Journal articles on the topic 'Polarimetry'
To see the other types of publications on this topic, follow the link: Polarimetry.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Polarimetry.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Kalina, Jiří, and Michal Lach. "Experiment for "Polarimetry" Teaching." Chemické listy 117, no. 1 (January 15, 2023): 30–36. http://dx.doi.org/10.54779/chl20230030.
Full textAbstract:
Polarimetry enables one to quantitatively determine certain substance (optically active substances) in a solution on the basis of rotation of the plane of the polarized light of a single wavelength. The main goal of this work is to measure concentration of optically active substances using homemade device, so called "polarimeter". The device measures the degree of light attenuation instead of the polarization angle of the polarized light as in commercial instruments. The designed "polarimeter" allows one to determine the concentration of optically active substances. It is a home-made device using a smartphone with a selected software, which is many times cheaper than commercially available ones. The authors would like to see the device find use in polytechnic education of students.
Polarimetrie umožňuje kvantitativně stanovit určitou látku (opticky aktivní látky) v roztoku na základě měření úhlu stočení roviny polarizovaného světla jedné vlnové délky. Hlavním cílem této práce je měření koncentrace opticky aktivních látek pomocí podomácku vyrobeného přístroje, tzv. „polarimetru“. Zařízení měří míru zeslabení světla namísto úhlu stočení polarizovaného světla jako u komerčních přístrojů. Navržený „polarimetr“ umožňuje stanovit koncentraci opticky aktivních látek. Jde o podomácku vyrobené zařízení využívající chytrý telefon s vybraným softwarem, který je mnohonásobně levnější než komerčně dostupné. Autoři by rádi viděli využití zařízení v polytechnické výchově studentů.
2
Wolfe, T. M., R. Stencel, and G. Cole. "Commissioning Results of a New Polarimeter: Denver University Small Telescope Polarimeter (DUSTPol)." Proceedings of the International Astronomical Union 10, S305 (December 2014): 200–206. http://dx.doi.org/10.1017/s1743921315004779.
Full textAbstract:
AbstractDUSTPol is a dual-beam polarimeter that operates in optical wavelengths, and was built to promote the study of linear polarimetry with smaller telescopes. DUSTPol's performance has demonstrated low instrumental polarization at 0.05 ± 0.02%. This poster presents commissioning results as well as early science observations, and describes software used for data reduction. Recent polarimetric results of RS CVn systems and Wolf-Rayet stars, discussed herein, indicate shape and interaction parameters. By promoting the development of similar polarimeters at other institutions, DUSTPol will serve to establish new collaborative surveys of cool active stars, as well as systems showing evidence of containing complex stellar environments.
3
Leiber, Th, and K. Reif. "First Observations by the Bonn Wide-Field Photometer and Polarimeter (WWFPP): Surface Polarimetry of the Crab Nebula." Symposium - International Astronomical Union 161 (1994): 481–83. http://dx.doi.org/10.1017/s0074180900047926.
Full textAbstract:
To test the performance of the WWFPP in polarimetric mode, we performed surface polarimetry of the Crab nebula in February 1993 using the Asiago 1.82 m telescope of the ‘Osservatorio Astronomico di Padova’. The polarimeter is a new design and enables us to do simultaneous wide-field polarimetry (15 × 15 arcmin field with 0.43 arcsec/pixel) of four polarization angles using a twin Wollaston prism or simultaneous polarimetry of two angles using a double wedge plate with orthogonal sheet polarizers in combination with an achromatic half wave plate. For the observations described here we used the twin Wollaston. The advantages of this design are independency of fluctuations of atmospheric transmission and identical seeing for one set of Stokes parameters. The results of the observations are in agreement with results of other investigators who performed surface polarimetry of the Crab Nebula.
4
Ladygin, V. P., P. K. Kurilkin, A. Yu Isupov, M. Janek, and S. G. Reznikov. "The Deuteron Beam Polarimetry at Nuclotron-NICA." International Journal of Modern Physics: Conference Series 40 (January 2016): 1660087. http://dx.doi.org/10.1142/s2010194516600879.
Full textAbstract:
The current deuteron beam polarimetry at Nuclotron is provided by the Internal Target polarimeter based on the use of the asymmetry in dp- elastic scattering at large angles in the c.m.s. at 270 MeV. The calibration of the existing deuteron beam polarimeter at Internal Target in the wide energy range will allow to obtain the accuracy of the vector and tensor beam polarization values of about 3-5%. Further upgrade of low energy and extracted beam polarimeters is discussed.
5
MATT, GIORGIO. "HIGH-ENERGY PHENOMENA STUDIED WITH X–RAY POLARIMETRY." International Journal of Modern Physics D 19, no. 06 (June 2010): 723–28. http://dx.doi.org/10.1142/s0218271810016889.
Full textAbstract:
After more than 30 years since the last X–ray polarimetric measurements, performed in the 70's by the OSO-8 satellite, thanks to recent technological advances, polarimetry is considered again as a viable technique for studing X–ray sources. In this contribution the author briefly discusses a couple of astrophysical situations, related to the topics of this conference, where X–ray polarimetry can be extremely useful. The author also discusses the observational perspectives, listing the main future space missions (proposed or even already approved) carrying on-board an X–ray polarimeter.
6
Zhang, Haocheng. "Scientific Potential of MeV Polarimetry for Relativistic Jets." Proceedings of the International Astronomical Union 17, S375 (December 2022): 76–85. http://dx.doi.org/10.1017/s1743921323000881.
Full textAbstract:
AbstractRelativistic jets from supermassive black holes or stellar mass black holes are among the most powerful astrophysical phenomena. Magnetic field plays an important role in the jet launching and propagation, as well as particle acceleration and radiation. Polarimetry is the only way to observe the magnetic field evolution. The recent launch of the Imaging X-ray Polarimetry Explorer (IXPE) has opened up the X-ray polarization window, which has revealed very interesting phenomena for relativistic jets. However, the field of MeV gamma-ray polarimetry remains largely unexplored. This paper aims to summarize key scientific potentials for MeV polarimetry for blazars and gamma-ray bursts (GRBs) from recent theoretical modeling. These predictions, which are closely related to the cosmic ray acceleration, neutrino production, radiation mechanism, and the jet evolution, can be examined by future MeV polarimeters, such as the Compton Spectrometer and Imager (COSI), the LargE Area burst Polarimeter (LEAP), and the All-sky Medium-Energy Gamma-ray Observatory eXplorer (AMEGO-X).
7
Tinbergen, J. "Array Polarimetry and Optical-Differencing Photometry." Symposium - International Astronomical Union 167 (1995): 197–205. http://dx.doi.org/10.1017/s0074180900056448.
Full textAbstract:
Array detectors have improved the efficiency of optical polarimetry sufficiently for this technique to become part of the standard arsenal of observational facilities. However, we could gain even more: spatially-differentiating photometry can be implemented as an option of array Polarimeters and low-noise, high-frame-rate array detectors will allow extremely high precision both in polarimetry and in such differentiating photometry. The latter would be valuable for analyzing many kinds of optical or infrared images of very low contrast; the essence of the technique is to use optical (and extremely stable) means to produce the spatial derivative of the flux image, in the form of a polarization image which is then presented to a “standard” array polarimeter. The polarimeter should incorporate a polarization modulator of sufficient quality for the photometric application in mind. If developed properly, using a state-of-the-art array detector and the most sensitive type of polarization modulator (stress-birefringence), optical differencing will allow levels of relative photometric precision not otherwise obtainable. With the optical differencing option taken out of the beam, the same instrument can be used for high-quality polarimetry.
