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https://www.readbyqxmd.com/read/29323211/single-pixel-imaging-with-morlet-wavelet-correlated-random-patterns
#1
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
https://www.readbyqxmd.com/read/29313524/multichannel-spectrometers-in-animals
#2
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
https://www.readbyqxmd.com/read/29296490/detection-of-optical-activity-with-diode-integrated-hyperbolic-metasurfaces
#3
Joseph S T Smalley, Felipe Vallini, Yeshaiahu Fainman
We present an analytical technique for designing integrated polarized light-emitting diodes (LEDs) and polarization-sensitive photodiodes (PD) based on hyperbolic metasurfaces (HMS) for the detection of optical activity. Leveraging effective medium theory and the scattering matrix method, we first derive the conditions for optimizing the transmission efficiency of an LED-integrated HMS and the absorption efficiency of a PD-integrated HMS. We then propose using a differential detection technique with orthogonally oriented PD-integrated HMS to measure optical activity in an extremely compact volume...
December 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29289238/noise-characterization-for-resonantly-enhanced-polarimetric-vacuum-magnetic-birefringence-experiments
#4
M T Hartman, A Rivère, R Battesti, C Rizzo
In this work we present data characterizing the sensitivity of the Biréfringence Magnetique du Vide (BMV) instrument. BMV is an experiment attempting to measure vacuum magnetic birefringence (VMB) via the measurement of an ellipticity induced in a linearly polarized laser field propagating through a birefringent region of vacuum in the presence of an external magnetic field. Correlated measurements of laser noise alongside the measurement in the main detection channel allow us to separate measured sensing noise from the inherent birefringence noise of the apparatus...
December 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29248662/coronary-plaque-microstructure-and-composition-modify-optical-polarization-a-new-endogenous-contrast-mechanism-for-optical-frequency-domain-imaging
#5
Martin Villiger, Kenichiro Otsuka, Antonios Karanasos, Pallavi Doradla, Jian Ren, Norman Lippok, Milen Shishkov, Joost Daemen, Roberto Diletti, Robert-Jan van Geuns, Felix Zijlstra, Gijs van Soest, Peter Libby, Evelyn Regar, Seemantini K Nadkarni, Brett E Bouma
OBJECTIVES: This study aimed to evaluate whether polarimetry, performed using a modified optical frequency domain imaging (OFDI) system, can improve the assessment of histological features relevant to characterizing human coronary atherosclerosis. BACKGROUND: The microscopic structure and organization of the arterial wall influence the polarization of the infrared light used by OFDI. Modification of the OFDI apparatus, along with recently developed image reconstruction methods, permits polarimetric measurements simultaneously with conventional OFDI cross-sectional imaging through standard intravascular imaging catheters...
December 9, 2017: JACC. Cardiovascular Imaging
https://www.readbyqxmd.com/read/29240675/improvement-of-gaofen-3-absolute-positioning-accuracy-based-on-cross-calibration
#6
Mingjun Deng, Guo Zhang, Ruishan Zhao, Shaoning Li, Jiansong Li
The Chinese Gaofen-3 (GF-3) mission was launched in August 2016, equipped with a full polarimetric synthetic aperture radar (SAR) sensor in the C-band, with a resolution of up to 1 m. The absolute positioning accuracy of GF-3 is of great importance, and in-orbit geometric calibration is a key technology for improving absolute positioning accuracy. Conventional geometric calibration is used to accurately calibrate the geometric calibration parameters of the image (internal delay and azimuth shifts) using high-precision ground control data, which are highly dependent on the control data of the calibration field, but it remains costly and labor-intensive to monitor changes in GF-3's geometric calibration parameters...
December 14, 2017: Sensors
https://www.readbyqxmd.com/read/29240104/validity-of-the-kirchhoff-approximation-for-the-scattering-of-electromagnetic-waves-from-dielectric-doubly-periodic-surfaces
#7
M Franco, M Barber, M Maas, O Bruno, F Grings, E Calzetta
Accuracy of Kirchhoff approximation (KA) for rough-surface electromagnetic wave scattering is studied by comparison with accurate numerical solutions in the context of three-dimensional dielectric surfaces. The Kirchhoff tangent plane approximation is examined without resorting to the principle of stationary phase. In particular, it is shown that this additional assumption leads to zero cross-polarized backscattered power, but not the tangent plane approximation itself. Extensive numerical results in the case of a bisinusoidal surface are presented for a wide range of problem parameters: height-to-period, wavelength, incidence angles, and dielectric constants...
