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This is a historical translation of the seminal paper by H. Gamo, originally published in Oyo Buturi (Applied Physics, a journal of The Japan Society of Applied Physics) Vol. 25, pp. 431–443, 1956. English translation by Kenji Yamazoe, with further editing by the translator and Anthony Yen. Since optical systems have distinctive features as compared to electrical communication systems, some formulation should be prepared for the optical image in order to use it in information theory of optical systems. In this paper the following formula for the intensity distribution of the image by an optical system having a given aperture constant α in the absence of both aberration and defect in focusing is obtained by considering the nature of illumination, namely coherent, partially coherent, and incoherent: I (y) = ∑ n ∑ m a n m u n (y) u m * (y) , where un(y) = sin 2πα/λ (y − nλ/2α) / 2πα/λ (y − nλ/2α) and anm = (2α/λ)2 ∬ Γ12(x1 − x2) E(x1) E* (x2) | A(x1) || A* (x2) | un(x1)um(x2)dx1 dx2. I(y) is the intensity of the image at a point of coordinate y, Γ12 the phase coherence factor introduced by H. H. Hopkins et al., E (x) the complex transmission coefficient of the object and A (x) the complex amplitude of the incident waves at the object, and the integration is taken over the object plane. The above expression has some interesting features, namely the "intensity matrix" composed of the element anm mentioned above is a positive-definite Hermitian matrix, and the diagonal elements are given by the intensities sampled at every point of the image plane separated by a distance λ / 2α, and the trace of the matrix or the sum of diagonal elements is equal to the total intensity integrated over the image plane. Since a Hermitian matrix can be reduced to diagonal form by a unitary transformation, the intensity distribution of the image can be expressed as I (y) = λ 1 | ∑ S i 1 u i | 2 + λ 2 | ∑ S i 2 u i | 2 + ⋯ + λ n | ∑ S i n u i | 2 + ⋯ , where λ1 , λ2 , ... , λn , ... are non-negative eigenvalues of the intensity matrix. In case of coherent illumination, only the first term of the above equation remains and all the other terms are zero, because the rank of the coherent intensity matrix is one, and its only non-vanishing eigenvalue is equal to the total intensity of the image. On the other hand, the rank of the incoherent intensity matrix is larger than the rank of any other coherent or partially coherent cases. The term of the largest eigenvalue in the above formulation may be especially important, because it will correspond to the coherent part of the image in case of partially coherent illumination. From the intensity matrix of the image obtained by uniform illumination of the object having uniform transmission coefficient, we may derive an interesting quantity, namely d = − ∑ n (λ n / I 0) log (λ n / I 0) , where λn is the n-th eigenvalue of the intensity matrix and I0 is the trace of the matrix. d is zero for the coherent illumination and becomes log N for the incoherent illumination, where N is the "degree of freedom" of the image of the area S, namely N = 4α2S / λ2. The value of d for partially coherent illumination is a positive quantity smaller than log N. A quantity δ = (d0 − d) / d0 may be regarded as a measure of the "degree of coherence" of the illumination, where d0 = log N and δ is unity for the coherent case and zero for the perfectly incoherent case. The sampling theorem for the intensity distribution is derived, and the relation between elements of intensity matrix and intensities sampled at every point separated by the distance λ / 4α is shown. [ABSTRACT FROM AUTHOR]

We present and characterize an optical zoom system with lateral movement of an Alvarez freeform lens for imaging. Mathematical analysis for determining the required freeform surfaces is presented, and optical simulations are performed to confirm and refine the expected zooming behavior. A 3× optical zoom system that was equivalent to a photographic objective lens with focal length ranging from 34.5 to 103.5 mm and field of view ranging from 60 deg to 22.4 deg is developed by using two pairs of Alvarez lenses and conventional aspheric lenses. The optical performances of the Alvarez zoom system are demonstrated experimentally. [ABSTRACT FROM AUTHOR]