8
Ilyov, S., Ts Genova, P. Troyanova, A. Gisbrecht, and L. Avramov. "Linear polarimetry for analysis of skin degenerative alterations." Journal of Physics: Conference Series 2487, no. 1 (May 1, 2023): 012025. http://dx.doi.org/10.1088/1742-6596/2487/1/012025.
Full textAbstract:
Abstract Investigation and characterization of the basic polarimetric characteristics on different cutaneous degenerative conditions (Syndrome of Raynaud, lupus, and psoriasis) histological samples was carried out to evaluate the potential for analysis of skin degenerative alterations. Stained and unstained histological samples from the different groups of degenerative conditions of the skin were histologically addressed and were used for polarimetric measurements. Diode laser linearly polarized beam at 635 nm was used for irradiation of the samples and polarimeter, working in the visible spectral range 400-700 nm was applied for polarimetric measurements. We will present the results of histology tissue slides evaluation through Stokes polarimetry in transmission geometry. These studies allow analysis of skin degenerative alterations in collagen anisotropic structuration in extracellular matrix and could be used as indicators of the tissue condition. Therefore, the present work would make possible the establishment of database with polarimetric features of degenerative skin conditions.
9
Dimitrov, Zlatomir. "Polarimetric Analysis of ALOS PALSAR data (POL-SAR) over Test Areas in North-West Bulgaria – Polarimetric Descriptors, Decompositions and Classifications." Aerospace Research in Bulgaria 34 (2022): 29–55. http://dx.doi.org/10.3897/arb.v34.e03.
Full textAbstract:
This study is focused on utilizing full-polarimetric L-band radar data from ALOS PALSAR (JAXA) by means of Polarimetry (POL-SAR), over mountainous test sites in Bulgaria. General aim is to show feasibility of the Polarimetry to describe natural targets, which exhibits various scattering mechanisms in respect to their bio-physical and geometrical properties. Firstly, the importance of Covariance and Coherent matrices is shown, which is followed by calculation of the polarimetric coherences with their particular significance. The mathematical and physical model based decompositions are applied to describe backscattering media from scattering mechanisms. Radar indices resulted from H/A/α-decomposition showed radnomization of scattering mechanisms over forest areas, whilst two major scattering mechanisms are observed mainly in crop lands. Α comparison is made between polarimetric descriptors from acquisitions in different seasonality over mountainous forest and agricultural lands. Polarimetric segmentations and classifications are applied, with 8 (H/A) and 16 (H/A/α) components. Finally, a forest mask is proposed based on relevant polarimetric descriptors. Study showed good utilization and importance of the full-polarimetric L-band SAR data, derived from ALOS PALSAR, in natural targets and forest areas. This report resulted from a course GEO414 -“Polarimetrie”, held at the University of Jena, Lehrstuhl für Fernerkundung, in the framework of ERASMUS+, with the kind support of – Dr. T. Jagdhuber (DLR) and Prof. C. Schmullius.
10
González-Gaitán, S., A. M. Mourão, F. Patat, J. P. Anderson, A. Cikota, K. Wiersema, A. B. Higgins, and K. Silva. "Tips and tricks in linear imaging polarimetry of extended sources with FORS2 at the VLT." Astronomy & Astrophysics 634 (February 2020): A70. http://dx.doi.org/10.1051/0004-6361/201936379.
Full textAbstract:
Context. Polarimetry is a very powerful tool for uncovering various properties of astronomical objects that otherwise remain hidden in standard imaging or spectroscopic observations. While common observations only measure the intensity of light, polarimetric measurements allow us to distinguish and measure the two perpendicular components of the electric field associated with the incoming light. By using polarimetry it is possible to unveil asymmetries in supernova explosions, properties of intervening dust, characteristics of atmosphere of planets, among others. However, the reliable measurement of the low polarization signal from astronomical sources requires a good control of spurious instrumental polarization induced by the various components of the optical system and the detector. Aims. We perform a detailed multi-wavelength calibration study of the FORS2 instrument at the VLT operating in imaging polarimetric mode to characterize the spatial instrumental polarization that may affect the study of extended sources. Methods. We used imaging polarimetry of high signal-to-noise ratio blank field BVRI observations during the full moon, when the polarization is expected to be constant across the field of view and deviations originate from the instrument, and a crowded star cluster in broad-band RI and narrow-band Hα filters, where the individual polarization values of each star across the field can be measured. Results. We find an instrumental polarization pattern that increases radially outwards from the optical axis of the instrument reaching up to 1.4% at the edges, depending on the filter. Our results are closely approximated by an elliptical paraboloid down to less than ∼0.05% accuracy, and ∼0.02% when using non-analytic fits. We present 2D maps to correct for this spurious instrumental polarization. We also give several tips and tricks for analyzing polarimetric measurements of extended sources. Conclusions. FORS2 is a powerful instrument that allows the linear polarimetry of extended sources to be mapped. We present and discuss a methodology that can be used to measure the polarization of such sources, and to correct for the spatial polarization induced in the optical system. This methodology could be applied to polarimetric measurements using other dual-beam polarimeters.
11
Raney, R. Keith. "Hybrid Dual-Polarization Synthetic Aperture Radar." Remote Sensing 11, no. 13 (June 27, 2019): 1521. http://dx.doi.org/10.3390/rs11131521.
Full textAbstract:
Compact polarimetry for a synthetic aperture radar (SAR) system is reviewed. Compact polarimetry (CP) is intended to provide useful polarimetric image classifications while avoiding the disadvantages of space-based quadrature-polarimetric (quad-pol) SARs. Two CP approaches are briefly described, π/4 and circular. A third form, hybrid compact polarimetry (HCP) has emerged as the preferred embodiment of compact polarimetry. HCP transmits circular polarization and receives on two orthogonal linear polarizations. When seen through its associated data processing and image classification algorithms, HPC’s heritage dates back to the Stokes parameters (1852), which are summarized and explained in plain language. Hybrid dual-polarimetric imaging radars were in the payloads of two lunar-orbiting satellites, India’s Earth-observing RISAT-1, and Japan’s ALOS-2. In lunar or planetary orbit, a satellite equipped with an HCP imaging radar delivers the same class of polarimetric information as Earth-based radar astronomy. In stark contrast to quad-pol, compact polarimetry is compatible with wide swath modes of a SAR, including ScanSAR. All operational modes of the SARs aboard Canada’s three-satellite Radarsat Constellation Mission (RCM) are hybrid dual-polarimetric. Image classification methodologies for HCP data are reviewed, two of which introduce errors for reasons explained. Their use is discouraged. An alternative and recommended group of methodologies yields reliable results, illustrated by polarimetrically classified images. A survey over numerous quantitative studies demonstrates HCP polarimetric classification effectiveness. The results verify that the performance accuracy of the HCP architecture is comparable to the accuracy delivered by a quadrature-polarized SAR. Four appendices are included covering related topics, including comments on inflight calibration of an HCP radar.
