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Real-time concealed-object detection and recognition with passive millimeter wave imaging

OPTICS EXPRESS 2012年第9期20卷 9371-81页

作者： Yeom, Seokwon Lee, Dong-Su Jang, YuShin Lee, Mun-Kyo Jung, Sang-Won Daegu Univ Div Comp & Commun Engn Gyongsan 712714 Gyeongbuk South Korea Samsung Thales Yongin 449885 South Korea

Millimeter wave (MMW) imaging is finding rapid adoption in security applications such as concealed object detection under clothing. A passive MMW imaging system can operate as a stand-off type sensor that scans people in both indoors and outdoors. However, the imaging system often suffers from the diffraction limit and the low signal level. Therefore, suitable intelligent image processing algorithms would be required for automatic detection and recognition of the concealed objects. This paper proposes real-time outdoor concealed-object detection and recognition with a radiometric imaging system. The concealed object region is extracted by the multi-level segmentation. A novel approach is proposed to measure similarity between two binary images. Principal component analysis (PCA) regularizes the shape in terms of translation and rotation. A geometric-based feature vector is composed of shape descriptors, which can achieve scale and orientation-invariant and distortion-tolerant property. Class is decided by minimum Euclidean distance between normalized feature vectors. Experiments confirm that the proposed methods provide fast and reliable recognition of the concealed object carried by a moving human subject. (C) 2012 Optical Society of America

关键词： Diffraction limit image processing algorithms image quality Millimeter wave imaging Millimeter waves Object detection

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Single-shot digital phase-shifting Moire patterns for 3D topography

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APPLIED OPTICS 2021年第4期60卷 A84-A92页

作者： Guo, Haiyun Zhou, Haowen Banerjee, Partha P. Univ Dayton Electroopt & Photon Dayton OH 45469 USA

A simple and robust technique of Moire topography with single-image capture and incorporating digital filtering along with a four-step digitally implemented phase-shifting method is introduced for three-dimensional (3D) surface mapping. Feature details in the order of tens to hundreds of microns can be achieved using interferometrically generated structured light to illuminate the object surface. Compared to the traditional optical phase-shifting method, a digital phase-shifting method based on Fourier processing is implemented with computer-generated sinusoidal patterns derived from the recorded deformed fringes. This enables a single capture of the image that can be used to reconstruct the 3D topography of the surface. Single-shot imaging is simple to implement experimentally and avoids errors in introducing the correct phase shifts. The feasibility of this technique is verified experimentally, and applications to metallic surfaces are demonstrated. (C) 2020 Optical Society of America

关键词： image processing algorithms Moire patterns Moire topography Spatial frequency Surface light scattering Surface mapping

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Terahertz pulse time-domain holography with balance detection: complex-domain sparse imaging

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APPLIED OPTICS 2019年第34期58卷 G61-G70页

作者： Kulya, Maksim Petrov, Nikolay V. Katkovnik, Vladimir Egiazarian, Karen ITMO Univ Digital & Display Holog Lab St Petersburg Russia Tampere Univ Fac Informat Technol & Commun Tampere Finland

We investigated the peculiarities of the terahertz pulse time-domain holography principle in the case of raster scanning with the balance detection system. The noise in this system represents a Skellam distribution model, which differentiates it from systems based on a photoconductive antenna. We analyzed this Skellam model and provided both numerical and experimental investigations. We found that the variance of the noise in the balance detection system does not depend on the true signal. Complex-domain images obtained in this model are filtered by block-matching algorithms adapted for spatio-temporal and spatiospectral volumetric data. We presented a new cube complex-domain filter algorithm that uses block matching in all 3D data sets simultaneously in spatial and frequency coordinates. A combination of temporal and complex-domain filters allows us to expand the dynamic range of terahertz frequencies for which we can obtain amplitude/phase information. Experimental data demonstrate an improvement in the quality of the resultant images both in the time domain and complex-spectral domain. The simulation and experimental results are in good agreement. (C) 2019 Optical Society of America

关键词： Electric fields image processing algorithms Photoconductivity Spatial frequency Terahertz spectroscopy Wave front sensing

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Enhanced Coherent BOTDA System Without Trace Averaging

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Journal of Lightwave Technology 2017年第4期36卷 871-878页

作者： Nan Guo Liang Wang Huan Wu Chao Jin Hwa-Yaw Tam Chao Lu Liang Wang Huan Wu Chao Jin Hwa-Yaw Tam Chao Lu 871

We propose and experimentally demonstrate a scheme of a coherent Brillouin time domain analysis (BOTDA) system without any trace averaging. Assisted by a commercial integrated coherent receiver with a local oscillator generated through single sideband modulation from the same laser source, the Brillouin signals carried on a stable intermediate frequency (IF) are extracted by electrical/digital filters and then recovered to baseband by digital signal processing. This increases the signal-to-noise ratio and avoids the need of trace averaging and enables real-time signal acquisition. To eliminate the Brillouin gain fluctuation, two adjacent Brillouin time-domain traces stimulated by two sequential orthogonal pump pulses are recovered after the IF signals are detected in a real-time manner. Based on this configuration, a spatial resolution of 4 m and Brillouin frequency shift uncertainty of 1.473 MHz are realized in distributed temperature sensing over 40.63 km range. With the nonlocal means algorithm and distributed Raman amplification integrated into the system, the BFS uncertainty is enhanced to 0.843 MHz and better spatial resolution of 2 m over the same sensing fiber is achieved.

