This PDF file contains the editorial “Confidentiality” for OE Vol. 45 Issue 05

A differential all-birefringent-fiber frequency-modulated continuous-wave Sagnac gyroscope is described. The gyroscope employs a birefringent fiber coil to construct a double unbalanced fiber optic Sagnac interferometer and uses the phase difference between the two beat signals from the fiber coil to measure the rotation velocity. The advantages of this gyroscope include doubled rotation sensitivity and less nonreciprocal phase drift.

Two all-fiber frequency comb generators were combined to produce interlaced continuous-wave frequency combs with a maximum mode detuning of 25 GHz±10 MHz. These combs were used to demonstrate the feasibility of continuous-wave frequency-comb Fourier-transform spectroscopy.

We experimentally study the behavior of one multimode fiber–hollow core fiber–multimode fiber structure when nanofilms are deposited on it with the aim of developing practical evanescent field-based devices, such as sensors, filters, etc. The electrostatic self-assembly (ESA) method is used as the deposition technique and the chosen polymers are PDDA and Poly R-478 because of their well-known optical properties and their potential application as humidity sensors. Three different types of hollow core, fibers are used for the fabrication of the devices and at two different wavelengths. An oscillatory-decreasing transmitted optical power is obtained as the thickness of the nanofilms is increased.

An optical packet switch based on wavelength routing and optical waveband conversion is demonstrated. The switch performs header extraction, packet routing, and regeneration and exhibits very good physical performance.

In survivable wavelength-division multiplexed networks, the backup resource can be shared by the primary light paths, which is called primary-backup sharing. We find that primary-backup sharing can have an effect on the link availability. We focus on routing under dynamic availability of the wavelength resource while the requested reliability of traffic has to be met, using the modified shortest path algorithm. We propose a new algorithm called the dynamic link availability algorithm and evaluate the performance of the proposed algorithm on the NSFNET.

This feasibility study compares several optical configurations for an orbiting high-resolution (<1 m) panchromatic push-broom camera. This is an optical subsystem of the CIA (Camera Iperspettrale Avanzata, Advanced Hyperspectral Camera) project, promoted by the Italian Space Agency (ASI), aimed at high-resolution imaging for applications in Earth observation, mainly for environmental control, geology (especially volcanoes), and coastal and inland water monitoring. The study includes optics and radiometric analyses, used to select a fan of candidate optical configurations, including all the solutions suitable for the specific task, namely, Ritchey-Chretien with and without relay, Korsch, and Schmidt-Cassegrain on axis, off axis, and with relay. The result of a trade-off analysis, considering not only optical performance but also other aspects such as cost, volume, complexity, and technological criticality, shows that the Korsch configuration is currently the best compromise, and it is potentially able to satisfy all project requirements. However, the other configurations have advantages that may be considered in the whole-mission assessment.

A novel method for measuring the imaging quality of a projection system with mirror-symmetric FOCAL marks is proposed, and the principle of the method is described. Through experiments, it is demonstrated that not only the axial aberrations but also the lateral aberrations can be measured with high accuracy by the method. The advantages of the method include obtaining more aberrations than the FOCAL technique and making it much simpler to perform a full-scale measurement of the imaging quality of a lithographic projection system.

Removal-function models play an important role in computer-controlled optical surfacing. We investigate removal-function models of fluid jet polishing experimentally to obtain an optimum one. We adjust the nozzle and let the slurry jet guided by it impact the workpiece with both normal and oblique incidence angle from different positions. The experimental results indicate that when the slurry jet impacts workpiece obliquely from four positions, the profile of material removal approximates to an ideal one with maximum removal at the center, decreasing to zero at the edges. This new removal-function model avoids the disadvantages of the ring-shaped one, and satisfies the requirement of optical manufacturing to obtain a high degree of precision.

Resolution testing of imaging optical equipment is still commonly performed using the USAF 1951 target. The limiting resolution is normally calculated from the group and element that can just be resolved by an observer. Although resolution testing has limitations, its appeal lies in the fact that it is a quick test with low complexity. Resolution uncertainty can serve as a diagnostic tool, aid in understanding observer variability, and assist in planning experiments. It may also be necessary to satisfy a customer requirement or international standard. This paper derives theoretical results for estimating resolution and calculating its uncertainty, based on observer measurements, while taking the target spatial-frequency quantization into account. We show that estimating the resolution by simply averaging the target spatial frequencies yields a biased estimate, and we provide an improved estimator. An application illustrates how the results derived can be incorporated into a larger uncertainty analysis.

