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Osamu Takayama, Graciana Puentes
We demonstrate experimentally the lateral circular birefringence of a tunable birefringent polymer, the first example of the spin Hall effect of light in a polymeric material, and we demonstrate that this light shift can be significantly enhanced by tuning the effective birefringence in the polymer. We report experimental observations of this effect using polarimetric techniques and quantum-weak-measurement techniques, reporting a weak amplification factor of 200.
March 15, 2018: Optics Letters
Si He, Xia Wang, Runqiu Xia, Weiqi Jin, Jian'an Liang
A novel method to simulate the polarimetric infrared imaging of a synthetic sea surface with atmospheric Mie scattering effects is presented. The infrared emission, multiple reflections, and infrared polarization of the sea surface and the Mie scattering of aerosols are all included for the first time. At first, a new approach to retrieving the radiative characteristics of a wind-roughened sea surface is introduced. A two-scale method of sea surface realization and the inverse ray tracing of light transfer calculation are combined and executed simultaneously, decreasing the consumption of time and memory dramatically...
March 1, 2018: Applied Optics
Julien Fade, Estéban Perrotin, Jérôme Bobin
We propose an original concept of compressive sensing (CS) polarimetric imaging based on a digital micromirror (DMD) array and two single-pixel detectors, without using any polarizer. The polarimetric sensitivity of the proposed setup is due to the tiny difference in Fresnel's coefficients of reflecting mirrors, which is exploited here to form an original reconstruction problem including a CS problem and a source-separation task. We show that a two-step approach, tackling each problem successively, is outperformed by a dedicated combined reconstruction method, which is demonstrated in this paper and preferably implemented through a reweighted fast iterative shrinkage-thresholding algorithm...
March 1, 2018: Applied Optics
Firooz A Sadjadi, Cornell S L Chun
We propose an automated method for detecting neutral points in the sunlit sky. Until now, detecting these singularities has been done manually. Results are presented that document the application of this method on a limited number of polarimetric images of the sky captured with a camera and rotating polarizer. The results are significant because a method for automatically detecting the neutral points may aid in the determination of the solar position when the sun is obscured and may have applications in meteorology and pollution detection and characterization...
March 10, 2018: Applied Optics
Sha Jiang, Xiaolan Qiu, Bing Han, Wenlong Hu
The GaoFen-3 (GF-3) satellite, launched on 10 August 2016, is the first C-band polarimetric synthetic aperture radar (PolSAR) satellite in China. The PolSAR system of GF-3 can collect a significant wealth of information for geophysical research and applications. Being used for related applications, GF-3 PolSAR images must be of good quality. It is necessary to evaluate the quality of polarimetric data and achieve the normalized quality monitoring during 8-year designed life of GF-3. In this study, a new quality assessment method of PolSAR data based on common distributed targets is proposed, and the performance of the method is analyzed by simulations and GF-3 experiments...
March 7, 2018: Sensors
Lei Wang, Xin Xu, Hao Dong, Rong Gui, Fangling Pu
Convolutional neural networks (CNN) have achieved great success in the optical image processing field. Because of the excellent performance of CNN, more and more methods based on CNN are applied to polarimetric synthetic aperture radar (PolSAR) image classification. Most CNN-based PolSAR image classification methods can only classify one pixel each time. Because all the pixels of a PolSAR image are classified independently, the inherent interrelation of different land covers is ignored. We use a fixed-feature-size CNN (FFS-CNN) to classify all pixels in a patch simultaneously...
March 3, 2018: Sensors
Alem Gebru, Samuel Jansson, Rickard Ignell, Carsten Kirkeby, Jord C Prangsma, Mikkel Brydegaard
We present a dual-wavelength polarimetric measurement method to distinguish species and sexes of disease transmitting mosquitoes in flight. By measuring co- and de-polarized backscattered light at 808 and 1550 nm, the degree of linear polarization, wingbeat frequency, reflectance, spectral ratio and glossiness of mosquitoes can be retrieved. Body and wing contributions to these signals can be separated. Whereas the optical cross-section is sensitive to the aspect of observation, thus the heading direction of the insect in flight, we demonstrate that polarimetric- and spectral- band ratios are largely invariant to the aspect of observation...
