Showing papers on "Total internal reflection published in 1983"

Total internal reflection fluorescent microscopy

Abstract: SUMMARY This review discusses applications of fluorescence microscopy using totally internally reflected excitation light. When totally internally reflected in a transparent solid at its interface with liquid, the excitation light beam penetrates only a short distance into the liquid. This surface electromagnetic field, called the ‘evanescent wave’, can selectively excite fluorescent molecules in the liquid near the interface. Total internal reflection fluorescence (TIRF) has been used to examine the cell/substrate contact regions of primary cultured rat myotubes with acetylcholine receptors labelled by fluorescent α-bungarotoxin and human skin fibroblasts labelled with a membrane-incorporated fluorescent lipid. TIRF examination of cell/substrate contacts dramatically reduces background from cell autofluorescence and debris. TIRF has also been combined with fluorescence photobleaching recovery and correlation spectroscopy to measure the chemical kinetic binding rates and surface diffusion constant of fluorescent labelled serum protein binding (at equilibrium) to a surface.

On the origin of plasmaspheric hiss: Ray path integrated amplification

Abstract: An investigation has been made of processes responsible for the growth, damping, and propagation characteristics of whistler mode emissions within the earth's plasmasphere. Three-dimensional ray path calculations of the integrated wave gain in a realistic model plasmasphere have provided an explicit confirmation of the anisotropic electron cyclotron resonant generation mechanism for the maintenance of plasmaspheric hiss. Peak wave amplification occurs for field-aligned waves in the outer plasmasphere. The majority of unstable low-frequency waves follow ray trajectories that internally reflect at the plasmapause and are thus trapped within the plasmasphere. This reflection allows waves to subsequently propagate into the locally stable inner and middle plasmasphere and also migrate substantially in longitude. The combination of internal reflection at the plasmapause and magnetospheric reflection at high latitude provide an important class of wave trajectories that are recycled back to the equatorial growth region with sufficiently small wave normal angles to allow further cyclotron resonant amplification. It is unlikely that wave growth can occur from the natural incoherent emissivity level within the plasmasphere since the required gains (≈100 dB) would mandate unreasonably high energetic electron flux. An alternate, as yet unidentified, embryonic source is therefore required to initiate the growth process. But once established the observed spectrum of broad band plasmaspheric hiss can be maintained by the modest net gains anticipated along ray trajectories that are recycled back to the favorable equatorial growth region. A simulation of the spectral properties of waves arriving at selected observation points following several equatorial transits shows that the largest accumulated gain occurs for recycled waves that reflect from the plasmapause following each equatorial crossing. Furthermore, the peak gain is relatively insensitive to the location of the observation point, and waves are expected to arrive over a broad solid angle in k space consistant with observations. The ability of waves to gain access to regions far from the source is a direct result of the relatively weaker Landau damping of oblique waves along the high latitude portion of the recycled ray path in comparison to the equatorial cyclotron resonant growth. The hiss upper frequency cutoff can result from the limited anisotropy of the cyclotron resonant electrons, the more severe Landau damping at higher frequencies, or in part, from the decreased ability of the higher frequency waves to recycle and thus experience multitransit growth. The characteristic lower frequency cutoff can be due to either the decrease in flux of energetic electrons that cyclotron resonate with the lower frequency waves or from thermal electron Landau damping should the plasmaspheric electron temperature exceed several electron volts.

Reflection and transmission of obliquely incident Rayleigh waves by a surface‐breaking crack

Abstract: Reflection, transmission, and scattering of Rayleigh waves that are obliquely incident on a surface‐breaking crack are investigated. The formulation of the problem has been reduced to two systems of singular integral equations of the first kind for the dislocation densities across the crack faces. The systems of integral equations are solved numerically. Substitution of the dislocation densities into appropriate representation integrals yields the reflected and transmitted surface waves. Reflection and transmission coefficients are plotted versus the angle of incidence for various values of the frequency and versus the frequency for various values of the angle of incidence. A critical angle of incidence, which depends on the material properties of the solid, has been observed. Beyond this angle no mechanical energy is radiated into the solid by body waves.