Typically, the printing of contact patterns uses a dark-field (DF) mask in combination with a positive tone resist and positive tone development (PTD) process. PTD, which has a mature process and simulation model, had been widely applied in high-volume manufacturing. For the low aerial image quality of a DF mask in advanced node, PTD is substituted by negative tone development (NTD), which uses a positive tone resist and bright-field mask. Due to the high cost and immature simulation model of NTD process, it is worthwhile to extend PTD to some critical patterns. With the purpose of improving the resist profile and process window (PW) of the contact pattern with a PTD process in advanced node, an optimization method combined with the idea of a genetic algorithm is put forward. For performance of the optimized resist under the conditions of best focus and best dose, an evaluation based on the through pitch square contact patterns with the critical dimension (CD) fixed at 50 nm has been provided. The generalization performance of the optimized resist is also analyzed by a systematic method, which contains the resist profile and PW simulation on the base of through CD and through pitch contact patterns. The above simulation results verify the effectiveness and validity of the proposed optimization method. [ABSTRACT FROM AUTHOR]

The existing Krawtchouk moment invariants are derived by a linear combination of geometric moment invariants. This indirect method cannot achieve perfect performance in rotation, scale, and translation (RST) invariant image recognition since the derivation of these invariants are not built on Krawtchouk polynomials. A direct method to derive RST invariants from Krawtchouk moments, named explicit Krawtchouk moment invariants, is proposed. The proposed method drives Krawtchouk moment invariants by algebraically eliminating the distorted (i.e., rotated, scaled, and translated) factor contained in the Krawtchouk moments of distorted image. Experimental results show that, compared with the indirect methods, the proposed approach can significantly improve the performance in terms of recognition accuracy and noise robustness. [ABSTRACT FROM AUTHOR]

Locality preserving projections (LPP) is a recently developed linear-feature extraction algorithm that has been frequently used in the task of face recognition and other applications. However, LPP does not satisfy the shift-invariance property, which should be satisfied by a linear-feature extraction algorithm. In this paper, we analyze the reason and derive the shift-invariant LPP algorithm. Based on the analysis of the geometrical meaning of the shift-invariant LPP algorithm, we propose two algorithms to minimize the locality and maximize the globality under an orthogonal projection matrix. Experimental results on face recognition are presented to demonstrate the effectiveness of the proposed algorithms. [ABSTRACT FROM AUTHOR]

This paper proposes a curvature-based corner detector that detects both fine and coarse features accurately at low computational cost. First, it extracts contours from a Canny edge map. Second, it computes the absolute value of curvature of each point on a contour at a low scale and regards local maxima of absolute curvature as initial corner candidates. Third, it uses an adaptive curvature threshold to remove round corners from the initial list. Finally, false corners due to quantization noise and trivial details are eliminated by evaluating the angles of corner candidates in a dynamic region of support. The proposed detector was compared with popular corner detectors on planar curves and gray-level images, respectively, in a subjective manner as well as with a feature correspondence test. Results reveal that the proposed detector performs extremely well in both fields. [ABSTRACT FROM AUTHOR]

A quantum LIDAR for improving resolution using quantum entanglement in the polarization degree of freedom is described. A thorough mathematical analysis of this device is provided. A mathematical discussion of how to generate other more robust entangled states is developed. Internal loss within the entanglement generator and external loss due to atmosphere, detectors, and targets are modeled. A method using these approaches for imaging is provided giving N times classical resolution, where N is the number of photons entangled with explicit results exhibited for N ¼ 3. Closed form expressions for the wave function, normalization, density matrix, reduced density matrix, visibility, and probabilities of detection of one through three photons using detectors with general polarization characteristics are provided. An explicit entanglement generator and detector designs are provided in terms of linear and nonlinear photonics devices. The fundamental role of postselection measurement for generating entanglement is included. Discussions of entanglement devices that will produce general M&M states at near-visible frequencies are given. A discussion of a bearing measurement device that exhibits both super sensitivity and resolution is provided. Computational results are provided that compare probabilities of detection for three single photon detectors with -45- deg, 45-deg, and 45-deg linear polarization. Results for detecting one to three photons or the vacuum state are compared. Computational results for detecting three photons with these detectors for various values of internal and atmospheric loss are provided. Resolution improvements born of quantum entanglement are shown not to degrade with loss. Loss degrades probability of detection not resolution. [ABSTRACT FROM AUTHOR]

We propose a method for solving one of the significant open issues in computer vision: material recognition. A time-of-flight range camera has been employed to analyze the characteristics of different materials. Starting from the information returned by the depth sensor, different features of interest have been extracted using transforms such as Fourier, discrete cosine, Hilbert, chirp-z, and Karhunen-Loeve. Such features have been used to build a training and a validation set useful to feed a classifier (J48) able to accomplish the material recognition step. The effectiveness of the proposed methodology has been experimentally tested. Good predictive accuracies of materials have been obtained. Moreover, experiments have shown that the combination of multiple transforms increases the robustness and reliability of the computed features, although the shutter value can heavily affect the prediction rates. [ABSTRACT FROM AUTHOR]

