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Demonstration of 136 dB dynamic range capability for a simultaneous dual optical band CAOS camera

OPTICS EXPRESS 2016年第26期24卷 29427-29443页

作者： Riza, Nabeel A. La Torre, J. Pablo Univ Coll Cork Sch Engn Coll Rd Cork Ireland

For the first time, proposed and demonstrated is a simultaneous dual optical band coded access optical sensor (CAOS) camera design suited for extreme contrast multispectral bright target scenarios. Deploying a digital micromirror devices (DMDs)-based time-frequency agile pixels CAOS-mode within a two point detector spatially and spectrally isolating framework, this imager simultaneously and independently detects pixel selective image information for two different broad spectral bands that further undergo independent spectral image data extraction via finer-tuned wavelength filtering using all-optical or CAOSmode electronic filters. A proof-of-concept visible-near infrared band CAOS imager is successfully demonstrated using a target scene containing LEDs and engaging narrowband optical filters. In addition, using the CAOS-mode, demonstrated is the RF domain simultaneous color content monitoring of a white light LED image pixel. Also proposed is the use of a higher bit count analog-to-digital converter (ADC) with both range and sampling duration parameter control along with a larger data set electronic DSP to extract higher DSP gain and realize additional noise suppression. Using a 16-bit ADC and 2,097,152 point fast Fourier transform (FFT) digital signal processing (DSP) for a 633 nm laser engaged test target scene that is subject to nearly 7 decades (10(7)) of gradual optical attenuation, the experimental camera demonstrates an agile pixel extreme dynamic range of 136 dB, which is a 56 dB improvement over the previous CAOS-imaging demonstrations. (C) 2016 Optical Society of America

关键词： Digital micromirror devices image processing image processing algorithms Multispectral imaging Optical wireless communication Variable optical attenuators

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Noncontact detection of Teflon inclusions in glass-fiber-reinforced polymer composites using terahertz imaging

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APPLIED OPTICS 2016年第36期55卷 10215-10222页

作者： Zhang, Jin Wang, Jie Han, Xiaohui Cui, Hong-Liang Shi, Changcheng Zhang, Jinbo Shen, Yan Jilin Univ Coll Instrumentat & Elect Engn Changchun 130061 Peoples R China Chinese Acad Sci Chongqing Inst Green & Intelligent Technol Key Lab Multiscale Mfg Technol Res Ctr Terahertz Technol Chongqing 400714 Peoples R China Harbin FRP Inst Harbin 150036 Peoples R China Chongqing Polycomp Int Corp Chongqing 400082 Peoples R China

We employed terahertz (THz) time-domain spectroscopy (TDS) imaging technology, a new nondestructive testing method, to detect the inclusions of glass-fiber-reinforced polymer (GFRP) composites. The refractive index and absorption coefficient of two types of GFRP composites (epoxy GFRP composites and polyester GFRP composites) were first extracted, and GFRP composites with Teflon inclusions were examined, including an epoxy GFRP solid panel with a smaller Teflon inclusion hidden behind a larger Teflon inclusion, and polyester GFRP solid panels with Teflon inclusions of various sizes, at different depths. It was experimentally demonstrated that THz TDS imaging technology could clearly detect a smaller inclusion hidden behind a larger inclusion. When the reflected THz pulse from the inclusion did not overlap with that from the front surface of the sample, removal of the latter before Fourier transform was shown to be helpful in imaging the inclusions. With sufficiently strong incident THz radiation, inclusion insertion depth had little impact on the ability of the THz wave to detect inclusions. However, as the thickness of the inclusion became thinner, the inclusion detection ability of the THz wave deteriorated. In addition, with a combination of reflected C-scan imaging and B-scan imaging using the reflected time-domain waveform, both the lateral sizes and locations of the inclusions and the depths and thicknesses of the inclusions were clearly ascertained. (C) 2016 Optical Society of America

关键词： Absorption coefficient image processing image processing algorithms Imaging techniques Refractive index Terahertz imaging

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Broadening the detection view of 2D photoacoustic tomography using two linear array transducers

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OPTICS EXPRESS 2016年第12期24卷 12755-12768页

作者： Shu, Weihang Ai, Min Salcudean, Tim Rohling, Robert Abolmaesumi, Purang Tang, Shuo Univ British Columbia Dept Elect & Comp Engn 2332 Main Mall Vancouver BC V6T 1Z4 Canada

Although commercial linear array transducers are widely used in clinical ultrasound, their application in photoacoustic tomography (PAT) is still limited due to the limited-view problem that restricts the image quality. In this paper, we propose a simple approach to address the limited-view problem in 2D by using two linear array transducers to receive PAT signal from different orientations. The positions of the two transducers can be adjusted to fit the specific geometry of an imaging site. This approach is made possible by using a new calibration method, where the relative position between the two transducers can be calibrated using ultrasound by transmitting ultrasound wave with one transducer while receiving with the other. The calibration results are then applied in the subsequent PAT imaging to incorporate the detected acoustic signals from both transducers and thereby increase the detection view. In this calibration method, no calibration phantom is required which largely simplifies and shortens the process. The efficacy of the calibration and improvement on the PAT image quality are demonstrated through phantom studies and in vivo imaging. (C) 2016 Optical Society of America

