Showing papers on "Total external reflection published in 2008"

Blazed high-efficiency x-ray diffraction via transmission through arrays of nanometer-scale mirrors

Abstract: Diffraction gratings are ubiquitous wavelength dispersive elements for photons as well as for subatomic particles, atoms, and large molecules. They serve as enabling devices for spectroscopy, microscopy, and interferometry in numerous applications across the physical sciences. Transmission gratings are required in applications that demand high alignment and figure error tolerances, low weight and size, or a straight-through zero-order beam. However, photons or particles are often strongly absorbed upon transmission, e.g., in the increasingly important extreme ultraviolet (EUV) and soft x-ray band, leading to low diffraction efficiency. We demonstrate the performance of a critical-angle transmission (CAT) grating in the EUV and soft x-ray band that for the first time combines the advantages of transmission gratings with the superior broadband efficiency of blazed reflection gratings via reflection from nanofabricated periodic arrays of atomically smooth nanometer-thin silicon mirrors at angles below the critical angle for total external reflection. The efficiency of the CAT grating design is not limited to photons, but also opens the door to new, sensitive, and compact experiments and applications in atom and neutron optics, as well as for the efficient diffraction of electrons, ions, or molecules.

A simple demonstration of frustrated total internal reflection

Abstract: We describe a quantitative and inexpensive method of demonstrating frustrated total internal reflection based on the attenuation of a laser beam through a wedge-shaped air gap between two glass prisms. An advantage of this method is that the thickness of the air gap can be determined by observing interference effects with only a slight modification of the setup. The experiment avoids the need to employ high-precision translation stages as is often the case in standard demonstrations of frustrated total internal reflection.

Microelectronic sensor device for optical examinations in a sample medium

Abstract: The invention relates to a microelectronic sensor device with a light source (21) for emitting an input light beam (L1) into a transparent carrier (11) such that it is totally internally reflected at a contact surface (12) as an output light beam (L2), which is detected by a light detector (31) Frustration of the total internal reflection at the contact surface (12) can then for example be used to determine the amount of target particles (1) present at this surface The sensor device further comprises a refractive index measurement unit (100, 200, 300) for measuring the refractive index (nB) of the sample medium, and an evaluation unit (50) for evaluating the measurement of the light detector (31) taking the measured refractive index (nB) into account and/or for changing the conditions of total internal reflection of the input light beam (L1) The refractive index measurement unit may particularly be designed to infer the refractive index (nB) from the deflection of a test-light beam (L3) that is transmitted through the sample medium, or from a reflection of a test-light beam (L1) at an interface (12) to the sample medium In the latter case, it is possible to determine the critical angle of total internal reflection and/or to measure the reflectivity of the interface

Reflection and refraction at the boundary of a medium with negative group velocity

Abstract: Mandelshtam's views on the role of informal physical arguments in deriving the geometric law of refraction are discussed. It is shown that Sivukhin's theorem allows reconciling different approaches to justifying the choice of the refracted wave vector. Wave reflection and refraction are considered for a periodically heterogeneous half-space. It is shown that the analogy between the Snell–Descartes refraction law and the properties of a wave propagating in a chain of discrete interacting elements and in a periodically heterogeneous space is incorrect. The principal role of the homogeneity of interfacing media is stressed. The only case that corresponds to the 'purely' negative refraction is that of a homogeneous refracting medium in which both the dielectric constant and the magnetic permeability are negative.

Investigation of metal nanoparticles on a Si surface using an x-ray standing wave field

Abstract: An x-ray standing wave field generated under total external reflection condition is used to characterize the average vertical dimension of metal nanoparticles as well as their nature of dispersion on a flat surface. This approach is applied to characterize the distribution of Fe nanoparticles deposited on a silicon surface using a solution dip method. The atomic force microscopy results on these nanoparticles reinforce our interpretation. The authors believe that the present method has a strong utility in characterizing, over a large area, the morphology of the surfaces coated with nanoparticles. The method also provides element specific analysis for the nanoparticulate matter.

Refractive index distribution measuring method and refractive index distribution measuring device

Abstract: PROBLEM TO BE SOLVED: To measure highly accurately an internal refractive index distribution of a specimen, even if a medium having an approximately same refractive index as the refractive index is not used, when the specimen has a high refractive index. SOLUTION: This refractive index distribution measuring method includes steps for: measuring a first transmission wave front of the specimen by allowing reference light 102 to enter the specimen, in a first medium having a first refractive index which is smaller by 0.01 or more than the refractive index of the specimen 120; measuring a second transmission wave front of the specimen by allowing the reference light to enter the specimen, in a second medium having a second refractive index which is smaller by 0.01 or more than the refractive index of the specimen and which is different from the first refractive index; and determining the refractive index distribution of the specimen based on measurement results of the first and second transmission wave fronts. COPYRIGHT: (C)2010,JPO&INPIT

