Proceedings Volume 7072

Optics and Photonics for Information Processing II

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Proceedings Volume 7072

Optics and Photonics for Information Processing II

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Volume Details

Date Published: 28 August 2008
Contents: 7 Sessions, 44 Papers, 0 Presentations
Conference: Optical Engineering + Applications 2008
Volume Number: 7072

Table of Contents

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Table of Contents

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  • Front Matter: Volume 7072
  • Switching
  • Holography/Modeling
  • Imaging
  • Computing
  • Image Processing
  • Poster Session
Front Matter: Volume 7072
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Front Matter: Volume 7072
This PDF file contains the front matter associated with SPIE Proceedings Volume 7072, including the Title Page, Copyright information, Table of Contents, Introduction (if any), and the Conference Committee listing.
Switching
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All-optical swapping of spectral amplitude code labels for packet-switched networks
Packet-switched networks have attracted considerable attention as a basis for next-generation optical networks due to their advantages in terms of flexibility and network efficiency over traditional circuit-switched networks. Optical code multi-protocol label switching (OC-MPLS) promises fast, flexible, power-efficient switching by keeping signals in the optical domain and avoiding costly conversions to the electrical domain. In this paper, we review the use of spectral amplitude codes (SACs) for implementing OC-MPLS labels. We discuss the principles and features, as well as key enabling technologies required for their processing. In particular, we compare three different approaches for low cost all-optical swapping of SAC labels. All approaches are based on semiconductor fiber lasers and exploit nonlinearity in a semiconductor device: the first uses cross-absorption modulation in an electroabsorption modulator, the second uses cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA), and the third makes use of XGM in an SOA as well as injection locking in a Fabry-Pérot laser. We present the static and dynamic responses of each for swapping a multi-wavelength input label to a multi-wavelength output label. The benefits and limitations of each approach as well as future improvements are discussed. We also present the results of systems experiments which demonstrate error-free all-optical label swapping, recognition, and switching of multi-rate packets in packet-switched networks using multi-wavelength labels.
Liquid crystal-based dynamic channel blocker/equalizer for optical networks
Inter-channel crosstalk for a liquid crystal-based dynamic channel blocker/equalizer has been experimentally studied. With the optimal interpixel width, a 32-channel, 100-GHz channel-spacing sample is fabricated and characterized. The maximum insertion loss (IL) of 5 dB and the polarization dependent loss (PDL) of 0.5 dB within the ITU ± 14 GHz are achieved. The 45 dB extinction ratio is obtained. The variations of the IL and PDL within the temperature range from - 5°C to 65°C cross the C-band are less than 1 dB and 0.4 dB respectively.
Applying the triple correlation functions to characterizing high-frequency repetition trains of picosecond optical pulses
A. L. Muñoz Zurita, A. S. Shcherbakov, E. Tepichin-Rodriguez, et al.
We consider an opportunity of measuring the train-averaged parameters of picosecond optical pulses with asymmetric envelopes being arranged in high-frequency repetition trains and corrupted by additive Gaussian noise. In so doing, one can exploit the temporal triple auto-correlation function, whose Fourier transformation gives the bispectrum of signal. The advantages of similar auto-correlation function consist in the capability of recovering signals almost unambiguously and low sensitivity to noise. We implement the technique and algorithmic investigation for recognizing the width as well as the magnitude and the sign of the frequency chirp peculiar to pulses with Gaussian-like, rectangular, and smooth asymmetric shapes.
Application of the effect polarization self-modulation for processing an output signal one-fiber few-mode interferometers
To the present time photorefractive (PRC) crystals have found wide application at creation interferometers devices. It is caused by presence in photorefractive environments of nonlinear optical effects. One of such effects is the effect polarization self-modulation One-fiber few-modes interferometers are used for creation of sensors of physical sizes, but there is a problem of processing of their output signals. In this report, I review the method of processing of output signal with the help of the effect polarization self-modulation in PRC for one-fiber few-mode interferometer (in which propagate only 2 or 3 modes). The submitted method in comparison with existing methods has the following advantages: the linear transfer characteristic and signal is formed on the first harmonic. The installation is assembled, with which help the idea of processing of an output registered signal in one-fiber few-modes interferometer was embodied. Besides as addition, the application photorefractive crystals opens an opportunity of giving to measuring system an ability to adapt under at slow changes of an environment, for example, slow temperature changes.