12
Espinosa-Soria, Alba, Francisco J. Rodríguez-Fortuño, Amadeu Griol, and Alejandro Martínez. "Full Measurement of the Stokes Parameters Using a Subwavelength Silicon On-Chip Polarimeter." Advances in Science and Technology 98 (October 2016): 103–8. http://dx.doi.org/10.4028/www.scientific.net/ast.98.103.
Full textAbstract:
Polarimetry enables to measure the state of polarization (SoP) of a light beam, which is essential in many disciplines. Typical polarimeters use bulky and expensive optical elements such as half-wave plates and grid polarizers. Plasmonic nanostructures may help to transform such bulky components into subwavelength metallic elements showing similar performance. Based on the concept of spin-orbit coupling, here we demonstrate a nanophotonic polarimeter that measures the Stokes parameters of a light beam over an ultrabroad bandwidth in a less than a square wavelength active region. Furthermore, the presented approach is applicable to any wavelength regime and technological platform, paving the way for the miniaturization of polarimeters.
13
Gledhill, Tim M. "Imaging polarimetry as a diagnostic tool." Proceedings of the International Astronomical Union 4, S259 (November 2008): 613–22. http://dx.doi.org/10.1017/s1743921309031445.
Full textAbstract:
AbstractSome of the earliest polarimetric measurements made in astronomy were concerned with the polarization of the interstellar medium resulting from dust grains aligned in the Galactic magnetic field. More than 50 years later, polarimetry continues to be an important diagnostic of field structure on size scales ranging from planetary to galactic. The use of both linear and circular polarimetry at optical and infrared wavelengths can provide additional insights into the nature of dust particles, their alignment in magnetic fields and the field topology. Given the science benefits that polarimetry offers it is perhaps surprising that the continued existence of polarimetric facilities on current and next generation large telescopes needs to be ensured.
14
Li, Xiaobo, Fei Liu, and Jian Liang. "Advanced Polarimetry and Polarimetric Imaging." Photonics 11, no. 4 (March 29, 2024): 317. http://dx.doi.org/10.3390/photonics11040317.
Full text
15
Yu, Tian-You, Xiao Xiao, and Yadong Wang. "Statistical Quality of Spectral Polarimetric Variables for Weather Radar." Journal of Atmospheric and Oceanic Technology 29, no. 9 (September 1, 2012): 1221–35. http://dx.doi.org/10.1175/jtech-d-11-00090.1.
Full textAbstract:
Abstract Spectral polarimetry for weather radar capitalizes on both Doppler and polarimetric measurements to reveal polarimetric variables as a function of radial velocity through spectral analysis. For example, spectral differential reflectivity at a velocity represents the differential reflectivity from all the scatterers that have the same radial velocity of interest within the radar resolution volume. Spectral polarimetry has been applied to suppress both ground and biological clutter, retrieve individual drop size distributions from a mixture of different types of hydrometeors, and estimate turbulence intensity, for example. Although spectral polarimetry has gained increasing attention, statistical quality of the estimation of spectral polarimetric variables has not been investigated. In this work, the bias and standard deviation (SD) of spectral differential reflectivity and spectral copolar correlation coefficient estimated from averaged spectra were derived using perturbation method. The results show that the bias and SD of the two estimators depend on the spectral signal-to-noise ratio, spectral copolar correlation coefficient, the number of spectrum average, and spectral differential reflectivity. A simulation to generate time series signals for spectral polarimetry was developed and used to verify the theoretical bias and SD of the two estimators.
16
Kim, Dawoon E., Alessandro Di Marco, Paolo Soffitta, Enrico Costa, Sergio Fabiani, Fabio Muleri, Ajay Ratheesh, et al. "The future of X-ray polarimetry towards the 3-dimensional photoelectron track reconstruction." Journal of Instrumentation 19, no. 02 (February 1, 2024): C02028. http://dx.doi.org/10.1088/1748-0221/19/02/c02028.
Full textAbstract:
Abstract The development of the first X-ray polarimeter, based on the photoelectric effect 20 years ago and implemented thanks to advances in gas amplification structures and readout techniques, had a significant impact in opening a new window for X-ray polarimetry. This system measures the X-ray polarization by reconstructing the initial direction of the photoelectron, emitted by the interaction of an incident photon with an atomic electron, in a gas mixture from an ionization track collected on a two-dimensional plane. However, actual X-ray polarimeters, are still requiring relatively long exposure time and cannot coupled with high effective area mirrors or concentrators. In this context, the high yield polarimetry experiment in X-rays (Hype-X) project is currently underway, aiming to improve the sensitivity of the next generation X-ray polarimetry detectors taking advantage of the recent advancements in imaging techniques for high-resolution time projection chambers. In particular, we are evaluating the use of TIMEPIX3 to be applied for the read-out of a gas detector, which will allow us to obtain a three-dimensional image of the photoelectron track. To evaluate the improvement achievable by using a 3D track reconstruction, in this paper, we have reproduced a three-dimensional photoelectron track from a `Geant4' Monte Carlo simulation and examined the sensitivity of X-ray polarimetry using a new three-dimensional track reconstruction algorithm. We report the improvement of the modulation factor with three-dimensional track reconstruction as ∼5% (relative) in the 2–8 keV range and ∼17% (relative) in the 2–4 keV range compared to the current two-dimensional polarimetry system. This is equivalent to add a further telescope to the three-telescope systems now employed in space on board the IXPE mission.
17
Guo, Jing, Deqing Ren, Yongtian Zhu, and Xi Zhang. "A high-speed and high-efficiency imaging polarimeter based on ferroelectric liquid crystal retarders: Design and test." Publications of the Astronomical Society of Japan 73, no. 2 (February 16, 2021): 405–16. http://dx.doi.org/10.1093/pasj/psab007.
Full textAbstract:
Abstract Polarimeters play a key role in investigating solar magnetic fields. In this paper, a High speed and high efficiency Imaging POlarimeter (HIPO) is proposed based on a pair of ferroelectric liquid crystal retarders (FLCs), with the ultimate goal of measuring magnetic fields of prominences and filaments from the ground. A unique feature of the HIPO is that it enables high cadence polarization measurements covering a wide field of view (FOV); the modulation frequency of the HIPO is able to achieve ∼100 Hz, which greatly suppresses the seeing-induced crosstalk, and the maximum FOV can reach 62″ × 525″. Additionally, FLC retardances under low and high states were calibrated individually and found to have a slight discrepancy, which is neglected in most works. Based on FLC calibration results, an optimization was performed using a constrained nonlinear minimization approach to obtain the maximum polarimetric efficiency. Specifically, optimized efficiencies of the Stokes Q, U, and V are well balanced and determined as (ξQ, ξU, ξV) = (0.5957, 0.5534, 0.5777), yielding a total efficiency of 0.9974. Their practical efficiencies are measured as (ξQ′, ξU′, ξV′) = (0.5934, 0.5385, 0.5747), slightly below the optimized values but still resulting in a high total efficiency of 0.9861. The HIPO shows advantages in terms of modulation frequency and polarimetric efficiency compared with most other representative ground-based solar polarimeters. In the observations, measurement accuracy is found to be better than 2.7 × 10−3 by evaluating full Stokes Hα polarimetry results of the chromosphere. This work lays a foundation for the development of high-speed and high-accuracy polarimeters for our next-generation solar instruments.
18
Topasna, Gregory. "Optical Polarimetry in Undergraduate Education." EPJ Web of Conferences 200 (2019): 02003. http://dx.doi.org/10.1051/epjconf/201920002003.
