Alfred Hitchcock once said, “Always make your audience suffer as much as possible.” He has made me suffer many times in my life, including the first, second, and third time I watched Psycho. More importantly, we have all suffered many times at the hands of presenters, where the presenter does not consider who their audience is or what their audience wants. Part of this suffering stems from presenters being “me”-centric and presenting what they themselves want to present. The other part is presenters just not knowing who their audience is and what their audience wants or needs.

Sophisticated strategies have been recently proposed for the detection of moving objects in non-stabilized camera setups. These strategies model both, background and foreground, using spatio-temporal non-parametric estimation. However, as no appropriate methods for dynamical kernel bandwidth are available, high-quality results cannot be obtained in all situations. Here, an automatic and efficient kernel bandwidth estimation strategy for spatio-temporal modeling is proposed. Background kernel bandwidth is estimated via a novel statistical analysis of spatially weighted data distributions, whereas foreground kernel bandwidth is estimated using a mean shift based analysis of previously detected foreground regions.

We present a fast, novel method for building porous silicon-based silicon-on-insulator photonic crystals in which a periodic modulation of the refractive index is built by alternating different electrochemical etching currents. The morphology and reflectance spectra of the photonic crystals, prepared by the proposed method, are investigated. The scanning electron micrograph and atomic force microscopy images show a very uniform structure and the porous silicon demonstrates an 829 nm wide photonic band gap.

A multidirectional edge-directed interpolation algorithm that features a region division method is proposed. In the proposed method, an interpolation pixel is newly modeled as a weighted sum of 12 neighboring pixels representing 12 different directions. Each weight is estimated by Wiener filter theory using geometric duality. The proposed method for dividing the interpolation region reduces the heavy computational complexity of the proposed model. Analyzing edge continuities, the model divides an image into three regions, and only strong edge regions are interpolated. Simulation results show that several directional edges are restored clearly in a subjective test, with fair performance in an objective test.

This letter presents the issue of interpolating missing line components at the interlaced signals, a procedure called deinterlacing. A filter design method is introduced in detail, utilizing a least-squares algorithm with training set for the requested deinterlacing filter. A thorough research of deinterlacing performance and system complexity is executed. The proposed filter design and its application on deinterlacing is compared with other conventional filter-based deinterlacing methods in terms of quality measures. It was concluded to show outstanding performance and speed trade-off among the methods compared.

An 112  Gbit/s real-time coherent passive optical network downlink transmission experiment over 100 km standard single mode fiber with 1∶128 splitting ratio is demonstrated. Adaptive dispersion compensation digital signal processing in the real-time receiver has compensated 100 km dispersion and 50 km dispersion difference with almost no power penalty and 43.5 dB power budget has been achieved.

An optical security device providing the function of a fingerprint for authentication along with a designed pattern storage function has been proposed. The proposed device uses the random fingerprint texture in the chiral nematic phase of an ultraviolet-curable liquid crystal. Using photopolymerization along with a mask of the designed pattern, a unique pattern can be fixed in the shape of the designed pattern. The random patterns can be used as a fingerprint for such devices. This proposed device has the potential to be an optical security device and an authenticity or information indicator for the user.

The authors propose a novel architecture of passive optical network (PON), which consists of time division multiplexing (TDM) based downstream (10  Gbit/s) and quasi-synchronization (Q-S) electrical code division multiplexing access (ECDMA) based upstream (2.5  Gchip/s), and realize the prototype of this TDM-ECDMA PON. The high speed (2.5  Gchip/s) all digital en/decoding of upstream have been achieved by field-programmable gate array in this prototype. The frames error rate (FER) free transmission of Q-S ECDMA based upstream is demonstrated after 20 km fiber link. Then receiver sensitivity of optical line terminal in upstream transmission can be improved ∼ 6  dB by coding gain compared with traditional 2.5  Gbit/s TDM PON.

A simple method for phase stabilization of ultrashort optical pulse train is presented. By using cross-polarization effect in high nonlinear photonic crystal fiber, optical pulses from a mode-locked fiber laser are wavelength converted with stable phase character. A differential phase shift keying modulation system is successfully built to test the performance of this method.

This paper proposes a zoom lens system based on liquid lenses. The system design consists of a fixed lens and four two-chamber liquid lenses. The chambers are filled with different liquids. The design principle is analyzed. Optimization method is used to get the optimal solution. With the solution, the proposed zoom lens system can obtain achromatic and spherical aberration corrected images in a particular zooming range, and no moving element is needed in the proposed zoom lens system. By choosing proper liquids, it can be designed to work within particular working regions with improved optical performance. We give the detailed simulation examples. The results indicate that the proposed design can help to improve the optical performances of zoom lens systems.

Freeform lenses can be designed for diverse illumination profiles with good uniformity. However, most of the previous studies were formulated for a single point source and the lens were designed to have a spherical bottom. In this study, the formulation is extended for multiple point sources and for lenses with a flat bottom in favor of prototyping and manufacturing. The extended formulation requires only a freeform surface to design. However, it could be over determined if the light rays emitted from the multiple point sources overlap at the near field. The weighted least-square method is introduced to solve the over-determined problem. A weighting function correlated with the emitting intensities of the sources is proposed to design for illumination profile fit and uniformity in trade-off. The adequacy of the extended formulation is demonstrated by simulation. Circular and rectangular illuminations of multiple point sources in different layouts are illustrated. The simulation results show that profile fit and uniformity could be significantly affected by a source offset. With the offset taken into account in the extended formulation, the effects can be properly collimated.