December 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
https://www.readbyqxmd.com/read/29221042/image-processing-pipeline-for-segmentation-and-material-classification-based-on-multispectral-high-dynamic-range-polarimetric-images
#8
Miguel Ángel Martínez-Domingo, Eva M Valero, Javier Hernández-Andrés, Shoji Tominaga, Takahiko Horiuchi, Keita Hirai
We propose a method for the capture of high dynamic range (HDR), multispectral (MS), polarimetric (Pol) images of indoor scenes using a liquid crystal tunable filter (LCTF). We have included the adaptive exposure estimation (AEE) method to fully automatize the capturing process. We also propose a pre-processing method which can be applied for the registration of HDR images after they are already built as the result of combining different low dynamic range (LDR) images. This method is applied to ensure a correct alignment of the different polarization HDR images for each spectral band...
November 27, 2017: Optics Express
https://www.readbyqxmd.com/read/29194354/assessment-of-gf-3-polarimetric-sar-data-for-physical-scattering-mechanism-analysis-and-terrain-classification
#9
Junjun Yin, Jian Yang, Qingjun Zhang
On 10 August 2016 China launched the GF-3, its first C-band polarimetric synthetic aperture radar (SAR) satellite, which was put into operation at the end of January, 2017. GF-3 polarimetric SAR has many advantages such as high resolution and multi-polarization imaging capabilities. Polarimetric SAR can fully characterize the backscatter property of targets, and thus it is of great interest to explore the physical scattering mechanisms of terrain types, which is very important in interpreting polarimetric SAR imagery and for its further usages in Earth observations...
December 1, 2017: Sensors
https://www.readbyqxmd.com/read/29188092/real-time-complete-stokes-polarimetric-imager-based-on-a-linear-polarizer-array-camera-for-tissue-polarimetric-imaging
#10
Ji Qi, Chao He, Daniel S Elson
Tissue polarimetric imaging measures Mueller matrices of tissues or Stokes vectors of the emergent light from tissues (normally using incidence with a fixed polarization state) over a field of view, and has demonstrated utility in a number of surgical and diagnostic applications. Here we introduce a compact complete Stokes polarimetric imager that can work for multiple wavelength bands with a frame-rate suitable for real-time applications. The imager was validated with standard polarizing components, and then employed as a polarization state analyzer of a Mueller imaging polarimeter and a standalone Stokes imaging polarimeter respectively to image the process of dehydration of bovine tendon tissue...
November 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/29165382/review-of-the-functions-of-archimedes-spiral-metallic-nanostructures
#11
REVIEW
Zhongyi Guo, Zixiang Li, Jingran Zhang, Kai Guo, Fei Shen, Qingfeng Zhou, Hongping Zhou
Here, we have reviewed some typical plasmonic structures based on Archimedes' spiral (AS) architectures, which can produce polarization-sensitive focusing phenomenon and generate plasmonic vortices (PVs) carrying controllable orbital angular momentum (OAM) because of the relation between the incident polarized states and the chiralities of the spiral structures. These features can be used to analyze different circular polarization states, which has been one of the rapidly developing researching topics in nanophotonics in recent years...
November 22, 2017: Nanomaterials
https://www.readbyqxmd.com/read/29158622/kinematic-and-microphysical-significance-of-lightning-jumps-versus-non-jump-increases-in-total-flash-rate
#12
Christopher J Schultz, Lawrence D Carey, Elise V Schultz, Richard J Blakeslee
Thirty-nine thunderstorms are examined using multiple-Doppler, polarimetric and total lightning observations to understand the role of mixed phase kinematics and microphysics in the development of lightning jumps. This sample size is larger than those of previous studies on this topic. The principal result of this study is that lightning jumps are a result of mixed phase updraft intensification. Larger increases in intense updraft volume (≥ 10 m s(-1)) and larger changes in peak updraft speed are observed prior to lightning jump occurrence when compared to other non-jump increases in total flash rate...
February 2017: Weather and Forecasting
https://www.readbyqxmd.com/read/29140363/snapshot-second-harmonic-generation-polarimeter-based-on-spectral-analysis
#13
Matthieu Dubreuil, Sylvain Rivet, Yann Le Grand
A new high-speed second-harmonic generation (SHG) polarimetric method is reported. It is based on the spectral analysis of the SHG radiation emitted by a nonlinear medium excited with circularly polarized femtosecond laser pulses. The setup uses only passive components for polarization encoding and a fast spectrometer for spectral analysis. The method is validated on a z-cut quartz plate, then on a collagen-rich biological tissue with a view to single image polarization-resolved SHG microscopy.