Full textAbstract:
Polarimetry plays an important part in observational astronomy, but it is all too often given limited attention in astronomy textbooks. Coupled with a sometimes confusing mathematical introduction, students may feel that polarization is a difficult subject best left for study at a different time, or worse, not at all. Additionally, polarimetric observations and analysis are not typical exercises students are likely to engage in as part of an observational astronomy course. Over the past few years students at Virginia Military Institute have used an optical polarimeter, which was designed and constructed in-house, on the 20 cm Cassegrain telescope at the VMI Observatory to study the polarization of stars. These observations have enhanced their astronomical knowledge and allowed them the opportunity to gain valuable experience using this important technique. The subsequent analysis of stellar polarization has led to a better understanding of the mathematics of polarization, its interpretation, and statistical treatment. In this paper I describe the design and construction of an optical polarimeter suitable for a small college observatory and outline the observing and data analysis strategies. I will also present observations that range from brief introduction exercises that can be included as part of an observational astronomy course to longer programs suitable for undergraduate research projects.
19
Figueras i Ventura, Jordi, and Pierre Tabary. "The New French Operational Polarimetric Radar Rainfall Rate Product." Journal of Applied Meteorology and Climatology 52, no. 8 (August 2013): 1817–35. http://dx.doi.org/10.1175/jamc-d-12-0179.1.
Full textAbstract:
AbstractIn 2012 the Météo France metropolitan operational radar network consists of 24 radars operating at C and S bands. In addition, a network of four X-band gap-filler radars is being deployed in the French Alps. The network combines polarimetric and nonpolarimetric radars. Consequently, the operational radar rainfall algorithm has been adapted to process both polarimetric and nonpolarimetric data. The polarimetric processing chain is available in two versions. In the first version, now operational, polarimetry is only used to correct for attenuation and filter out clear-air echoes. In the second version there is a more extensive use of polarimetry. In particular, the specific differential phase Kdp is used to estimate rainfall rate in intense rain. The performance of the three versions of radar rainfall algorithms (conventional, polarimetric V1, and polarimetric V2) at different frequency bands (S, C, and X) is evaluated by processing radar data of significant events offline and comparing hourly radar rainfall accumulations with hourly rain gauge data. The results clearly show a superior performance of the polarimetric products with respect to the nonpolarimetric ones at all frequency bands, but particularly at higher frequency. The second version of the polarimetric product, which makes a broader use of polarimetry, provides the best overall results.
20
Gil, José J., and Ignacio San José. "Universal Synthesizer of Mueller Matrices Based on the Symmetry Properties of the Enpolarizing Ellipsoid." Symmetry 13, no. 6 (June 1, 2021): 983. http://dx.doi.org/10.3390/sym13060983.
Full textAbstract:
Polarimetry is today a widely used and powerful tool for nondestructive analysis of the structural and morphological properties of a great variety of material samples, including aerosols and hydrosols, among many others. For each given scattering measurement configuration, absolute Mueller polarimeters provide the most complete polarimetric information, intricately encoded in the 16 parameters of the corresponding Mueller matrix. Thus, the determination of the mathematical structure of the polarimetric information contained in a Mueller matrix constitutes a topic of great interest. In this work, besides a structural decomposition that makes explicit the role played by the diattenuation-polarizance of a general depolarizing medium, a universal synthesizer of Muller matrices is developed. This is based on the concept of an enpolarizing ellipsoid, whose symmetry features are directly linked to the way in which the polarimetric information is organized.
21
Yin, Junjun, Wooil Moon, and Jian Yang. "Model-Based Pseudo-Quad-Pol Reconstruction from Compact Polarimetry and Its Application to Oil-Spill Observation." Journal of Sensors 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/734848.
Full textAbstract:
Compact polarimetry is an effective imaging mode for wide area observation, especially for the open ocean. In this study, we propose a new method for pseudo-quad-polarization reconstruction from compact polarimetry based on the three-component decomposition. By using the decomposed powers, the reconstruction model is established as a power-weighted model. Further, the phase of the copolarized correlation is taken into consideration. The phase of double-bounce scattering is closer toπthan to 0, while the phase of surface scattering is closer to 0 than toπ. By considering the negative (double-bounce reflection) and positive (surface reflection) copolarized correlation, the reconstruction model for full polarimetry has a good consistency with the real polarimetric SAR data.L-band ALOS/PALSAR-1 fully polarimetric data acquired on August 27, 2006, over an oil-spill area are used for demonstration. Reconstruction performance is evaluated with a set of typical polarimetric oil-spill indicators. Quantitative comparison is given. Results show that the proposed model-based method is of great potential for oil-spill observation.
22
Boularbah, S., M. Ouarzeddine, and A. Belhadj-Aissa. "Investigation of the capability of the Compact Polarimetry mode to Reconstruct Full Polarimetry mode using RADARSAT2 data." Advanced Electromagnetics 1, no. 1 (June 11, 2012): 19. http://dx.doi.org/10.7716/aem.v1i1.12.
Full textAbstract:
Recently, there has been growing interest in dual-pol systems that transmit one polarization and receive two polarizations. Souyris et al. proposed a DP mode called compact polarimetry (CP) which is able to reduce the complexity, cost, mass, and data rate of a SAR system while attempting to maintain many capabilities of a fully polarimetric system. This paper provides a comparison of the information content of full quad-pol data and the pseudo quad-pol data derived from compact polarimetric SAR modes. A pseudo-covariance matrix can be reconstructed following Souyris’s approach and is shown to be similar to the full polarimetric (FP) covariance matrix. Both the polarimetric signatures based on the kennaugh matrix and the Freeman and Durden decomposition in the context of this compact polarimetry mode are explored. The Freeman and Durden decomposition is used in our study because of its direct relationship to the reflection symmetry. We illustrate our results by using the polarimetric SAR images of Algiers city in Algeria acquired by the RadarSAT2 in C-band.
23
Wang, Yadong, Tian-You Yu, Alexander V. Ryzhkov, and Matthew R. Kumjian. "Application of Spectral Polarimetry to a Hailstorm at Low Elevation Angle." Journal of Atmospheric and Oceanic Technology 36, no. 4 (April 2019): 567–83. http://dx.doi.org/10.1175/jtech-d-18-0115.1.
Full textAbstract:
AbstractSpectral polarimetry has the potential to be used to study microphysical properties in relation to the dynamics within a radar resolution volume by combining Doppler and polarimetric measurements. The past studies of spectral polarimetry have focused on using radar measurements from higher elevation angles, where both the size sorting from the hydrometeors’ terminal velocities and polarimetric characteristics are maintained. In this work, spectral polarimetry is applied to data from the 0° elevation angle, where polarimetric properties are maximized. Radar data collected by the C-band University of Oklahoma Polarimetric Radar for Innovations in Meteorology and Engineering (OU-PRIME) during a hailstorm event on 24 April 2011 are used in the analysis. The slope of the spectral differential reflectivity exhibits interesting variations across the hail core, which suggests the presence of size sorting of hydrometeors caused by vertical shear in a turbulent environment. A nearby S-band polarimetric Weather Surveillance Radar-1988 Doppler (KOUN) is also used to provide insights into this hailstorm. Moreover, a flexible numerical simulation is developed for this study, in which different types of hydrometeors such as rain and melting hail can be considered individually or as a combination under different sheared and turbulent conditions. The impacts of particle size distribution, shear, turbulence, attenuation, and mixture of rain and melting hail on polarimetric spectral signatures are investigated with the simulated Doppler spectra and spectral differential reflectivity.