We shed light on the optimization of lithographic metrics for the semi-isolated dark field two-bar logic building block. Under standard D90Y illumination, this building block suffers from large mask three-dimensionalinduced relative focus-dependent critical dimension (CD) asymmetries. Such behavior limits its overlapping process window (oPW) and gives rise to untenable full wafer CD uniformity and intrafield pattern shifts. We found that besides a Ta absorber thickness reduction and illumination, pupil optimization is necessary to fully remove these CD asymmetries. The pupil optimization is achieved by relating the aerial image decomposition (here, symmetrization and balancing of intensities across the diffracted orders) with lithographic metrics for each pupil plane location. The resulting pupil allows us (i) to lift the focus-dependent CD asymmetries and (ii) to co-optimize a number of lithographic metrics, such as oPW, contrast, nontelecentricity, and pattern shift. The importance of subsidiary conditions (e.g., symmetry of the pupil, required depth-of-focus) will be discussed. [ABSTRACT FROM AUTHOR]

A set of invariant quaternion moments based on an adaptation of the three-dimensional (3-D) spherical harmonic transform (SHT) for describing two-dimensional color shapes is proposed. The use of quaternions to deal with the color part is beneficial in the way the three color components are integrated in a single feature. An adequate mapping from the 3-D SHT to the unit disc allows a fast and accurate computation of the proposed moments. Experiments are conducted to evaluate the performance of the obtained moments in terms of color image reconstruction, robustness to geometric and photometric transformations, content-based color shape retrieval, and computation time. For this purpose, two image databases (COIL-100 and ALOI) are used. Results illustrate the effectiveness of the proposed moments in dealing with the color information. © 2016 SPIE and IS&T [DOI: 10.1117/1.JEI.25.5.053026] [ABSTRACT FROM AUTHOR]

An investigation has been done on the parameters of a hysteretic bistable optical Schmitt trigger device. From a design point of view, it is important to know the regions where this bistability occurs and is fully functional with respect to its subsystem parameters. Otherwise experimentally reaching such behavior will be very time-consuming and frustrating, especially with multiple devices employed in a single photonic circuit. A photonic Schmitt trigger consisting of two feedbacked inverting amplifiers, each characterized by −m (slope), A (y-intercept), and B (constant base) parameters is considered. This system is investigated dynamically with a varying input to find its stable and unstable states both mathematically and with simulation. In addition to a complete mathematical analysis of the system, we also describe howm, A, and B can be properly chosen in order to satisfy certain system conditions that result in bistability. More restrictions are also imposed to these absolute conditions by the system conditions as will be discussed. Finally, all results are verified in a more realistic photonic simulation. [ABSTRACT FROM AUTHOR]

An elliptical multilayer-core fiber (EMCF) with low nonlinearity for wide-band dual-mode operation was proposed. The EMCF, in which only the HE11 and HE21 modes could be propagated, supported a distinct dual-mode operation. The characteristics of the EMCF, including modal properties, the operating wavelength, the transmission loss, the effective area, and the bending loss, were systematically investigated. For EMCFs, a large modal diameter (33.48 µm) was achieved to reduce the fiber nonlinear penalty; meanwhile, the bending loss could be kept in a lower level. In addition, the single-polarization property in EMCFs could be realized by combining stress applying elements. [ABSTRACT FROM AUTHOR]

