Showing papers on "Total external reflection published in 1983"

Frustrated total internal reflection optical power limiter

Abstract: In order to protect a delicate photo-detector from high-intensity optical radiation such as from a laser, a device for limiting power to the detector is interposed between the radiation and detector This device has two embodiments and is made such that high-intensity radiation is totally reflected In the absence of high-intensity radiation, total reflection is frustrated, and desired radiation passes to the detector Both embodiments use two prisms with parallel surfaces skewed to incident radiation and with a slightly absorbant optical material between the surfaces Desired radiation normally passes through the prisms and the material to the detector In one embodiment, the material is a liquid which vaporizes in response to high-intensity radiation, and in the other embodiment, the material expands and pushes the prisms apart In either case, transmission of radiation halts, and the radiation is totally reflected by a prism skewed surface

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.

X-ray Guide Tube for Diffraction Experiments

Abstract: For diffraction experiments with an extremely small crystal or with very long distance from X-ray source to detecting instrument, the use of an `X-ray guide tube' (XGT) is proposed on the basis of a simple consideration and experiment with a Pyrex-glass tube. X-ray intensities through an XGT of glass and also through a pin hole were measured as a function of photon energy and compared to derive the gain by use of XGT. At wavelengths between Cu Kα and Mo Kα radiations, the observed gain in brightness is about thirty to twenty for the present setup, corresponding to about 50 to 80% of the maximum possible gain calculated on the assumption that the reflectivity of X-ray total external reflection is 1.0.

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.

X‐ray total external reflectance–diffraction as a probe of the structure of the liquid–vapor interface

Abstract: For potential use in the study of the structure of the liquid–vapor interface of a liquid metal, we analyze the scattering of a collimated beam of x rays which strike the plane surface of a liquid metal at an angle below the range for total external reflection. Our analysis of the diffraction pattern is based on the Von Laue model of a condensed phase scatterer and the distorted wave approximation. The x‐ray total reflectance–diffraction is expressed in terms of the structure factor of the inhomogeneous transition zone between the liquid and vapor of a metal.

Refraction through a prism

Abstract: A simple formula is derived which describes the refraction of light through a prism for an arbitrary angle of incidence. This formula can be represented by an ellipse whereby the minimum deviation condition and the transmission cutoff due to total internal reflection have a simple geometrical interpretation.

Ray Model for Attenuated Total Reflection from a Weakly Absorbing Dielectric

Abstract: An approximate ray picture has been presented for attenuated total reflection of a plane electromagnetic wave from a weakly absorbing dielectric. An analytical expression for the reflection coefficient has been obtained for an angle of incidence larger than the critical angle. The method of limiting absorption is seen to establish the Carter-Hora conjecture regarding the validity of Renard's formula for lateral shift on account of total reflection. Potential applications of the work are discussed.

Energy loss from internal reflection off metal layers on glass

Abstract: The reflection characteristics of metal layers are considered for the situation where the electromagnetic radiation is incident from the glass side. Theoretical and measured reflectance values are presented which indicate that for some metals the reflection has a strong dependence on the refractive index of the incident medium. Some examples are given of recent cases where the above results were an important consideration in the choice of the metallic reflecting material. These results indicate that aluminium should not be automatically considered the best choice for the visible region nor gold for the infra-red.

Influence of refraction losses on laser radiation characteristics

Abstract: A method is developed for solving the self-consistent problem of lasers with internal losses due to the refraction of light in an optically inhomogeneous active medium. The dependences of the power, of the transverse distribution of the intensity, and of a factor representing refraction losses of laser radiation on the reflection coefficients of the resonator mirrors and on the relationship between the transverse profiles of the refractive index and pumping rate are obtained. An analysis is made of the special features of the behavior of the laser radiation characteristics on increase in the reflection coefficients of the resonator mirrors to unity and of the limiting characteristics of laser radiation when the reflection coefficient of the exit resonator mirror is close to zero. The new method is used to analyze the characteristics of the radiation emitted by iodine lasers pumped by ultraviolet radiation generated in high-current open discharges. It is shown that in these lasers an increase in the reflection coefficient of the resonator mirrors reduces the refraction loss factor.