Calculations and measurements of the Mueller matrix of an ellipsoidal mirror have been performed. In the calculations we have considered six different input polarization states to obtain a system of 24 equations, of which only 16 are independent, to yield 16 expressions for the elements of the Mueller matrix. We have compared experimental measurements of the elements of the matrix with the theoretical results. Some differences between theory and experiment have been found. Thess differences suggest that Mueller matrix ellipsometry could be used as an optical testing method.

Good alignment is needed in various wafer processes. Reflectometry is a well-established technique that continues to be widely used to monitor the thickness of wafer thin films. The use of a reflectometer was investigated to detect incorrect tilt and height of wafer placement. We found that it could be used in the spectroscopic or the monochromatic mode and provided results whether the wafer was bare or coated. We also found that the technique was somewhat more sensitive to tilt of bare wafers, and more sensitive to height displacements of coated wafers.

Digital photogrammetric systems have been used to solve various measurement problems in industrial applications for many years. Industrial line-scan video cameras have been widely used in these systems and in machine vision applications. This paper addresses the use of a digital photogrammetric expert measurement system for deformation measurements on the surface of concrete materials. The system consists of two industrial cameras having fixed-focus lenses. Because the accuracy of the photogrammetrically derived object data mostly depends on the camera calibration, the system had to be calibrated first. A 3-D wooden object was specially designed and constructed for that purpose. A measurement process of 17 steps was carried out to determine the displacements on the surface of the samples. Linear variable differential transducers were also used to measure the deformations in a conventional way. Data obtained from the two sets of measurements confirmed the system's reliability and allowed us to monitor surface behavior of the concrete samples under loading.

A nonlinear holographic lenslet array is used to extend the angular dynamic range of a Shack-Hartmann wavefront sensor. The lenslet array has two focal distances defined by the first- and second-order diffracted beams. The second-order beam channel is used for preliminary estimation of the spot position in the first-order beam channel. The sensor has an angular dynamic range twice as large as that of a sensor with single-focus lenslets, while retaining the same accuracy.

We discuss a new versatile setup for goniometric measurements of spectral radiances with two modes of operation: (1) it can operate as a 2-D goniometer for measurements in a horizontal plane of the singly scattered radiance from particles in suspension and (2) it can be used as a 3-D goniometer for measuring spectral radiances over an entire hemisphere. In our setup, various kinds of light sources and detectors can easily be inserted. Among the detectors, a spectral imager is designed and used. Proper hardware and software is chosen so as to make our setup fully automated and easy to operate. We present results from two different investigations to demonstrate the utilization of our setup. The first investigation is concerned with measurements of the volume scattering function (VSF) over a large forward and backward angular range. Our experimental results for the VSF show good agreement with theoretical simulations. We also use our setup to obtain a series of 1-D angular spectral images of the skin on the dorsal side of a human hand in vivo by employing various illumination angles. Our setup provides a robust, highly automated, and flexible framework for carrying out goniometric measurements in a variety of applications.

A variety of gradient-doping reflection-mode GaAs photocathode materials are designed and are prepared into negative electron affinity (NEA) GaAs photocathodes by (Cs,O) activation technique for the first time. These gradient-doping photocathodes are grown by molecular beam epitaxy (MBE), in which from GaAs bulk to surface doping concentration is distributed gradiently from high to low. The activation experimental results show that for gradient-doping GaAs photocathodes that are grown over p-type GaAs (100) wafer, where the epitaxial layer doping concentration range is 10¹⁹ to 10¹⁸ cm^–3 and the epitaxial layer thickness is 1 µm, can achieve high integral sensitivity. The highest integral sensitivity 1798 µA/lm is achieved for gradient-doping GaAs photocathodes, which is much higher than that of a common uniform-doping GaAs photocathode under identical cleaning and activation condition. The inherent mechanism responsible for the fact that a gradient-doping GaAs photocathode can obtain higher quantum efficiency is also discussed.