24
Taverna, R., R. Turolla, V. Suleimanov, A. Y. Potekhin, and S. Zane. "X-ray spectra and polarization from magnetar candidates." Monthly Notices of the Royal Astronomical Society 492, no. 4 (January 24, 2020): 5057–74. http://dx.doi.org/10.1093/mnras/staa204.
Full textAbstract:
ABSTRACT Magnetars are believed to host the strongest magnetic fields in the present universe ($B\gtrsim 10^{14}$ G) and the study of their persistent emission in the X-ray band offers an unprecedented opportunity to gain insight into physical processes in the presence of ultra-strong magnetic fields. Up to now, most of our knowledge about magnetar sources came from spectral analysis, which allowed to test the resonant Compton scattering scenario and to probe the structure of the star magnetosphere. On the other hand, radiation emitted from magnetar surface is expected to be strongly polarized and its observed polarization pattern bears the imprint of both scatterings on to magnetospheric charges and quantum electro-dynamics (QED) effects as it propagates in the magnetized vacuum around the star. X-ray polarimeters scheduled to fly in the next years will finally allow to exploit the wealth of information stored in the polarization observables. Here we revisit the problem of assessing the spectro-polarimetric properties of magnetar persistent emission. At variance with previous investigations, proper account for more physical surface emission models is made by considering either a condensed surface or a magnetized atmosphere. Results are used to simulate polarimetric observations with the forthcoming Imaging X-ray Polarimetry Explorer. We find that X-ray polarimetry will allow to detect QED vacuum effects for all the emission models we considered and to discriminate among them.
25
Bjorkman, Karen S. "Polarimetry of Binary Stars and Exoplanets." Proceedings of the International Astronomical Union 7, S282 (July 2011): 173–80. http://dx.doi.org/10.1017/s1743921311027281.
Full textAbstract:
AbstractPolarimetry is a useful diagnostic of asymmetries in both circumstellar environments and binary star systems. Its sensitivity to asymmetries in systems means that it can help to uncover details about system orbital parameters, including providing information about the orbital inclination. Polarimetry can probe the circumstellar and/or circumbinary material as well. A number of significant results on binary systems have been produced by polarimetric studies. One might therefore expect that polarimetry could similarly play a useful role in studies of exoplanets, and a number of possible diagnostics for exoplanets have been proposed. However, the application of polarimetry to exoplanet research is only in preliminary stages, and the difficulties with applying the technique to exoplanets are non-trivial. This review will discuss the successes of polarimetry in analyzing binary systems, and consider the possibilities and challenges for extending similar analysis to exoplanet systems.
26
Gibson, Sarah. "Data-model comparison using FORWARD and CoMP." Proceedings of the International Astronomical Union 10, S305 (December 2014): 245–50. http://dx.doi.org/10.1017/s1743921315004846.
Full textAbstract:
AbstractThe FORWARD SolarSoft IDL package is a community resource for model-data comparison, with a particular emphasis on analyzing coronal magnetic fields. FORWARD allows the synthesis of coronal polarimetric signals at visible, infrared, and radio frequencies, and will soon be augmented for ultraviolet polarimetry. In this paper we focus on observations of the infrared (IR) forbidden lines of Fe XIII, and describe how FORWARD may be used to directly access these data from the Mauna Loa Solar Observatory Coronal Multi-channel Polarimeter (MLSO/CoMP), to put them in the context of other space- and ground-based observations, and to compare them to synthetic observables generated from magnetohydrodynamic (MHD) models.
27
Dutta, D. "High Precision Electon Beam Polarimetry." International Journal of Modern Physics: Conference Series 40 (January 2016): 1660085. http://dx.doi.org/10.1142/s2010194516600855.
Full textAbstract:
Over the last three decades high precision electron beam polarimetry has been at the fore-front of progress made in leveraging the spin degrees of freedom in nuclear and particle physics experiments. We review the three main types of polarimeters, Compton, Møller and Mott, that are typically used in experiments. We discuss some of the recent results in high precision electron polarimetry and some of the new ideas that are being explored for future application at current and proposed accelerators.
28
Zhou, Changyu, Youpeng Xie, Jianxin Ren, Zepeng Wei, Luping Du, Qiang Zhang, Zhenwei Xie, Bo Liu, Ting Lei, and Xiaocong Yuan. "Spin separation based on-chip optical polarimeter via inverse design." Nanophotonics 11, no. 4 (October 14, 2021): 813–19. http://dx.doi.org/10.1515/nanoph-2021-0455.
Full textAbstract:
Abstract Polarimetry has been demonstrated essential in various disciplines, such as optical communications, imaging, and astronomy. On-chip nanostructures for polarization measurements are most expected to replace the conventional bulk elements, and hence minimize the polarimeter for integrated applications. Some on-chip nanophotonic polarimeter via polarization detection has been implemented, in which the separation of two spin polarized states is needed. However, due to the relatively low coupling efficiency or complicated photonic silicon circuits, on-chip polarimetry using a single device still remains challenging. Here, we introduce and investigate an on-chip polarimeter with nanostructures using the inverse design method. The developed device shows the ability to detect the four polarization components of light, two of which are the spin polarizations, and the other two are the linear polarizations. The retrieved Stokes parameters with experimentally tested data are in close agreement with the numerical results. We also show the proof of concept demonstration for high-speed Stokes vector optical signals detection. In the high-speed communication experiment with data rate up to 16 GBd, the detected optical signals via polarization measurements at multiple wavelengths in the C-band were recovered with the bit error rate below the 20% forward error correction threshold. The proposed on-chip polarimeter shows promising performance both in Stokes polarimetry and high-speed optical communication applications.
29
Gil, José J., and Ignacio San José. "Synthetic Mueller Imaging Polarimetry." Photonics 10, no. 9 (August 24, 2023): 969. http://dx.doi.org/10.3390/photonics10090969.
Full textAbstract:
The transformation of the state of polarization of a light beam via its linear interaction with a material medium can be modeled through the Stokes–Mueller formalism. The Mueller matrix associated with a given interaction depends on many aspects of the measurement configuration. In particular, different Mueller matrices can be measured for a fixed material sample depending on the spectral profile of the light probe. For a given light probe and a given sample with inhomogeneous spatial behavior, the polarimetric descriptors of the point-to-point Mueller matrices can be mapped, leading to respective polarimetric images. The procedure can be repeated sequentially using light probes with different central frequencies. In addition, the point-to-point Mueller matrices, consecutively measured, can be combined synthetically through convex sums leading to respective new Mueller matrices, in general with increased polarimetric randomness, thus exhibiting specific values for the associated polarimetric descriptors, including the indices of polarimetric purity, and generating new polarimetric images which are different from those obtained from the original Mueller matrices. In this work, the fundamentals for such synthetic generation of additional polarimetric images are described, providing a new tool that enhances the exploitation of Mueller polarimetry.
30
Harvey, J. W. "Two Centuries of Solar Polarimetry." Proceedings of the International Astronomical Union 10, S305 (December 2014): 2–11. http://dx.doi.org/10.1017/s1743921315004457.