The authors propose an asymmetric stereo imaging system that acquires stereoscopic images through the installation of an additional small sub-camera module into a conventional single-lens digital camera. The small sub-camera offers advantages in the proposed system, such as reduced manufacturing cost and a reduction in hardware size. The proposed imaging system provides a practical configuration by considering the variations in focal length, which cause disagreement between the stereoscopic images. In order to resolve the disagreement problem, registration models are established to transform the asymmetric stereo images into symmetric stereo images. Experimental results confirm the accuracy of the registration algorithm and also show subjective evaluation of the images from the proposed system. Some applications of the proposed system, such as automatic horizontal image translation and a depth-based refocusing technique are implemented to show its practicality.

To improve the diagnostic accuracy of breast ultrasound classification, a novel computer-aided diagnosis system based on B-Mode ultrasound and color Doppler flow imaging is proposed. First, different feature extraction methods were used to obtain the texture and geometric features from B-Mode ultrasound images. In the color Doppler feature stage, both vascularity and hemodynamic features are studied by applying color distribution and periodograms analysis to Doppler signals. Finally, a support vector machine classifier with selected feature vectors is used to classify breast tumors into benign and malignant. The accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and areas under the ROC curves of the proposed system are 94.28%, 96.36%, 92.00%, 92.98%, 95.83%, and 0.9679, respectively. The experimental results demonstrate that the proposed computer-aided diagnosis system can improve the true-positive and decrease the false-positive diagnostic rate, which is useful for reducing the unnecessary biopsy and death rate.

A mirror facet's angle correction approach is presented for eliminating pupil plane distortions and sub-field image vignetting in the image mapping spectrometry (IMS). The two-axis light reflection problem on the image mapper is solved and a rigorous analytical solution is provided. The cellular fluorescence imaging experiment demonstrates that, with an angle-corrected image mapper, the acquired image quality of spectral channels has been significantly improved compared to previous IMS images. The proposed mathematical model can also be used in solving general two-axis beam steering problems for instruments with active optical mirrors.

An instrument has been prototyped for the purpose of determining the effective focal length of a spherical lens. The instrument employs a two-dimensional position-sensitive detector, two diode laser modules, a microcontroller, and an LCD readout. The system is designed to be automated, be immune to modest misalignment of the test lens, require no mechanical adjustments or image processing, and be accurate for spherical lenses with positive or negative focal lengths in the range of 25 mm<|f|<1,000 mm, and lens diameters no less than 25 mm. The user only needs to insert the test lens. By incorporating a Fourier lens in front of the detector and averaging the signals from the two beams that enter the system parallel and symmetrical with respect to the optic axis, the effect of a modest longitudinal, lateral, or tilt misalignment may be negated.

A digital image correlation (DIC) algorithm for displacement measurements combining cross-correlation and a differential technique was validated through a set of experimental tests. These tests consisted of in-plane rigid-body translation and rotation tests, a tensile mechanical test, and a mode I fracture test. The fracture mechanical test, in particular, was intended to assess the accuracy of the method when dealing with discontinuous displacement fields, for which subset-based image correlation methods usually give unreliable results. The proposed algorithm was systematically compared with the Aramis® DIC-2D commercial code by processing the same set of images. When processing images from rigid-body and tensile tests (associated with continuous displacement fields), the two methods provided equivalent results. When processing images from the fracture mechanical test, however, the proposed method obtained a better qualitative description of the discontinuous displacements. Moreover, the proposed method gave a more reliable estimation of both crack length and crack opening displacement of the fractured specimen.©

An experimental study on the application of the digital image correlation (DIC) technique to measure the deformation of rotating helicopter blades is described. Measurements on two different rotors of diameter 24 and 39 in., with different rotor hubs, were carried out to explore applicability of the technique over a range of scales. Commercial DIC software was synchronized with the frequency of rotation such that rotor blade images could be obtained at a constant rotor azimuth. Bending and torsion mode shapes were extracted from the data with deformation as high as 0.4 in. measured with an accuracy of 0.0038 in. This technique is very advantageous because it is noncontact, cost effective, accurate and simple to implement while yielding full-field, three-dimensional data with a high spatial resolution.

The swing-arm optical coordinate measuring machine (SOC), a profilometer with a distance-measuring interferometric probe for in situ measurement of the topography of aspheric surfaces,has been used for measuring highly aspheric mirrors with a performance rivaling full aperture interferometric tests. Recently, we implemented a dual probe, self-calibration mode for the SOC. Data from the dual probes can be used to calibrate the swing-arm air bearing errors since both probes see the same bearing errors while measuring different portions of the test surface. Bearing errors are reconstructed from modal estimation of the sheared signal.

A metrology system to measure the on-orbit movement of a ten meter mast has been built for the Nuclear Spectroscopic Telescope Array (NuSTAR) x-ray observatory. In this paper, the metrology system is described, and the performance is measured. The laser beam stability is discussed in detail. Pre-launch alignment and calibration are also described. The invisible infrared laser beams must be aligned to their corresponding detectors without deploying the telescope in Earth's gravity. Finally, a possible method for in-flight calibration of the metrology system is described.

An innovative, noncontact, dynamic method is proposed for linear velocity measurement based on phototransistor array. According to the method, an optoelectronic measurement system has been established with three parts: a stable linear laser, fixed on the moving target, is applied as the optical signal emitting unit; a phototransistor array with complex programmable logic devices, positioned parallel to the moving direction and face to face with the laser, is designed as optical signal detecting unit; high-speed data picking cards and a signal processing software are used as the signal acquisition and processing unit. The single cycle frequency measurement theory and the piecewise polynomial fitting are applied in the instrumentation. The effectiveness and reliability of the measurement was demonstrated through three example linear movements.

A transmission type plasmonic multilayer filter is theoretically investigated using three-dimensional rigorous coupled wave analysis (RCWA) method. The design rule of the resonance properties associated with the weakly localized surface plasmon modes in metal/insulator/metal waveguide arrays is discussed. The optical performances with respect to the geometrical parameters of the plasmonic structure are evaluated. Through manipulating the geometric parameters of the metal/insulator/metal waveguide, the optical properties of the filter can be engineered.