In standard acousto-optic Bragg analysis, the incident light and sound beams are assumed to be uniform plane waves (with constant profiles) leading to the results based on standard weak interaction theory. As a follow-up to earlier work dealing with nonuniform incident optical beams, we revisit the problem of Bragg diffraction under nonuniform profiles, and include Gaussian, third-order Hermite--Gaussian, and zeroth-order Bessel profiles in our investigation, along with a few others. The first-order diffracted beam is examined (using a transfer function formalism based on angular spectra) under several parametric limits [such as the Klein--Cook parameter Q, the effective profile width, and the optical phase-shift parameter (â0) in the sound cell]. Wherever feasible, the numerical results are compared with analytic theory. The scattered first-order profile output versus the optical phase-shift appears to maintain behavior similar to the known first-order characteristics (sin2 in intensity) encountered for the uniform incident beam case. It is observed, however, that such conformity exists seemingly only at relatively small values of Q (typically about 20 to 50). At higher Qs, on the other hand (where one would otherwise expect behavior closer to standard Bragg theory based on large Qs), it is found that the first-order intensity deviates substantially from the expected sin2- (or related) pattern. This deviation actually becomes more severe at even higher Qs. Additionally, the output profiles at higher Qs are also found to be distorted relative to the incident profiles. These results, though anomalous, are nevertheless generally compatible with earlier studies. Based on the transfer function theory, it is also known that for very large optical phase shifts (i.e., when â0 goes to infinity), the scattered first-order output for a Gaussian profile undergoes an axial (spatial) shift past the output plane of the sound cell. This predicted result is corroborated in our numerical simulation for both the Gaussian and third-order Hermite--Gaussian profiles, but not the zeroth-order Bessel or Airy profiles. These results provide both confirmation of some expected behavior for profiled beam scattering (including likely affirmation of the well known and unique diffractionless properties of certain Bessel beams), but also some insight into unexpected and anomalous photon-phonon interaction behavior. [ABSTRACT FROM AUTHOR]

Retina-like sensors maximize both field of view and resolution in addition to economizing on pixel count, so they play an important role in both biological and machine vision. A new retina-like sensor model for compensating motion blur introduced by forward motion imaging is proposed. Next, the determination of pixel arrangement of a retina-like sensor according to visual task requirements is formulated into a multiobjective optimization problem. Then, three retina-like sensors are designed to meet different visual task requirements using the particle swarm optimization algorithm. The results are robust and approximate to design criteria. [ABSTRACT FROM AUTHOR]

This paper addresses the representation of binary images using mathematical morphology, a nonlinear theory for image processing, based on set theory. The new image representation, called “five-step” skeleton representation, is an extension of the morphological binary skeleton. It consists of calculating the morphological digital binary skeleton using squares or crosses and then reiterating the above procedure for skeleton subsets using lines (horizontal, vertical, 45° and 135°). The theoretical background of the new morphological iterative image representation is presented. Applications and results are illustrated by computer simulations. [ABSTRACT FROM AUTHOR]

A quantum random number generation method based on measuring the time differences between photon detections is analyzed mathematically in terms of bit generation efficiency and bit generation rate. It was found that these two values cannot be maximized simultaneously by altering the incident photon rate of a light source with Poisson statistics, but the generation rate can be increased at the expense of efficiency. Analytical results are presented for both an idealized and a practical case. The detector's dead time has been taken into consideration in the latter case, implying that, for certain combinations of the dead time and the measurement clock period, the generation rate becomes a two-peaked function of the incident photon rate. The theoretical results are confirmed by simulations, showing excellent agreement between the two. [ABSTRACT FROM AUTHOR]

Saccharide interferences such as Dextran, Galactose, etc. have a great potential to interfere with near infrared (NIR) glucose analysis since they have a similar spectroscopic fingerprint and are present physiologically at large relative concentrations. These can lead to grossly inappropriate interpretation of patient glucose levels and resultant treatment in critical care and hospital settings. This study describes a methodology to reduce this effect on glucose analysis using an NIR Fourier transform spectroscopy method combined with a multivariate calibration technique (PLS) using preprocessing by orthogonal signal correction (OSC). A mathematical approach based on the use of a single calibration based bias and slope correction was applied in addition to a standard OSC was investigated. This approach is combined with a factorial interferent calibration design to accommodate for interference effects. We named this approach as a slope and bias OSC (sbOSC). sbOSC differs from OSC in the way it handles the prediction. In sbOSC, statistics on slope and bias obtained from a set of calibration samples are then used as a validation parameter in the prediction set. Healthy human volunteer blood with different glucose (80 to 200 mgdL) and hematocrit (24 to 48 vol.) levels containing high expected levels of inteferents have been measured with a transmittance near-infrared Fourier transform spectrometer operates in the broadband spectral range of 1.25–2.5 m (4000–8000 cm−1). The effect of six interferents compounds used in intensive care and operating rooms, namely Dextran, Fructose, Galactose, Maltose, Mannitol, and Xylose, were tested on blood glucose. A maximum interference effect (MIE) parameter was used to rank the significance for the individual interferent type on measurement error relative to the total NIR whole blood glucose measurement error. For comparison, a YSI (Yellow Springs Instrument) laboratory reference glucose analyzer and NIR data were collected at the same time as paired samples. MIE results obtained by sbOSC were compared with several standard spectral preprocessing approaches and show a substantial reduced effect of saccharide interferences. NIR glucose measurement results are substantially improved when comparing standard error of prediction from validation samples; and resulting MIE values are small. [ABSTRACT FROM AUTHOR]