Refractive-index measurement of bulk materials: prism coupling method.

Abstract: A simple method of measuring refractive indices of bulk materials using a prism coupling procedure is described. Refractive indices are determined from the measurement of the angle incident to the prism at which total reflection on the prism base breaks. This method is shown to possess the advantages of its simple procedure and sample preparation. The accuracy is comparable with that of minimum deviation method if the prism is well calibrated. Experimental results for several materials are given with an evaluation of possible errors.

Measuring refractive index and thickness of thin films: a new technique

Abstract: Properties of a leaky quasi-waveguide formed by a thin film of refractive index smaller than the substrate are described. By exciting these leaky waves through the substrate, we have demonstrated a convenient and accurate method of measuring both the refractive index and thickness of thin films. Experimental results are given for polystyrene, with a demonstrated accuracy comparable with both that of prism coupling into a waveguiding film and with ellipsometry.

Experimental Studies on Reflection Spectra in Monodomain Cholesteric Liquid Crystal Cells: Total Reflection, Subsidiary Oscillation and Its Beat or Swell Structure

Abstract: Many optical properties are presented here in the reflection spectra for monodomain cholesterics of various cell thicknesses at various angles of incidence. It is reported for the first time that left-circularly polarized light incident on a left-handed helix gives rise to a beat structure in the subsidiary oscillation, while right-circularly polarized light causes a swell to be superimposed on the subsidiary oscillation. The beat structure is ascribed to the excitation of two sets of optical eigen modes, each set consisting of two optical eigen modes of slightly different wavelength. The polarization characteristics of the total reflection band as well as the selective reflection band are also discussed.

The viscoelastic reflection/transmission problem: Two special cases

Abstract: In the general problem of plane wave reflection and transmission at a boundary separating two linear viscoelastic media, the mathematical formulas for the reflection and transmission coefficients, the transmission angle, the attenuation vector, etc., are not easily interpretable because they cannot easily be expressed in terms of the basic input parameters ( Q , incidence angle, etc.). To gain further insight, we study two special cases in which mathematical simplifications occur. No low-loss approximations are involved. In the first case, the incident wave is homogeneous, and the Q values of the two layers are equal, and we find, among other things, that the reflection and transmission coefficients are the same as the ones for perfect elasticity (they do not involve complex velocities, etc., and are independent of Q ). In the second special case, the degree of inhomogeneity of the incident wave approaches its upper limit, and we find that the reflection and transmission coefficients approach constant (complex) values independent of the incidence angle, and that there is almost no ray-bending (refraction) upon transmission of the incident wave through the boundary.

Enhanced scattering in voltage sensitive encapsulated liquid crystal

Abstract: In the present invention encapsulated liquid crystal material in a support medium illuminated from the viewing side or direction will appear bright or white relative to background when in distorted alignment, e.g. in the absence of an electric field. Incident light impinging on the liquid crystal material is isotropically scattered thereby into the support medium, and using the principle of total internal reflection a relatively large part of the isotropically scattered light is reflected 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 causes the liquid crystal material to appear relatively light or bright as compared to the background where there is no liquid crystal material or where the liquid crystal material is in parallel alignment in field-on condition, i.e. aligned with respect to an electric field, and, thus, substantially transmissive. 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 and 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.

Liquid crystal display panel

Abstract: PURPOSE:To enable the illumination of a liq. crystal display panel having a switching transistor array from the rear side and to enhance the display performance, by laminating insulating films in the vicinity of the transistor of the panel. CONSTITUTION:A liq. crystal display panel is composed of a panel substrate 1, a transistor 2, light shielding films 3, 4 made of metal or metallic silicide, insulating films 5, 6 formed by the plasma deposition of gaseous hydrocarbon and having a higher refractive index, insulating films 7-10 of silicon oxide having a lower refractive index, and a transparent electrode 11. Light incident on the substrate 1 at a large angle is captured in the films 5, 6 by total reflection, and it does not reach the transistor 2. Accordingly, the panel can be illuminated from the rear side, and the display performance is enhanced.