A computed tomographic imaging spectrometer (CTIS) disperses the three-dimensional (3-D) datacube (x, y, λ) into two-dimensional (2-D) projections on a focal plane array (FPA). The 3-D datacube is subsequently reconstructed from these 2-D projections using iterative computed tomography algorithms. Conventional designs achieve the 3-D to 2-D mapping by incorporating an optimized disperser. However, these dispersers suffer from the linearity constraint inherent in the first-order grating equation. This constraint means that many of the FPA's pixels are either unilluminated or they are used to image redundant projections; in both cases, they can not be used to increase the datacube's spectral resolution. Here, we outline various hardware improvements that increase the CTIS's spectral resolution by making use of these previously unilluminated or redundant pixels. Specifically, we incorporated a new disperser based on a 2-D grating prism and a division of aperture approach. Included is an optical design analysis of the system, in addition to an experimental characterization of the instrument's performance. Lastly, the new disperser is compared to a conventional disperser to quantify the increased spectral resolution.

The authors build on previous experience in the optimization of white light sources based on combinations of known narrow-band spectra. The authors extend these concepts by using synthetic (mathematically generated) four-band spectra to study the prospects for the spectral design of future optimal light sources. The optimization is based on achieving a trade-off of the color rendering properties against the luminous efficacy of the radiation, using the differential evolution (DE) algorithm. It is shown that this trade-off is controllable through the choice of the optimization parameters, specifically the choice of terms in the optimization fitness function. Depending on the choice of the shapes for the synthetic spectral bands, the results are comparable with those achieved in earlier work on the optimization of four-band light-emitting diode (LED) spectra. However, the range of color temperatures achieved in the present study is considerably wider than was previously found for optimum four-band LED mixtures.

We have experimentally observed the Q-switched mode-locking (QML) and dissipative soliton operations in the passively mode-locked fiber laser operating in large-anomalous-dispersion regime. With the increase of pump power, the proposed fiber laser gradually evolves from continuous-wave to QML and finally to dissipative soliton operations. The transition state between QML and dissipative solitons has been observed. The experimental results suggest that the fiber laser based on the nonlinear polarization rotation technique exhibits Q-switching instabilities.

A set of analytical equations are proposed to describe the near elliptical shape mode of a typical single spatial mode laser diode (SD). A general theoretical model is established to analyze and explain the near field and far field modes of the SD. The model takes into account the material loss of laser waveguide, and the results agree better with measurement results. The model parameters can be adjusted to be applicable to different types of SDs.

A numerical model of an all-fiber Nd³⁺ laser passively Q-switched with Cr⁴⁺ is presented. The repetition rate, average output power, and pulse width have been calculated with the same parameters as those of an experimental setup of another group. We found a qualitative agreement between the two results. The validated model has been used on another proposed setup to investigate and optimize laser parameters. The low and high self-impulse amplitude regimes were found for different Cr⁴⁺ ion densities. The optimal efficiency of the high regime was established when the saturable absorber density increases.

A practical plane-cone resonator for the high-power, transverse-flow CO₂ laser has been designed. The output characteristics of the plane-cone resonator are researched experimentally and compared with a traditional plane-concave resonator. The output mode is an approximate TEM₀₃ mode with a resonator length of 3 m and an equivalent aperture radius of 30 mm. The beam divergence angles of the plane-concave resonator and the plane-cone resonator are 2.6 and 2.1 mrad, respectively. In the experiments that studied the misalignment characteristics, the miss rates of the output beam are 16% and 8%, respectively, when the misaligned angles of the output mirrors are both 0.41 mrad. Also, the miss rates are 20% and 5%, respectively, when the misaligned angles of the reflectors are both 0.41 mrad. The results indicate that this plane-cone resonator has a better anti-misaligned stability than plane-concave resonators.

We report on designing a new raster-scanned CO₂ laser heater for homogenous heating of the disk-shaped substrates during pulsed laser depositioning of materials. This new design aims at concentrating the laser energy near the substrate peripheral edge, which mostly tends to remain cooler than the inner parts during the heating process. A comprehensive heat diffusion model has been developed to predict the temperature and its homogeneity on the substrate depositioning face. Conduction and radiation heat transfer in three dimensions with temperature dependant material properties and a moving heat source are taken into account in this transient model. The model is validated by a simple stationary Gaussian laser heat source whose results are in good agreement with our measured values. Using this model, optimum conditions for the growth of garnets are calculated. Short heat-up times, some within minutes, are corroborated by calculations and measurements. An experimental procedure is designed to test the possibility of optical damage occurring in the substrate during this short temperature heat-up time.

A highly sensitive liquid-level sensor based on weak uniform fiber Bragg grating (FBG) with narrow-bandwidth is proposed and demonstrated. The resonance wavelength of FBG varies as a result of the change of axial strain. According to this characteristic, a precise approach utilizing fiber grating as sensing element to measure height of liquid is achieved. The grating is directly bonded to a float which can transfer buoyancy into axial strain on the fiber. Measurement of liquid level can be realized by monitoring the central wavelength shift of the sensing FBG. The experimental results show that for a liquid-level variation of 25 mm, a high sensitivity of 5.9×10−6  m/pm with a good linearity of 0.991 is achieved. Within bidirectional change of liquid level, crossing sensitivity and long term stability taken into account, the system is of good reliability and stability.

