Polarization State Of Radiation Research Articles

Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

Using multilayer linear polarizers, we have characterized the polarization state of radiation from bend-magnet beamline 9.3.2 at the Advanced Light Source as a function of vertical opening angle at photon energies of 367 and 722 eV. Both a fine slit and a coarse semi-aperture were stepped across the beam to accept different portions of the vertical radiation fan. Polarimetry yields the degree of linear polarization directly and the degree of circular polarization indirectly assuming an immeasurably small amount of unpolarized radiation based on the close agreement of the theoretical and experimental results for linear polarization. The results are in good agreement with theoretical calculations, with departures from theory resulting from uncertainty in the effective aperture of the measured beam. The narrow 0.037-mrad aperture on the orbit plane transmits a beam whose degree of linear polarization exceeds 0.99 at these energies. The wide semi-aperture blocking the beam from above and below transmits a beam with a maximum figure of merit, given by the square root of flux times the degree of circular polarization, when the aperture edge is on the orbit plane thus blocking only half of the total available flux.

Multilayer transmission polarizers in the soft X-ray region

The phaseshifting properties of multilayer transmission filters in the XUV region are examined. The possibility of changing the polarization state of electromagnetic radiation from linear to circular by means of such devices is carefully considered using a realistic model and proper optimization criteria. The performances of different transmission multilayers in some energy windows are presented.

Solving Einstein's equations for rotating spacetimes: Evolution of relativistic star clusters.

A numerical relativity code designed to evolve rotating axisymmetric spacetimes is constructed. Both polarization states of gravitational radiation can be tracked. The source of the gravitational field is chosen to be a configuration of collisionless particles. The code is used to evaluate the stability of polytropic and toroidal star clusters. The formation of Kerr black holes by the collapse of unstable clusters is demonstrated. Unstable clusters with $\frac{J}{{M}^{2}}<1$ collapse to black holes, while those with $\frac{J}{{M}^{2}}>1$ collapse to new equilibrium configurations.

The colours of opaque minerals

Part 1 The nature of light and colours Planck's radiation law the eye subjective colour problems quantitative colour vision CIE chromatically diagram illuminants colour atlases colour names metamerism defective colour vision. Part 2 Light and crystals: polarization state of light waves classical oscillator models dispersion radiation of electromagnetic waves photons quantum mechanical models classical bond models molecular orbital theory bank theory. Part 3 Reflected light: Fresnel equations tensors relative permittivity tensor propagation of light through anistropic media reflectances of oriented sections colours of oriented sections anisotropy (polarization) colour between crossed and uncrossed polars. Part 4 Mineral data - metals and stoichiometric alloys (including gold, copper, niggliite, arsenic, graphite) rmXn minerals (including algodonite, maldonite, chalcosine, acanthite, ikunolite, pentlandite) RX minerals (including galena, sphalerite, chalcopyrite, stannite, enargite, nickeline, covelline) thiospinels stibnite RX2 minerals (including pyrite group, marcasite group, arsenopyrite group, molybdenite, melonite, krennerite) skutterudite sulphosalts (including tetrahedrite, bournonite, proustite) oxide minerals (including spinel group, rutile group, wolframite group).

The Sobolev-P method - A generalization of the Sobolev method for the treatment of the polarization state of radiation and the polarizing effect of resonance line scattering

La methode de Sobolev est generalisee pour l'etude de l'etat de polarisation du rayonnement et les effets polarisants de la diffusion des raies resonnantes. Une application de la methode pour le transfert radiatif, avec ou sans opacite de continuum, est realisee pour les modeles axisymetriques de systemes de supernova

Low-loss directional couplers utilizing single-mode fiber-optic waveguides

A new design of Y-type directional couplers with end matching and utilizing single-mode fiberoptic waveguides is proposed. The optimal parameters required to attain losses of ~0.5–1 dB are determined. A method is described for making such couplers by welding single-mode waveguides with a partially retained cladding in an electric-arc apparatus. The additional losses of the couplers when used for splitting a signal between two channels are 1–3 dB, in good agreement with numerical calculations. The decoupling of the counterpropagating channels is better than 60 dB, indicating a high directivity. It was found experimentally that the polarization state of radiation propagating in these couplers is conserved.