Selectively light transmitting panel

Abstract: A one panel (41) which transmits rays of light incident at a range of angles of incidence while reflecting rays of light incident within a narrow range of angles of incidence, comprising a plurality of adjacent triangular prisms (43), the prisms having one right angle, the other two angles being such as to result in the double total internal reflection of rays (44) incident within the narrow range of angles of incidence. In addition, a substantially transparent panel which selectively transmits rays of light within a range of angles of incidence while reflecting rays of light incident within a narrow range of angles of incidence, comprising at least one pair of complementary one layer sheets (122, 124), each comprising a plurality of adjacent right triangular prisms, the prisms having two other angles such as to result in the double total internal reflection of rays incident within the narrow range of angles of incidence, the prisms of the two sheets fitting together in a complementary relationship and being separated by an air gap (123).

Multiple internal reflection cell optical system for use in infrared spectrophotometry of liquid and fluidized samples

Abstract: The present invention provides reflaxicon optics for directing infrared radiation from a source into the cone-shaped entry end of a cylindrically shaped internal reflection element, as well as for directing radiation from the cone-shaped exit end of the element towards a detector. Preferably, the contours of the surfaces for the secondary and primary mirrors included in the reflaxicon optics are segments of revolution where the segments are defined as off-axis ellipsoids, in the case where the source infrared radiation is converging, and as cones and off-axis paraboloids, respectively, in the case where the source radiation is collimated. The cylindrically shaped internal reflection element is sealed into a tubular member in order to provide a sample chamber. Liquids and fluidized samples preferably can be passed through the chamber for nondestructive IR analysis.

Immunoassay apparatus and methods

Abstract: A method and apparatus for fluorescent immunoassay utilizes total internal reflection at the interface between a solid phase and a liquid phase of lower index of refraction to produce an evanescent wave in the liquid phase. The solid phase is arranged and illuminated so as to provide multiple total internal reflections at he interface. In a preferred embodiment, the solid phase is in the form of an optical fiber (10) to which is immobilized a component of the complex formed in the immunochemical reaction. A fluorophore is attached to another component of the complex. The fluorescent labelled component may be either the complement to or an analog of the immobilized component, depending or whether competitive or sandwich assays are to be performed. In the case of competitive or sandwich assays are to be performed. In the case of competitive assays, the labelled component is preferably pre-loaded to the immobilized component in a controlled concentration. The fiber (and the attached constituent of the assay) is immersed in the liquid phase sample (12). The evanescent wave is used to excite fluorescence in the liquid phase, and that fluorescence which tunnels back into the solid phase and accumulates during multiple reflections while channeled in the solid phase detected. Diffusional preconcentration onto the reactive surface and double passing enhance the signal and signal/background ratio.

Strength of interaction and penetration of infrared radiation for polymer films in internal reflection spectroscopy

Abstract: The strength of interaction of infrared radiation with relatively thick polymer films was systematically studied by internal reflection spectroscopy. The so-called “effective thickness” was used as a measure of the strength of interaction. The experimental and theoretical effective thickness were compared, and it was found that the theoretically predicted effective thickness can be approached or achieved experimentally with film samples routinely encountered in the polymer industry when moderate attention is paid to surface preparation and clamping force on the film in the internal reflection sample holder. A series of curves for various types of film samples was developed and found to be useful in predicting the spectral contrast for KRS-5 and germanium internal reflection elements. These data were collected for infrared radiation polarized parallel and perpendicular to the plane of incidence and for unpolarized radiation. The data for unpolarized radiation was checked for the effects of the inherent polarization of the Fourier-Transform Infrared Spectrometer used by comparing it to the arithmetic mean of the data for parallel and perpendicular polarization. These data were in good agreement and this indicated that the inherent polarization of the instrument introduced only minor errors into the data collected with unpolarized radiation. The concept of the “sampling depth” was established where the sampling depth ds was defined as the depth normal to the surface sampled. The sampling depth was found to be on the order of three times the value of dp, the depth of penetration, at 45° for polypropylene and polystyrene on KRS-5 and was observed to exceed the effective thickness values at the same conditions. The value of the electric field amplitude was observed to fall to 5% of its value at the surface at ds.