关键词： image processing algorithms image quality In vivo imaging Medical imaging Phantom studies Three dimensional imaging

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Effective star tracking method based on optical flow analysis for star trackers

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APPLIED OPTICS 2016年第36期55卷 10335-10340页

作者： Sun, Ting Xing, Fei Wang, Xiaochu Li, Jin Wei, Minsong You, Zheng Tsinghua Univ Dept Precis Instrument Beijing 100084 Peoples R China Beijing Informat Sci & Technol Univ Sch Instrument Sci & Opto Elect Engn Beijing 100192 Peoples R China China Acad Space Technol Qian Xuesen Lab Space Technol Beijing 100094 Peoples R China

Benefiting from rapid development of imaging sensor technology, modern optical technology, and a high-speed computing chip, the star tracker's accuracy, dynamic performance, and update rate have been greatly improved with low power consumption and miniature size. The star tracker is currently one of the most competitive attitude measurement sensors. However, due to restrictions of the optical imaging system, difficulties still exist in moving star spot detection and star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this paper. Spot-based optical flow, based on a gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain an accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct an angular velocity estimation to ensure region prediction of the star spot;this can be combined with the optical flow analysis result. Experiment results show that the method proposed in this paper has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved;thus, the star tracker can be more widely applied in small satellites, remote sensing, and other complex space missions. (C) 2016 Optical Society of America

关键词： image analysis image processing algorithms image sensors Imaging noise Optical flow Remote sensing

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Advanced video extensometer for non-contact, real-time, high-accuracy strain measurement

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OPTICS EXPRESS 2016年第17期24卷 19082-19093页

作者： Pan, Bing Tian, Long Beihang Univ Inst Solid Mech Beijing 100191 Peoples R China

We developed an advanced video extensometer for non-contact, real-time, high-accuracy strain measurement in material testing. In the established video extensometer, a "near perfect and ultra-stable" imaging system, combining the idea of active imaging with a high-quality bilateral telecentric lens, is constructed to acquire high-fidelity video images of the test sample surface, which is invariant to ambient lighting changes and small out-of-plane motions occurred between the object surface and image plane. In addition, an efficient and accurate inverse compositional Gauss-Newton algorithm incorporating a temporal initial guess transfer scheme and a high-accuracy interpolation method is employed to achieve real-time, high-accuracy displacement tracking with negligible bias error. Tensile tests of an aluminum sample and a carbon fiber filament sample were performed to demonstrate the efficiency, repeatability and accuracy of the developed advanced video extensometer. The results indicate that longitudinal and transversal strains can be estimated and plotted at a rate of 117 fps and with a maximum strain error less than 30 microstrains. (C) 2016 Optical Society of America

关键词： Digital image processing image processing algorithms image registration Optical imaging Speckle imaging Strain measurement

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On-orbit calibration approach for optical navigation camera in deep space exploration

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OPTICS EXPRESS 2016年第5期24卷 5536-5554页

作者： Wang, Mi Cheng, Yufeng Yang, Bo Jin, Shuying Su, Hongbo Wuhan Univ State Key Lab Informat Engn Surveying Mapping & R Wuhan 430079 Peoples R China Wuhan Univ Collaborat Innovat Ctr Geospatial Technol Wuhan 430079 Peoples R China Florida Atlantic Univ Dept Civil Environm & Geomat Engn Boca Raton FL 33431 USA

A spacecraft-borne optical navigation camera is one of the key instruments for optical autonomous navigation, and the line of sight (LOS) of the camera directly affects the accuracy of navigation. We developed an on-orbit calibration approach for a navigation camera to ensure the accuracy, in which a stepwise calibration is performed, external parameters estimated, and internal parameters estimated in a generalized camera frame determined by external parameters. In addition, we proposed a batch and sequential on-orbit estimation method to save on-orbit computing power, and established a strategy to reject misidentified reference stars while keeping consistency in on-orbit parameters estimation. After the calibration, the accuracy of LOS in inertial frame satisfied the need in optical autonomous navigation. The results have been proven precise and robust in three experiments. (C) 2016 Optical Society of America

关键词： Antennas Calibration Camera calibration image processing image processing algorithms Sensors

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Fast ultrasound signal and image processing on a tablet device

Fast ultrasound signal and image processing on a tablet devi...