The use of cladding-mode-recoupling-based hybrid long period grating (LPG)/fiber Bragg grating (FBG) sensors for the simultaneous measurement of temperature and strain is proposed. A set of counter-propagation cladding modes can be achieved through a specially fabricated hybrid LPG/FBG structure, and experimental results indicate that the intensity of cladding modes and FBG resonance show different temperature and strain response, which can be used for simultaneous measurement of temperature and strain through power-reference-based ratiometric detection.

We propose a novel design of optical buffer to generate slow light based on delay time. In the framework of the nonlinear waveguide, we investigate propagation of solitons through microring resonators. Dynamical control over slow-light solitons is realized via controlling fields generated by bright soliton and Gaussian pulse. The nonlinear dependence of the velocity of the signal on the controlling field is analytically described. The buffering effect is achieved by slowing the optical signal using an external control light source to vary the dispersion characteristic of the medium via microring resonators. A graphical approach with a signal flow graph method is used to derive the optical transfer functions in z-domain of filters. The characteristics of the optical buffer devices including the transmittance and time delay of the through and drop port are simulated. Simulated results show the criteria of achieving slow light in semiconductor microring resonators. Finally, output signal shows the delay time rate by propagation through the semiconductor microring resonators.

We address the behavior of a Y-laser junction, in which the fundamental modes generated by a twin-stripe semiconductor laser are guided for mixing. When the mode-locked laser emission of the pulses in-phase is launched in the waveguide, coherent combination of the modes in the junction is possible. Fast laser oscillations allow for a reduction in the waveguide angle, which serves to diminish transmission losses produced by bending. Shorter separation distances between stripes and reduced branch lengths also optimize the operation of the device.

Two layers of buried optical waveguides are manufactured in silicate glass substrate. Using ion-exchange process, this procedure is composed of two successive cycles of buried waveguide fabrication. Characterizations of these waveguides show that the two layers have similar dimensions for both waveguide core and for mode field, and thus similar optical properties. Loss analysis indicates that coupling loss of top and bottom layer waveguide with single-mode-fiber being 0.80 dB/facet and 0.75 dB/facet, respectively.

Series coupled triple ring resonators are designed and fabricated on a SOI platform as a thermo-optic wavelength selective switch (TO-WSS) having individual ring resonance tunability and narrow band, flat-top spectrum with high channel isolation. Optimal detuning combinations of the ring resonators are identified in the WSS to achieve an effective OFF state with high channel extinction, low switching cross talk, and low loss of OFF state. It is observed that detuned OFF states with a single ring which is adjacent to the input bus waveguide and two rings which are adjacent to the drop waveguide, are more effective for the highest channel extinction, lowest switching cross talk, and zero loss of OFF state in the WSS. A maximum channel extinction of 22 dB, lowest switching cross talk of −30  dB, and a zero loss of OFF state is achieved with a single ring detuned OFF state using a switching power of 48 mW.

For rectilinear mobile/free-space optical (RM-FSO) links, laser beam divergence and deflection angles are key factors to get highly accurate receiving power. The effective receiving area of the receiving-lens (R-lens) is presented and used to investigate receiving power under different circumstances. By comparing the optical spot size on the receiving plane with the R-lens diameter, the effects of laser beam divergence and deflection angles on receiving power are analyzed. The results show that the theoretical simulation is basically consistent with the experimental data, and the errors are given. Thus, given different moving situations of RM-FSO links, the solution can be used to analyze the receiving power more effectively by considering the effect of laser beam divergence and deflection angles.

As optical networks are evolving from traditional opaque networks toward future transparent networks, physical impairments from transmission and switching have become the significant transparent reach limitation for signals. To overcome physical impairments, sparsely deploying optical-electrical-optical regenerators in transparent networks is currently the most economic and reliable solution, namely translucent networks. We study the impairment aware protection issues and propose an impairment aware sharing constraint relaxed path protection (ISRPP) scheme for single-link failures in translucent optical networks. By relaxing the traditional sharing constraint in a limited degree, ISRPP effectively enhances the resource utilization on both wavelengths and regenerators, which contributes to improve the performance of connection blocking probability. Simulation results show that ISRPP can obtain notable resource efficiency and achieve satisfactory tradeoff between blocking probability and vulnerability ratio with respect to its counterpart.

Raman effect brings the inevitable limitation of gain flatness in the fiber-optical parametric amplifier even if the phase-matched condition is well satisfied. Phase-matched gain is modulated by the real part of Raman susceptibility especially when it is on the anti-Stokes side. The real part mainly determines the gain profile and limits the flat-gain bandwidth to be less than 180 nm. An asymmetric modulated gain spectrum appears due to the assistance of the imaginary part on the Stokes side. Simulation results also show that the single- and dual-pump configurations have different gain amplitude modulation factors induced by Raman.

We present a detailed experimental investigation of a hybrid optical-fiber wireless communication system operating at the 75 to 110 GHz (W-band) for meeting the emerging demands in short-range wireless applications. Measured W-band wireless channel properties such as channel loss, frequency response, phase noise, and capacity are reported. Our proposed system performs a sextuple frequency up-conversion after 20 km of fiber transmission, followed by a W-band wireless link. A 500 Mbit/s amplitude shift keying signal transmission is experimentally demonstrated for performance analysis purposes.

Investigation into optical pattern effects at ultra-high speed all-optical signal processing in a quantum dot (QD) semiconductor optical amplifier is presented by numerical modeling of nonlinear QD carrier dynamics. In a control-probe scheme, modulation properties of continuous probe light are examined under the propagation of a train of the subpicosecond control (data) pulses of random bits at ultra-high repetition rates (data processing bandwidths) that range from 200 GHz to a few THz. Various optoelectronic parameters such as the pulse width, the pulse energy, the data processing bandwidth, and the injection current are varied to examine the properties of modulation and pattern effects, to provide those properties as functions of such parameters with the discussion using the time-dependent nonlinear gain dynamics at the ultra-high bandwidths, for processing parameter optimization. The parameter dependence of those properties, which is revealed to rely on the other parameter condition, follows the non-simple behavior, which may not be estimated without scanning the relevant parameters nor simply by nonlinear gain dynamics under the propagation of a single data pulse.