Focus detecting device

Abstract: PURPOSE:To facilitate the control for setting an incident angle, by unifying at least an optical dividing element and a critical angle prism and setting the incident angle of a reflected luminous flux given from an object to be irradiated with control of the optical axis of the irradiating luminous flux. CONSTITUTION:The 2nd prism 8 and a critical angle prism 9 are formed into one body and fixed completely to each other. In such a constitution, the incident angle of an incident luminous flux to the prism 9 is set and fixed at a value equal to or little larger than the critical angle by moving a laser diode 1 by a movable fixing mechanism 14 and within a plane which is orthogonal to the optical axis O of a collimator lens 2. Therefore the position of the diode 1 is controlled and fixed so that the incident angle of the incident luminous flux to the prism 9 is set equal to or slightly larger than the critical angle to reflecting surfaces 10 and 10' of the prism 9. This can facilitate the control for setting an incident angle.

Coupling between finite electromagnetic beam and long-range surface-plasmon mode

Abstract: In this paper, we consider a layered structure consisting of dielectric, metal, and dielectric media and compute the fields produced in the structure by a finite width beam of incident radiation which couples to a long-range surface-plasmon mode in the metallic layer. The analysis allows for complex dielectric constants in all media and focuses on optical radiation. Curves are presented which show the profiles of the reflected field intensity for different values of the propagation length of the mode relative to the width of the incident beam. We discuss the conditions in which the field reradiated from the long-range surface mode can interfere with the specularly reflected radiation so as to produce an interference zero in the reflected profile. In these conditions our analysis allows for a determination of the separate loss coefficients of the mode associated with energy reradiation and dissipation, respectively

Internal reflection prism liquid cell

Abstract: An internal reflection cell for use in internal reflection spectroscopy comprising a transparent body having at a bottom surface two reflecting mirrors and at a top surface means for mounting of an internal reflection prism element. A sealed cell construction is also described. The cell is intended primarily for analysis of liquid samples.

A nondestructive approach to characterize deposits on various surfaces

Abstract: Multiple internal reflection spectroscopy, a very sensitive technique, has been used in the past to characterize deposits from various environments (such as the oral cavity), on internal reflection elements such as germanium. To understand the surface interactions with real surfaces (such as the apatitic tooth surface or stainless steel heat exchange surfaces), the use of appropriate methods to deposit thin films of the substrata of interest, on suitable internal reflection elements, is suggested. This permits the application of multiple internal reflection spectroscopy, to characterize the deposits formed on various types of real surfaces. This approach is illustrated by depositing a thin, solid film of hydroxyapatite (a multicomponent compound which forms the major constituent of the outermost part of the tooth surface) on germanium internal reflection elements, by radiofrequency sputtering. The chemical composition and molecular structure of the films deposited under suitable conditions were very close to those of the bulk material. The adsorption of salivary components on these sputter coated internal reflection elements could be detected by multiple internal reflection infrared spectroscopy.

Number of terms required in the Fourier expansion of the reflection function for optically thick atmospheres.

Abstract: Computational results are presented for the separate terms in the Fourier expansion of the phase function and the reflection function of a semiinfinite, conservatively scattering atmosphere composed of cloud particles. The calculations involve successive applications of invariant imbedding, doubling, and asymptotic fitting methods to cover the range from very thin to very thick atmospheres. From the results, the ratio of the total reflection function to the first-order reflection function is determined as well as the number of terms required to describe the reflection function to an accuracy of 0.1 percent. The number of terms required depends strongly on the zenith angles of incidence and reflection as well as on details of the phase function. These results are compared with similar results obtained for a Henyey-Greenstein phase function having the same asymmetry factor as in the cloud model.

