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The force-free parameter $\alpha$, also known as helicity parameter or twist parameter, bears the same sign as the magnetic helicity under some restrictive conditions. The single global value of $\alpha$ for a whole active region gives the…

Solar and Stellar Astrophysics · Physics 2009-07-22 Sanjiv Kumar Tiwari , P. Venkatakrishnan , Sanjay Gosain , Jayant Joshi

Mm and sub-mm waves polarimetry is the new frontier of research in Cosmic Microwave Background and Interstellar Dust studies. Polarimeters working in the IR to MM range need to be operated at cryogenic temperatures, to limit the systematic…

Instrumentation and Methods for Astrophysics · Physics 2012-04-09 Maria Salatino , Paolo de Bernardis , Silvia Masi

We report the experimental super-resolution of pairs of point-like fluorescent sources using a modified image inversion interferometer microscope. The technique is inspired by recent developments in the application of quantum parameter…

Using a scheme based on a Mach-Zehnder interferometer, we propose an analysis of the superposition of polarized laser beams at a given angle. The focus of our study is the spatially varying polarization state of the resulting field, also…

Optics · Physics 2009-11-18 B. M. Rodriguez-Lara , I. Ricardez-Vargas

Context: Polarimetry is a very powerful tool to uncover various properties of astronomical objects that remain otherwise hidden in standard imaging or spectroscopic observations. However, the reliable measurement of the low polarization…

Instrumentation and Methods for Astrophysics · Physics 2020-02-12 S. González-Gaitán , A. M. Mourão , F. Patat , J. P. Anderson , A. Cikota , K. Wiersema , A. B. Higgins , K. Silva

The Stokes parameters of the pulsed synchrotron radiation produced in the striped pulsar wind model are computed and compared with optical observations of the Crab pulsar. We assume the main contribution to the wind emissivity comes from a…

Astrophysics · Physics 2009-11-11 J. Petri , J. Kirk

Gravitational lensing deals with general-relativistic effects in the propagation of electromagnetic radiation. We consider wavelength-dependent contributions in case of a (micro)lensing of an extended Gaussian source by a point mass under…

Astrophysics of Galaxies · Physics 2012-11-07 V. I. Zhdanov , D. V. Gorpinchenko

The dichroism and birefringence effects in stumulated Raman scattering (SRS) in polyatomic molecules were studied theoretically. General expressions have been derived describing the change of the intensity and polarization of the probe…

Chemical Physics · Physics 2023-11-07 Bogdan V. Semak , Yaroslav M. Beltukov , Oleg S. Vasyutinskii

Stokes Muller formalism is important to understand the optical properties of materials by measuring the change in the polarization state of light upon scattering. The formalism can be extended to nonlinear scattering processes involving two…

Optics · Physics 2015-10-21 Chitra Shaji , Raseena Ismail , SVM Satyanarayana , Alok Sharan

We extend the work of Mishchenko et al. (2000) regarding the exact results of the polarization effect, using the theory of Amic et al. (1997) to derive a model prediction for the polarization coherent opposition effect at small angles. Our…

Instrumentation and Methods for Astrophysics · Physics 2017-07-27 Adrian J. Brown

We have worked out simple analytical formulae that accurately approximate the relationship between the position of the source with respect to the lens center and the amplification of the images, hence the lens cross section, for realistic…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 A. Lapi , M. Negrello , J. Gonzalez-Nuevo , Z. -Y. Cai , G. De Zotti , L. Danese

The complete expression for the intensity in pseudo-scalar meson photoproduction with a polarized beam, target, and recoil baryon is derived using a density matrix approach that offers great economy of notation. A Cartesian basis with spins…

High Energy Physics - Phenomenology · Physics 2011-06-20 Biplab Dey , Michael E. McCracken , David G. Ireland , Curtis A. Meyer

The Stokes parameters have been found in the framework of quantum electrodynamics for the description of polarization of radiation emitted by relativistic positrons channeled between (110) planes in Si crystal. The degree of polarization,…

Accelerator Physics · Physics 2017-08-31 S. Bellucci , M. Shatnev

The polarization of bremsstrahlung photon in the processes $ee^\pm\to (e\gamma)e^\pm$, and $ep\to (e\gamma)p$ is calculated for peripheral kinematics, in the high energy limit where the cross section does not decrease with the incident…

High Energy Physics - Phenomenology · Physics 2009-04-22 S. Bakmaev , Yu. M. Bystritskiy , E. A. Kuraev , E. Tomasi-Gustafsson

Inversion codes are numerical tools used for the inference of physical properties from the observations. Despite their success, the quality of current spectropolarimetric observations and those expected in the near future presents a…

Solar and Stellar Astrophysics · Physics 2015-05-27 A. Asensio Ramos , J. de la Cruz Rodriguez

Polarization of the cosmic microwave background, though not yet detected, provides a source of information about cosmological parameters complementary to temperature fluctuations. This paper provides a complete theoretical treatment of…

Astrophysics · Physics 2014-10-13 Arthur Kosowsky

An eight stage balanced modulation scheme for dual beam polarimetry is presented in this paper. The four Stokes parameters are weighted equally in all the eight stages of modulation resulting in total polarimetric efficiency of unity. The…

Astrophysics · Physics 2007-10-10 K. Nagaraju , K. B. Ramesh , K. Sankarasubramanian , K. E. Rangarajan

An electromagnetic wave can be uniquely characterized by the four Stokes parameters: I, Q, U, and V. Typical observations in astronomy rely solely on total intensity measurements of the incoming radiation (Stokes I). However, a significant…

Astrophysics of Galaxies · Physics 2010-07-08 Jo-Anne C. Brown , Jeroen M. Stil , Tom L. Landecker

When polarized light is absorbed by an atom, the excited atomic system carries information about the initial polarization of light. For the light that carries an orbital angular momentum, or the twisted light, the polarization states are…

Quantum Physics · Physics 2020-05-18 Andrei Afanasev , Carl E. Carlson , Hao Wang

We consider cross-spectral purity in random nonstationary electromagnetic beams in terms of the Stokes parameters representing the spectral density and the spectral polarization state. We show that a Stokes parameter being cross-spectrally…

Optics · Physics 2023-07-24 Jyrki Laatikainen , Ari T. Friberg , Tero Setälä