March 5, 2018: Journal of Biophotonics
Bence Kutus, Csilla Dudás, Gábor Peintler, István Pálinkó, Pál Sipos
The calcium sugar carboxylate interactions in hyperalkaline solutions are of relevance in radioactive waste repositories and in certain industrial processes. The complex formation between L-gulonate and Ca2+ ions was studied in strongly alkaline medium at 25 °C and 1 M ionic strength and was compared with previous results reported for D-gluconate and D-heptagluconate. The deprotonation of the ligand was confirmed by potentiometric and13 C NMR spectroscopic measurements. Pronounced pH effects were seen in the presence of Ca2+ indicating strong complex formation...
February 23, 2018: Carbohydrate Research
Ying Zhang, Jiabin Xuan, Huijie Zhao, Ping Song, Yi Zhang, Wujian Xu
We propose a method for eliminating the atmospheric effect in polarimetric imaging remote sensing by using polarimetric imagers to simultaneously detect ground targets and skylight, which does not need calibrated targets. In addition, calculation efficiencies are improved by the skylight division method without losing estimation accuracy. Outdoor experiments are performed to obtain the polarimetric bidirectional reflectance distribution functions of painted surfaces and skylight under different weather conditions...
March 1, 2018: Optics Letters
Ruiying Xu, Yongchao Li, Fan Zheng, Guanghao Zhu, Lin Kang, Labao Zhang, Xiaoqing Jia, Xuecou Tu, Qingyuan Zhao, Biaobing Jin, Weiwei Xu, Jian Chen, Peiheng Wu
Polarization sensitive photo-detectors are the key to the implementation of the polarimetric imaging systems, which are proved to have superior performance than their traditional counterparts based on intensity discriminations. In this article, we report the demonstration of a superconducting nanowire single photon detector (SNSPD) of which the response is ultra-sensitive to the polarization state of the incident photons. Measurements carried out on a fabricated SNSPD show that a device efficiency of ~48% can be achieved at 1550 nm for the case of parallel polarization, which is ~420 times larger than that for the case of perpendicular polarization...
February 19, 2018: Optics Express
Jérémy Vizet, Razvigor Ossikovski
We propose a detailed procedure to determine the two retardance matrix factors entering the symmetric decomposition of Mueller matrices when the depolarizer matrix is partially degenerate (i.e., two out of three of its depolarization coefficients are equal), which is a common occurrence. Thanks to a relatively simple algebraic method, we show that linear retardance, as well as its eigenaxes orientation can be determined unambiguously from each retardance matrix factor. The method, applied on both experimental Mueller matrices of an ad hoc sample, as well as on that of a biological tissue, shows its efficiency for decoupling the different polarimetric effects of retardance that occur during the propagation of light throughout a complex medium...
February 10, 2018: Applied Optics
Marko Ilić, Andrej Meglič, Marko Kreft, Gregor Belušič
Microvillar photoreceptors are intrinsically capable of detecting the orientation of e-vector of linearly polarized light. They provide most invertebrates with an additional sensory channel to detect important features of their visual environment. However, polarization sensitivity (PS) of photoreceptors may lead to the detection of polarization-induced false colors and intensity contrasts. Most insect photoreceptors are thus adapted to have minimal PS. Flies have twisted rhabdomeres with microvilli rotated along the length of the ommatidia to reduce PS...
2018: Frontiers in Cellular Neuroscience
Hao Dong, Xin Xu, Lei Wang, Fangling Pu
The launch of the Chinese Gaofen-3 (GF-3) satellite will provide enough synthetic aperture radar (SAR) images with different imaging modes for land cover classification and other potential usages in the next few years. This paper aims to propose an efficient and practical classification framework for a GF-3 polarimetric SAR (PolSAR) image. The proposed classification framework consists of four simple parts including polarimetric feature extraction and stacking, the initial classification via XGBoost, superpixels generation by statistical region merging (SRM) based on Pauli RGB image, and a post-processing step to determine the label of a superpixel by modified majority voting...
February 17, 2018: Sensors
Ling Zhang, Yue Hu, Elizabeth Galella, Frank P Tomasella, William P Fish
In the pharmaceutical industry, the analysis of atropisomers is of considerable interest from a scientific and regulatory perspective. The compound of interest contains two stereogenic axes due to the hindered rotation around the single bonds connecting the aryl groups, which results in four potential configurational isomers (atropisomers). The separation of the four atropisomers is achieved on a derivatized β-cyclodextrin bonded stationary phase. Further investigation shows that low temperature conditions, including sample preparation (-70 °C), sample storage (-70 °C), and chromatographic separation (6 °C), were critical to preventing interconversion...
