This PDF file contains the editorial “2002 in Review” for OE Vol. 42 Issue 02

Intrinsically acentric self-assembled superlattices (SASs) have been directly grown in a layer-by-layer process on the commercially available polymer Cyclotene^TM. Using the high-temperature/high-transparency fluoropolyether Cytop^TM as a cladding layer, the SAS films have been used to successfully fabricate traveling-wave electro-optic (EO) modulators, demonstrating a straightforward approach toward "all-organic" modulators.

Simultaneous oscillation of 23 wavelengths, spaced at 100 GHz, is demonstrated from a stable semiconductor optical amplifier source. The wavelength comb is generated from a fiber Lyot filter and each wavelength has 12.5-GHz linewidth.

A new photosensitive negative-tone inorganic-organic hybrid SiO₂/TiO₂ glass with improved linear UV response property is investigated for fabrication of multilevel structures. The UV response of the sol-gel material is studied as a function of optical densities (ODs) of a high-energy beam-sensitive (HEBS) gray-scale mask. It is shown that the sol-gel material exhibits a good linear response to the OD values, which is ultimately used to define the surface profile height for a specific design. The linearity is especially useful for fabrication of diffractive optical elements with linear phase distributions. As an example, we apply the sol-gel process and the gray-scale mask to the fabrication of a blazed grating.

Active deformable sheets are integrated smart planar sheet structures performing off-plane deformations under computer actuation and control, to take up a desired dynamic 3-D morphology specified in CAD software or obtained by 3-D scanning of a solid surface. The sheet prototypes are implemented in the laboratory by elastic neoprene foil layers with embedded asymmetric grids of shape memory alloy (SMA) wires [nickel-titanium Naval Ordinance Laboratory (Nitinol)], which on electrical contraction bend the sheet to the necessary local curvature distribution. An analytical model of such prototypes, consisting of an electrical, thermal, material, and mechanical module, as well as a more complex finite element mechanical simulation of the sheet structure, have been developed and validated experimentally. Besides open-loop control of the sheet curvatures by modulation of the SMA wire actuation current, a closed-loop control system has been implemented, using feedback of the wire electrical resistance measurements in real time, correlating to the material transformation state. Prototypes with a reflective foil surface are also tested as cylindrical reflectors with real-time variable focal length. The active deformable sheets are intended for applications such as reconfigurable airfoils and aerospace structures, optics and electromagnetic reflectors, flexible and rapid tooling, and microrobotics.

We present the design and fabrication of holographic diffusers for diffuse IR wireless home networking. Three optimization methods—error reduction, input-output, and simulated annealing—are studied and used to calculate the computer-generated holograms, which are employed to fabricate the holographic diffusers. To evaluate the performance of the computer-generated holograms generated using these techniques, a cost function is defined and calculated for each hologram. The computer-generated hologram generated from the simulated annealing is found to have the best output compared to the other two techniques. The diffusers are verified by displaying them onto a spatial light modulator. The fabrication of the computer-generated hologram onto a piece of quartz with a pixel size of 14×14 μm using a laser writing system is achieved, and the diffraction pattern of the diffuser is demonstrated.

We evaluate the feasibility of implementing correlation spectroscopy for remote sensing with a passive IR sensor that incorporates a diffractive grating on which a synthetic spectrum is imbedded. The spectral diffraction reflectances of diffractive gratings are measured and compared to the theoretical design spectra and to the library absorbance spectra. Five gratings are evaluated: sulfur hexafluoride (SF6), [(dimethoxyphosphinothioyl)thio]butanedioic acid, diethyl ester (malathion), diisopropyl-methylphosphonate (DIMP), methylphosphonofluoridic acid,(1-methylethyl) ester (Sarin or GB), and O-ethyl-S-(2-diisopropylamino)ethyl methylphosphonothioate (VX). While the gratings were designed from liquid phase infrared spectra, the measurements and models provide a satisfactory proof of principle for the exploitation of synthetic spectra in correlation spectroscopy. The predicted noise equivalent concentration pathlength (NECL) for detecting GB and VX in a desert environment is computed for distances up to 5 km. The device was found to have high sensitivity in terms of NECL. The selectivity of the grating is found to be poor, but can be improved dramatically with the use of orthogonal subspace projection (OSP) filters that reduce the false alarm (improve selectivity) from misidentifying a GB as VX (and vice versa) at the "cost" of a slight increase of the NECL (reduce sensitivity).

