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Gábor Horváth, Péter Takács, Balázs Kretzer, Szilvia Szilasi, Dénes Száz, Alexandra Farkas, András Barta
If a human looks at the clear blue sky from which light with high enough degree of polarization d originates, an 8-shaped bowtie-like figure, the yellow Haidinger's brush can be perceived, the long axis of which points towards the sun. A band of high d arcs across the sky at 90° from the sun. A person can pick two points on that band, observe the yellow brushes and triangulate the position of the sun based on the orientation of the two observed brushes. This method has been suggested to have been used on the open sea by Viking navigators to determine the position of the invisible sun occluded by cloud or fog...
February 2017: Royal Society Open Science
Changhun Lee, Eunji Sim, Donghyun Kim
We explore plasmon-enhanced wire-gird polarizers (WGPs) to achieve improved polarimetric performance with more relaxed fabrication parameters compared to conventional WGP. A WGP designed with a blazed wire-grid profile was considered for plasmonic enhancement. The results show that a blazed WGP can achieve extremely high polarimetric extinction at a longer wire-grid period (Λ) compared to conventional WGP structure. Under the optimum geometrical parameters, a blazed WGP may attain an extinction ratio of over 40 dB at Λ = 800 nm, which may allow photolithography for fabrication...
April 3, 2017: Optics Express
Chaodong Wang, Ruolin Liao, Wenbo Chen, Ming Tang, Songnian Fu, Jianguan Tang, Ciming Zhou, Deming Liu
In polarization optical time domain reflectometry (POTDR) system, the performance of polarimetric measurement is constrained by the low signal to noise ratio (SNR) due to the weak Rayleigh backscattering and the degradation of the degree of polarization (DOP) of signal light. Therefore, it is indispensable to improve the SNR without sacrificing the DOP of backscattered signal for a sufficient dynamic range. In this paper, a Simplex coded POTDR (sc-POTDR) system is proposed and demonstrated. The relationships between the signal's DOP and coding length/bit width are studied...
March 6, 2017: Optics Express
François Goudail, Matthieu Boffety
We quantitatively determine the target detection performance of different passive polarization imaging architectures perturbed by signal-independent detection noise or signal-dependent Poisson shot noise. We compare the fully adaptive polarimetric imager and the best channel of a static polarimetric imager, and in each case, we compare the use of a polarizer and a polarizing beam splitter as the polarization analyzing device. For all these configurations, we derive a closed-form expression of the target/background separability and quantify the performance gain brought by polarization imaging compared to standard intensity imaging...
April 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Premananda Dey, Rohit Shukla, D Venkateswarlu
With the commercialization of powerful solid-state lasers as pointer lasers, it is becoming simpler nowadays for the launch and free-space reception of polarized light for polarimetric applications. Additionally, because of the high power of such laser diodes, the alignment of the received light on the small sensor area of a photo-diode with a high bandwidth response is also greatly simplified. A plastic sheet polarizer taken from spectacles of 3D television (commercially available) is simply implemented as an analyzer before the photo-receiver...
April 1, 2017: Applied Optics
Aleksandr Bystrov, Edward Hoare, Thuy-Yung Tran, Nigel Clarke, Marina Gashinova, Mikhail Cherniakov
In this paper we shall discuss a novel approach to road surface recognition, based on the analysis of backscattered microwave and ultrasonic signals. The novelty of our method is sonar and polarimetric radar data fusion, extraction of features for separate swathes of illuminated surface (segmentation), and using of multi-stage artificial neural network for surface classification. The developed system consists of 24 GHz radar and 40 kHz ultrasonic sensor. The features are extracted from backscattered signals and then the procedures of principal component analysis and supervised classification are applied to feature data...
April 1, 2017: Sensors
Michael Woolman, Adam Gribble, Emma Bluemke, Jing Zou, Manuela Ventura, Nicholas Bernards, Megan Wu, Howard J Ginsberg, Sunit Das, Alex Vitkin, Arash Zarrine-Afsar
Spatially Targeted Mass Spectrometry (MS) analysis using survey scans with an imaging modality often requires consecutive tissue slices, because of the tissue damage during survey scan or due to incompatible sample preparation requirements between the survey modality and MS. We report two spatially targeted MS analysis workflows based on polarized light imaging guidance that use the same tissue sample for survey and targeted analysis. The first workflow is applicable for thin-slice analysis, and uses transmission-polarimetry-guided Desorption ElectroSpray Ionization Mass Spectrometry (DESI-MS), and confirmatory H&E histopathology analysis on the same slice; this is validated using quantitative digital pathology methods...
