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Adaptive coded-aperture imaging with subpixel superresolution

OPTICS LETTERS 2012年第5期37卷 854-856页

作者： Slinger, Chris Bennett, Helen Dyer, Gavin Gordon, Neil Huckridge, David McNie, Mark Penney, Richard Proudler, Ian Rice, Kevin Ridley, Kevin Russell, Lee de Villiers, Geoffrey Watson, Philip Malvern Innovat The Elms Courtyard HR8 1RZ Bromesberrow England QinetiQ Ltd Great Malvern WR14 3PS Worcs England Goodrich ISR Syst Westford MA 01886 USA Cooke Opt Ltd Leicester LE4 8P Leics England

We describe an adaptive coded-aperture imager operating in the midwave IR. This consists of a coded-aperture mask, a set of optics, and a 4k x 4k focal plane array (FPA). This system can produce images with a resolution better than the detector pixel limit by combining multiple frames of data recorded with different coding. This superresolution capability has been demonstrated both in the laboratory and with targets placed outside, the highest resolution being one-half of the FPA pixel pitch. (C) 2012 Optical Society of America

关键词： Adaptive imaging image processing algorithms Modulation transfer function Optical design Optical systems Spatial frequency

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Joint contrast optimization and object segmentation in active polarimetric images

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OPTICS LETTERS 2012年第16期37卷 3321-3323页

作者： Anna, Guillaume Bertaux, Nicolas Galland, Frederic Goudail, Francois Dolfi, Daniel Univ Paris 11 CNRS Inst Opt Lab Charles FabryUMR 8501 F-91127 Palaiseau France Aix Marseille Univ Inst Fresnel Ecole Cent Marseille CNRS F-13013 Marseille France Thales Res & Technol France RD128 F-91767 Palaiseau France

We present a method for automatic target detection based on the iterative interplay between an active polarimetric imager with adaptive capabilities and a snake-based image segmentation algorithm. It successfully addresses the difficult situations where the target and the background differ only by their polarimetric properties. This method illustrates the benefits of integrating digital processing algorithms at the heart of the image acquisition process rather than using them only for postprocessing. (C) 2012 Optical Society of America

关键词： image processing image processing algorithms Light scattering Medical imaging Mueller matrices Polarimetric imaging

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Modeling of the optical system illuminated by quasi-monochromatic spatially incoherent light: new numerical approach

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OPTICS LETTERS 2012年第22期37卷 4723-4725页

作者： Czerwinski, A. Kakarenko, K. Sypek, M. Makowski, M. Ducin, I. Suszek, J. Kolodziejczyk, A. Bomba, J. Warsaw Univ Technol Fac Phys PL-00662 Warsaw Poland

This Letter presents a new method for modeling of complex optical setups illuminated by quasi monochromatic spatially incoherent light. The algorithm provides better performance and quality than other modeling methods both for isoplanatic and nonisoplanatic systems. The algorithm maintains energy relations, image orientation, and magnification of the system. Computer modeling and experimental results are presented. (C) 2012 Optical Society of America

关键词： Computer simulation image processing algorithms Imaging systems Point spread function Speckle patterns Thermal imaging

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Optical coherence tomography for quality assessment of embedded microchannels in alumina ceramic

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OPTICS EXPRESS 2012年第4期20卷 4603-4618页

作者： Su, Rong Kirillin, Mikhail Ekberg, Peter Roos, Arne Sergeeva, Ekaterina Mattsson, Lars Royal Inst Technol Dept Prod Engn S-10044 Stockholm Sweden Inst Appl Phys RAS Lab Biophoton Nizhnii Novgorod 603950 Russia Uppsala Univ Angstrom Lab S-75121 Uppsala Sweden