On the localization of shallow water waves by a random bottom

Abstract: Linear shallow water waves have a velocity which varies with the water depth h(x). We expect that a plane wave (wave vector k parallel to x) will be partially reflected by modulations of the bottom. We argue that this should lead, in the presence of a random modulation of the depth extending over a long enough distance, to exponential localization of all proper modes and to the total reflection of an incident wave, a phenomenon analogous to the one of localization discovered and widely studied in solid state physics. As a first step in the experimental study of localization of water waves, we show the effect of a periodic modulation of the bottom (Bragg scattering) and the additional effect created by using a random amplitude.

Reflection of electromagnetic waves at a biaxial–isotropic interface

Abstract: The reflection of electromagnetic waves at a plane boundary between isotropic and biaxial media has been investigated using the kDB approach. The general case has been considered in which the principal dielectric axes of the biaxial medium are oriented at an arbitrary angle to the normal of the plane boundary. In general, two characteristic waves propagate in the biaxial medium, leading to coupling of vertical and horizontal polarizations in the reflected waves. Some special cases are illustrated. The results have applications to problems in remote sensing and integrated optics.

On the plane‐wave reflection coefficient and nonspecular reflection of bounded beams for layered half‐spaces underwater

Abstract: We study the recently derived reflection coefficient for plane waves in a liquid that are incident on the liquid–solid interface of a solid half‐space, which consists of a single layer of one elastic material bonded to a substrate of a different material. Plots of the magnitude of the reflection coefficient versus the incident angle are presented for many sets of material parameters and values of frequency f and layer thickness d. The use of the results presented for the study of nonspecular reflection of bounded acoustic beams is of primary interest. We therefore seek to identify all the critical incidence angles for nonspecular reflection. We find that nonspecular reflection can occur, not only in connection with surface waves that are purely propagating modes in the absence of the liquid, but also for leaky modes on a layered half‐space, provided the leakage is not too great. We also investigate, in particular, the surface wave propagation for the case of a stiff layer on a soft half‐space, and we find...

Experimental Study on Higher Order Reflection by Monodomain Cholesteric Liquid Crystals

Abstract: Reflection spectra have been measured in the spectral region of the second and the third order selective reflections for monodomain cholesterics of various cell thicknesses at various angles of incidence. Thicker cells give rise to higher reflectance at larger angles of incidence. The second order reflection region consists of three bands which show characteristic polarization correlation: The central band is a total reflection band, where incident light of any polarization is reflected. The reflected light is a polarized when it polarized light is incident and vice versa. Contrary to the central band, two side bands are selectively reflected; σ(π) polarized light is reflected in the longer (shorter) wavelength band retaining its polarization. The third order reflection bands observed for the first time have been found to give the same polarization characteristics as that of the second order reflection bands.

Optical bistability in the frustrated-total-reflection optical cavity.

Abstract: The nonlinear behavior of a frustrated-total-reflection (FTR) optical cavity containing a nonlinear Kerr medium is considered. It is shown that optical bistability may occur at lower incident power than in the nonlinear interface system. Other potential advantages of the resonant FTR configuration over other geometries are also briefly discussed.

Investigation of light amplification by enhanced internal reflection. Part I. Theoretical reflectance and transmittance of an exponentially nonuniform gain region

Abstract: We investigate the reflection of plane waves of s and p polarization from the interface between a homogeneous transparent medium and an amplifying medium with a gain profile decreasing exponentially with depth of penetration. For angles of incidence less than critical angle, the reflectance curves are essentially the same as those deduced from the usual Fresnel formulas for two transparent media. In the vicinity of critical angle, the reflection coefficients are virtually the same for both polarizations and are greater than unity. Beyond critical angle, the reflectances fall toward unity as grazing incidence is approached. Both the reflectance and the far-field transmittance peak in the immediate vicinity of critical angle. For angles less than critical angle, the transmittance can be 2 orders of magnitude greater than the reflectance. Certain values of gain parameters and incident angle lead to singularities in the theoretical reflectance. At these points the usual neglect of the effect of the transmitted wave on the population inversion is no longer valid.