A simple cw mode-locked solid-state laser, which is end-pumped by a low-power laser diode, was demonstrated by optimizing the laser-mode size inside the gain medium. The optimum ratio between mode and pump spot sizes inside the laser crystal was estimated for a cw mode-locked laser, taking into account the input pump power. Calculation and experiment have shown that the optimum ratio was about 3 when the pump power is 2 W, which is different from the value regularly used in passively mode-locked solid-state lasers. This conclusion is also helpful in increasing the efficiency of high-power ultrashort lasers.

The strain and temperature response of fiber Bragg grating (FBG) sensors has been measured from 123 to 317 K. The wavelength shift of FBGs is found to be linear with applied tensile strain at a constant temperature. On the other hand, their strain sensitivity is found to increase linearly with decreasing temperature. The nonlinear temperature dependence of FBG sensors is confirmed.

Planar multilayer optical waveguides consisting of thin dielectric films with metal cladding have been investigated as TM-mode absorption polarizers. Two types of structure are analyzed. In the first one, the guided-mode losses were calculated as a function of the thicknesses of the buffer layer and the metal. Another polarizer, utilizing a MgF₂/metal/MgF₂ overlayer, is discussed. It is observed that in this configuration TM absorption losses are enhanced and thus we get a better extinction ratio. The polarizer has also been fabricated and characterized on ion exchange optical planar waveguides with a MgF₂/Ag/MgF₂ overlayer.

We discuss the design of a compact ring resonator (RR) and Mach-Zehnder interferometer (MZI) in a low-refractive-index-contrast waveguide material system through the use of air trenches. A narrow air trench at the intersection of one input and two output waveguides can function as a high-efficiency splitter, while wider air trenches operate as waveguide bends. We first discuss the design of individual splitters and bends and then show how they can be used to realize a compact MZI and RR. The RR has a footprint of only 70×100 µm, and its optical efficiency at the drop wavelengths is ≈86%. The free spectral range and full width at half maximum are 7.2 and 0.5 nm, while the Q factor is >3,000. The MZI occupies only 165×130 µm, and its calculated optical efficiency is 90%.

A novel tunable optical add-drop multiplexer based on a silicon forward or backward directional coupler is proposed. This device enables one wavelength channel or a small band of channels to be inserted into or extracted from a wavelenghth-division multiplexing (WDM) signal with the capability that the wavelength for which this occurs can be varied utilizing injection current variation. For the backward coupling configuration, an adjacent sidelobe level rejection of –7.5 dB, coupling efficiency of 96.13%, and a 3-dB bandwidth of 0.174 nm with central wavelength at 1549.93 nm are simulated. Wavelength tunability of 169.3 nm (forward coupling) or 0.78 nm (backward coupling) result from our simulations, corresponding to a voltage-induced refractive index change Δn of 0.0021. The forward coupling configuration provides a somewhat wider 3-dB bandwidth and more extensive tuning capability.

The effect of polarization mode dispersion (PMD) remains a central consideration in the practical development of a universal communication system. A huge number of measurements of polarization mode dispersion have been recorded for single-mode fibers (SMFs), but the white-light interferometry setup used by our research group has yielded more relevant quantitative results, not only for SMFs but also encompassing polarization-maintaining fibers and suggesting devices to cope with the complex scenarios of communication. The setup is unique in measuring PMD for single-mode and highly birefringent specialty fibers. Useful application results have been achieved for different light sources, which reflect exact measurements and their comparison for effective application in the field of communication and precision characterization of the optical fiber.

A 1.16-W superfluorescent fiber source (SFS) centered at 1561 nm with a 3-dB bandwidth of 8 nm has been achieved, under the pumping of a 3.56-W 976-nm laser diode array. The optical conversion efficiency reaches 32%. The source is constructed in a dual-stage configuration. The first stage is an ASE seed source with output power about 30 mW in the C band. The second stage is a backward-pumped high-power erbium-ytterbium-codoped double-clad fiber amplifier. An interesting phenomenon has been observed: low-power ASE seed source causes laser oscillation in the SFS, yet a relatively high-power ASE seed source prevents the SFS from lasing. The Rayleigh backscattering and the saturation effect of the amplifier are considered to explain the phenomenon.