A model is set up to simulate the fabrication infidelity of diffractive-optical elements using halftone gray-scale masks. The infidelity includes, for different spatial frequencies, variations in maximum exposure depth in photoresist, relative transition width between adjacent ramps, and nonlinearity. The attenuation of the modulation transfer function (MTF) of the fabrication system at a high spatial frequency is the main reason for all the fabrication infidelity. The component whose MTF attenuates most in the fabrication system is generally photoreduction.

Digital watermarks offer means of protecting the copyright of digital multimedia. However, many of the proposed watermarking methods are vulnerable to the geometrical distortions that occur during normal use of the media. We propose a new image watermarking method that is resilient to rotation, scaling, and translation (RST). We use the higher order spectra (HOS), in particular, the bispectrum feature vector of an image as the watermark. The bispectrum is the Fourier spectrum of the triple correlation of a signal. Phases of the integrated bispectra are invariant to translation and scaling. Rotation invariance is achieved using the Radon transform of the image. An image is decomposed into the 1-D projections and we construct a feature vector from them. A watermark is embedded by modifying the vector. We measure the distance between the feature vector extracted from the test image and the watermark at detector. Results of experimental studies show that our method is robust to geometric attacks, JPEG compression, and Gaussian noise.

By analyzing the error of discrete hyper-wavelet transform Y = MX, we derive the relation between errors and eigenvalues of matrix MM^T. Three new theorems about the eigenvalues of MM^T are developed. Based on these theorems, a model for designing optimal biorthogonal wavelets is built. Optimal 8-8-tap and 9-7-tap filters for image compression are found by employing the model presented. Experiment has shown that the optimal 9-7-tap filters have better performance than Cohen and Daubechies' 9-7-tap wavelet for many images. Experiment has also shown that optimal 8-8-tap filters have better visual effects than optimal 9-7-tap filters.

With a view of quantitatively evaluating image quality in mammographic systems from an automated computerized analysis of digitized mammographic phantom films, an image enhancement method for such images is presented. In this framework an adaptive neighborhood image processing technique with a contrast-enhancement function is used. The method consists of computing a local contrast around each pixel using a variable neighborhood whose size and shape depend on the statistical properties around the given pixel. The obtained image is then transformed into a new contrast image using several contrast-enhancement functions. Finally, an inverse contrast transform is applied to the previous image. To compare contrast-enhancement functions, images simulating objects similar to those observed in the phantom image, with various relative contrasts and signal-to-noise ratio (SNR) levels, are generated. Several parameters including the output-to-input SNR ratio and the mean squared error are used as comparison criteria. Results show that this process enhances features in the image with little enhancement of noise and that a trigonometric contrast-enhancement function performs best for studying phantom images.

Surface profile measurement of smooth surfaces is a vital area in many of today's industries, especially in wafer fabrication. The increased need for high-speed, noncontact online measurement with high accuracy and repeatability is of great interest for practical purposes. In this work, a modification of Michelson interferometers in combination with instantaneous phase-shifting interferometry is proposed for high-speed large flat-surface profiling. Experiments are carried out on a patterned wafer surface. The results obtained using this system are compared with a commercial profiler system to demonstrate the validity of the principle.