Full textAbstract:
AbstractIn 1811, François Arago observed the disk of the Sun with his “lunette polariscopique”. From the absence of detectable polarization compared with his laboratory observations of glowing solids, liquids, and flames he concluded that the Sun's visible surface is an incandescent gas. From this beginning, thanks to orders of magnitude technology improvements, a remarkable amount of what we know about the physics of the Sun has continued to flow from solar polarimetry. This short review compares some selected polarimetric discoveries with subsequent recent observations to illustrate the tremendous progress of solar polarimetry during the last two centuries.
31
Takahashi, J., Y. Itoh, T. Matsuo, Y. Oasa, Y. P. Bach, and M. Ishiguro. "Polarimetric signature of the oceans as detected by near-infrared Earthshine observations." Astronomy & Astrophysics 653 (September 2021): A99. http://dx.doi.org/10.1051/0004-6361/202039331.
Full textAbstract:
Context. The discovery of an extrasolar planet with an ocean has crucial importance in the search for life beyond Earth. The polarimetric detection of specularly reflected light from a smooth liquid surface is anticipated theoretically, though the polarimetric signature of Earth’s oceans has not yet been conclusively detected in disk-integrated planetary light. Aims. We aim to detect and measure the polarimetric signature of the Earth’s oceans. Methods. We conducted near-infrared polarimetry for lunar Earthshine and collected data on 32 nights with a variety of ocean fractions in the Earthshine-contributing region. Results. A clear positive correlation was revealed between the polarization degree and ocean fraction. We found hourly variations in polarization in accordance with rotational transition of the ocean fraction. The ratios of the variation to the typical polarization degree were as large as ~0.2–1.4. Conclusions. Our observations provide plausible evidence of the polarimetric signature attributed to Earth’s oceans. Near-infrared polarimetry may be considered a prospective technique in the search for exoplanetary oceans.
32
Tuominen, I., J. Huovelin, Yu S. Efimov, N. M. Shakhovskoy, and A. G. Shcherbakov. "Polarimetry of Stellar Active Regions and Flares." International Astronomical Union Colloquium 104, no. 1 (1989): 419–29. http://dx.doi.org/10.1017/s0252921100032036.
Full textAbstract:
AbstractObservations of regular and irregular polarimetric variability in late-type stars are reviewed, and the related physical and geometrical effects are discussed. There are indications that the irregular part of the variability could be caused by transient events, possibly associated with flares. Polarimetric observations during flares are reviewed, and preliminary results of new observations of a well-known flare star, YY Geminorum, are presented. The results show that the small flare in YY Gem did not cause any significant variations in linear polarization, while the binary eclipse evidently causes an enhancement in the polarization. The reasons for the difficulties in stellar flare polarimetry are discussed. Finally, future prospects for the observations of flaring stars and for the utilization of linear polarimetry as a complementary method to other techniques of surface imaging of stellar activity and flares are presented.
33
Kwon, Jungmi. "Magnetic field structures in star-forming regions revealed by imaging polarimetry at multi-wavelengths." Proceedings of the International Astronomical Union 14, A30 (August 2018): 102. http://dx.doi.org/10.1017/s1743921319003570.
Full textAbstract:
AbstractMagnetic fields are ubiquitous in various scales of astronomical objects, and they are considered as playing significant roles from star to galaxy formations. However, the role of the magnetic fields in star forming regions is less well understood because conventional optical polarimetry is hampered by heavy extinction by dust. We have been conducting extensive near-infrared polarization survey of various star-forming regions from low- and intermediate-mass to high-mass star-forming regions, using IRSF/SIRPOL in South Africa. Not only linear but also circular polarizations have been measured for more than a dozen of regions. Both linear and circular polarimetric observations at near-infrared wavelengths are useful tools to study the magnetic fields in star forming regions, although infrared circular polarimetry has been less explored so far. In this presentation, we summarize our results of the near-infrared polarization survey of star forming regions and its comparison with recent submillimeter polarimetry results. Such multi-wavelength approaches can be extended to the polarimetry using ALMA, SPICA in future, and others. We also present our recent results of the first near-infrared imaging polarimetry of young stellar objects in the Circinus molecular cloud, which has been less studied but a very intriguing cluster containing numerous signs of active low-mass star formation.
34
Rousselet-Perraut, K., C. Stehlé, J. B. Le Bouquin, S. Jankov, and F. Vakili. "Stellar polarimetry with SPIN (Spectro-Polarimetric INterferometry)." EAS Publications Series 9 (2003): 123. http://dx.doi.org/10.1051/eas:2003094.
Full text
35
Strohmayer, T. E. "X-Ray Spectro-polarimetry with Photoelectric Polarimeters." Astrophysical Journal 838, no. 1 (March 27, 2017): 72. http://dx.doi.org/10.3847/1538-4357/aa643d.
Full text
36
van Harten, Gerard, Frans Snik, Jeroen H. H. Rietjens, J. Martijn Smit, and Christoph U. Keller. "Spectral line polarimetry with a channeled polarimeter." Applied Optics 53, no. 19 (June 25, 2014): 4187. http://dx.doi.org/10.1364/ao.53.004187.
Full text
37
Cellino, A., and S. Bagnulo. "Polarimetry: a primary tool for the physical characterization of asteroids." Proceedings of the International Astronomical Union 10, S305 (December 2014): 313–18. http://dx.doi.org/10.1017/s1743921315004974.
Full textAbstract:
AbstractAsteroid polarimetry has taken profit in recent years of a renewed interest triggered by exciting results from observing campaigns and theoretical studies. One of the most important applications of polarimetry to asteroid studies is the derivation of the geometric albedo and of the typical sizes of the particles forming the regolith layer covering the surface. Moreover, the serendipitous discovery of a new class of asteroids displaying unusual polarimetric properties, the so-called “Barbarians”, has been followed by increasing evidence that these objects can be extremely primitive and may be interpreted as remnants of the very first generation of solid bodies accreted in the inner Solar System. In addition, some results of asteroid polarimetry are going to be interpreted, for the first time, in terms of some “ground truth” evidence, made possible by in situ observations of the surface of the asteroid (4) Vesta by the Dawn space probe. Finally, some preliminary evidence suggests that spectro-polarimetry is going to become a major tool for the physical characterization of the small bodies of the solar system.
38
Paranjpye, D., A. Mahabal, A. N. Ramaprakash, G. V. Panopoulou, K. Cleary, A. C. S. Readhead, D. Blinov, and K. Tassis. "Eliminating artefacts in polarimetric images using deep learning." Monthly Notices of the Royal Astronomical Society 491, no. 4 (November 28, 2019): 5151–57. http://dx.doi.org/10.1093/mnras/stz3250.
Full textAbstract:
ABSTRACT Polarization measurements done using Imaging Polarimeters such as the Robotic Polarimeter are very sensitive to the presence of artefacts in images. Artefacts can range from internal reflections in a telescope to satellite trails that could contaminate an area of interest in the image. With the advent of wide-field polarimetry surveys, it is imperative to develop methods that automatically flag artefacts in images. In this paper, we implement a Convolutional Neural Network to identify the most dominant artefacts in the images. We find that our model can successfully classify sources with 98 per cent true positive and 97 per cent true negative rates. Such models, combined with transfer learning, will give us a running start in artefact elimination for near-future surveys like WALOP.