March 28, 2017: Scientific Reports
Zhongqiu Sun, Di Wu, Yunfeng Lv
The optical scattering property of a target is the essential signal for passive remote sensing. In this study, we performed the photopolarimetric measurements of a manmade target in the wavelength range of 400-1000 nm over the hemispherical directions using the Northeast Normal University Laboratory Goniospectrometer System (NENULGS). We discussed the influence of the absorption of a polarizer on the measured Stokes parameters, and used the BRF (bidirectional reflectance factor) and BPRF (bidirectional polarized reflectance factor) to characterize the scattering property of our sample at selected wavelengths...
February 20, 2017: Optics Express
Mingxuan Yu, Hesong Huang, Haofeng Hu, Lan Wu, Hongchen Zhai, Tiegen Liu
Traditional methods of discrimination for Stokes polarimetric imaging use grayscale images, in which the difference of the polarimetric properties is only reflected by the difference of grayscale. In this paper, we propose a method of colorimetric discrimination and classification for Stokes polarimetric imaging by the composed color polarimetric image, in which the objects with different polarization properties can appear in different colors. We show with real-world experiment that compared with the traditional method for the grayscale Stokes scalar image, the method proposed in this paper has a better performance for distinguishing objects with different polarization properties...
February 20, 2017: Optics Express
Francois Parnet, Julien Fade, Noé Ortega-Quijano, Goulc'hen Loas, Ludovic Frein, Mehdi Alouini
We report the design and optimization of an active polarimetric imaging demonstrator operating at 1.55 μm that is based on the orthogonality breaking technique. It relies on the use of a fibered dual-frequency dual-polarization source raster scanned over the scene. A dedicated opto-electronic detection chain is developed to demodulate the optical signal backscattered at each location of the scene in real time, providing multivariate polarimetric image data in one single scan with limited acquisition time. We experimentally show on a homemade scene that contrast maps can be built to reveal hidden dichroic objects over a depolarizing background, as well as their orientation...
February 15, 2017: Optics Letters
Bo Zhang, Chao Wang, Hong Zhang, Fan Wu, Yi-Xian Tang
By acquiring information over a wide area regardless of weather conditions and solar illumination, space-borne Synthetic Aperture Radar (SAR) has the potential to be a promising application for traffic monitoring. However, the backscatter character of a vehicle in a SAR image is unstable and varies with image parameters, such as aspect and incidence angle. To investigate vehicle detectability in SAR images for traffic monitoring applications, images of four common types of vehicles in China were acquired using the fully polarimetric (FP) SAR of Radarsat-2 in our experiments...
February 6, 2017: Sensors
Wenfei Zhang, Jian Liang, Liyong Ren, Haijuan Ju, Enshi Qu, Zhaofeng Bai, Yao Tang, Zhaoxin Wu
Polarimetric dehazing methods have been proven to be effective in enhancing the quality of images acquired in turbid media. We report a new full-Stokes polarimetric camera, which is based on the division of aperture structure. We design a kind of automatic polarimetric dehazing algorithm and load it into the field programmable gate array (FPGA) modules of our designed polarimetric camera, achieving a real-time image haze removal with an output rate of 25 fps. We demonstrate that the image quality can be significantly improved together with a good color restoration...
February 1, 2017: Applied Optics
Xiao Huang, Jian Bai, Kaiwei Wang, Qun Liu, Yujie Luo, Kailun Yang, Xianjing Zhang
Structured light is a prevailing and reliable active approach of 3D object reconstruction. But complex ambience is undesirable in the measurement because it could cause severe noise and increase computing overhead. In this paper, we propose a structured light coded by spatially-distributed polarization state of the illuminating patterns. The proposed structured light has the advantage of enhancing target in 3D reconstruction by polarization cues. Specifically, this method can estimate the degree of linear polarization (DOLP) in the scene, distinguish target by DOLP and selectively reconstruct it...