IR-transmissive hollow waveguides have been fabricated by depositing Cu and CuI thin-film coatings inside silica and polycarbonate tubing. These guides, which are similar in design to Ag/AgI-coated ones, have straight losses as low as 0.19 dB/m for a 1000-µm-bore waveguide at 10.6 µm. They also transmit IR wavelengths from 2 to more than 15 µm. This makes them very useful for broadband IR applications, including chemical sensing and radiometry, as well as for use in the delivery of IR laser power for laser surgery and low-power cutting. The thin-film coatings are deposited using a liquid-chemistry technique in which a Cu film is first formed on the inside of the tubing, followed by the deposition of the dielectric CuI layer. The thickness of the CuI layer is adjusted to give low loss at specific IR laser wavelengths or to give a broadband response for the transmission of incoherent light.

A new technique for measuring the accumulated chromatic dispersion (CD) in single-mode fiber (SMF) is presented. The technique uses the ratio of the beating power between pump and probe signals and the beating power between probe signal and the four-wave mixing (FWM) conjugated signal. The technique is successfully demonstrated using dispersion-flattened fiber (DFF) as a phase conjugator to achieve a 20-dB relative power variation as a result of up to 1000 ps/nm accumulated CD change.

We provide the expression of the probability density function (pdf) of polarization mode dispersion (PMD) in the optical fiber system concatenated with different pdf distribution sections. In recursive form for the first time, this makes the calculation of the characteristic pdf much easier. This calculation method is confirmed by the experiment.

An optical code-division multiple-access (OCDMA) protocol based on selective retransmission technique is proposed. The protocol is modeled using a detailed state diagram and is analyzed using equilibrium point analysis (EPA). Both traditional throughput and average delay are used to examine its performance for several network parameters. In addition, the performance of the proposed protocol is compared to that of the R³T protocol, which is based on a go-back-n technique. Our results show that a higher performance is achieved by the proposed protocol at the expense of system complexity.

We present the design and results of a cylindrical-lens-based reversal shear interferometer for measuring the spatial coherence of partially or fully coherent UV beams. This is a modified Michelson interferometer consisting of only four optical components. The wavefront is reversed in one of the interferometer's arm by the combination of a plane mirror located at the focal plane of a cylindrical lens. The selected wavefront can be sheared at any arbitrary angle with respect to the incident wavefront by rotating the cylindrical lens, thus enhancing the capability of this design for a real 3-D wavefront evaluation. This interferometer is used to measure the spatial coherence of 255-nm UV radiations obtained from the second harmonic of a copper vapor laser for pump beams of different spatial coherence characteristics, a result being reported for the first time.

We propose an integrated waveguide depolarizer for use in interferometric fiber optic gyroscopes (IFOGs) with single-mode fiber coils. The integrated waveguide depolarizer is based on a Mach-Zender interferometer with polarizing beamsplitters. A waveguide polarizing beamsplitter is designed using multiple air trench structures oriented at the Brewster angle. We also analyze the effect of component imperfections on the degree of polarization achievable with an integrated waveguide depolarizer.

An optical microscopic system for measuring multifiber-end surface based on scanning white light interferometer is described. The designed Michelson interferometric configuration in which light reflectivity of a reference flat is selected to match that of a test surface enables a better contrast of the resulting interference fringes to be recorded. A local peak comparison approach is used to determine a fractional phase from the best-focus frame of a correlogram acquired by a vertical scanning achieved with a piezoelectric translator (PZT). The whole field measurement on a 12-fiber array of the plastic ferrule with a low reflective, rough, and discontinuous surface is implemented. Experimental results show that surface geometric profile on a multifiber-end is measurable. Comparison with measurements on standard calibrated objects shows that the accuracy of the proposed system is comparable with that of existing white light interferometer and atomic force microscope.

The dependence of angle-of-arrival fluctuations on source coherence for free-space optics links in a turbulent atmosphere is examined. A monochromatic beam is taken, and the variation of the angle-of-arrival fluctuations for a spatially partially coherent source is investigated. Results are obtained for the currently used free-space optics links, which use infrared wavelengths of 0.85 and 1.55 µm with link lengths of 3 and 5 km. The angle-of-arrival fluctuations are calculated and plotted against normalized source size and inner and outer scales of turbulence. It is observed that the angle-of-arrival fluctuations show behavior that is essentially independent of the degree of source partial coherence. In fact, as the source size increases, this dependence seems to almost disappear. It is further observed that mean square angle-of-arrival fluctuations become larger at greater propagation distances, at smaller inner scales of turbulence, and at larger outer scales of turbulence. However, the numerical values of the angle-of-arrival fluctuations found for all cases are not expected to degrade substantially the performance of a practical optical receiver having a field of view in the order of several milliradians. Our results presented here are compared with the existing theoretical and experimental work, and the range of applicability of our formulation is discussed.