39
Maund, J. R., G. Leloudas, D. B. Malesani, F. Patat, J. Sollerman, and A. de Ugarte Postigo. "Polarimetry of the superluminous transient ASASSN-15lh." Monthly Notices of the Royal Astronomical Society 498, no. 3 (August 20, 2020): 3730–35. http://dx.doi.org/10.1093/mnras/staa2517.
Full textAbstract:
ABSTRACT ASASSN-15lh is the intrinsically brightest transient observed to date. Despite being the subject of concerted photometric and spectroscopic observing campaigns, there is still significant debate about the true nature of this transient and the mechanism responsible for its great luminosity. Here we report five epochs of imaging polarimetry and two epochs of spectropolarimetry conducted with the ESO Very Large Telescope (VLT) FOcal Reducer and low dispersion Spectrograph (FORS) polarimeter, spanning +28–91 d (rest frame) with respect to the light-curve maximum. The overall level of polarization across this period is seen to be low ${\sim} 0.5\!-\!0.8 {{\ \rm per\ cent}}$, however at +51.6 d, approximately corresponding to a dip in the ultraviolet (UV) photometric light curve, the polarization is seen to briefly rise to $1.2{{\ \rm per\ cent}}$ in the observed V band. We discuss this behaviour in the context of previous polarimetric observations of superluminous supernovae (SLSNe) and tidal disruption events (TDEs). Although the level of polarization could be consistent with polarization observed for SLSNe, the behaviour around the UV light-curve dip could also be consistent with a TDE observed almost edge on.
40
Magalhães, Antonio Mârio. "Optical Polarimetry of Symbiotic Stars." International Astronomical Union Colloquium 103 (1988): 89–100. http://dx.doi.org/10.1017/s0252921100103203.
Full textAbstract:
AbstractA review of some physical mechanisms that may give rise to detectable optical polarization in symbiotic stars is presented, emphasizing the ability of polarimetry in studying the evolution of dust envelopes, the atmospheric structure of the cool component and the geometry of these systems. A brief summary of the techniques is also given. General polarimetric properties of symbiotics as well as data for a few specific systems are discussed. Proposed models for symbiotics that include the prediction of their polarimetric properties are highly encouraged. Specific suggestions for future work from the ultraviolet through the infrared and which explore the potential of the technique are advanced.
41
Li, Han-Cheng, Nicolas Produit, Shuang-Nan Zhang, Merlin Kole, Jian-Chao Sun, Ming-Yu Ge, Nicolas De Angelis, et al. "Gamma-ray polarimetry of the Crab pulsar observed by POLAR." Monthly Notices of the Royal Astronomical Society 512, no. 2 (February 25, 2022): 2827–40. http://dx.doi.org/10.1093/mnras/stac522.
Full textAbstract:
ABSTRACT The X/gamma-ray polarimetry of the Crab pulsar/nebula is believed to hold crucial information on their emission models. In the past, several missions have shown evidence of polarized emission from the Crab. The significance of these measurements remains, however, limited. New measurements are therefore required. POLAR is a wide Field of View Compton-scattering polarimeter (sensitive in 50–500 keV) onboard the Chinese spacelab Tiangong-2 that took data from 2016 September to 2017 April. Although not designed to perform polarization measurements of pulsars, we present here a novel method, which can be applied to POLAR as well as that of other wide Field of View polarimeters. The novel polarimetric joint-fitting method for the Crab pulsar observations with POLAR, allows us to obtain constraining measurements of the pulsar component. The best-fitting values and corresponding 1σ deviations for the averaged phase interval: (PD = $14\substack{+15 \\-10}$ per cent, PA = $108\substack{+33 \\-54} ^{\circ }$), for Peak 1: (PD = $17\substack{+18 \\-12}$ per cent, PA = $174\substack{+39 \\-36} ^{\circ }$) and for Peak 2: (PD = $16\substack{+16 \\-11}$ per cent, PA = $78\substack{+39 \\-30} ^{\circ }$). Furthermore, the 3σ upper limits on the polarization degree are for the averaged phase interval (55 per cent), Peak 1 (66 per cent) and Peak 2 (57 per cent). Finally, to illustrate the capabilities of this method in the future, we simulated 2 yr observation to the Crab pulsar with POLAR-2. The results show that POLAR-2 is able to confirm the emission to be polarized with 5σ and 4σ confidence level if the Crab pulsar is polarized at $20{{\,\rm per\,cent}}$ and $10{{\,\rm per\,cent}}$, respectively.
42
Goïta, Kalifa, Ramata Magagi, Vincent Beauregard, and Hongquan Wang. "Retrieval of Surface Soil Moisture over Wheat Fields during Growing Season Using C-Band Polarimetric SAR Data." Remote Sensing 15, no. 20 (October 12, 2023): 4925. http://dx.doi.org/10.3390/rs15204925.
Full textAbstract:
Accurate estimation and regular monitoring of soil moisture is very important for many agricultural, hydrological, or climatological applications. Our objective was to evaluate potential contributions of polarimetry to soil moisture estimation during crop growing cycles using RADARSAT-2 C-band images. The research focused on wheat field data collected during Soil Moisture Active Passive Validation Experiment (SMAPVEX12) conducted in 2012 in Manitoba (Canada). A sensitivity analysis was performed to select the most relevant non-polarimetric and polarimetric variables extracted from RADARSAT-2, and statistical models were developed to estimate soil moisture. In fine, three models were developed and validated: a non-polarimetric model based on cross-polarized backscattering coefficient σHV0; a polarimetric mixed model using six polarimetric and non-polarimetric retained variables after the sensitivity analysis; and a simplified polarimetric mixed model considering only the phase difference (ϕHH−VV) and the co-polarized backscattering coefficient σHH0. The validation reveals significant positive contributions of polarimetry. It shows that the non-polarimetric model has a much larger error (RMSE = 0.098 m3/m3) and explains only 19% of observed soil moisture variation compared to the polarimetric mixed model, which has an error of 0.087 m3/m3, with an explained variance of 44%. The simplified model has the lowest error (0.074 m3/m3) and explains 53.5% of soil moisture variation.
43
Di Marco, Alessandro, Paolo Soffitta, Enrico Costa, Riccardo Ferrazzoli, Fabio La Monaca, John Rankin, Ajay Ratheesh, et al. "Handling the Background in IXPE Polarimetric Data." Astronomical Journal 165, no. 4 (March 3, 2023): 143. http://dx.doi.org/10.3847/1538-3881/acba0f.
Full textAbstract:
Abstract Imaging X-ray Polarimetry Explorer (IXPE) is a Small Explorer mission by NASA and Agenzia Spaziale Italiana, launched on 2021 December 9, dedicated to investigating X-ray polarimetry allowing angular-, time-, and energy-resolved observations in the 2–8 keV energy band. IXPE is in the science observation phase since 2022 January; it is comprised of three identical telescopes with grazing-incidence mirrors, each one having in the focal plane a gas pixel detector. In this paper, we present a possible guideline to obtain an optimal background selection in polarimetric analysis, and a rejection strategy to remove instrumental background. This work is based on the analysis of IXPE observations, aiming to improve as much as possible the polarimetric sensitivity. In particular, the developed strategies have been applied as a case study to the IXPE observation of the 4U 0142+61 magnetar.