Measurement of Refractive Index of Solid Medium by Critical Angle Method When Air Gap is Present

Abstract: A critical angle method was used to measure the index of refraction of a solid medium when an air gap between the prism and the medium is present. The gap effect was analyzed both numerically and experimentally. Since the total internal reflection is severely disturbed by the large gap, determination of the critical angle and the resulting refractive index becomes ambiguous and inaccurate. By using an index matching fluid, we could determine the index of refraction with an uncertainty of ${\pm}2{\times}1^{-3}$ even when the gap is as large as 1 ${\mu}m$ .

Electromagnetic Wave Propagation from a Point Source in Air through a Medium with a Negative Refractive Index

Abstract: Refraction of an electromagnetic wave from a point source to a medium with a negative refractive index is considered. An electric Hertz dipole that is located in air and directed parallel to a plane interface is considered as the point source. It is rigorously shown that the electromagnetic radiation propagated from the dipole into the medium with the negative refractive index is focused within a certain region in this medium. The sizes of the focusing region are determined. As a result, it is pointed out that the diffraction limit cannot be overcome by using homogeneous materials with negative refractive indices.

A new method to demonstrate frustrated total internal reflection in the visible band

Abstract: We describe a new method to demonstrate frustrated total internal reflection in the visible band using the 100nm thick air film near the center of Newton’s rings. Experimental measurements of the light intensity distribution validate the theoretical predictions.

A Point Radiator Parallel to a Plane Layer with Negative Refractive Index

Abstract: Focusing of an electromagnetic wave radiated by a point source and transmitted through a plane layer filled with a medium with negative refractive index is considered. An elementary electric Hertzian dipole located in the air (or vacuum) parallel to the boundaries of the layer is considered as a point source of radiation. It is rigorously shown that, after transmitting through a layer with negative refractive index, the electromagnetic wave of the dipole is focused into a certain domain. The dimensions of the focusing region are investigated. The results of the investigation show that the use of homogeneous materials with negative refraction does not allow one to overcome the diffraction limit.

Negative refraction with high transmission at visible and near-infrared wavelengths

Abstract: A left-handed material, a metal waveguide with arrays of metal rods within it, is investigated in this letter. The simulation results have shown that the refractive indices are negative between 512 and 898nm, while the negative-index band with high transmission ranges roughly from 672to798nm. This is an effective method to the realization of negative refraction at visible frequencies. The mechanism of resonance has been revealed by simulating the distributions of induced current in a unit cell. A wedge-shaped structure has also been designed to provide direct evidence for the negative refraction behavior.

Experimental observation of light refraction going from negative to positive in the visible region at the pure air/Au interface

Abstract: We report wavelength-dependent refraction going from negative to positive in the visible region for the pure air/Au interface by fabricating a series of prismlike Au film samples. Results qualitatively agree with dispersion of the group refractive index ng, in which the spectral properties of the phase refractive index np, play a significant role to make both the magnitude and sign of ng change in the energy region where interband transitions occur. The net refraction observed for the simplest air and metal interface will stimulate further exploration of the physical origin of slow or fast light characterized by the law of refraction in nature.

Refractive index decrement film, polarizing member having the same and display device having the same

Abstract: A refractive index decrement film, includes: a transparent base layer; a plurality of refraction decreasing layers that is formed on the base layer and has different refractive indices, where the refraction decreasing layers closer to the base layer have a relatively high refractive index and the refraction decreasing layers farther from the base layer have a relatively low refractive index.

Artificial surface with asymmetric reflection properties

Abstract: An artificial surface with asymmetric reflection properties is presented. By covering a metal ground plane with periodic metal-dielectric composite textures, the electromagnetic reflection properties can be altered. By tuning the individual lattice of a periodic mushroom-type texture to vary the surface impedance, a surface with graded reflection phases as a function of position can be designed. Applying a linear gradient in the reflection coefficient phase along the face, the proposed surface is electromagnetically inclined, even though physically flat. For the whole ranges of the incident angle, this metasurface reveals asymmetric reflection properties contrary to the law of reflection. The reflection patterns from the surface, the boundary condition, and the relation between the incident angle and the reflection angle are presented.

Total internal reflection of evanescent plane waves

Abstract: Describing the phenomenon of total internal reflection in terms of a reflection coefficient of unit magnitude, we found that not only can propagating plane waves be total internally reflected at the planar interface of two dissimilar, homogeneous, isotropic dielectric–magnetic mediums, but evanescent plane waves can also be. The refracting medium must be the optically denser of the two mediums for total internal reflection of an evanescent plane wave to occur.