January 23, 2017: Optics Express
Alex J Yuffa, Vadym Kaydash, Viktor Korokhin, Yuriy Shkuratov, Evgenij Zubko, Gorden Videen
The phase function is a measure of the light-scattered intensity, or radiance, as a function of scattering angle θ. A phase ratio is the ratio of two values of the phase function measured at different scattering angles and relates to the slope of the phase function. By taking the ratio of two images acquired at different illumination or observation conditions, a phase-ratio image can be constructed. Such images accentuate differences in the phase curves, rather than their intensities, and are more sensitive to microtopography than to material properties...
January 20, 2017: Applied Optics
Moshe Hamaoui
Vehicle state estimation is an essential prerequisite for navigation. The present approach seeks to use skylight polarization to facilitate state estimation under autonomous unconstrained flight conditions. Atmospheric scattering polarizes incident sunlight such that solar position is mathematically encoded in the resulting skylight polarization pattern. Indeed, several species of insects are able to sense skylight polarization and are believed to navigate polarimetrically. Sun-finding methodologies for polarized skylight navigation (PSN) have been proposed in the literature but typically rely on calibration updates to account for changing atmospheric conditions and/or are limited to 2D operation...
January 20, 2017: Applied Optics
Kai Wang, Jingping Zhu, Hong Liu, Bingzheng Du
An expression of the degree of polarization (DOP) based on the geometrical optics polarimetric bidirectional reflectance distribution function model is presented. In this expression, the DOP is related to the surface roughness and decreases at different reflection angles because diffuse reflection is taken into consideration. A shadowing/masking function introduced into the specular reflection expression makes the DOP values decrease as the angle of incidence or observation approaches grazing. Different kinds of materials were measured to validate the accuracy of this DOP expression...
February 1, 2017: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Licheng Jiao, Fang Liu
Inspired by the popular deep learning architecture - Deep Stacking Network (DSN), a specific deep model for polarimetric synthetic aperture radar (POLSAR) image classification is proposed in this paper, which is named as Wishart Deep Stacking Network (W-DSN). First of all, a fast implementation of Wishart distance is achieved by a special linear transformation, which speeds up the classification of POLSAR image and makes it possible to use this polarimetric information in the following Neural Network (NN). Then a single-hidden-layer neural network based on the fast Wishart distance is defined for POLSAR image classification, which is named as Wishart Network (WN) and improves the classification accuracy...
May 11, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
Andre Neumann, Jessica Lindlau, Léo Colombier, Manuel Nutz, Sina Najmaei, Jun Lou, Aditya D Mohite, Hisato Yamaguchi, Alexander Högele
Transition metal dichalcogenide semiconductors represent elementary components of layered heterostructures for emergent technologies beyond conventional optoelectronics. In their monolayer form they host electrons with quantized circular motion and associated valley polarization and valley coherence as key elements of opto-valleytronic functionality. Here, we introduce two-dimensional polarimetry as means of direct imaging of the valley pseudospin degree of freedom in monolayer transition metal dichalcogenides...
May 2017: Nature Nanotechnology
Tingkui Mu, Zeyu Chen, Chunmin Zhang, Rongguang Liang
In this paper, the design, optimization and analysis of broadband full-Stokes polarimeters with immunity to both Poisson and Gaussian noise are presented. Different from the commonly-used optimization metrics such as, the condition number (CN), the equally weighted variance (EWV), or the polarimetric modulation efficiency (PME) for Gaussian noise, the optimally balanced condition for Poisson noise (BCPN) is, for the first time, proposed and used as a metric for the optimization of polarimeters. The numerical results show that the polarimeters optimized with the BCPN have immunity to both Poisson and Gaussian noise...
December 26, 2016: Optics Express
Amalya Minasyan, Clément Trovato, Jérôme Degert, Eric Freysz, Etienne Brasselet, Emmanuel Abraham
We propose a topological beam-shaping strategy of terahertz (THz) beams using geometric phase elements made of space-variant birefringent slabs. Quasi-monochromatic THz vortex beams are produced and characterized both in amplitude and phase from the reconstructed real-time two-dimensional imaging of the electric field. Nonseparable superpositions of such vortex beams are also obtained and characterized by two-dimensional polarimetric analysis. These results emphasize the versatility of the spin-orbit electromagnetic toolbox to prepare on-demand structured light endowed with polarization-controlled orbital angular momentum content in the THz domain, which should find many uses in future THz technologies...
January 1, 2017: Optics Letters
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