November 15, 2017: Optics Letters
https://www.readbyqxmd.com/read/29131523/assessment-of-tissue-polarimetric-properties-using-stokes-polarimetric-imaging-with-circularly-polarized-illumination
#14
Ji Qi, Honghui He, Jianyu Lin, Yang Dong, Dongsheng Chen, Hui Ma, Daniel S Elson
Tissue depolarization and linear retardance are the main polarization characteristics of interest for bulk tissue characterization, and are normally interpreted from Mueller polarimetry. Stokes polarimetry can be conducted using simpler instrumentation and in a shorter time. Here we use Stokes polarimetric imaging with circularly polarized illumination to assess the circular depolarization and linear retardance properties of tissue. Results obtained were compared with Mueller polarimetry in transmission and reflection geometry respectively...
November 13, 2017: Journal of Biophotonics
https://www.readbyqxmd.com/read/29092500/use-of-a-novel-infrared-wavelength-tunable-laser-mueller-matrix-polarimetric-scatterometer-to-measure-nanostructured-optical-materials
#15
Jason C Vap, Stephen E Nauyoks, Michael R Benson, Michael A Marciniak
Nanostructured optical materials, for example, metamaterials, have unique spectral, directional, and polarimetric properties. Samples designed and fabricated for infrared (IR) wavelengths have been characterized using broadband instruments to measure specular polarimetric transmittance or reflectance as in ellipsometry or integrated hemisphere transmittance or reflectance. We have developed a wavelength-tunable IR Mueller-matrix (Mm) polarimetric scatterometer which uses tunable external-cavity quantum-cascade lasers (EC-QCLs) to tune onto and off of the narrowband spectral resonances of nanostructured optical materials and performed full polarimeteric and directional evaluation to more fully characterize their behavior...
October 2017: Review of Scientific Instruments
https://www.readbyqxmd.com/read/29092221/computational-polarimetric-microwave-imaging
#16
Thomas Fromenteze, Okan Yurduseven, Michael Boyarsky, Jonah Gollub, Daniel L Marks, David R Smith
We propose a polarimetric microwave imaging technique that exploits recent advances in computational imaging. We utilize a frequency-diverse cavity-backed metasurface, allowing us to demonstrate high-resolution polarimetric imaging using a single transceiver and frequency sweep over the operational microwave bandwidth. The frequency-diverse metasurface imager greatly simplifies the system architecture compared with active arrays and other conventional microwave imaging approaches. We further develop the theoretical framework for computational polarimetric imaging and validate the approach experimentally using a multi-modal leaky cavity...
October 30, 2017: Optics Express
https://www.readbyqxmd.com/read/29091628/methods-of-polarimetric-calibration-and-reconstruction-for-a-fieldable-channeled-dispersive-imaging-spectropolarimeter
#17
Bin Yang, Junqiang Zhang, Changxiang Yan, Xueping Ju
Polarimetric calibration and reconstruction methods for a fieldable channeled dispersive imaging spectropolarimeter (CDISP) are presented. A theoretical model for the polarimetric calibration is derived first. In the polarimetric calibration for the CDISP, the alignment errors of the polarimetric spectral intensity modulation module, and the polarization effects of the optical system and phase factors of the high-order retarders at different viewing angles, are considered and determined independently. Based on the results of the polarimetric calibration, the Stokes vector of the target is reconstructed through the derived reconstruction model...
October 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29091625/polar-decompositions-of-negative-determinant-mueller-matrices-featuring-nondiagonal-depolarizers
#18
Razvigor Ossikovski, Jérémy Vizet
We generalize an existing algebraic procedure for the polar decomposition of Mueller matrices with negative determinants [Opt. Commun.281, 2406 (2008)OPCOB80030-401810.1016/j.optcom.2007.12.076] to the case of nondiagonal depolarizer matrix factors. The generalized procedure is applied to experimental Mueller matrices illustrating its potential for the phenomenological interpretation of complex polarimetric data.
October 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29091613/polarization-optics-of-the-brewster-s-dark-patch-visible-on-water-surfaces-versus-solar-height-and-sky-conditions-theory-computer-modeling-photography-and-painting
#19
Péter Takács, András Barta, David Pye, Gábor Horváth
When the sun is near the horizon, a circular band with approximately vertically polarized skylight is formed at 90° from the sun, and this skylight is only weakly reflected from the region of the water surface around the Brewster's angle (53° from the nadir). Thus, at low solar heights under a clear sky, an extended dark patch is visible on the water surface when one looks toward the north or south quarter perpendicular to the solar vertical. In this work, we study the radiance distribution of this so-called Brewster's dark patch (BDP) in still water as functions of the solar height and sky conditions...
October 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/29076312/use-of-combined-polarization-sensitive-optical-coherence-tomography-and-mueller-matrix-imaging-for-the-polarimetric-characterization-of-excised-biological-tissue-erratum
#20
Joseph Chue-Sang, Yuqiang Bai, Susan Stoff, David Straton, Sharan Ramaswamy, Jessica C Ramella-Romana
This erratum corrects two errors in the original paper.
October 2017: Journal of Biomedical Optics
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