We demonstrate theoretically the feasibility of the full-attitude measurement of a moving target by laser tracking systems. Based on the combination of retroreflector target, laser tracking, and interferometry techniques, two kinds of laser tracking systems known as distance-angle-measurement (DAM) and distance-only-measurement (DOM) systems are proposed for the attitude measurement of a moving target in real time. Mathematical models and algorithms of both systems are built to determine and calculate the dynamic attitude of the target under the world coordinate system and the target's initial coordinate system respectively. The coordinate transform between different coordinate systems and the initial geometric parameters of the laser tracking stations can be self-calibrated. The coordinate transform self-calibration algorithm can be solved by the singular matrix decomposition method, while the self-calibration algorithm of the initial geometric parameters of the DOM system can be solved by the Levenberg-Marquardt method. The simulation results show that the self-calibration algorithm converges rapidly and its accuracy is satisfactory under noise measurement.

Cylindrical dielectric and semiconducting microdisks are becoming attractive for use as electromagnetic resonators for optical and terahertz-frequency devices. The effects of the substrate and the support pedestal on microdisk performance, however, are not well understood due to limitations of conventional analytical techniques. We present a study of the influence of the support structure, namely, the substrate and pedestal, on microdisk resonator performance using the finite-difference time-domain method. The field distributions, resonant frequencies, and Q factors of the microdisk are computed at various distances from the substrate and for different pedestal sizes. Results show that the supporting structure can significantly distort the field distribution in the disk, and therefore have significant effects on both resonant frequency and Q factor, which are major parameters in microdisk design.

Implementation of the Johnson criteria for infrared images is the probabilities of a discrimination technique. The inputs to the model are the size of the target, the range to it, and the temperature difference against the background. The temperature difference is calculated without taking the background structure into consideration, but it may have a strong influence on the visibility of the target. We investigated whether a perceptually based temperature difference should be used as input. Four different models are discussed: 1. a probability of discrimination model largely based on the Johnson criteria for infrared images, 2. a peak signal-to-noise ratio model, 3. a signal-to-clutter ratio model, and 4. two versions of an image discrimination model based on how human vision analyzes spatial information. The models differ as to how much they try to simulate human perception. To test the models, a psychophysical experiment was carried out with ten test persons, measuring contrast threshold detection in five different infrared backgrounds using a method based on a two-alternative forced-choice methodology. Predictions of thresholds in contrast energy were calculated for the different models and compared to the empirical values. Thresholds depend on the background, and these can be predicted well by the image discrimination models, and better than the other models. Future extensions are discussed.

Unlike traditional refracting telescopes, dialyte and Schupmann-medial refractors manage the correction of chromatic aberration through the use of correcting elements well spaced from their companion, single-element objectives. Dialyte designs leave a large contribution to lateral color, and Schupmann-medial types require the tilting of the mangin corrector to make the focus available, which restricts the field unless at least one toroidal curvature is included. A new dialyte design that combines attributes of both systems results in an all-refractive telescope that offers correction for lateral color and an accessible field unrestricted by tilt-induced astigmatism. The design can also be adapted to correct the secondary spectrum of a traditional achromat.

The large amount of spherical aberration generated by a spherical mirror can be corrected by an image relay having a diameter much smaller than that of the pupil of the system. Described is a high-performance catadioptric corrector with a maximum input numerical aperture (NA) of 0.29 (f/1.7), a fixed output NA of 0.67 (f/0.75), and a passband of 405 to 1000 nm, that can be adapted to operate with spherical primary mirror systems having small to medium pupil diameters. Design examples are presented of systems with pupil diameters 0.5, 1, 2, and 4 m, with corresponding angular fields of 4, 2, 1, and 0.5 deg. The image in all examples is ~26 mm diameter, resolved to <4 μm root mean square (rms) over the whole field.