A two-pass Sagnac loop for high-contrast ultrafast switching at 1053nm
A. Jolly, L. Lago, S. Jonathas, et al.
An original polarization - maintaining Sagnac switch is proposed for use in optical sampling and short pulse measurement applications, in the range of signal wavelengths of interest for Inertial Confinement Fusion. Our design is implemented using highly-nonlinear photonic-crystal fibres. It enables the search of huge switching contrasts together with very large sampling bandwidths, in relationship with an elevated temporal resolution. A unique two-pass Sagnac loop is fed with input signal pulses at 1053nm while triggered with pump pulses at 1550nm. Starting from a single-pass contrast and a temporal resolution in the ranges of 30dB and of a couple of picoseconds, the two-pass architecture provides optical contrasts in excess of 45dB and sub-picosecond gating durations. Thanks to two-pass operation, we can get nearly free from any environmental perturbation. Furthermore the spectral and the temporal clipping features related to switching are analyzed using comprehensive modeling with higher order dispersion effects. The issue of the optimization of the sampling bandwidth is discussed in details by means of the synchronization of the pump return, which involves a sub-picosecond precision. This way, the output energy from the switch can be kept constant and proportional to the signal power, whatever the input pulse width. The sampling bandwidth then extends up to RF frequencies in the range 300-500GHz.
Holography/Modeling
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Removing the twin image in digital holography by segmented filtering of in-focus twin image
We propose and investigate a new digital method for the reduction of twin-image noise from digital Fresnel holograms. For the case of in-line Fresnel holography the unwanted twin is present as a highly corruptive noise when the object image is numerically reconstructed. We propose to firstly reconstruct the unwanted twin-image when it is in-focus and in this plane we calculate a segmentation mask that borders this in focus image. The twin-image is then segmented and removed by simple spatial filtering. The resulting digital wavefield is the inverse propagated to the desired object image plane. The image is free of the twin-image resulting in improved quality reconstructions. We demonstrate the segmentation and removal of the unwanted twin-image from in-line digital holograms containing real-world macroscopic objects. We offer suggestions for its rapid computational implementation.
Segmentation of three-dimensional scenes encoded in digital holograms
This study investigates segmentation algorithms applicable to digital holography. An assessment of image segmentation tecnhniques applied to intensity images of reconstructions of digital holograms is provided. Digital holography differs from conventional imaging as 3D information is encoded. This allows depth information to be exploited so that focusing of 3D objects, or part there of, at different depths can be achieved. In this paper, segmentation of features is attained in microscopic and macroscopic scenes. We investigate a number of recently proposed segmentation techniques including (i) depth from focus, (ii) active contours and (iii) hierarchical thresholding. The influence of noise reduction on the segmentation capabilities of each of the techniques on these scenes is demonstrated. For the macrocsopic scenes, each technique is applied before and after speckle noise reduction is performed using a wavelet based approach. The performance of the segmentation techniques on the intensity information obtained from reconstructed holograms of microscopic scenes is also investigated before and after twin-image reduction has been applied. A comparison of the techniques and their performances in these circumstances is provided.
Coherence holography and singular optical coherence
The principle of unconventional holography, called coherence holography, is reviewed with particular emphasis on the formal analogy between an optical field and its coherence function, which gives a clue for developing a new technique for synthesizing singular optical coherence. We present experimental demonstrations of generic coherence vortices generated by coherence holography, and show an experimental evidence of an angular coherence momentum created by coherence currents circulating around the core of the coherence vortex and a conservation law of coherence currents.
Characterizations of multi-segment DFB laser
Tunable semiconductor laser has various applications including Wavelength Division Multiplexing (WDM), Frequency Division Multiplexing (FDM), optical switching in Local Area Networks (LAN) and Chemical Sensing, or Spectroscopy. There are different approaches for tunable semiconductor lasers. Large wavelength tuning range is required for communication applications, such as WDM. Whereas a frequency modulation (FM) requires small but fast frequency shifts. Two-Segment laser is one of the methods to realize continuous optical tuning. The device consists of two coupled cavities having a series of well-defined modes. The modes are equally spaced within a cavity but the mode spacing between the two cavities is slightly different. Characterization results of such lasers are very important. In this paper we will present the characterization results of two segment InGaAs/InP distributed feed back (DFB) tunable lasers.
Imaging
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Measuring chromatic dispersion using single-arm interferometers: from millimeters to kilometers
Li Qian, Bing Qi, Waleed S. Mohammed, et al.
We present three new interferometric techniques for dispersion characterization covering from millimeter waveguides to kilometers of fibers. The first is a Frequency-Shifted Interferometer (FSI) that measures fibers from meters to tens of kilometers. The second is a three-wave Single-Arm Interferometer (SAI), where the envelope of a three-wave interference pattern yields the second-order dispersion directly. It is suitable for fibers from centimeters to >1m. The third is a Common-Path Interferometer (CPI) that measures dispersion of millimeter-long fibers/waveguides. These techniques offer high precision in their respective ranges, and are all "single-arm" interferometers: the two interfering beams go through the same arm of the interferometer. They are simple, low-cost, and more resilient to phase and polarization instabilities than conventional interferometric techniques for dispersion measurement.