Large-scale and cost-effective manufacturing of ceramic micro devices based on tape stacking requires the development of inspection systems to perform high-resolution in-process quality control of embedded manufactured cavities, metal structures and defects. With an optical coherence tomography (OCT) system operating at 1.3 mu m and a dedicated automated line segmentation algorithm, layer thicknesses can be measured and laser-machined channels can be verified in alumina ceramics embedded at around 100 mu m depth. Monte Carlo simulations are employed to analyze the abilities of OCT in imaging of the embedded channels. The light scattering parameters required as input data for simulations are evaluated from the integrating sphere measurements of collimated and diffuse transmittance spectra using a reconstruction algorithm based on refined diffusion approximation approach. (C)2012 Optical Society of America

关键词： image processing algorithms image quality Light scattering Optical coherence tomography Reconstruction algorithms Speckle reduction

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Depth measurements through controlled aberrations of projected patterns

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OPTICS EXPRESS 2012年第6期20卷 6561-6574页

作者： Birch, Gabriel C. Tyo, J. Scott Schwiegerling, Jim Univ Arizona Coll Optic Sci Tucson AZ 85719 USA

Three-dimensional displays have become increasingly present in consumer markets. However, the ability to capture three-dimensional images in space confined environments and without major modifications to current cameras is uncommon. Our goal is to create a simple modification to a conventional camera that allows for three dimensional reconstruction. We require such an imaging system have imaging and illumination paths coincident. Furthermore, we require that any three-dimensional modification to a camera also permits full resolution 2D image capture. Here we present a method of extracting depth information with a single camera and aberrated projected pattern. A commercial digital camera is used in conjunction with a projector system with astigmatic focus to capture images of a scene. By using an astigmatic projected pattern we can create two different focus depths for horizontal and vertical features of a projected pattern, thereby encoding depth. By designing an aberrated projected pattern, we are able to exploit this differential focus in post-processing designed to exploit the projected pattern and optical system. We are able to correlate the distance of an object at a particular transverse position from the camera to ratios of particular wavelet coefficients. We present our information regarding construction, calibration, and images produced by this system. The nature of linking a projected pattern design and image processing algorithms will be discussed. (C) 2012 Optical Society of America

关键词： image processing image processing algorithms image quality Imaging systems Three dimensional imaging Three dimensional reconstruction

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Objective speckle velocimetry for autonomous vehicle odometry

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APPLIED OPTICS 2012年第16期51卷 3478-3490页

作者： Francis, D. Charrett, T. O. H. Waugh, L. Tatam, R. P. Cranfield Univ Sch Engn Dept Engn Photon Bedford MK43 0AL England EADS Astrium Stevenage SG1 2AS Herts England

Speckle velocimetry is investigated as a means of determining odometry data with potential for application on autonomous robotic vehicles. The technique described here relies on the integration of translation measurements made by normalized cross-correlation of speckle patterns to determine the change in position over time. The use of objective (non-imaged) speckle offers a number of advantages over subjective (imaged) speckle, such as a reduction in the number of optical components, reduced modulation of speckles at the edges of the image, and improved light efficiency. The influence of the source/ detector configuration on the speckle translation to vehicle translation scaling factor for objective speckle is investigated using a computer model and verified experimentally. Experimental measurements are presented at velocities up to 80 mm s(-1) which show accuracy better than 0.4%. (C) 2012 Optical Society of America

关键词： Digital image correlation image processing algorithms Laser light Laser speckle Optical components Speckle patterns

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Selective polarization imager for contrast enhancements in remote scattering media

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APPLIED OPTICS 2012年第18期51卷 4092-4102页

作者： Miller, Darren A. Dereniak, Eustace L. Univ Arizona Coll Opt Sci Tucson AZ 85721 USA

Conventional intensity imaging through turbid media suffers from rapid loss of image contrast due to light scattering from particles or random variations of refractive index. This paper features the development of an active imaging, snapshot, system design and postprocessing algorithms that differentiate between radiation that scatters or reflects from remote, obscured objects and the radiation from the scattering media itself through a combination of polarization difference imaging, channel blurring, and Fourier spatial filtering. The produced sensor acquires and processes image data in real time, yielding improved image contrasts by factors of 10 or greater for dense water vapor obscurants. (C) 2012 Optical Society of America