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IEEE International Ultrasonics Symposium (IUS)

作者： Kiss, Gabriel Khan, Naiad Hossain Tegnander, Eva Eik-Nes, Sturla H. Torp, Hans Norwegian Univ Sci & Technol Dept Circulat & Med Imaging N-7034 Trondheim Norway Norwegian Univ Sci & Technol MI Lab N-7034 Trondheim Norway St Olavs Hosp Natl Ctr Fetal Med Trondheim Norway Norwegian Univ Sci & Technol Childrens & Womens Hlth Dept Lab Med N-7034 Trondheim Norway

ISBN: (纸本)9781479981823

During the last decade, portable ultrasound devices have been proven beneficial in a variety of situations (e.g. OB/GYN, point of care and cardiovascular applications). The aim of this work is to investigate the feasibility of implementing standard signal and image processing algorithms on a tablet device, instead of the scanner's backend unit. Furthermore, the additional benefit of using the tablet's graphical processing unit to offload the CPU intensive tasks and balance the battery consumption was tested. A plugin for streaming data over a wired or wireless TCP/IP connection from an ultrasound scanner was implemented and data sent to a tablet device which runs the image and signal processing algorithms. The use of compute shaders for further optimizations was investigated. The prototype was tested by midwives, both experienced and inexperienced in the use of ultrasound, in Norway and South Africa. Afterwards they were asked to fill out standard system usability scale forms. Conclusively, most of the backend components of an ultrasound scanner can be implemented on a tablet's GPU. Compute shaders have a significant impact on battery consumption, which can be reduced by a factor of up to 3 and as such significantly extend the scanning time of a portable system.

关键词： biomedical equipment biomedical ultrasonics medical image processing transport protocols CPU intensive tasks battery consumption cardiovascular applications graphical processing unit image processing algorithms portable system portable ultrasound devices signal processing algorithms tablet device ultrasound image processing ultrasound scanner ultrasound signal processing wireless TCP/IP connection Doppler effect image color analysis Message systems Prototypes Standards Streaming media Ultrasonic imaging ultrasound scanner portable system Computer based information systems image processing algorithm Signal processing algorithms Medical device image colour analysis biomedical ultrasonics Streaming Video Ultrasonography Medical image processing transport protocols Doppler effect PROTOTYPE

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Improved cancer diagnostics by different image processing techniques on OCT images

Improved cancer diagnostics by different image processing te...

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Conference on Optical Coherence Imaging Techniques and Imaging in Scattering Media

作者： Kanawade, Rajesh Lengenfelder, Benjamin Menezes, Tassiana Marini Hohmann, Martin Kopfinger, Stefan Hohmann, Tim Grabiec, Urszula Klaempfl, Florian Menezes, Jean Gonzales Waldner, Maximilian Schmidt, Michael Univ Erlangen Nurnberg Inst Photon Technol D-91052 Erlangen Germany Univ Erlangen Nurnberg Erlangen Grad Sch Adv Opt Technol SAOT Clin Photon Lab D-91052 Erlangen Germany Univ Erlangen Nurnberg Dept Med 1 D-91054 Erlangen Germany Univ Halle Wittenberg Inst Anat & Zellbiol Med Fak D-06108 Martin Saale Germany

ISBN: (纸本)9781628417067

Optical-coherence tomography (OCT) is a promising non-invasive, high-resolution imaging modality which can be used for cancer diagnosis and its therapeutic assessment. However, speckle noise makes detection of cancer boundaries and image segmentation problematic and unreliable. Therefore, to improve the image analysis for a precise cancer border detection, the performance of different image processing algorithms such as mean, median, hybrid median filter and rotational kernel transformation (RKT) for this task is investigated. This is done on OCT images acquired from an ex-vivo human cancerous mucosa and in vitro by using cultivated tumour applied on organotypical hippocampal slice cultures. The preliminary results confirm that the border between the healthy and the cancer lesions can be identified precisely. The obtained results are verified with fluorescence microscopy. This research can improve cancer diagnosis and the detection of borders between healthy and cancerous tissue. Thus, it could also reduce the number of biopsies required during screening endoscopy by providing better guidance to the physician.

关键词： Optical-coherence tomography cancer diagnosis image processing algorithms

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Improved edge detection of regions enriched with gold nanorods inside biological phantom

Improved edge detection of regions enriched with gold nanoro...

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Conference on Lasers and Electro-Optics Europe

作者： Yossef Danan Moshe Sinvani Zeev Zalevsky Faculty of Engineering Bar-Ilan University Ramat-Gan 52900 Israel

ISBN: (纸本)9781509067374

The ability to resect a tumor completely is a key merit in preventing recurrence of the disease. In order to achieve more complete tumor resection the surgeon must clearly identify the tumor margins. This identification is even more crucial when the tumor growth is adjacent or in neurological structures, and therefore it is dangerous to remove extra tissue [1], [2].

关键词： Edge detection image processing algorithms Nanorods Spatial resolution Thermal imaging Tissue

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Advances in Infrared Technology and Applications: introduction

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APPLIED OPTICS 2016年第34期55卷 ITA1-ITA4页

作者： Strojnik, Marija D'Acunto, Mario Rogalski, Antoni Opt Res Ctr Apartado Postal 1-948 Leon 37000 Mexico Univ Guadalajara Av Juarez 976 Guadalajara 44100 Jalisco Mexico Polish Acad Sci PL-00901 Warsaw Poland

The special issue of Applied Optics on Advanced Infrared Technology andApplications(AITA) arose out of the biannual conference of the samename, most recently held in Pisa, Italy, 29 September to 2 October,2015.

关键词： Digital image processing Finite element method image processing algorithms Indium tin oxide Laser beams Physical vapor deposition

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