June 2017: Journal of Pharmaceutical Analysis
Gilles Roy, Gregoire Tremblay, Xiaoying Cao
The backscattering lidar depolarization parameter D of water droplets contains information on their size that can be directly modeled as a function of the forward-scattering diffraction peak. Using a polarimetric Monte Carlo simulator, water clouds having different extinctions and droplet size distributions are analyzed to estimate their depolarization parameter at various backscattering off-axis angles. It is shown that the depolarization parameter of the polarimetric phase function can be found using off-axis lidar measurements at multiple angles, and that it could be used to estimate the water-cloud droplet size...
February 1, 2018: Applied Optics
Morten Sales, Markus Strobl, Takenao Shinohara, Anton Tremsin, Luise Theil Kuhn, William R B Lionheart, Naeem M Desai, Anders Bjorholm Dahl, Søren Schmidt
Through the use of Time-of-Flight Three Dimensional Polarimetric Neutron Tomography (ToF 3DPNT) we have for the first time successfully demonstrated a technique capable of measuring and reconstructing three dimensional magnetic field strengths and directions unobtrusively and non-destructively with the potential to probe the interior of bulk samples which is not amenable otherwise. Using a pioneering polarimetric set-up for ToF neutron instrumentation in combination with a newly developed tailored reconstruction algorithm, the magnetic field generated by a current carrying solenoid has been measured and reconstructed, thereby providing the proof-of-principle of a technique able to reveal hitherto unobtainable information on the magnetic fields in the bulk of materials and devices, due to a high degree of penetration into many materials, including metals, and the sensitivity of neutron polarisation to magnetic fields...
February 2, 2018: Scientific Reports
Yonglei Chang, Pingxiang Li, Jie Yang, Jinqi Zhao, Lingli Zhao, Lei Shi
The GaoFen-3 (GF-3) satellite is the first fully polarimetric synthetic aperture radar (SAR) satellite designed for civil use in China. The satellite operates in the C-band and has 12 imaging modes for various applications. Three fully polarimetric SAR (PolSAR) imaging modes are provided with a resolution of up to 8 m. Although polarimetric calibration (PolCAL) of the SAR system is periodically undertaken, there is still some residual distortion in the images. In order to assess the polarimetric accuracy of this satellite and improve the image quality, we analyzed the polarimetric distortion errors and performed a PolCAL experiment based on scattering properties and corner reflectors...
January 30, 2018: Sensors
Tao Zhou, Zhaofu Li, Jianjun Pan
This paper focuses on evaluating the ability and contribution of using backscatter intensity, texture, coherence, and color features extracted from Sentinel-1A data for urban land cover classification and comparing different multi-sensor land cover mapping methods to improve classification accuracy. Both Landsat-8 OLI and Hyperion images were also acquired, in combination with Sentinel-1A data, to explore the potential of different multi-sensor urban land cover mapping methods to improve classification accuracy...
January 27, 2018: Sensors
Krzysztof M Czajkowski, Anna Pastuszczak, Rafał Kotyński
Single-pixel imaging is an indirect imaging technique which utilizes simplified optical hardware and advanced computational methods. It offers novel solutions for hyper-spectral imaging, polarimetric imaging, three-dimensional imaging, holographic imaging, optical encryption and imaging through scattering media. The main limitations for its use come from relatively high measurement and reconstruction times. In this paper we propose to reduce the required signal acquisition time by using a novel sampling scheme based on a random selection of Morlet wavelets convolved with white noise...
January 11, 2018: Scientific Reports
Thomas Wells Cronin, Missael Garcia, Viktor Gruev
Multispectral, hyperspectral, polarimetric, and other types of multichannel imaging spectrometers are coming into common use for a variety of applications, including remote sensing, material identification, forensics, and medical diagnosis. These instruments are often bulky and intolerant of field abuse, so designing compact, reliable, portable, and robust devices is a priority. In contrast to most engineering designs, animals have been building compact and robust multichannel imaging systems for millennia - their eyes...
January 9, 2018: Bioinspiration & Biomimetics
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