The simulation and numerical analysis of erbium-doped fiber-ring lasers for generation and enhancement of chaos is presented. The degree of chaos determines the level of security in chaotic optical communication systems. Various parameters such as pump power, modulation index, modulation frequency, decay rate, and cavity gain can be varied as a control in producing higher degree optical chaos. The effect of each pertinent model parameter is analyzed in time-expanded mode using a phase plot direct-observation method and time series analysis of the time domain wave form by calculating its Lyapunov exponents. The mathematical and numerical analysis of the generated chaos helps in generalizing the trend through variation of cavity parameters and driving conditions in achieving a relatively higher degree of chaos. These trends help in optimizing various parameters for generation of new sequences of optical chaos in realizing better security. To gain an insight into chaotic signatures, the width and height of individual pulses, relationship of their time periods, gain quenching, shape, formation of bunches, and humps of the chaotic wave forms are also analyzed. The study of individual and cumulative behavior of all the parameters in enhancing optical chaos leads toward a reliable development in designing secure communication systems. [ABSTRACT FROM AUTHOR]

Even though odd-order aspherical surfaces have sometimes been used in optics, their meaning and effectiveness have not been discussed enough to be fully understood. However, we have already discussed and derived mathematically that odd-order aspherical surfaces cannot be represented in the form of a power series of even-order even when rotationally symmetric. We have also explained that this result does not contradict the fact that the set of Zernike’s circle polynominals forms a complete system and that their rotational symmetric terms consist only of even-order terms of radial coordinates. First, we reconsider these mathematical discussions. Second, we reveal that the first- and third-order aspherical surfaces are valuable in practical lens designing for catoptoric projection optics of extreme ultraviolet lithography. [ABSTRACT FROM AUTHOR]

A locality projection discriminant analysis (LPDA) method by using local structure-based projection techniques is proposed to extract discriminative features in high-dimensional sample space. Two locality metric matrices are defined to make the discriminative projections preserve the intrinsic neighborhood geometry of the within-class samples while enlarging the margins of extra-class samples near to the class boundaries. LPDA efficiently addresses the nonlinear property of data and the small sample size problem in face recognition scenario; moreover, it can reduce the dimensionality of the original data (such as the role of principle component analysis) as well as extract complete discriminative features in dual subspaces. Experiments on synthetic data sets and ORL, PIE, and FERET low-resolution face databases are performed to evaluate LPDA-based methods and some known methods. The results demonstrate the effectiveness of LPDA and reveal some characteristics of this pure local structure-based method. [ABSTRACT FROM AUTHOR]

We present a very simple and straightforward approach for the generation of broadband radiation in the visible region covering 397 to 529 nmby taking advantage of the angular dispersion of the broadband (0.8- to 1.6-m)idler radiation of a Ti:sapphire second-harmonic (i.e., 395 nm)-pumped type I noncollinear optical parametric amplifier (NOPA). Type I broadband sum-frequency mixing (SFM) between the Ti:sapphire laser fundamental radiation (790 nm)and the octave-spanned carrier-envelope-phase (CEP)-locked idler radiation from a broadband NOPA is considered for generation of broadband radiation in several relatively recently developed borate crystals. Moreover, it is also shown that by applying simple SFM, it is possible to obtain a very large bandwidth in a 5-m-thick crystal without requiring any angularly dispersed input radiation. Furthermore it is found that the performance of the most recently developed KBe2BO3F2crystal is the best among all the available borate group crystals. [ABSTRACT FROM AUTHOR]

We present a formula connecting the change in the output of a multiple-channel waveguide to a micron-scale alteration in the physical properties of a segment of the waveguide. The analysis is motivated by the need to “tune” the properties of photonic devices after fabrication, necessitated by the present impossibility of fabrication to within the severe tolerances required to produce desired output characteristics. The results point to a method by which tuning can be carried out in an optimal manner. Example device application is illustrated by use of a simulation program. [ABSTRACT FROM AUTHOR]