Simulating paraxial optical systems using the linear canonical transform: properties, issues, and applications
The linear canonical transform (also known as the quadratic phase integral and the special affine Fourier transform, among others) is an important tool for the modeling of quadratic phase systems for coherent optical signal processing, as it is a generalization of a number of important and widely used transforms such as the Fresnel transform, the Fourier transform and the fractional Fourier transform. We consider properties of the linear canonical transform which are important for numerical approximation of the integral transform, and thus for simulation of the related paraxial optical systems. Some of these properties have been previously developed in the literature, but are analyzed here in the context of linear canonical transform simulations, others are developed here for the first time. We examine these properties analytically, including how the support and bandwidth of the signal are related to transform parameters, a review of sampling issues and some new proposals in this area. Finally, we examine the effect of the linear canonical transform on the sparsity of signals, which is useful for efficient transmission or storage or to aid certain signal processing tools such as blind source separation.
Point spread function (PSF) measurement for cell phone camera with a high resolution PSF of the imaging lens and a sub-pixel digital algorithm
An accurate measurement of the point spread function (PSF) for the extended depth of field (EDoF) cell phone camera with CMOS sensor is very important for image processing and image restoration. But due to the coarse sampling of the PSF by CMOS sensor, the overall system including the imaging subsystem and sampling subsystem is a shift-variant system with respect to the sample-scene phase parameter within sub-pixel range. In this paper, we present the sub-pixel digital algorithm to estimate the overall camera PSF based on the measurement of a high resolution PSF of the imaging lens. The sub-pixel digital algorithm averages the shifted high resolution PSFs of the lens over one active pixel area with the assumption of uniform random distribution of point source location within one active pixel area. Then the averaged high resolution PSF is down sampled onto Bayer plane to obtain the shift-invariant overall system PSF. We applied this shift-invariant PSF for image restoration of blurred images captured with an extended depth of field camera. The processed images are compared with originally captured images. Improvement of image quality is seen.
A compound-eye imaging system with irregular lens-array arrangement
Ryoichi Horisaki, Yoshizumi Nakao, Takashi Toyoda, et al.
TOMBO (Thin Observation Module by Bound Optics) is a compound-eye imaging system inspired by a visual organ of insects. TOMBO has various advantages over conventional imaging systems. However, to demonstrate applicability of TOMBO as an imaging system, high-resolution imaging is significant and unavoidable. In this study, a TOMBO system with irregular lens-array arrangement is proposed and a high-resolution imaging method integrating a super-resolution process with depth acquisition of three-dimensional objects is presented. The proposed TOMBO system improves image resolution for far objects, because it can alleviate degeneration of the sampling points on the far objects caused by the regular arrangement of the lens array in the conventional TOMBO system. An experimental TOMBO has 1.3 mm focal length of lens, 0.5 mm pitch of lenses, 0.5 mm diameter of aperture, 3 × 3 of units, 160 × 160 pixels per unit, and 3.125 μm pitch of pixel. The target planar object is located at 5 m from the TOMBO system. The simulation result shows that the coverage ratio of the sampling points, PSNR of the super-resolved image, and the error of the depth estimation for the object are improved by 50%, 3 dB, and 56%, respectively. The experimental result shows that the error of depth estimation for the planar object located at 3.2 m is 18% and that the contrast of 123 lp/mm at the center of a unit is improved by 0.38 with the super-resolution processing.
Package inspection using inverse diffraction
More efficient cost-effective hand-held methods of inspecting packages without opening them are in demand for security. Recent new work in TeraHertz sources,1 millimeter waves, presents new possibilities. Millimeter waves pass through cardboard and styrofoam, common packing materials, and also pass through most materials except those with high conductivity like metals which block light and are easily spotted. Estimating refractive index along the path of the beam through the package from observations of the beam passing out of the package provides the necessary information to inspect the package and is a nonlinear problem. So we use a generalized linear inverse technique that we first developed for finding oil by reflection in geophysics.2 The computation assumes parallel slices in the packet of homogeneous material for which the refractive index is estimated. A beam is propagated through this model in a forward computation. The output is compared with the actual observations for the package and an update computed for the refractive indices. The loop is repeated until convergence. The approach can be modified for a reflection system or to include estimation of absorption.
Aperture synthesis imaging through turbulence with the aid of lucky imaging
Aperture synthesis allows a number of small apertures to operate cooperatively in the synthesis of a large full aperture telescope. For earth-based systems, the effects of atmospheric turbulence, which introduces time-varying aberrations, must somehow be corrected if good imagery is to be obtained. One correction scheme relies on a comparison, in a range of overlap, of correctly-phased spatial frequency components with new components that are in error by unknown piston (constant) and tip-tilt (linear) phase terms. Normally this method requires that the subapertures employed in the synthesis be sufficiently small that phase aberrations beyond piston and tip-tilt be ignorable. Through the exploitation of lucky imaging conditions, however, larger apertures can be used, with a subsequent increase in resolution and light-gathering power for the optical system.