The possibilities of applying a fluorescent lidar based on the second harmonic of a Nd:YAG laser to study vegetation under natural conditions are analyzed. The dynamics of development has been studied for several species of arboreous plants grown in West Siberia in a five-year measurement cycle. The fluorescent lidar developed has been used for identification of plant species and for investigation of fading caused by an adverse environment. It is shown that the fluorescent signal can be used for remote detection of plant stresses at earlier stages, when there are no visible symptoms. For the first time, the quantitative relations are established between the intensity of red nanosecond fluorescence and the chlorophyll concentration in needles and leaves of the most typical representatives of West Siberian arboreous plants. Fluorescent data were checked using the traditional spectrophotometric method. The spectrophotometric data and lidar measurements were used to calibrate the lidar, and this calibration has allowed the chlorophyll concentration in arboreous plants to be determined from the ratio of signals of laser-induced fluorescence.

Originated from the extensive applications of remotely sensed imagery, Earth observation missions have drawn increasing attention from the scientific and industrial communities. Mostly available in digital forms, remote sensing imagery is easily distributed for unauthorized use, and its copyright protection is becoming nontrivial. For the watermarking of pan-sharpened IKONOS and QuickBird imagery, in this work, a fast and robust approach is proposed for preventing illegal use and malicious modification. Directly in RGB color space, multiple watermarks are embedded into the saturation component by exploiting the properties of intensity-hue-saturation color space and the discrete cosine transform. To resist general cropping, rotation, and resizing attacks on remote sensing imagery, a real system, named StarMarker, was implemented and tested. Experimental results show that this scheme can successfully make the multiple watermarks perceptually invisible and defeat composite attacks of cropping with rotation, high-pass filtering, saturation and hue adjustment, and JPEG compression. The merits of the proposed watermarking system not only provide promising performance but also achieve the purpose of copyright protection.

Fundamental to the design of an infrared sensor is controlling the stray light and internal radiation emission. A series of bidirectional reflectance distribution function (BRDF) measurements at two infrared bandpasses in the mid-wave infrared (MWIR) and long-wave infrared (LWIR) are acquired. Incident beams were oriented 10 and 60 deg from normal. Forward-scatter (key to baffles and cold shields) data are presented for infrared black surface preparations, including: anodizing, copper oxide, nickel oxide, black paints, and trademarked black surfaces. Comparison is also made between selected surfaces before and after exposure to 78 K (LN₂) thermal cycles. This work also includes scanning electron microscope (SEM) images and discrete Fourier transform (DFT) measurements for selected black surfaces, including comparisons of damaged and undamaged nickel oxide.

The basic photometry quantities of a dual-panel backlight are investigated from an energy flow viewpoint. A Gaussian-like distribution of the main panel and subpanel luminances is assumed and the luminous flux, illuminance, and luminance of the two panels are solved analytically. The influence of the luminance cone angle on the photometry quantities of the main panel and the subpanel is carefully examined. Finally, an assessment of the attainability of either equal or nonequal luminance conditions of the main panel and the subpanel is presented. The results show that the upward luminance cone angles of the subpanel region and the main panel area minus the subpanel region play an important role in determining the luminous flux and illuminance in these regions. The luminance cone angles of the upward and downward directed fluxes govern the luminance difference between the main panel and the subpanel. Finally, the relationship between the luminous flux ratio and the subpanel luminance cone angle ratio suggests that a maximum luminance difference of 70% can be obtained between the main panel and the subpanel when the dual-panel backlight is designed with a symmetrical layout about the light guide.

We present simple, mathematically tractable definitions of signal-to-noise ratio (SNR), contrast, and contrast-to-noise ratio (CNR) for imaging systems when photon-counting statistics are the dominant source of noise. These definitions lead to a simple expression for CNR that is convenient for comparing images taken under different conditions and/or in different wave bands. Furthermore, this real-space CNR is directly proportional to the SNR in Fourier space. The sampling factor Q with which a focal plane array records an image is shown to be a primary determinant of exposure time and of SNR. If Q is known (or assumed), the f-number, resolution, and pixel size are not required.