In this study, we propose a pulsed Nd:YAG laser system that uses a sequential charge and discharge circuit to adhere polymethylmethacryl (PMMA) plastics. Two PMMA plastics adhere to each other when the red one transmits the laser beam and the black one absorbs it. The optimal adhesion depends on several process parameters, such as the charging voltage of the capacitor, the pulse rate in pulses per second (pps), the velocity of the target, and the laser beam diameter. We try to optimize the adhesion process parameters from trial-and-error experiments. It has proposed that the optimal adhesion process parameters are a charging voltage of 650 V, a pulse rate of 11 pps, a target velocity of 4.20 mms, and a laser beam diameter of 4.00 mmin this pulsed Nd:YAG laser system. In addition, we generalize the optimal conditions for plastic adhesion, such as energy per pulse, peak power, and the velocity of the target. [ABSTRACT FROM AUTHOR]

The problem of spreading secret data to embed into multiple cover images is called batch steganography and has been theoretically considered recently. Few works have been done in batch steganography, and in all of them, the payload is spread between cover images unwisely. We present the Adaptive batch steganography (ABS) approach and consider embedding capacity as a property of images. ABS is an approach to adaptively spread secret data among multiple cover images based on their embedding capacity. By splitting the payload based on image embedding capacity constraint, embedding can be done more secure than the state when the embedder does not know how much data can be hidden securely in an image. Furthermore, the number of required cover images to embed a piece of secret data in ABS is smaller than the number of required cover images in usual batch steganography. We apply an ensemble system that uses different steganalyzer units to determine the embedding capacity of a cover image. Each steganalyzer unit is formed by a combination of multiple steganalyzers from a same type, but each one trained to detect a certain payload. Experimental results showed the effectiveness of embedding in ABS and security enhancement of produced stego images. [ABSTRACT FROM AUTHOR]

We have constructed a new type of modal wavefront sensor that uses a multiplexed hologram and position-sensing detectors to measure the amplitudes of a preselected set of eight Zernike modes in an input beam. The measurement is all optical, with the calculations made in encoding the holograms themselves. The result is a sensor with no computational overhead or postprocessing that has the potential to operate at megahertz speeds without the need for computer calculations. We have built and tested a prototype device, demonstrating its operation both as a stand-alone wavefront sensor and in a closed-loop adaptive optics control system. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a mathematical model that could be used to obtain the approximate focal length of O-ring-driven liquid-filled lenses. An O-ring-driven liquid-filled lens is composed of a base plate, a glass-covered liquid reservoir, a pliable membrane, an O-ring, a spring, and three actuators. The movement of the ring changes the focal length or the focus position. In previous studies, the commercial software ANSYS was used to find the membrane deformation and ZEMAX was used to find the focal length. The procedures used in those previous studies are complicated and generally require considerable design work. The proposed mathematical method employs the principle of liquid volume conservation to simplify the calculations that approximate the focal length of the lens. The result is confirmed on ZEMAX to ensure that the method is practicable. Consequently, focal lengths of lenses with different ring thicknesses, radii, and squeezing depths to contact the membrane can be calculated immediately. [ABSTRACT FROM AUTHOR]

Finding good new local minima in the merit function landscape of optical system optimization is a difficult task, especially for complex design problems where many minima are present. Saddle-point construction (SPC) is a method that can facilitate this task. We prove that, if the dimensionality of the optimization problem is increased in a way that satisfies certain mathematical conditions (the existence of two independent transformations that leave the merit function unchanged), then a local minimum is transformed into a saddle point. With SPC, lenses are inserted in an existing design in such a way that subsequent optimizations on both sides of the saddle point result in two different system shapes, giving the designer two choices for further design. We present a simple and efficient version of the SPC method. In spite of theoretical novelty, the practical implementation of the method is very simple. We discuss three simple examples that illustrate the essence of the method, which can be used in essentially the same way for arbitrary systems. [ABSTRACT FROM AUTHOR]

A new method for 3-D object recognition is proposed. The method combines structured light coding with the joint fractional transform correlator (JFrTC).When projecting sinusoidal grating fringes onto the surface of 3-D objects, the fringes are distorted due to the height of the objects. Then the distorted fringe patterns are regarded as the joint input image used for correlation recognition. Simultaneously, to achieve JFrTC, we can replace either (or both) Fourier transforms in the joint transform correlator (JTC) by a fractional Fourier transform. Four architectures of JFrTC with the distorted fringe pattern and four JFrTC with the intensity map are analyzed in detail. By comparing these different structures, a JFrTC with distorted fringe patterns, especially for the FrT-FT architecture, is suggested to improve the discernment performance, to more decrease the widths of the correlation peaks, and to flexibly change the intensity and position of correlation peaks. Both mathematical analysis and computer simulation results are presented in support of the proposed idea. [ABSTRACT FROM AUTHOR]