Characteristics Of The Linear Array Total Internal Reflection (TIR) Electrooptic Spatial Light Modulator For Optical Information Processing

Abstract: A first order analytical model which describes the imaging performance of the total internal reflection (TIR) linear array spatial light modulator is presented. Two modulator configurations are identified, each with a distinct imaging response. The modulator crystal orientation defines which image response model applies. Several optical readout techniques for converting the optical phase modulation into an intensity modulation are described.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Light collection apparatus for a scanner.

Abstract: In apparatus for scanning a transparent original with a scanning beam relative an optical axis, a tapered optical bar is positioned adjacent the transparent original to collect a diverging beam emerging from the original and, by means of internal reflection, reduce the divergence of the beam relative the optical axis. The emerging beam is especially diverged when the scanning beam sweeps away from the optical axis or is scattered by an artifact, such as a scratch, on the original. Particularly in the case of a polychromatic beam emerging from a color transparency, the tapered bar is interposed between the transparency and color dichroic beam separating mirrors to reduce angle shift and polarization color shading due to light rays diverging from the optical axis upon the dichroic interference layers.

Optical sensor constituting a light transmissive medium with luminescent particles

Abstract: An optical sensor is made of light transmissive material and has luminescent particles distributed throughout its volume. The luminescent particles are excited by a suitable type of energy, preferably light. As they return to their original state, they emit light uniformly in all directions. Depending upon the relationship of the index of refraction of the sensor body material to that of a test medium abutting a boundary surface of the sensor body, part of the luminescent light is reflected, the remainder passing into the test medium with a change in direction (refraction). When the test medium is optically less dense than the sensor medium luminescent light incident on the boundary surface at an angle exceeding the critical angle undergoes total reflection. For an elongated sensor body, this totally reflected part is transmitted to the end faces of the sensor, where its intensity constitutes a desired measure of a physical quantity. The sensor is effective for any physical characteristic which can change the index of refraction of the surrounding medium or that of the sensor itself. In addition, the quantity of totally reflected light can be varied also by changing the quantity of primary light applied to the sensor. Possible applications of a sensor of this type include measurements of liquid level in a container, the measurement of concentrations of a given component in a solution, temperature and pressure measurements of gases, monitoring of the boiling point of a liquid at very low temperatures, measurements of humidity, and a variety of position and length measurements. The sensor can also be used as a unit in a keyboard.

Solar light collector

Abstract: PURPOSE:To make it possible to contain most effectively the solar light collecting part within a capsule by setting the diameters of the capsule and the solar heat collecting part so that the inclination of a planar transparent body of the capsule part falls at maximum in the proximity of a range capable of introducing solar light to a lens. CONSTITUTION:Since the incident angle theta3 of solar light with respect to a transparent plate 203 is selected smaller than the incident angle theta2 with respect to a transparent plate 202 and further the incident angle theta4 with respect to a transparent plate 204 is smaller than the incident angle theta3, the total reflection does not occur at the time of the incident angle being any of the both, and solar light is introduced into the capsule. Accordingly, if the diameter D of the solar heat collecting part is selected so that the outer peripheral part of the solar heat collecting part comes to a position where solar light at this time reaches, the solar light collecting part is most effectively accommodated in the capsule. In other words, the inclination theta of the planar transparent body which an imaginary line l extending from the peripheral part of the light receiving surface of the solar light collecting part in parallel toward the capsule intersects, is set at maximum in the proximity of a range capable of introducing solar light to the lens of the solar light collecting part.