Computing
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A defect inspection technique using polarized images for steel strip surface
A. Kazama, T. Oshige
An in-line defect inspection technique using polarized images for steel strip surface is developed. In inspection for low contrast defects, excessive-detection will be caused by harmless patterns such as slight oil patterns, chemical liquid patterns, and other patterns. We have adopted quasi-ellipsometric method using polarized images of the target samples to obtain their ellipsometric parameters, and found that the ellipsometric characteristics of the defects and the harmless patterns differ from each other. Based on this finding, we have developed an inspection system utilizing three polarized images with different azimuth angles to discriminate defects from harmless patterns at a high- speed production line.
Ultra-fast wave-optical computing
I present a method for optical computing based on white-light interferometry. The problem to be solved is coded by optical path lengths and the superposition of all possible paths that a photon can travel is used for computing the solution. The solution itself is chosen by interference with the reference light. Several gedankenexperiments demonstrate how this method can be used for solving computational hard problems. Especially, I will introduce the basic principle with two maze-type puzzles and then concentrate on how the method can be employed for performing ultra-fast (sub-ps) digital-optical arithmetic with arbitrary precision.
Three-channel dynamic photometric stereo: a new method for 4D surface reconstruction and volume recovery
Walter Schroeder, Wolfram Schulze, Thomas Wetter, et al.
Three-dimensional (3D) body surface reconstruction is an important field in health care. A popular method for this purpose is laser scanning. However, using Photometric Stereo (PS) to record lumbar lordosis and the surface contour of the back poses a viable alternative due to its lower costs and higher flexibility compared to laser techniques and other methods of three-dimensional body surface reconstruction. In this work, we extended the traditional PS method and proposed a new method for obtaining surface and volume data of a moving object. The principle of traditional Photometric Stereo uses at least three images of a static object taken under different light sources to obtain 3D information of the object. Instead of using normal light, the light sources in the proposed method consist of the RGB-Color-Model's three colors: red, green and blue. A series of pictures taken with a video camera can now be separated into the different color channels. Each set of the three images can then be used to calculate the surface normals as a traditional PS. This method waives the requirement that the object imaged must be kept still as in almost all the other body surface reconstruction methods. By putting two cameras opposite to a moving object and lighting the object with the colored light, the time-varying surface (4D) data can easily be calculated. The obtained information can be used in many medical fields such as rehabilitation, diabetes screening or orthopedics.
Temperature and field effects on reflectivity of gallium selenide surface
Bader Alhasson, Yashar Hajiyev, Mohammad Matin
Monocrystals of gallium selenide (GaSe) has recently attracted significant attention in the field of new optoelectronic devices, due to the original combination of its specific features such as nonlinear optical properties, layered structure and high-photo sensitivity. GaSe crystals show both high reflectivity and unique surface perfection, which leads to a promising candidate for next generation optical devices. We will present our experimental results of reflection spectra of such crystals for various temperatures (273°K-383°K) and applied electric field (1 V/cm - 20 V/cm). The reflection spectra were analyzed to identify the mechanism of the reflective coefficient change in GaSe as a function of wavelength, temperature and electric field. This study will identify the optimal electrical field regimes and spectral segments, where we experimentally revealed reflective properties of GaSe are suitable for creating the field regulated optical applications of decoder and depolarizer. The temperature dependence of GaSe reflectance spectrum, its temperature and applied field dependences exemplified that the processes of photon-electron inter-exchanging on the surfaces are dominated over the bulk processes in forming the reflectance properties of layered crystals. The perfectness of natural surface and their high reflective properties weren't changed in the interval of experimental temperatures. The monolayer surface of GaSe can be utilized as an easy prepared natural plane surface for new optical devices on their surface basis in their original combinations. Such devises are applicable for optical information processing systems because of the stability function and weak dependence of the function of bulk properties.
Which optical processes are suitable to make probabilistic single photon sources for quantum cryptography?
Single photon sources to be used in quantum cryptography must show higher order antibunching (HOA). HOA is reported by us in several many wave mixing processes. In the present work we have investigated the possibility of observing HOA in multiwave mixing processes in general. The generalized Hamiltonian is solved for several particular cases in Heisenberg picture and possibility of observing HOA is investigated with the help of criterion of Pathak and Garcia. The generalized interaction Hamiltonian of a multiwave mixing process is considered as (a†l bm cn + Hermitian conjugate) where 'a', 'b' and 'c' are the annihilation operators corresponding to pump, Stokes and Signal modes respectively. Several particular cases of the generalized Hamiltonian are solved with the help of short time approximation technique and HOA is reported for pump modes of different multiwave mixing processes. It is also found that HOA can not be observed for the signal and stokes modes in of the cases studied here.