A novel fiber-optic sensor structure for noncontact quantification tests on internal MJ threads is presented. It is based on the light reflex measurement principle, but unlike traditional fiber-optic sensors in which the light is emitted from the end face of the fibers, this sensor uses the side cylindrical face, where the converging beam can be obtained. This improves the lateral resolution. The sensor is very compact because a 45 deg, fully reflecting surface is polished at the emitting end of the sensor probe, instead of a fiber-bending structure often used for internal dimension measurement cases. Both theoretical analysis and experimental results indicate the feasibility of measurement of internal threads. Contour of the longitudinal section of an internal thread is measured, based on which shape and parameters of threads can be estimated. The expected accuracy of ∓2 μm for pitch measurement, and ∓10 μm for minor and major diameter measurement have been achieved due to the complex surface shape and measurement conditions.

We propose a compact triangular-shaped bulk-optic glass sensor for simultaneous measurement of three ac currents using only one laser source. The sensor consists of three glass rods arranged as the three arms of a triangle, each of which is mounted with a coil of conducting wire that carries a current to be measured. Laser light is guided through the glass rods in a closed loop by reflecting twice at the critical angle of the two corners of the triangle. On the reflection surface of each corner, light is tapped with a right-angle prism that is pressed against the surface. The three unknown currents are determined by processing the light beams tapped from the two corners and that emerge from the exit face of the sensor. To demonstrate the principle, we construct an experimental sensor with SF6 glass and tested it with three-phase currents.

The dynamic response of a fiber optic Bragg grating to mechanical vibrations is examined both theoretically and experimentally. The theoretical expressions describing the consequences of changes in the grating's reflection spectrum are derived for partially coherent beams in an interferometer. The analysis is given in terms of the dominant wavelength, optical bandwidth, and optical path difference of the interfering signals. Changes in the reflection spectrum caused by a periodic stretching and compression of the grating are experimentally measured using an unbalanced Michelson interferometer, a Michelson interferometer with a nonzero optical path difference. The interferometer's sensitivity to changes in the dominant wavelength of the interfering beams is measured as a function of interferometer unbalance and is compared to theoretical predictions. The theoretical analysis enables the user to determine the optimum performance for an unbalanced interferometer.

Wavelength multiplexing of optically interrogated microelectromechanical system (MEMS) pressure and temperature sensors using both fiber Bragg gratings (FBGs) and arrayed waveguide gratings (AWGs) is demonstrated. The multiplexed sensor system using FBGs has the potential to multiplex about 70 sensors, depending on the FBG bandwidth and the one using AWGs has the potential to multiplex about eight sensors, depending on the number of AWG channels and the bandwidth of each channel. A dual-wavelength method incorporating a tunable laser is used to interrogate either the applied pressure or temperature experienced by the sensor, while a three-wavelength method can be used to simultaneously interrogate pressure and temperature. The Fabry-Pérot cavity-based pressure sensors and temperature sensors are designed and fabricated using MEMS techniques. Experimental results, including response as a function of pressure or temperature, are characterized by good agreement between experimental and theoretical results. There is no observable crosstalk between the multiplexed sensors.

A high-speed, large-scale architecture, three-dimensional micro-optical switching system (3-D MOSS) is proposed. A switching network is divided into subnetwork blocks, followed by stacking them to construct a multilayer structure. The interblock waveguide connection is replaced with short-distance vertical optical wiring, that is, optical z connections. Thus, 3D-MOSS, in contrast with conventional planar structures, reduces waveguide cross points, wiring length, and system size. Expected applications are switching for fiber communications, reconfigurable 3-D micro optoelectronic (OE) systems, and so on. 3D-MOSS consists of OE films, in which thin-film high-speed micro-optical switches are embedded. Two critical issues for 3D-MOSS, micro-optical switch and optical z connection, are investigated. The beam propagation method (BPM) calculation shows that waveguide-prism-deflector micro-optical switch (WPD-MOS), in which prism-shaped electrodes are formed on an electro-optic slab waveguide, is suitable for the micro-optical switch. The finite difference time domain method (FDTD)/BPM coupled simulation demonstrates a possibility of low-loss optical z connection in a 4-μm width waveguide-based 3-D micro-optical network. Performance of 3D-MOSS for a 32×32 Banyan network is assessed as follows: system size is 2250 (length)×600 (width)×320 (height) μm³, operation voltage 110 V, switching speed <1 μs, power consumption 520 mW at a switching rate of 3×10⁵/s, and maximum insertion loss 14 dB. This indicates the viability of 3D-MOSS from viewpoints of channel count, switching speed, thermal management, and power budget. A material/cost-saving device integration process "photolithographic packaging with selectively occupied repeated transfer (PL-Pack with SORT)" is briefly described as an example of a fabrication method for 3D-MOSS.