Semiconductor laser device including highly reflective coating film

Abstract: A semiconductor light-emitting device includes a light generation unit generating light with an oscillation wavelength λ, a light outgoing facet from which light generated at the light generation unit emerges, a light reflecting facet at which light generated at the light generation unit is reflected, and a high reflection film at the light reflecting facet and made of a dielectric multilayered film of at least three layers. The high reflection film includes a first layer which is in contact with the light reflection facet, is constituted of Al 2 O 3 , and has a thickness smaller than λ/4n, wherein n is the refractive index of Al 2 O 3 , a second layer which is in contact with the first layer, and a third layer which is in contact with the second layer and has a refractive index different from the refractive index of the second layer.

External light blocking film and filter for display device having the same

Abstract: An external light blocking film includes a base transmitting external light, and an external light blocking pattern which blocks the external light and is formed at the base. A refraction index of the base is larger than a refraction index of air by more than 0 and not more than 0.56. The base satisfies the following equation: 0°<(θ1−θ2)≦35°, where θ1 is an incident angle at which the external light is incident onto the base, and θ2 is an refraction angle at which the external light refracts due to a difference between the refraction index of the base and the refraction index of air.

Radiation modulation via violation of total internal reflection with excitation of a waveguide mode

Abstract: The transverse transmission coefficient of a multilayer structure with a planar waveguide is numerically simulated under the conditions of modulation of the refractive index or absorption coefficient of the waveguide. The optical properties of this structure are shown to be highly sensitive to variation in the refractive index or absorption (amplification) coefficient of its waveguide layer. The influence of optical and geometric characteristics of the structure on its optical properties is analyzed. Modulation of the transmission and reflection coefficients of the structure containing a waveguide with an amplifying medium is considered.

Novel optical properties of a submerged light bulb

Abstract: When an unlit frosted light bulb is immersed in water, the inside frosting appears to shrink, and the outside surface of the bulb appears to become reflective. We explore these interesting effects using geometric optics at the level of introductory physics. It is found that rays emitted from the particles of powder that coat the inside surface of a frosted bulb emerge in conical beams when the bulb is submerged, which results in a reduction of the apparent size of the bulb’s internal surface. The observed reflectivity is explained by the total internal reflection that occurs at the internal glass-gas interface. Light rays that refract through a clear bulb are analyzed to understand why a small spherical internal surface appears to exist in this case. The effects of bulb thickness, viewing height, and frustrated total internal reflection are also considered.

Keypad with increased refractive index

Abstract: A keypad with increased refractive index includes a light-guiding elastic element, an optical refractive layer and at least one light-emitting element. The optical refractive layer is applied on an upper surface of the light-guiding elastic element. The light-emitting element is provided on one side of the light-guiding elastic element. The refractive index of air is defined as a real number x. The refractive index of the light-guiding elastic element is defined as a real number y. The refractive index of the optical refractive layer is defined as a real number z. The refractive index z is larger than the refractive index x. Since the optical refractive layer is applied on the light-guiding elastic element and the refractive index of the optical refractive layer is different from that of the light-guiding elastic element, the angle of total reflection of the light in the light-guiding elastic element can be changed.

Reflection and polarization characteristics of circularly polarized light at the surface of a chiral negative refraction medium

Abstract: The reflection and transmission characteristics are analyzed theoretically when circularly polar- ized light is incident upon the surface of a chiral negative refraction medium.Normalized reflected and transmission power curves vs incident angle,and Brewster angle curves vs the chirality parameter are plot- ted.When the incident angle is larger than the critical angles of two eigen waves,the total internal reflection occurs.Due to the negative refraction of one eigenwave in the chiral medium,the polarization state of the reflected waves caused by the incidence of right or left circularly polarized light is very different from that in the common medium.The reflected waves are linearly polarized with different polarization direction when the light is incident at the Brewster angle.

Energy Distribution of Natural Light in the Process of Reflection and Refraction

Abstract: According to the Fresnel formula,the law of the natural light energy distribution is derived in the process of reflection and refraction.And the distribution of energy is also discussed when light acts by especial angle of incidence.At last,the energy distribution of natural light is simply narrated in uniaxial crystal.

Flashless light source with effects of light refraction and reflection

Abstract: A flashless light source with effects of light refraction and reflection, comprises a refraction body, a metal cup, a metal reflecting lampshade, an LED lamp body. Light emitted from the LED lamp body is reflected by the metal cup to be vertically incident into the refraction body so that the light is refracted by the refraction body; the refraction body is installed at a focus of the cambered tapered surface of the metal reflecting lampshade so that the light is reflected to have a predetermined reflected shape so as to remove the flashing effect due to the small light emitted area of the LED.