Fluctuations of the polarization state of CO2laser radiation

Observations are reported of fluctuations in the polarization state of radiation from a CO2 laser having an unstable resonator without selective elements. A connection is established between such fluctuations and changes in the spectral composition of the radiation during lasing. A demonstration is given of the influence of the effects discovered on the penetration of laser radiation into long metal channels which can be manifested in deep-penetration laser welding.

Infrared absorption enhancement of monolayer species on thin evaporated Ag films by use of a Kretschmann configuration: Evidence for two types of enhanced surface electric fields

Infrared absorption enhancement of m- and p-nitrobenzoic acid deposited on thin-evaporated silver films has been investigated using the Kretschmann's ATR coupling method. The absorption spectra provide direct evidence that enhancement is prominent only for vibrations of the first monolayer adsorbed on the Ag surface. It is shown that all of the vibrational modes observed obey the normal dipole selection rule. Moreover, it was found that there exist two types of absorption enhancement; the first is enhanced (∼300) by both p- and s-polarized radiation, and the second is enhanced (∼60) by p-polarized radiation alone. The Ag film thickness optimum is about 50 A in the former case and about 200 A in the latter. The enhancement insensitive to the polarization state of radiation can well be explained by the excitation of the transverse collective electron resonance of the Ag islands, whereas that obtained by p-polarized radiation may be due to the excitation of delocalized surface plasmons modified by surface roughness. The image-dipole effect may also be significant in the mechanisms.

Inverting the ratio of the complex parallel and perpendicular reflection coefficients of an absorbing substrate using a transparent thin-film coating

An absorbing substrate can be coated with a transparent thin film of refractive index N1 (within a certain range) and thickness d such that the ratio of complex reflection coefficients for the p and s polarizations of the film-covered substrate ρ = Rp/Rs is the inverse of that of the film-free substrate ρ¯=R¯p/R¯s at an angle of incidence ϕ. A method to determine the relationship among ϕ, N1, and d that inverts ρ (i.e., makes ρ = 1/ ρ¯) for a given substrate at a given wavelength is described and is applied to aluminum and silver substrates at 0.6328- and 10.6-μm wavelengths, respectively. Sensitivity of the inversion condition to incidence-angle and film-thickness errors is analyzed. ρ-inverting layers can be applied to one of the two metallic mirrors of a beam displacer or axicon to preserve the polarization state of incident monochromatic radiation.

A new approach to radiative transfer theory using Jones's vectors

Radiative transfer of partially polarized radiation in an anisotropically scattering, inhomogeneous atmosphere containing an arbitrary polydispersion of particles is described using Jones's amplitude vectors and matrices. This novel approach exploits the close analogy between the quantum mechanical states of spin 1/2 systems and the polarization states of electromagnetic radiation described by Jones's vector, and draws on the methodology of such spin 1/2 systems. The complete equivalence between the transport equation for Jones's vectors and the classical radiative transfer equation for Stokes's intensity vectors is demonstrated in two independent ways after deriving the transport equations for the polarization coherency matrices and for the quaternions corresponding to the Jones's vectors. A compact operator formulation of the theory is provided, and used to derive the necessary equations for both a local and a global description of the transport of Jones's vectors. Lastly, the integro-differential equations for the amplitude reflection and transmission matrices are derived, and related to the usual corresponding equations. The present formulation is the most succinct and the most convenient one for both theoretical and experimental studies. It yields a simpler analysis than the classical formulation since it reduces by a factor of two the dimensionality of transfer problems. It preserves information on phases, and thus can be used directly across the entire electromagnetic spectrum without any further conversion into intensities.