An analytical model has been developed to theoretically examine the noise performance of an optically controlled GaAs metal semiconductor field effect transistor (MESFET) at microwave frequencies. The model enables one to characterize the device under optically controlled conditions in both linear and saturation regions. It is seen that the photogenerated carriers play a significant role in deciding the overall noise performance of the device. The output signal to noise ratio depends on the frequency of operation of the device and also on the incident optical power. The device comparatively exhibits a high value of noise equivalent power that may make it less attractive as a photodetector.

Single-crystal films of an organic molecular salt, 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) with exceptional optical quality are prepared by a modification of the shear method. Electro-optic modulation for light propagating perpendicular to the film is measured at 720 and 750 nm wavelengths with electric fields over the frequency range of 2 kHz to 100 MHz. A modulation depth of 80% was measured at 750 nm for a field of 4 V/μm in a 4-μm-thick film. The measured electro-optic response is flat over the frequency range used (2 kHz to 100 MHz), indicating electronic origin of the electro-optic effect. The results show that these films may lead to a new generation of electro-optic devices.

A method for three-dimensional particle position estimation employed in particle image velocimetry applications is presented. The method includes the application of a robust optimization process, which involves the use of a genetic algorithm. The algorithm derives particle position by pattern matching theoretical to experimental images, using the concept of image peak signal-to-noise ratio as the objective error measure for this comparison. To produce sufficiently accurate theoretical images comparable to experimental images for positioning purposes, it is found that a Lorenz-Mie treatment of the seeding scattering field was required, which also took into consideration the incident wavefront. The use of a genetic algorithm for positioning proved to be more accurate and faster than a Nelder-Mead algorithm combined with neural nets used previously. This method has also been shown to be an effective means of isolating contaminant particles in velocimetry images, which can substantially increase the overall error. We discuss some aspects of the theory regarding this method, illustrate the ideas with a simple experimental image, as well as detail our implementation of a pattern-matching approach combined with a genetic algorithm for positioning purposes.

We introduce some basic optical rules dealing with Mueller matrices as phenomenological descriptors of optical devices. Specific simple examples illustrate how all the Stokes parameters of a beam passing through a system of several devices can be determined by the multiplication of the individual Mueller matrices of the respective system components and the Stokes vector of the incident beam. Two resulting families of interference fringes in the (visible) emerging field of the devices considered are separated from each other by the introduction of suitable additional system components. The "isochromatic" family of fringes can thus be isolated from the "isoclinic" family, and a natural application to photoelastic problems becomes evident. Thus, a second purpose is to use this technique and these fringes to photoelastically determine the stress distribution in a disk with a square perforation, when the disk is subjected to a uniformly distributed pressure, acting at its outside or at its inside periphery. This enables the visualization and quantification of the stresses developed during the burning of the grain. The size of the square hole and the radii of the fillets at the corners of the square are variables of the study. Results are given as stress concentration factors, in dimensionless form, and are of use to the designer of solid propellant rocket grains. An analogy is given to suggest another application at longer wavelengths to calibrate or discriminate between some radar signals in the microwave region.