Image Processing
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Single camera-based object detection and tracking for mobile robots
J. Keith Anderson, Khan M. Iftekharuddin, Elizabeth Threlkeld, et al.
In order for a mobile robot to successfully navigate its environment, it must have knowledge about the objects in its immediate vicinity. The robot can use this information for localization, navigation and object avoidance. Among many sensors available for object detection we are primarily interested in camera-based vision for indoor robot navigation. In this work, we focus on using a single camera to detect objects in the field of view of the robot for the purpose of obstacle avoidance. In order to obtain an integrated robot obstacle avoidance and navigation technique, we investigate a modular approach. In the first module, we extend an appearance based object detection (ABOD) technique to automatically identify individual objects. We then extract strong corner features, overlaying them over the identified objects. This allows us to select a few representative corners for each object. In the second module, we attempt to group these strong corner features using a planar homography technique to define more natural features such as 'planes' for further processing. As an added feature, we utilize the strong corner features generated from module 1, the corresponding features in the next frame from module 2 and a basic optical flow technique for tracking these identified objects. In the third and final module, we obtain distance and heading information for each of obstacles as the robot avoids and navigates in an indoor environment. We show both simulation and actual results on a mobile robot for each of these three modules. We hope to integrate these three modules to obtain a single camera-based integrated robot obstacle avoidance and navigation technique in future.
Shadow extraction
This paper examines the shadow extraction problem associated with satellite images; namely the fact that images taken at a different time include different shadow components. In the present research we attempt to define the shadow component of an image in a controlled lab environment in terms of the phase of the Fourier spectrum of the image, devise a novel method for extracting the simple shadow component from the image, and to create a meta-image suitable for change detection post processing.
Higher accuracy template for corner cube reflected image
Abdul A. S. Awwal, Kenneth L. Rice, Richard R. Leach, et al.
Video images of laser beams are analyzed to determine the position of the laser beams for alignment purpose in the National Ignition Facility (NIF). Algorithms process beam images to facilitate automated laser alignment. One such beam image, known as the corner cube reflected pinhole image, exhibits wide beam quality variations that are processed by a matched-filter-based algorithm. The challenge is to design a representative template that captures these variations while at the same time assuring accurate position determination. This paper describes the development of a new analytical template to accurately estimate the center of a beam with good image quality. The templates are constructed to exploit several key recurring features observed in the beam images. When the beam image quality is low, the algorithm chooses a template that contains fewer features. The algorithm was implemented using a Xilinx Virtex II Pro FPGA implementation that provides a speedup of about 6.4 times over a baseline 3GHz Pentium 4 processor.
Two-dimensional pattern processing by means of image compression
Kouichi Nitta, Tomoyuki Minami, Osamu Matoba
A method for SIMD (Single Instruction stream Multi Data Stream) processing of two dimensional images. is improved. We study on characteristics of patterns on intermediate data in the algorithm. From the study, it is found that the patterns are periodical. A novel method for the improvement is developed by use of the characteristics. We estimate effectiveness of the improved method. The method is implemented on a personal computer and compared with the simulator based on the conventional scheme. As results of estimation, it is verified that the computational costs of the method are about ten times as small as that with the conventional compressed scheme.
Enhanced 3D correlator using Blur metric-based resolution enhancement
Kang-Jae Eun, Keong-Jin Lee, Dong-Choon Hwang, et al.
In this paper, we proposed enhanced 3-dimentional correlator for extracting accurate location data using computationally reconstructed integral imaging. Elemental images of reference objects and target objects are computationally picked up by virtual pinhole model. These picked elemental images up, target images, reference images are reconstructed by mean of a modified computational integral imaging reconstruction technique. To find original location of target objects, Blur Metric are used to measure Plane object images(POIs) without advance information of target objects. Defocused areas in focused POIs can be efficiently reduced by erosion operation based on a blur metric. This method efficiently find out more accurate longitudinal location of 3D target images through correlation with reconstructed reference images and target plane images. With the propose of showing the feasibility of the proposed method, comparison a case of to use of Blur Metric with a case of to non-use of Blue Metric is implemented and the result are presented.
Poster Session
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Cost function statistical analysis in double random phase encoding
David S. Monaghan, Unnikrishnan Gopinathan, Guohai Situ, et al.