关键词： image processing image processing algorithms image quality Light scattering Refractive index Turbid media imaging

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3D shape reconstruction of large specular surface

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APPLIED OPTICS 2012年第31期51卷 7616-7625页

作者： Zhang, Hongwei Han, Shujian Liu, Shugui Li, Shaohui Ji, Lishuan Zhang, Xiaojie Tianjin Univ State Key Lab Precis Measuring Technol & Instrume Tianjin 300072 Peoples R China

A novel three-dimensional (3D) reconstruction method based on fringe reflection technique for shape measurement of large specular surfaces is presented in this paper, which effectively integrates path integration technique with zonal wavefront reconstruction algorithm. The height information of specular surface obtained from cross-path integration can then be used as the initial value in a zonal wavefront reconstruction algorithm. This method not only has the advantages of global integration, but also enables user-friendly, high-speed operation. A specific iterative algorithm is adopted to improve the antinoise capability of the measuring system, which accelerates the rate of convergence significantly and even improves the accuracy of the reconstructed 3D surface. Moreover, the proper use of boundary contour extraction of the acquired images reduces the computational load of 3D reconstruction dramatically and hence achieves high reconstruction accuracy and enhances the surface integrity at the boundary. An ultraprecision, diamond-turned planar mirror with diameter of 150 mm has been employed to implement the system calibration. The reconstruction results of simulated and actual hyperbolic surfaces and the gauge blocks identify the validity of this new method. It is demonstrated that the measurement error is about 50 mu m with reconstruction points of 150 x 560 pixels of gauge blocks. (C) 2012 Optical Society of America

关键词： Digital image processing Freeform surfaces image processing algorithms Phase unwrapping Reconstruction algorithms Three dimensional reconstruction

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Microelectromechanical-systems-driven two-layer rotary-blade-based adjustable iris diaphragm

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OPTICS LETTERS 2012年第10期37卷 1745-1747页

作者： Zhou, Guangya Yu, Hongbin Du, Yu Chau, Fook Siong Natl Univ Singapore Dept Mech Engn Singapore 117576 Singapore

We report a miniature adjustable multi-blade iris diaphragm driven by microelectromechanical-systems-based electrostatic rotary microactuators. A proof-of-concept device is designed and fabricated using a silicon-on-insulator micromachining process. The diameter of the developed iris diaphragm aperture is experimentally demonstrated to be able to adjust from 0.45 to 1.56 mm. When used in a miniature camera lens system, the current prototype device is capable of providing an adjustment range of more than three full f/stops. (C) 2012 Optical Society of America

关键词： Apertures image processing algorithms Iris Laser beams Microactuators Optical microscopy

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Binary-channel Can Covers Defects Detection System Based on Machine Vision

Binary-channel Can Covers Defects Detection System Based on ...

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6th International Conference on Anti-Counterfeiting, Security and Identification (ASID)

作者： Feng, Bin Guo, Shu-xia Zhang, Feng-ling Zhu, Chao-jun Wang, Lei Xiamen Univ Sch Phys & Mech & Elect Engn Xiamen 361005 Peoples R China

ISBN: (纸本)9781467321433

In order to realize the on-line detection and elimination of unqualified can covers, a binary-channel inspection system based on machine vision is proposed in this article. The system mainly consists of two illumination sources, two cameras, two sensors, an IPC, an interface circuit, two eliminating devices, a set of algorithms for image processing and a software for the control of independent binary-channel. In working status, each channel of the system is placed directly above a conveyor, which transports can covers to the detection position so that the camera is triggered, and then an image is captured with a flash. The cover images are transferred to the IPC and then processed by the algorithm that based on template matching and variation model. Depending on the processing results unqualified covers are eliminated. The system is proved to be non-pollution, low-cost, and defects such as double covers, no glue, shoulder scratch, distortion can be detected with a 98.7% accuracy and a speed of 1200 covers per minute.

关键词： machine vision can covers defects detection binary-channel image processing algorithms

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