44
Ajithkumar, K. C., and K. Pramod. "DEVELOPMENT AND VALIDATION OF A MODIFIED POLARIMETRIC ASSAY METHOD FOR SMALL VOLUME SAMPLES." International Journal of Applied Pharmaceutics 9, no. 6 (November 8, 2017): 91. http://dx.doi.org/10.22159/ijap.2017v9i6.22459.
Full textAbstract:
Objective: The objective of the present work was to develop a method to be useful for analyzing small volume samples of an optically active compound.Methods: The method employed quartz cuvette instead of a polarimeter tube. Quantification of optically active compound was successfully validated in terms of linearity and range, precision and robustness. The detection limit (DL) and quantitation limit (QL) were determined as per the ICH guidelines.Results: Polarimetry generally involves the quantification of optically active compounds by measuring its ability to rotate (in terms of angle of rotation) polarized light passed through it. The plot of angle of rotation versus concentration was linear in wide range of concentration with excellent coefficient of determination of 0.9989±0.0008. The low values of % relative standard deviation (RSD) for repeatability and intermediate precision suggested an excellent precision of the developed polarimetric method. The detection limit (DL) and quantitation limit (QL) were determined were found to be 0.5025 and 1.5225 %w/v respectively.Conclusion: A modified polarimetric method for the quantification of dextrose was successfully developed and validated. The method employed quartz cuvette instead of polarimeter tube. The method is expected to be useful in a variety of industries where dextrose finds its application. The method can also be extended to other optically active compounds.
45
McLean, I. S. "Commission 25. Stellar Photometry and Polarimetry Photometrie Et Polarimetrie Stellaires." Transactions of the International Astronomical Union 21, no. 1 (1991): 235–42. http://dx.doi.org/10.1017/s0251107x00010063.
Full textAbstract:
Technology has continued to influence the methods of stellar photometry and polarimetry in the last triennium. For example, CCDs continue to displace photographic plates in stellar photometry and other detector systems for imaging and spectro-polarimetry, new array detectors for infrared wavelengths have revolutionised the way infrared photometry and polarimetry is done and small automatic telescopes and robotic observatories have experienced a remarkable growth period. The volume of data to be archived and transformed to “standard” systems has become immense and all the problems of inter-comparing different systems still remain.
46
WOODS, M. "POLARIMETRY AT A FUTURE LINEAR COLLIDER — HOW PRECISE?" International Journal of Modern Physics A 15, no. 16 (June 30, 2000): 2529–36. http://dx.doi.org/10.1142/s0217751x00002603.
Full textAbstract:
At a future linear collider, a polarized electron beam will play an important role in interpreting new physics signals. Backgrounds to a new physics reaction can be reduced by choice of the electron polarization state. The origin of a new physics reaction can be clarified by measuring its polarization-dependence. This paper examines some options for polarimetry with an emphasis on physics issues that motivate how precise the polarization determination needs to be. In addition to Compton polarimetry, the possibility of using Standard Model asymmetries, such as the asymmetry in forward W-pairs, is considered as a possible polarimeter. Both e+e- and e-e- collider modes are considered.
47
Kim, Dawoon E., Laura Di Gesu, Frédéric Marin, Alan P. Marscher, Giorgio Matt, Paolo Soffitta, Francesco Tombesi, Enrico Costa, and Immacolata Donnarumma. "Investigating the Properties of the Relativistic Jet and Hot Corona in AGN with X-ray Polarimetry." Galaxies 12, no. 3 (April 23, 2024): 20. http://dx.doi.org/10.3390/galaxies12030020.
Full textAbstract:
X-ray polarimetry has been suggested as a prominent tool for investigating the geometrical and physical properties of the emissions from active galactic nuclei (AGN). The successful launch of the Imaging X-ray Polarimetry Explorer (IXPE) on 9 December 2021 has expanded the previously restricted scope of polarimetry into the X-ray domain, enabling X-ray polarimetric studies of AGN. Over a span of two years, IXPE has observed various AGN populations, including blazars and radio-quiet AGN. In this paper, we summarize the remarkable discoveries achieved thanks to the opening of the new window of X-ray polarimetry of AGN through IXPE observations. We will delve into two primary areas of interest: first, the magnetic field geometry and particle acceleration mechanisms in the jets of radio-loud AGN, such as blazars, where the relativistic acceleration process dominates the spectral energy distribution; and second, the geometry of the hot corona in radio-quiet AGN. Thus far, the IXPE results from blazars favor the energy-stratified shock acceleration model, and they provide evidence of helical magnetic fields inside the jet. Concerning the corona geometry, the IXPE results are consistent with a disk-originated slab-like or wedge-like shape, as could result from Comptonization around the accretion disk.
48
Tyo, J. S. "Imaging polarimetry in the LWIR with microgrid polarimeters." EPJ Web of Conferences 5 (2010): 04009. http://dx.doi.org/10.1051/epjconf/20100504009.
Full text
49
AGUDO, IVÁN, SOL N. MOLINA, JOSÉ L. GÓMEZ, ALAN P. MARSCHER, SVETLANA G. JORSTAD, and JOCHEN HEIDT. "MAPCAT: MONITORING AGN WITH POLARIMETRY AT THE CALAR ALTO TELESCOPES." International Journal of Modern Physics: Conference Series 08 (January 2012): 299–302. http://dx.doi.org/10.1142/s2010194512004746.
Full textAbstract:
We introduce MAPCAT, a long-term observing program for "Monitoring of AGN with Polarimetry at the Calar Alto Telescopes". Multi-spectral-range studies are critical to understand some of the most relevant current problems of high energy astrophysics of blazars such as their high energy emission mechanisms and the location of their γ-ray emission region through event associations across the spectrum. Adding multi-spectral-range polarimetry allows for even more reliable identification of polarized flares across the spectrum in these kind of objects, as well as for more accurate modeling of their magnetic field. As part of a major international effort to study the long term multi-spectral range polarimetric behavior of blazars, MAPCAT uses -since mid 2007- CAFOS on the 2.2m Telescope at the Calar Alto Observatory (Almería, Spain) to obtain monthly optical (R-band) photo-polarimetric measurements of a sample of 34 of the brightest γ-ray, optical, and radio-millimeter blazars accessible from the northern hemisphere.
50
Zheng, Chuan, Pavel Fedorets, Ralf Engels, Chrysovalantis Kannis, Ilhan Engin, Sören Möller, Robert Swaczyna, et al. "Polarimetry for 3He Ion Beams from Laser–Plasma Interactions." Instruments 6, no. 4 (October 10, 2022): 61. http://dx.doi.org/10.3390/instruments6040061.
Full textAbstract:
We present a compact polarimeter for 3He ions with special emphasis on the analysis of short-pulsed beams accelerated during laser–plasma interactions. We discuss the specific boundary conditions for the polarimeter, such as the properties of laser-driven ion beams, the selection of the polarization-sensitive reaction in the polarimeter, the representation of the analyzing-power contour map, the choice of the detector material used for particle identification, as well as the production procedure of the required deuterated foil-targets. The assembled polarimeter has been tested using a tandem accelerator delivering unpolarized 3He ion beams, demonstrating good performance in the few-MeV range. The statistical accuracy and the deduced figure-of-merit of the polarimetry are discussed, including the count-rate requirement and the lower limit of accuracy for beam-polarization measurements at a laser-based ion source.