We examine the Amplitude-Encoding (AE) case of the Double Random Phase Encoding (DRPE) technique. A cost function is the function we use to evaluate an attempted decryption with our original input image. For systems with a relatively small key-space we can evaluate the output of every key to get an overall idea of the spread of these keys in key-space. However for larger systems this is not practical. Based on a normalised root mean squared cost function we wish to identify expressions for the mean and variance of the output (decrypted) intensity for a sample set of keys in a large system (256x256 pixels).
An alternative design of holographic polarization-selective elements
The feasibility of conventional polarization-selective substrate-mode holograms is usually limited by the finite refractive index modulation strength. Therefore, in this study, a novel design of polarization selective element with a large diffraction angle is proposed based on the coupled-wave theory. The polarization selective element for 632.8nm is fabricated with VRP-M silver-halide recording material. The diffraction efficiencies of s- and p- components are 83% and 5%, and the calculated extinction ratios are 5.58 and 275, respectively. Polarization selective elements fabricated by the proposed method have all the merits of conventional substrate-mode hologram but not limited by the finite refractive index modulation of common recording materials.
Complex shadow extraction
This paper examines the shadow extraction problem associated with satellite images; namely the shadow component of the images. The present research extends our previous work on shadow extraction in simple scenes. Extraction of multivariable shadows caused by earth's rotation and satellite viewing angle is examined. Attempt is made to define the variables of such shadow component in a controlled lab environment in terms of the phase of the Fourier spectrum of the image, device a novel method for extracting complex shadow components from the image, and to create a meta-image suitable for change detection post processing.
Multi-beam coupling in doubly-doped photorefractive LiNbO3:Fe:Mn crystals
Cuixia Dai, Yingjie Yu, De'an Liu, et al.
A theoretical simulation of multi-beam coupling in LiNbO3:Fe:Mn crystals is given based on jointly solving the two-center material equations and the coupled-wave equations. Within a single crystal, multiple signals are amplified through coupling process from the pump light. The coupling gain of each signal results from coupling both between the pump and the signal and between different signals. The gain of each signal receives is dependent on the intensity of the signal light. And a competition is found between the various signals.
An improved quantum key distribution protocol
Ting-wan Wu, Guo-hua Wu
This paper presented an improved quantum key distribution protocol of the quantum cryptology. Using the same measure polarizer as BB84 protocol, the improved protocol we designed with not any classical channel, but a new looped quantum channel instead, so the job of sending and receiving can be finished only by one same person. It brings several good points: the utilization ratio of photons 100% in perfect condition, at least twice over other protocols, or even higher; the public channel easy to be attacked is avoided. Further, the improved protocol authenticates the legal communicators with pre-share information, so that no attacker can jump over the progress of authentication. Be alien from the protocol of BB84, the improved protocol uses message summary to detect whether messages intercepted by attacker. Because the message summary is encrypted by one-time-pad method using pre-share information, attacker could not alter the message summary and that not to be discovered. Moreover, some theoretical analysis to the improved protocol given with information theory: we used the measure channel concept for quantum detection, and calculated the information quantity obtained by attacker in the quantum secrecy communication. The analysis results provide the theory criterion for the legal communicators and the attackers.
A practical guide to digital holography and generalized sampling
The theorems of Nyquist, Shannon and Whittaker have long held true for sampling optical signals. They showed that a signal (with finite bandwidth) should be sampled at a rate at least as fast as twice the maximum spatial frequency of the signal. They proceeded to show how the continuous signal could be reconstructed perfectly from its well sampled counterpart by convolving a Sinc function with the sampled signal. Recent years have seen the emergence of a new generalized sampling theorem of which Nyquist Shannon is a special case. This new theorem suggests that it is possible to sample and reconstruct certain signals at rates much slower than those predicted by Nyquist-Shannon. One application in which this new theorem is of considerable interest is Fresnel Holography. A number of papers have recently suggested that the sampling rate for the digital recording of Fresnel holograms can be relaxed considerably. This may allow the positioning of the object closer to the camera allowing for a greater numerical aperture and thus an improved range of 3D perspective. In this paper we: (i) Review generalized sampling for Fresnel propagated signals, (ii) Investigate the effect of the twin image, always present in recording, on the generalized sampling theorem and (iii) Discuss the effect of finite pixel size for the first time.
A method to reduce the size of LUT for generation of a full-color CGH using a relation between distance and wavelength in Fresnel diffraction
Jung-Hoon Yoon, Seok-Chan Park, Seung-Cheol Kim, et al.
Even though many kinds of approaches to generate CGH patterns of the 3D object image were suggested, but most of them could be applied to single-color 3D objects, so that we still need some possible approach for implementation of full-color holograms for the 3D images. In this paper, a method to reduce the size of required N-LUTs for generating of a full-color CGH patterns using a relation of distance and wavelength in Fresnel diffraction is proposed. In addition, some simulations with test images are carried out, and finally the feasibility of the proposed method was confirmed.