A new photolithographic technique that combines the advantages of a programmable digital liquid crystal display (LCD) system and projection photolithography system to fabricate arbitrarily shaped microstructures using LCD panels as real-time masks is reported. Its principle and design method are explained. Based on a partial coherent imaging theory, the process to fabricate microaxicon arrays and zigzag gratings is simulated. The experiment has been set up using a color LCD as a real-time mask. Microaxicon arrays and zigzag gratings have been fabricated by a real-time photolithographic technique. The 3-D surface relief structures are made on panchromatic silver-halide sensitized gelatin (Kodak-131) with trypsinase etching. The pitch size of the zigzag grating is 46.26 μm, and the etching depth is 0.802 μm. The caliber of the axicon is 118.7 μm, and the etching depth is 1.332 μm.

We present an error compensation method for a full-field 3-D shape measurement system based on a digital fringe projection and phase shifting technique. The error map of the system is first established by comparing the measured coordinates with the coordinates defined by a coordinates measuring machine (CMM) at preselected sample points within the measurement volume. An eight-point interpolation algorithm based on the Shepard's method is then used to compensate for the errors in the measured coordinates. Experimental results showed that the accuracy of the system was improved by more than 60% after error compensation.

A 3-D surface shape measurement system based on a digital fringe projection and phase shifting technique is described. In this system, three phase-shifted fringe patterns and a centerline pattern are used to determine the absolute phase map of the object. This phase map is then converted to the x, y, and z coordinates of the object surface by a conversion algorithm. To determine the accurate values of the system parameters as required by the conversion algorithm, a two-step calibration procedure was developed. The parameters were first measured to determine their approximate values, then a calibration plate was measured by the system at various positions, and an iteration algorithm used to estimate the system parameters. Measurement results of several objects are presented. The standard deviation of the measurement error was found to be 0.23 mm.

×The solid state imaging (SSI) subsystem on the National Aeronautics and Space Administration's (NASA's) Galileo spacecraft has successfully completed a 4-yr extended mission exploring the Jovian system. The SSI remained in stable calibration throughout its total 12-yr flight time and returned valuable scientific data until the end of the mission. A slight loss in spatial resolution occurred between the last primary-mission calibration and that done during the extended mission. The absolute spectral radiometric calibration has been determined to 5 to 7% accuracy across the camera's eight spectral filters. A possible shift in the central wavelength of one of the methane-absorption-band filters of ~3 nm shortward may have occurred late in the extended mission. The charge-coupled device (CCD) detector endured the harsh radiation environment at Jupiter to a total dose of ~4 krad without any serious permanent damage. Some radiation-induced problems in the detector clocking and signal-chain electronics rendered the 2-×2-pixel summation modes unusable and required that the CCD light flood and erasure prior to each exposure be disabled. However, good-quality imaging continued to be possible even in the most extreme radiation fluxes encountered. The successful return of 1453 images during the extended mission nearly matched the number of frames returned during the primary mission.

Multiple reflections at cell walls give rise to modulation terms in the transmission coefficient of the beam passing through a spectrophotometric cell. Considering the cell as a planar layered system, these intrinsic modulation terms are subjected to numerical simulation according to a multilayer structure theory, assuming the system behaves as an infinitely thick medium contained between two layers that act as multilayered systems, which is approximated by a three layer system with a thicker second layer for simplicity. A frequency modulation is used to correct for lack of parallelism in cell walls. The degree of coherence of the incident beam is taken into account in the squared magnitude of the Fresnel transmission coefficient. The modulation pseudoperiod and an inner pseudoperiod are estimated, and noise in the average transmission signal due to intermodulation is explored.

We propose an automatic target recognition (ATR) algorithm for recognizing nonoccluded and partially occluded military vehicles in natural forward-looking infrared (FLIR) images. The proposed algorithm consists of global and local feature extraction from partitioned boundaries of a target, and a new classification method using multiple multilayer perceptrons (MLPs). After segmenting a target, the target contour is partitioned into four local boundaries. Radial and distance functions are defined from the target contour and local boundaries, and are used to define global and local shape features, respectively. The global and local shape features are more invariant to similarity transform than traditional feature sets. Four feature vectors are composed of the global and local shape features, and are used as inputs of MLPs. The outputs of MLPs are combined to recognize nonoccluded and partially occluded targets. In the experiments, we show that the proposed features are superior to the traditional feature sets with respect to invariance and recognition performance.