We report an implementation of a two-way, four-state quantum key distribution (QKD) protocol (namely, the LM05 protocol) over a free space medium. A stable quantum bit error rate of 3.34% and maximum tolerable channel loss for secure key generation of 5.68 dB in the absence of a photon number splitting attack were recorded. The result strongly indicates the feasibility of a two-way QKD protocol implementation over a free space medium.

We have numerically evaluated the transmission performances of digital backward propagation (DBP) algorithms based on the step-size selection methods: (a) constant step-size based modified DBP (M-DBP) and (b) logarithmic step-size based DBP (L-DBP). The nonlinear tolerance of homogeneous dispersion un compensated fiber links are compared in 224  Gb/s DP-16QAM transmission over 656 km of diverse fiber types, i.e., standard single mode fiber (SMF), non-zero dispersion shifted fiber (NZDSF), large effective area pure-silica-core-fiber (LA-PSCF), large effective area fiber, and true wave classic. In the case of homogeneous fiber links, LA-PSCF exhibits higher non linear threshold and gains 32% more transmission distance as compared with SMF by employing M-DBP, while we have observed an additional 13% increase in transmission distance by employing L-DBP.

The effects of chromatic dispersion (CD) and first order polarization mode dispersion (PMD) on constellation diagrams of phase modulated signals are investigated via simulation and different methods to visualize these effects are presented. It is shown that constellation diagrams of (D)QPSK signals sampled by an asynchronous receiver can be used to simultaneously monitor CD and first order PMD. The amount of accumulated impairments can be estimated by quantifying certain deformations in patterns of constellation diagrams.

Optical logic gates are a basic and fundamental component for optical networks and optical computing. The authors propose a structure for AND, NAND, XNOR, and NOR logic gates in two-dimensional photonic crystal, which utilizes dispersion-based self-collimation effect. The self-collimated beam is split by the line defect and interferes with other self-collimated beams. This interference may be constructive or destructive based on its phase difference. This phenomenon is employed to realize all optical logic gates. The gates are demonstrated numerically by computing electromagnetic field distribution using finite difference time domain (FDTD) method. The results ensure that this design could function as AND, NAND, XNOR, and NOR logic gates. The size of the structure is about 10 µm × 10 µm, which, in turn, results in increasing the speed, and all the gates are realized in the same configuration. On-off contrast ratios of the gates are about 6 dB.

An optical design for coupling light from off-chip lasers to on-chip surface-normal modulators is proposed in order to implement chip-to-chip free-space optical interconnects. The method uses a dual-prism module constructed from prisms made of two different glasses. The various alignment tolerances of the proposed system were investigated. For the off-chip lasers, vertical cavity surface emitting lasers (VCSEL) are proposed. The rationale behind using on-chip modulators rather than VCSELs is to avoid VCSEL thermal loads on the chip, and because of higher reliability of modulators than VCSELs. Particularly above 10  Gbit/sec (Gbit/sec⁡), an empirical model shows rapid decrease of VCSEL median time to failure vs. data rate. Thus the proposed interconnect scheme which utilizes continuous wave VCSELs that are externally modulated by on-chip multiple quantum well modulators is applicable for chip-to-chip optical interconnects at 20Gbit/sec⁡ and higher line data rates.

A new approach for smoothing and fringe normalization is proposed, using Bessel functions of the first kind to fit the intensity distribution, with application for skeletonizing and cancel background illumination in an interferogram. With this approach, high-frequency noise is immunized, and the contrast is enhanced by the computation of fitting coefficients by means of least squares. The new smoothing process works very well also with asymmetric interferograms. Its main advantages are the simplicity of implementation and almost automatic fringe skeletonizing and overcoming the problem of the nonuniformity illumination.

The floating 3-D image, when utilized as a 3-D display, gives a strong dimensional impression to the viewer. Few researches, however, have been conducted on the floating image display by means of the computer-generated hologram (CGH). Since the required pixel pitch is narrow compared with the non-floating image display, the CGH that displays the floating image could hardly be output. If the CGH is output by the device with insufficient pixel pitch, the viewing area and image size of the CGH are not suitable for practical use. Therefore, the object is usually placed behind the hologram to relax the pixel pitch. Reducing the time in calculation is also required. The authors have been developing the fringe printer, the device for fringe patterns, which can be reproduce holograms with the pixel pitch as fine as 0.44 μm. This study investigates the fabrication the floating image display, which is output by the fringe printer, with wider viewing angle and larger image size. It is clear that the image is necessarily reconstructed by the conjugate of the original reference wave to reproduce the real image.

A new method of lensless Fourier transform holography for color reconstruction image is presented. With this method, the recording distance can be kept invariant in recording process. The resolutions of reconstruction images can be adjusted in the same recording distance. Three lasers with different wavelengths are used in an experimental setup to synthesize a color image in a reconstruction process. An optical fiber is used effectively, and the quality of the reconstruction image is improved after filter operation.

Global horizontal irradiance (GHI) measured with rotating shadowband radiometer (RSR) is not accurate enough due to thermal sensitivity and nonuniform spectral response of the photovoltaic detector equipped inside. The purpose of this work is to develop a multiple regressive model to correct the errors posed by the temperature and spectrum. The ratio of the reference global horizontal irradiance (RGHI) to the RSR measured GHI is defined as correction factor, based on which, the model is built via device temperature, air mass, and solar zenith angle. Evaluated from various statistical tests such as coefficient of correlation R², mean bias deviation, root mean square deviation, t-statistic, skewness, and kurtosis, results show that the corrected RSR GHI can be comparable with the high-quality RGHI, which indicates the validity of the model.