Modeling and experiment of future hearing aid device
Houwen Tang, Yun-Bo Yi, M. A. Matin
During the past few years, many new technologies have been introduced to hearing aids for a better performance. Recently, we proposed an implantable piezoelectric hearing aid. The simulation of our hearing aid is presented with a detail study of its physical properties. However, an accurate experimental study of its performance is needed. Vibration frequency is a major factor that affects the quality of a hearing aid. Among various of existing measurement technologies, laser measurement is always considered to be a precise approach for measuring the frequency properties for MEMS (micro-mechanical-electrical-system) devices. In this paper, a piezoelectric transducer used as hearing aid speaker is demonstrated and an optical measurement method for frequency measurement of our device is discussed in detail. Our measurement system is based on Mach-Zehnder interferometer system. Experimental results show that the vibration of our sample can be accurately detected using a laser beam and spectrum analyzer. The vibration frequency is calculated by measuring the intensity variance. This system aims to provide a simultaneous optical measurement with high accuracy.
Decoding software of computer instruction codified as Fourier holograms in a LiNbO3:Fe
In this work, we describe a special software developed to interpret computer instructions codified as information binary pages; which are stored as Fourier holograms in a LiNbO3:Fe photorefractive crystal. The crystal has stored a computer sequence program, as a spatial distribution of Fourier holograms. To read each computer instructions, the position of the crystal is changed by an electro-mechanical setup. The holograms output images of each information binary page are captured over sampled as an image by a CCD camera in the output plane. Due to the spatial displacement of the crystal, the hologram output images are not focused on the same output plane. Therefore, we obtained a set of defocused captured images; which might produces a miss interpretation of the corresponding instructions. We solve this problem by pre-processing the image before decoding it, the proposed software solves the focusing problem with the implementation of a digital spatial filter and some special criteria expressed as a mathematical algorithm. After that, the program decodes each computer instructions from its information binary page to be executed as an electronic digital sequential system.
Digital holographic XNOR multi-gate (DHMG-XNOR)
In this work the description of a digital logic XNOR multi-gate device is made. This device is based in the holographic technology in which the inputs binary states are the polarization of the light field in the wavefront. The binary states are controlled by two liquid crystal displays which modulate the polarization of the wavefronts of the inputs, then the logic operation XNOR is made physically in a photorefractive crystal.
Phase retrieval in digital holographic microscopy using a Gerchberg-Saxton algorithm
Fourier interferometry (FI) is a robust and simple method for reconstruction of phase modulated objects. Its main advantage is that it only requires the recording of one interference pattern, avoiding the problems caused by mechanical vibrations in the optical setup. Unfortunately, the conventional FI method can be employed in digital holography (DH) only for samples with reduced frequency bandwidth, because of the low spatial resolution of available electronic image recording devices (CCDs). We report two methods that partially overcome this bandwidth limitation of the FI technique implemented in DH. The first of these methods consists in a modified version of the conventional FI approach where, instead of processing the Fourier transform of the hologram, we calculate its Fresnel back propagation to the object plane. Although this modified FI approach provides appropriate reconstruction of objects with increased bandwidth, the local SNR tends to be low at thin phase modulated features of the object. In order to increase this SNR we employ the sample reconstructed with the modified FI method as the input in a Gerchberg-Saxton (GS) iterative method. In this GS procedure, the constraints are the modules of the fields at the object and at the hologram planes. This iterative method, implemented by numerical simulations, provides highly accurate phase corrections with fast convergence.
Detection of circuit-board components with an adaptive multiclass correlation filter
A new method for reliable detection of circuit-board components is proposed. The method is based on an adaptive multiclass composite correlation filter. The filter is designed with the help of an iterative algorithm using complex synthetic discriminant functions. The impulse response of the filter contains information needed to localize and classify geometrically distorted circuit-board components belonging to different classes. Computer simulation results obtained with the proposed method are provided and compared with those of known multiclass correlation based techniques in terms of performance criteria for recognition and classification of objects.
Acousto-optical data processing exploiting the wave heterodyning
The process of co-directional collinear wave heterodyning, considered for the particular case of its realizing through interaction the longitudinal elastic waves of finite amplitudes, is studied theoretically and investigated experimentally via the acousto-optical technique. We examine possible applications of this phenomenon to a real-time scale acoustooptical analysis of the frequency spectrum belonging to ultra-high-frequency radio-wave signals. The first step along this way was connected with experimental modeling of the elastics wave heterodyning process in solids via exploitation of acousto-optical cell on the base of liquids, which allow the simplest realization of a cell with needed performance data. Then, these theoretical findings have been used in our experimental studies aimed at improving the accuracy of acousto-optical devices. In particular, the possibility of creating the acousto-optical data processing with the acoustic wave heterodyning has been experimentally observed in a cell made of lead molybdate crystal. The obtained results demonstrate efficiency of the approach presented.