关键词： Coherent receivers Coherent systems image processing algorithms Laser sources Spatial resolution Wavelength division multiplexers

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Automatic detection of the lung orientation in digital PA chest radiographs

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Journal of the Optical Society of Korea 1997年第1期1卷 60-64页

作者： Kie-B. Nahm Dept. of Physics Hallym University

An image processing algorithm is presented that can identify the orientation as well as the left/right side (parity) of the digitized radiographs. The orientation was found by computing the mean square deviation between the sampled gray values along the center and their best-fit linear regression relations. The parity was determined by comparing the area difference between two thresholded images of the left and the right side around the heart, which is assumed to be around the center of the image. This method was tested with 86 images with their orientations intentionally rotated. The rotation was limited to multiples of 90 degrees, as this was the way the rotation is most likely to happen in the clinical environment. We obtained positive responses for 85 out of 86 images subject to the screening.

关键词： image processing algorithms

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NEW SPACE DOMAIN processing TECHNIQUE FOR PULSED LASER VELOCIMETRY

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APPLIED OPTICS 1990年第23期29卷 3399-3417页

作者： WERNET, MP EDWARDS, RV CASE WESTERN RESERVE UNIV DEPT CHEM ENGNCLEVELANDOH 44106

Current pulsed laser velocimetry data processing techniques offer high precision (1%) velocity estimates, but can require several hours of processing time on specialized array processors. Under some circumstances, a simple, fast, less accurate (~5%), data reduction technique, which also gives unambiguous velocity vector information is acceptable. In this work, we examine a direct space domain processing technique. The direct space domain processing technique was found to be far superior to any other techniques known, in achieving the objectives listed above. It employs a new data coding and reduction technique, where the particle time history information is used directly. Further, it has no 180 degrees directional ambiguity. A complex convection vortex flow was recorded and completely processed in under 2 min on an 80386 based PC, producing a 2-D map of the flow field containing over 300 velocity vectors.

关键词： Far field diffraction Fringe analysis image processing algorithms Laser speckle Laser velocimetry Pulsed operation

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Obtaining images by Measuring Time

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Optics and Photonics News 2020年第12期31卷 50-50页

作者： Turpin, Alex Musarra, Gabriella Kapitany, Valentin Tonolini, Francesco Lyons, Ashley Starshynov, Ilya Murray-Smith, Roderick Faccio, Daniele Villa, Federica Conca, Enrico Fioranelli, Francesco University of Glasgow Glasgow United Kingdom Politecnico di Milano Milan Italy Technische Universiteit Delft Delft Netherlands

Obtaining an image of a scene is obvious and intuitive. The light refl ected from every object of the scene is collected with lenses and projected (imaged) onto an array of pixels (a sensor) that records the light int... 详细信息

关键词： image processing algorithms Light intensity Pulsed operation Sensors Single photon avalanche diodes Three dimensional imaging

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Biophotonics - A Powerful Tool for Non-invasive and Labelfree Cell- and Tissue Screening

Biophotonics - A Powerful Tool for Non-invasive and Labelfre...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Popp, Juergen Friedrich Schiller Univ Jena Inst Phys Chem Helmholtzweg 4 D-07743 Jena Germany Leibniz Inst Photon Technol Albert Einstein Str 9 D-07744 Jena Germany

In this presentation, we will highlight our recent advances in translating biophotonic approaches with special focus on linear and non-linear Raman spectroscopy towards routine clinical applications with focus on infe... 详细信息

ISBN: (纸本)9781943580279

关键词： Clinical applications image processing algorithms Laser surgery Multimodal imaging Raman spectroscopy Tissue

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Advanced Infrared Technology and Applications: introduction

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APPLIED OPTICS 2018年第18期57卷 AITA1-AITA4页

作者： Strojnik, Marija D'Acunto, Mario Rogalski, Antoni Mario D’Acunto Antoni Rogalski 10.1364/AO.57.0AITA1

This special issue of Applied Optics on Advanced Infrared Technology and Applications collects significantly expanded refereed papers presented at the conference of the same name, held in Quebec City, Canada, Sept. 27 to Sept. 30, 2017. All the authors who participated at the conference were contacted and invited to contribute to this special issue. Furthermore, the AO dedicated issue on AITA was open to contributions from other practitioners of IR, through direct contact and a call for papers published in AO. (C) 2018 Optical Society of America

关键词： Adaptive optics Diffuse reflectance spectroscopy Electron beam lithography image processing image processing algorithms Thermal infrared detectors

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MOIRE INSPECTION OF MULTICOMPONENT ASSEMBLIES

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APPLIED OPTICS 1979年第23期18卷 4046-4050页

作者： SHUPE, D GORMAN, RP The authors are with Bendix Corporation Bendix Research Laboratories SouthfieldMichigan 48037.

This paper discusses the use of moiré techniques to enhance optically the generation of binary images in automatic visual inspection systems. Techniques for enhancing the illumination of out-of-plane features or highlighting areas of missing or misaligned parts on an assembly were investigated. The applications of these techniques to a practical inspection problem were demonstrated.

关键词： image processing image processing algorithms Light scattering Moire techniques Printed circuit boards Ronchi gratings

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