This study investigates the use of simple, low-cost infrared sensors for the recognition of geometry and surface type of commonly encountered features or targets in indoor environments, such as planes, corners, and edges. The intensity measurements obtained from such sensors are highly dependent on the location, geometry, and surface properties of the reflecting target in a way that cannot be represented by a simple analytical relationship, therefore complicating the localization and recognition process. We employ artificial neural networks to determine the geometry and the surface type of targets and provide experimental verification with three different geometries and three different surface types. The networks are trained with the Levenberg–Marquardt algorithm and pruned with the optimal brain surgeon technique. The geometry and the surface type of targets can be correctly classified with rates of 99 and 78.4, respectively. An average correct classification rate of 78 is achieved when both geometry and surface type are differentiated. This indicates that the geometrical properties of the targets are more distinctive than their surface properties, and surface determination is the limiting factor in recognizing the patterns. The results demonstrate that processing the data from simple infrared sensors through suitable techniques can help us exploit their full potential and extend their usage beyond well-known applications. [ABSTRACT FROM AUTHOR]

Many applications produce three-dimensional points that must be further processed to generate a surface. Surface reconstruction algorithms that start with a set of unorganized points are extremely time-consuming. Sometimes, however, points are generated such that additional information is available to the reconstruction algorithms. There are triangulation algorithms based on mapping technology. Of these, some are fit only for nonoverlapping point sets. Some can process overlapping point sets, but they need manual intervention and their efficiency is low. In addition to sample point locations, our algorithm starts with usual information and knowledge of each point’s neighbors. Using that information and the base point’s normal vector, our algorithm automatically and dynamically partitions points into patches, and then projects 3-D points with more than k neighbors onto 2-D tangent planes. Then using a 2-D triangulation method to get 3-D triangles, and a special method for removing illegal triangles, we finally get our triangulation. An experiment shows that our algorithm can solve overlapping-set problems very well, and its efficiency is high. [ABSTRACT FROM AUTHOR]

An artificial neural network (ANN)-based model for erbium-doped fiber amplifiers (EDFAs) is developed. For a network with two input neurons and a single hidden layer, the number of neurons in the hidden layers is optimized by monitoring the mean square error (MSE) at the outputs. The model is used to optimize the design of EDFAs for central signal gain, 3-dB bandwidth, and noise factors, taking into account the influence of amplifier constructional parameters in the amplifier performance. For a given pump power and pulse width that correspond to the two input neurons, the model computes the constructional parameters to obtain values of central signal gain, 3-dB bandwidth, and noise figures in optimal range. The effects due to intrapulse stimulated Raman scattering (ISRS) are also considered by varying pulse widths from subpicosecond regime to hundreds of picoseconds. Self frequency shift due to ISRS is found to be prominent in the subpicosecond regime. The proposed model generates results with a MSE of 1×10−4, and needs relatively very low computational time compared to other analytical models. [ABSTRACT FROM AUTHOR]

The design requirements of a high-stability narrowband dye laser with a curved dye cell, pumped by a copper vapor laser, are discussed. The design is simple and easy to fabricate at low cost. It is shown that the curved dye-cell geometry, with hydraulic diameter varying from 23 to 1 mm and curvature ratio varying from 1 to 81, creates flow conditions that meet the requirements of a stable narrowband tunable dye laser. It is shown numerically that the eddy sizes, temperature fluctuations, and associated energies in boundary layer are responsible for the fluctuations in the output. A dye laser based on this geometry was operated from Reynolds number 184 to 1100. The numerical results agree with the experimental results showing better dye laser stability at higher Reynolds number. [ABSTRACT FROM AUTHOR]

A new dynamic flow allocation scheme to guarantee quality of service and more stabilized performance is proposed, replacing an Ethernet passive optical network. This new scheme improves a priority-based access network, converting it to a flow-based access network with a new access mechanism and scheduling algorithm. With this new scheme, a network service provider can provide upper limits of transmission delays by the flow. The modeling and simulation results with mathematical analyses obtained by this scheme are also provided. [ABSTRACT FROM AUTHOR]