We present a new segmentation method for multispectral remote sensing imagery using the K-means clustering aggregation coupled with local combination histogram (LCH). First of all, the bands are partitioned into several nearly uncorrelated subsets. Then, some band combinations of the multispectral images are generated from the subsets. After that, the LCHs are computed from quantized images in each band combination. The LCH represents a pixel in the sense of both spectral information and neighborhood spatial information implicitly and serves as the input feature. Identical K-means procedures are employed to get several relatively coarse segmentation maps. The final K-means procedure refines these intermediate segmentation maps to achieve the final results. The segmentation results are evaluated and compared with other multispectral image segmentation methods by visual inspection and object-based image classification. Experimental results show that the proposed method can achieve more accurate segmentation maps and higher classification accuracy.

The static wind imaging interferometer, based on a four-phase-divided mirror, is an attractive approach to acquiring the wind velocity and temperature of the upper atmosphere. Herein the operational principle of the interferometer is presented in detail. The throughput is theoretically analyzed with consideration of the reflections and transmittances of each systemic component. The throughput expression is derived by employing the Fresnel theorem. We conducted simulations, and the results show that the energy transmittance reaches 20% on the surface with high reflectivity-coating film when the inclination angle of the input light is limited to the range of -5 to +5 deg. The results presented herein provide a theoretical basis for the static design configuration and coating for the upper atmosphere wind imaging interferometer.

Numerical simulation of the performance of new beamlines and those under upgrade requires sophisticated and reliable information about the expected surface slope and height distributions of planned x-ray optics before they are fabricated. Obtaining such information should be based on the metrology data measured from existing mirrors that are made by the same vendor and technology; but, generally, with different sizes, slope, and height rms variations. In this work, we demonstrate a method for highly reliable forecasting of the expected surface slope distributions of prospective x-ray optics. The method is based on an autoregressive moving average (ARMA) modeling of the slope measurements with a limited number of parameters. With the parameters of the ARMA model, which we determined, the surface slope profile of an optic with the newly desired specification can reliably be forecast. The forecast profile, even if longer or differently shaped, still maintains the statistical properties of previously measured surfaces. We demonstrate the high accuracy of this type of forecasting by comparing the power spectral density distributions of the measured and forecast slope profiles.

GaAs, Cu, CdTe, and CdZnTe crystals have been studied as optical elements for lenses for hard x-ray astronomy. High-resolution x-ray diffraction at 8 keV in Bragg geometry and at synchrotron at energies up to 500 keV in Laue geometry has been used. A good agreement was found between the mosaicity evaluated in Bragg geometry at 8 keV with x-ray penetration of the order of few tens of micrometers and that derived at synchrotron in transmission Laue geometry at higher x-ray energies. Mosaicity values in a range between a few to 150 arcsec were found in all the samples but, due to the presence of crystal grains in the cm range, CdTe and CdZnTe crystals were found not suitable. Cu crystals exhibit a mosaicity of the order of several arcmin; they indeed were found to be severely affected by cutting damage which could only be removed with a very deep etching. The full width at half maximum of the diffraction peaks decreased at higher x-ray energies showing that the peak broadening is affected by crystallite size. GaAs crystals grown by Czochralski method showed a mosaic spread up to 30 arcsec and good diffraction efficiency up to energies of 500 keV. The use of thermal treatments as a possible method to increase the mosaic spread was also evaluated.

We propose a robust content-based video copy detection approach based on local tangent space alignment (LTSA), which is an efficient dimensionality reduction algorithm. The idea is motivated by the fact that the content of video becomes richer and the dimension of content becomes higher. It does not give natural tools for video analysis and understanding because of the high dimensionality. The proposed approach reduces the dimensionality of video content using LTSA, and then generates video fingerprints in low dimensional space for video copy detection. Furthermore, a dynamic sliding window is applied to fingerprint matching. Experimental results show that the video copy detection approach has good robustness and discrimination.

This paper proposes a novel local color correction algorithm that uses three dimensional (3D) point set registration especially for underwater stereo images. Due to the limited visibility in an underwater environment, underwater stereo images are usually captured by a half-mirror-based stereo camera that helps to prevent the unwanted visual fatigues induced by excessive disparities. However, the interaction between the half mirror and the scattered light components in the water may produce strong local color discrepancies. Thus, the proposed algorithm extracts sufficient information on the entire image area between the left and right images using 3D point set registration to counteract these effects. Since the proposed algorithm simultaneously processes all three color channels in the local color space, it is robust to the strong local color discrepancies in underwater stereo images. The proposed algorithm is both subjectively and objectively evaluated by comparing the histograms, the color similarities, and the disparity images before and after color correction. After color correction, the proposed algorithm achieves a color similarity up to 96.67%, while other conventional algorithms show color similarities only up to 90.66%. Although the proposed algorithm is designed for underwater stereo images, it can be used for various stereo images and applications.

Learning efficiency, related to not only the size of training set but also to the usage of samples, is an important issue of learning-based super-resolution (SR). We propose a face hallucination method with adaptive sample selection ability by learning from the facial manifold. Employing locality preserving projections (LPP) to analyze the intrinsic features on the local facial manifold, our method searches out image patches dynamically in the LPP subspace, which makes the training set tailored to the input patch. Using the selected training set, we develop a patch-based eigen-transformation algorithm to efficiently restore the lost high-frequency components of the low-resolution face image. Experiments on synthetic and real-life images fully demonstrate that the proposed adaptive sample selection SR method can achieve better performance than some state-of-the-art learning-based SR techniques with less computational cost by utilizing a relative small sample, especially under the case of low quality input images.

