environment 14 (eg a substrate) having a refractive index n 4 , n 3 being larger than the largest of n 4 , and n 1 , and the coupler, when suitably orientated to receive a coherent light beam, providing phase-matched coupling of said beam to a wave propagating in the thin film transverse to the direction of the beam The prism and the thin film 12 are optically decoupled beyond the region of frustrated internal reflection The decoupling may be effected by providing the prism with a second surface 21 cut at an obtuse angle to surface 18 The gap of refractive index n 1 may be air or it may be a dielectric material Where such a material is used the decoupling may be effected by increasing the thickness of the dielectric material Light propagating in the thin film may be coupled out of the film using either another portion of the said input prism 16 surface, or using a second prism In one embodiment Fig 4 (not shown) the coupler also includes a reflector to intercept light which has passed through the prism 16 This forms an optical resonator and causes light to propagate in two directions along the thin film Two output prisms are used in that embodiment In another embodiment Fig 6 the prism 86 receives a plurality of signal coherent light beams 91, 92, 93, at different angles, and phase-match couples them to different waves propagating in thin film 83 These different waves are coupled out by a prism 97 Prisms 86, 97 have multiple faces through different ones of which different beams and waves are coupled The light propagating in the thin film may be modulated during passage therethrough; the thin film could then be gallium arsenide having its crystalline axis normal to the planes of modulating electrodes and the substrate could be sapphire Alternatively the thin film may be a semi-conductive junction region, semiconductive material of different types being located on opposite sides of the junction region The dielectric gap in the coupling or uncoupling region is less than one wavelength of the light waves being propagated In an amplifier a frequency shifter Fig 10 signal energy 211 and pump energy 225 are fed to prism 216 and hence waveguide 212 A desired abstracted beam is coupled out by prism 222