Signal processing for hologram pattern generation in an image system with multi-vision capturing and wavefront reconstruction
Kouichi Nitta, Takanori Kurahashi, Naoki Nishikawa, et al.
Implementation for signal processing in a three-dimensional (3D) image system with multi vision capturing and holographic reconstruction is reported. In the implementation, we utilize a graphic processing unit (GPU) in stead of a central processing unit (CPU). This is because a GPU is specialized for image processing and it can execute parallel processing. In this research, the processing to generate hologram patterns from a set of 3D data obtained by analysis of multi vision is implemented on a GPU. We compare processing times of GPU implementation and CPU one. As a result, it is shown that the former implementation can complete the process faster than the latter. In the best case, the processing time with the GPU is 600 times as short as that with the CPU.
Near lossless medical image compression using JPEG-LS and cubic spline interpolation
Tsung-Ching Lin, Chien-Wen Chen, Shi-Huang Chen, et al.
In this paper, a near lossless medical image compression scheme combining JPEG-LS with cubic spline interpolation (CSI) is presented. The CSI is developed to subsample image data with minimal distortion and to achieve image compression. It has been shown in literatures that the CSI can be combined with the transform-based image compression algorithm to develop a modified image compression codec, which obtains a higher compression ratio and a better subjective quality of reconstructed image than the standard transform-based codecs. This paper combines the CSI with lossless JPEG-LS to form the modified JPEG-LS scheme and further makes use of this modified codec to medical image compression. By comparing with the JPEG-LS image compression standard, experimental results show that the compression ratio increased over 3 times for the proposed scheme with similar visual quality. The proposed scheme reduces the loading for storing and transmission of image, therefore it is suitable for low bit-rate telemedicine application. The modified JPEG-LS can reduce the loading of storing and transmitting of medical image.
Distortion-invariant target detection using shifted-reference joint transform correlator
A new pattern recognition system is proposed using multiple phase-shifted-reference fringe-adjusted joint transform correlation technique. The algorithm involves four different phase-shifted versions of the reference image, which eliminates all unwanted correlation terms and produces a single cross-correlation signal corresponding to each potential target. A fringe-adjusted filter is designed to generate a delta-like correlation peak with high discrimination between the signal and the noise. In addition, the detection performance is made invariant to different spatial distortions by incorporating a synthetic discriminant function, which is created from a set of training images of the reference object. The target detection system is also designed for recognition of multiple targets belonging to multiple reference objects simultaneously in the given input scene and hence provides a real-time class-associative decision on the presence of any target. The proposed technique is investigated using computer simulation with binary as well as gray images in various complex environments where it performs excellent in every case.
A new mean filter ratio technique for edge detection and foreground extraction
Edge detection is the primary step in image segmentation and target detection applications. The edge operators proposed so far in the literature, namely, Canny, Sobel, Prewitt, provide a number of unwanted edges which complicate the foreground object detection process. In this paper, a novel technique is proposed for edge detection and foreground segmentation employing two mean filters of different window sizes. A ratio of the filtered images is taken and normalized. Then a threshold is applied on the histogram of the resultant image to derive the final output which can detect the edges and hence separate the foreground from the background. Performance of the proposed method has been investigated through computer simulation and compared with other existing edge detection techniques using complex reallife image sequences, which verifies that the technique provides better detection results for any input scene.
Superresolution image reconstruction using panchromatic and multispectral image fusion
M. I. Elbakary, M. S. Alam
Hyperspectral imagery is used for a wide variety of applications, including target detection, tacking, agricultural monitoring and natural resources exploration. The main reason for using hyperspectral imagery is that these images reveal spectral information about the scene that is not available in a single band. Unfortunately, many factors such as sensor noise and atmospheric scattering degrade the spatial quality of these images. Recently, many algorithms are introduced in the literature to improve the resolution of hyperspectral images using co-registered high special-resolution imagery such as panchromatic imagery. In this paper, we propose a new algorithm to enhance the spatial resolution of low resolution hyperspectral bands using strongly correlated and co-registered high special-resolution panchromatic imagery. The proposed algorithm constructs the superresolution bands corresponding to the low resolution bands to enhance the resolution using a global correlation enhancement technique. The global enhancement is based on the least square regression and the histogram matching to improve the estimated interpolation of the spatial resolution. The introduced algorithm is considered as an improvement for Price’s algorithm which uses the global correlation only for the spatial resolution enhancement. Numerous studies are conducted to investigate the effect of the proposed algorithm for achieving the enhancement compared to the traditional algorithm for superresolution enhancement. Experiments results obtained using hyperspectral data derived from airborne imaging sensor are presented to verify the superiority of the proposed algorithm.