Considering the reality of image formation as well as the statistical characteristics of contourlet coefficients, we propose a method for statistical image fusion in the contourlet domain. For high-frequency subbands, an image formation model was established that has a continuous-valued blur factor to reflect the actual imaging situation. According to this model, fused contourlet coefficients were estimated by use of an expectation-maximization (EM) algorithm. During the estimation, a contourlet hidden Markov tree model was adopted to grasp all dependencies among coefficients and aim for better estimation results. Because the blur factor is a continuous variable, we exploited an explicit expression to update the factor in the EM algorithm, which contributed to a decline in the number of iterations for convergence. Experimental results indicated that, especially for multifocus images, the proposed method provides more satisfying fusion results in terms of visual effects and objective evaluations than some typical fusion methods based on multiscale decomposition and some statistical fusion methods using a discrete blur factor.

Toward the unsupervised clustering for color logo images corrupted by noise, we propose a novel framework in which the logo images are described by a model called singular values based region covariance matrices (SVRCM), and the mean shift algorithm is performed on Lie groups for clustering covariance matrices. To decrease the influence of noise, we choose the larger singular values, which can better represent the original image and discard the smaller singular values. Therefore, the chosen singular values are grouped and fused by a covariance matrix to form a SVRCM model that can represent the correlation and variance between different singular value features to enhance the discriminating ability of the model. In order to cluster covariance matrices, which do not lie on Euclidean space, the mean shift algorithm is performed on manifolds by iteratively transforming points between the Lie group and Lie algebra. Experimental results on 38 categories of logo images demonstrate the superior performance of the proposed method whose clustering rate can be achieved at 88.55%.

In this paper, we present a universal deblurring method for real images without prior knowledge of the blur source. The proposed method uses the transition region of the blurred image to estimate the point spread function (PSF). It determines the main edges of the blurred image with high edge measures based on the difference of Gaussians (DoG) operator. Those edge measures are used to predict the transition region of the sharp image. By using the transition region, we select the pixels of the blurred image to form a series of equations for calculating the PSF. In order to overcome noise disturbance, the optimal method based on the anisotropic adaptive regularization is used to estimate the PSF, in which the constraints of non-negative and spatial correlations are incorporated. Once the PSF is estimated, the blurred image is effectively recovered by employing nonblind restoration. Experimental results show that the proposed method performs effectively for real images with different blur sources.

We present a novel salient region detection scheme combining spatial distribution and global contrast. Our scheme considers not only global contrast between different colors/regions, but also spatial relationships within the same color/region. The variance of the spatial position within the same region/color is used to measure spatial saliency. And we incorporate spatial saliency and global contrast saliency into the final saliency map through linear combinations. Experiments show that the proposed scheme not only performs better than five state-of-the-art methods on the publicly available data set, but it also is simple, easy to implement and efficient.

The authors propose a self-reconfigurable approach to perform H.264/AVC variable block size motion estimation computation on field-programmable gate arrays. We use dynamic partial reconfiguration to change the hardware architecture of motion estimation during run-time. Hardware adaptation to meet the real-time computing requirements for the given video resolutions and frame rates is performed through self-reconfiguration. An embedded processor is used to control the reconfiguration of partial bitstreams of motion estimation adaptively. The partial bitstreams for different motion estimation computation arrays are compressed using LZSS algorithm. On-chip BlockRAM is used as a cache to pre-store the partial bitstreams so that run-time reconfiguration can be fully utilized. We designed a hardware module to fetch the pre-stored partial bitstream from BlockRAM to an internal configuration access port. Comparison results show that our motion estimation architecture improves toward data reuse, and the memory bandwidth overhead is reduced. Using our self-reconfigurable platform, the reconfiguration overhead can be removed and 367  MB/sec reconfiguration rate can be achieved. The experimental results show that the external memory accesses are reduced by 62.4% and it can operate at a frequency of 91.7 MHz.

The authors introduce an efficient intra-field deinterlacing algorithm using an advanced non-local means filter. The non-local means (NLM) method has received considerable attention due to its high performance and simplicity. The NLM method adaptively obtains the missing pixel by the weighted average of the gray values of all pixels within the image, and then automatically eliminates unrelated neighborhoods from the weighted average. However, spatial location distance is another important issue for the deinterlacing method. Therefore we introduce an advanced NLM (ANLM) filter while consider neighborhood similarity and patch distance. Moreover, the search region of the conventional NLM is the whole image, while, the ANLM can just utilize the limited search region and achieve good performance and high efficiency. When compared with existing deinterlacing algorithms, the proposed algorithm improves the peak signal-to-noise-ratio while maintaining high efficiency.

We present a nonlinear correlation methodology to recognize objects. This system is invariant to position, rotation, and scale by using vectorial signatures obtained from the target such as those from problem images. Vectorial signatures are calculated through several mathematical transformations such as scale and Fourier transform. In this application, vectorial signatures are compared using nonlinear correlations. Also, experiments were carried out in order to find the noise tolerance. The discrimination coefficient was used as a metric in performance evaluation in presence of noise. In addition, spectral index and vectorial signature index are obtained in order to recognize objects in a simpler way. This technique has low computational cost. The invariance to position, rotation, and scale digital system was tested with 21 different fossil diatoms images. The results obtained are good, and the confidence level is above 95.4%.

An object detection algorithm using multiple cameras is proposed. The information fusion is based on homography mapping of the foreground information from multiple cameras and for multiple parallel planes. Unlike the most recent algorithms, which transmit and project foreground bitmaps, it approximates each foreground silhouette with a polygon and projects the polygon vertices only. In addition, an alternative approach to estimating the homographies for multiple parallel planes is presented. It is based on the observed pedestrians and does not resort to vanishing-point estimation. The ability of this algorithm to remove cast shadows in moving object detection is also investigated. The results on open video datasets are presented as well.

