Phenomenon Of Total Internal Reflection Research Articles

Radar Glory from Buried Craters on Icy Moons

Three ice-covered moons of Jupiter, in comparison with rocky planets and Earth's moon, produce radar echoes of astounding strengths and bizarre polarizations. Scattering from buried craters can explain these and other anomalous properties of the echoes. The role of such craters is analogous to that of the water droplets that create the apparition known as "the glory," the optically bright region surrounding an observer's shadow on a cloud. Both situations involve the electromagnetic phenomenon of total internal reflection at a dielectric interface, operating in a geometry that strongly favors exact backscattering. Dim surface craters are transformed into bright glory holes by being buried under somewhat denser material, thereby increasing the intensity of their echoes by factors of hundreds. The dielectric interface thus formed at the crater walls nicely accounts for the unusual polarizations of the echoes.

OPTICAL MEASUREMENT OF THE MOTION OF SMALL PARTICLES CLOSE TO THE FLUID-SOLID INTERFACE

A novel and versatile optical method, based on the phenomenon of total internal reflection and useful for studying the motion of small particles in a moving fluid very close to the interface between a fluid and an optically flat solid, is described. Initial tests using 0.2 to 1 micron silica particles and 3.2 micron polystyrene spheres have demonstrated the effectiveness of the method and provide a basis for several extensions, which are discussed.

Refractive indices of the condensed rare gases, argon, krypton and xenon

A recently designed refractometer employing the phenomenon of total internal reflection is used to measure the refractive indices of the condensed phases of the rare gases argon, krypton and xenon in the temperature ranges 35-90K, 60-117K and 30-178K, respectively. The values obtained for argon and xenon are in good agreement with those obtained by the method of minimum deviation, but values for krypton obtained by the two methods differ by more than the combined experimental error. This difference does not appear to be due to impurities. Experimental values of the refractive indices have been used to compute values of the Lorentz-Lorenz function for comparison with predictions arising from the theoretical models of C.J.F. Bottcher and of H. Block and S.M. Walker and to obtain revised values of the parameters for the theoretical treatment of S. Doniach and R. Huggins. The effect of vacancy concentration on density and hence on the Lorentz-Lorenz function is discussed.

Mode spectrum of the modified Goubau line

The problem of surface-wave propagation over the modified Goubau line, which consists of a Goubau line with an airgap between the conductor and dielectric, is formulated by the boundary-value method. The various modes which exist on the line as well as their cutoff conditions and the specific effects of the airgap are obtained from a solution of the characteristic equation. The mode spectrum for the symmetric and hybrid modes as well as the transverse field distributions for the E00 and H01 modes are also presented. The axial power flow and the attenuation constant are calculated for the dominant mode and the salient low-loss feature may be explained perhaps in terms of total internal reflection or duct propagation phenomena.

Total internal reflection integrated-optics switch: a theoretical evaluation

Previously demonstrated planar thin-film optical switch employing the total internal reflection phenomenon is given a full theoretical evaluation for its possible adaptability to an optical channel waveguide system and also to polarization insensitive immultiport fiber-channel switch.

Acoustic tunnelling

SynopsisGeneral formulae are obtained for the reflection and transmission of harmonic acoustic waves by a curved interface between two media when the frequency is high. In addition to refracted rays there turn up tunnelling rays, if the surface is concave to the source, which are emitted from an evanescent region when the phenomenon of total internal reflection would be anticipated. Uniformly valid formulae dealing with the transition from refraction to tunnelling in both transmission and reflection are derived.The theory is applied to the circular cylinder and to the top-hat circular jet. In the latter case it is suggested that radiation may tend to be more significant at inclinations of 50°-65° (downstream) and 25°-40° (upstream) to the axis of the cylinder. The augmentation due to tunnelling rays in propagation upstream is mentioned.

Ideal prism solar concentrators

Non-imaging solar concentrators using both symmetrical[1–3] and asymmetrical mirrors have recently been described by several workers[4–6]. In this paper, a completely separate but parallel family of non-imaging concentrators is proposed which utilises the phenomenon of Total Internal Reflection within a material of high refractive index to achieve concentration. In both symmetrical and asymmetrical forms, the new concentrators satisfy the maximum concentration limits for ideal radiation transformers for a given acceptance angle[7]. Light radiating from the exit aperture is restricted in angle, but concentration performance is very good and irradiation of the exit aperture is much more uniform for a distant point source than in any other design. The new forms are easier to construct than CPC concentrators filled with refractive medium because, in most designs, only flat surfaces are required and far less refractive material is used for a given aperture. Stationary concentrators with acceptance angles up to that of a flat plate are possible.

A refractometer for use at low temperatures

A refractometer employing the phenomenon of total internal reflection of light has been designed for use at low temperatures. The instrument has been used to measure the refractive indices of argon, krypton and xenon at 546.1 nm in the temperature range 178 to 30K. The upper limit of the theoretical accuracy of the refractive index is +or-0.02% but the experimental uncertainty proved to be +or-0.1% maximum. This accuracy is comparable to that obtained using a spectrometer and the method of minimum deviation.

Use of a light beam to probe the cell surface in vitro

An optical nondestructuve microprobe technique is proposed to examine cell surfaces in vitro. Use is made of the phenomenon of total internal reflection to achieve spatially restricted interaction between a light beam and the peripheral zone of a substrate-adherent population of cells. With the help of a suitable optical model, the technique can provide fundamental information on the molecular organization of the cell membrane from measurements made on living cells. Variations of both the intensity and polarization ellipse of the reflected beam carry information about changes in the cell surface that can be induced by any stimulus to which the cells are subjected. This promises to have important applications such as the detection of normal-to-malignant cell transformations.

Nonlinear surface−wave propagation over plasmas and conductors

An investigation of nonlinear surface−wave propagation over plasmas and conductors has been carried out when the nonlinearity in the complex dielectric constant arises on account of ponderomotive force and energy−dependent collisions. Analytical expressions have been obtained for the decay rate and phase velocity of the evanescent wave in the limit of perturbation approximation. The nonlinearity is found to reduce the rate of decay of an evanescent wave in a conductor and also in the case of a dense plasma. A study of the phenomenon of total internal reflection reveals that the critical angle increases due to nonlinearity and the evanescent wave decays slower.

Refractive index and composition of poly(methyl methacrylate) fracture surface layers

AbstractBy using the phenomenon of total internal reflection of light the refractive index of the thin layer present on fresh poly(methyl methacrylate) fracture surfaces has been measured. The fracture surface refractive index, 1.32, is the same as that of the craze in the same polymer. The fracture surface layer is accordingly thought to be craze like in structure.

Measurement of ultrasonic velocities in some Indian rocks

The phenomenon of total internal reflection has been employed in developing a technique for measuring the ultrasonic velocities in solids using pulsed ultrasonic beams. The ease and accuracy with which the critical angles can be measured make this method superior to other methods in some respects. Besides the longitudinal velocities, torsional velocities have also been measured in a number of Indian rocks for the first time. It is essential to use fairly large sized samples in this method. An earlier observation indicating a dependence of sound transmission on granular texture of the rocks has been confirmed qualitatively in this investigation as well.