We focus on modeled atmospheric and image restoration effects on the human acquisition of a target. The image restoration is by filtering atmospheric effects, such as blur caused by absorption, scattering from aerosols, and distortion caused by turbulence that changes the wave front angle, moves the image on the image plane, and blurs it. The restoration method using an atmospheric wiener filter is intended to correct the atmospheric effects. This filter is based on the fact that the modulation transfer function (MTF) of the turbulence is composed of a mean value and a random component while the aerosol MTF changes slowly. The atmospheric wiener filter is more advantageous than an ordinary wiener filter in high turbulence situations. Using the atmospheric wiener filter, we consider the target acquisition limitations of the filter through perception experiments and statistical analysis of the results. We found that the atmospheric wiener filter can noticeably improve target acquisition probability at low noise levels. As the noise increases, however, the improvement becomes more limited because the restoration increases the noise level in the image.

We present a study of a family of maximum average correlation height (MACH) filters. MACH filters were introduced by Mahalanobis et al., and several modifications such as the extended MACH (EMACH) and generalized MACH (GMACH) have been introduced to enhance the utility of the MACH filter approach. A comparison between the different filtering approaches and processing techniques is presented for the specific case of laser radar (ladar) imagery. The comparison utilizes both synthetic data for training and testing in one case, and synthetic training data and collected ladar imagery for testing in the second case. The results indicate that the GMACH variant of MACH filters is superior to both MACH and EMACH filters for the case of laser radar.

We present a new approach to achieve object identification based on the use of phase correlation in the scale transform domain for automatic character recognition. The results are extensible to other fields. The proposed method is shown to be invariant to translation, rotation, and scale. We extended the methodology used by Casasent and Psaltis by considering a more efficient digital scale transform as an alternative to the Fourier-Mellin techniques. To improve the discriminative power, we introduce a new template matching based on the use of a modified weighted log-polar spectrum. The correlations have been calculated by using phase-only filters (POF) in a digital system. The proposed method is able to provide discrimination between scale and rotation in images to facilitate image registration.

We describe a simple pose estimation-based optoelectronic system for the recognition of facial images. The pose estimation described is a simple digital algorithm that is used to replace the composite image generation techniques while maintaining a low interclass cross-correlation. The optoelectronic fringe-adjusted joint transform correlator (FJTC) is then used to provide correlation. A description of the optoelectronic system and the entire process is presented. In addition, simulation results and comparison to synthetic discriminant function (SDF)-based recognition are provided to prove the effectiveness of the proposed system.

We present a formal protocol description for a just-in-time (JIT) signaling scheme running over a core dense wavelength division multiplexing (DWDM) network that utilizes optical burst switches (OBSs). We apply an eight-tuple extended finite state machine (EFSM) model to formally specify the protocol. Using the EFSM model, we define the communication between a source client node and a destination client node through an ingress and one or multiple intermediate switches. We work on on-the-fly and persistent unicast connections. The communication between the EFSMs is handled through messages.

Frame interpolation plays a crucial role in very low bit rate video coding, video format conversion, and slow motion replay. Motion-compensated interpolation is known to be the best solution for frame interpolation of video. In this work, three widely used motion-compensated algorithms for frame interpolation are compared and evaluated in terms of interpolated image quality, computation cost, and flexibility. The first algorithm considers motion occlusion, the second is the one used in the H.26L/JVT video codec, and the third uses bidirectional motion estimation. The results of the comparison and evaluation provide insight and serve as a guide to select an appropriate algorithm for a specific application.