The potential for the research of object tracking in computer vision has been well established, but previous object-tracking methods, which consider only continuous and smooth motion, are limited in handling abrupt motions. We introduce an efficient algorithm to tackle this limitation. A feature-driven (FD) motion model-based features from accelerated segment test (FAST) feature matching is proposed in the particle-filtering framework. Various evaluations have demonstrated that this motion model can improve existing methods’ performances to handle abrupt motion significantly. The proposed model can be applied to most existing particle-filter tracking methods.

Crowd density estimation in public areas with people gathering and waiting has been a challenging problem for visual surveillance over many years. Tiny motions, like when people turn around, wander about, and turn their heads, happen randomly now and then in crowds, which makes it difficult to achieve high-performance crowd density estimation based on traditional foreground detection. A novel accumulated mosaic image difference feature is proposed to represent these complicated random motion patterns for accurate foreground detection. The obtained foreground is then normalized based on the perspective distortion correction model to achieve a reasonable crowd density measurement for observed areas. Numerous experiments are conducted in different scenes of various view angles, and experimental results demonstrate the effectiveness and robustness of our proposed method.

Video transcoding is usually conducted when the device does not support the current format or has limited storage capacity. Video transcoding is a computation-intensive process that changes one format to another one, and various multimedia applications have made it important in recent years. We present a new motion vector (MV) composition algorithm for arbitrary frame-size video transcoding. The proposed method uses the relation between the prediction error and the required bits when encoding MVs to form an auxiliary function called the Lagrange function. Therefore, MV composition is converted into a constrained optimization problem. Through the Lagrangian optimization, a dominant MV is selected from a set of candidate MVs by minimizing this cost function. The major contribution of the proposed method is that we emphasize the effect of the bits required to encode MVs; therefore, at the same target bitrate, the proposed method provides better coding performance. Experimental results show that the proposed method has better performance in terms of both objective and subjective qualities than other existing methods.

Since digital video data can be easily manipulated, the importance of video authentication is increasing. We propose a watermarking technique that is simple to implement, yet quite effective for H.264/AVC. The proposed watermarking scheme inserts a watermark bit on the motion vectors for inter-coded macroblocks or on the mode number for intra-coded macroblocks. A scheme to watermark skipped macroblocks, which are vulnerable to forgery, is also proposed. The new watermarking scheme shows high watermark payload with small image quality and compression power degradation. The run-time increase for software implementation and design overhead for hardware implementation, of the proposed watermark, are very low due to the simplicity of the algorithm.

The authors present a wavelet tree-based video coding system, which is referred to as three-dimensional (3-D) backward coding of wavelet trees (BCWT). The 3-D BCWT algorithm encodes the wavelet trees from the lowest wavelet level to the highest wavelet level. All the coding steps for each wavelet coefficient are finished during one coding pass, which makes this algorithm very efficient. The coding process of the 3-D BCWT algorithm is subband by subband, so that a coefficient will be encoded only after all the coefficients in the next lower-level wavelet subbands have been encoded. The output bitstream of the encoder is therefore layered according to the wavelet level. The implementation results show that the 3-D BCWT algorithm has almost identical rate distortion performance to the well-known 3-D set partitioning in hierarchical trees (SPIHT) algorithm. However, it is computationally more efficient and uses significantly less memory than the 3-D SPIHT algorithm.

An adaptive selection approach for advanced video coding that reduces the number of unnecessary discrete cosine transform (DCT), quantization (Q), inverse quantization (IQ), and inverse DCT (IDCT) computations is proposed. An adaptive selection approach is used to detect zero-quantized DCT (ZQDCT) coefficients since certain zero-quantized DCT coefficients of the prediction residual block are difficult to identify. The presented algorithm detects ZQDCT coefficients according to the corresponding frequency positions before implementing DCT. Therefore, redundant DCT, Q, IQ, and IDCT procedures are removed. To carry out the proposed algorithm, three sufficient conditions are assumed for deriving eight prediction modes, which are employed to select various types of DCT, Q, IQ, and IDCT implementations. The computed results indicate that the proposed algorithm is capable of reducing the number of DCT, Q, IQ, and IDCT computations compared to those required by related methods, while retaining the coding performance of the original encoder.

Currently, the high complexity of video contents has posed the following major challenges for fast retrieval: (1) efficient similarity measurements, and (2) efficient indexing on the compact representations. A video-retrieval strategy based on fuzzy c-means (FCM) is presented for querying by example. Initially, the query video is segmented and represented by a set of shots, each shot can be represented by a key frame, and then we used video processing techniques to find visual cues to represent the key frame. Next, because the FCM algorithm is sensitive to the initializations, here we initialized the cluster center by the shots of query video so that users could achieve appropriate convergence. After an FCM cluster was initialized by the query video, each shot of query video was considered a benchmark point in the aforesaid cluster, and each shot in the database possessed a class label. The similarity between the shots in the database with the same class label and benchmark point can be transformed into the distance between them. Finally, the similarity between the query video and the video in database was transformed into the number of similar shots. Our experimental results demonstrated the performance of this proposed approach.

In conventional interference-based optical encryption schemes, a potential cracker can retrieve partial information (silhouette) of the secret image using only one phase-only mask (POM). We resolve this drawback using a phase-blend operation and piecewise linear chaotic map (PWLCM) to further encode the POMs. One cannot recover a secret image visibly when inverse phase-blend operation and inverse chaotic permutation are not carried out with the correct decryption keys. Chaotic parameters of PWLCM, and random phase-angle function in the phase-blend operation enlarge the key space and improve the security of the proposed system greatly. Numerical simulations and optoelectronic experiments are performed to verify the effectiveness of the proposed scheme.