Particle filtering is investigated extensively due to its importance in target tracking for nonlinear and non-Gaussian models. A particle filter can track an arbitrary trajectory only if the target dynamics models are known and the time instant when trajectory switches from one model to another model is known a priori. In real applications, it is unlikely to meet both these conditions. We propose a novel method that overcomes the lack of this knowledge. In the proposed method, an interacting multiple-model-based approach is exploited along with particle filtering. Moreover, we automate the model selection process for tracking an arbitrary trajectory. In the proposed approach, a priori information about the exact model that a target may follow is not required. Another problem with multiple trajectory tracking using a particle filter is data association, namely, observation to track fusion. For data association, we use three methods. In the first case, an implicit observation to track assignment is performed using a nearest neighbor (NN) method for data association; this is fast and easy to implement. In the second method, the uncertainty about the origin of an observation is overcome by using a centroid of measurements to evaluate weights for particles as well as to calculate the likelihood of a model. In the third method, a Markov random field (MRF)-based method is used. The MRF method enables us to exploit the neighborhood concept for data association, i.e., the association of a measurement influences an association of its neighboring measurement.

We propose a novel two-step approach for eyes detection in complex scenes including both indoor and outdoor environments. This approach adopts face localization to eye extraction strategy. First, we use energy analysis to remove most noise-like regions to enhance face localization performance, and then use the head contour detection (HCD) approach to search for the best combinations of facial sides and head contours with an anthropometric measure, and thereafter the face-of-interest (FOI) region is located. In the meantime, via the deedging preprocessing for facial sides, a wavelet subband interorientation projection method is adopted to select eye-like candidates. Along with the geometric discrimination among the facial components, such as the eyes, nose, and mouth, this eye verification rule verifies the selected eyes candidates. The eye positions are then marked and refined by the bounding box of FOI region as the ellipse being the best fit of the facial oval shape. The experimental results demonstrate that the performance of our proposed method has significant improvement compared to others on three head-and-shoulder databases.

A new method for color image segmentation is proposed. It is based on a novel region-growing technique with a growth tolerance parameter that changes with step size, which depends on the variance of the actual grown region. Contrast is introduced to determine which value of the tolerance parameter is taken, choosing the one that provides the region with the highest contrast in relation to the background. Color and texture information are extracted from the image by means of a novel idea: the construction of a color distance image and a texture energy image. The color distance image is formed by calculating CIEDE2000 distance in the L^*a^*b^* color space. The texture energy image is extracted from some statistical moments. Then, a novel texture-controlled multistep region-growing process is performed for the segmentation. One advantage of the method is that it is not designed to work with a particular kind of images. This method is tested on 80 natural color images of the Corel photo stock collection with excellent results. Numerical evidence of the quality of these results is provided by comparing them with the manual segmentation of five experts and with another color and texture segmentation algorithm.

Global motion estimation plays an important role in video compensation and video analysis. We present an efficient method to estimate global motion parameters. First, a feature point selection scheme that exploits the symmetry properties of camera motion is developed. Then, we use parametric motion models to characterize global motion and a recursive least-squares scheme to accelerate the computation of parameter estimation. In the proposed method, the motion vectors in the background area are selected to estimate the parameters of motion models, which improves estimate reliability. Simulation results show that the proposed method gives better performance than the previous methods in terms of the computational efficiency and the estimate accuracy.

An asymmetric 2+1 pass stereo matching algorithm is proposed for generating a depth map from the input of two real stereo images. In the first pass, the Canny edge detector is used to acquire edge images from the inputs. Component images are then generated from the edge images. The edges of each component in the left component image are cut to obtain asymmetric left and right component images. The concept of a disparity-space image (DSI) by components is introduced and dynamic programming (DP) techniques are applied to match the asymmetric left and right component images. In the second pass, the previous DSI is modified, applying the DP methods to acquire the matched pixel pairs of the matched component pairs, and to generate ground control pairs (GCPs). In the final pass, these GCPs are incorporated into the DP algorithms to determine the optimal path and acquire the depth image. The results show that the proposed approach produces reliable and efficient matching and preserves the shapes of objects effectively for real stereo images. The proposed algorithm makes contours clearer than other conventional methods for real stereo images.

New adaptive correlation filters based on a conventional synthetic discriminant function (SDF) for reliable recognition of an object in cluttered background are proposed. The information about an object to be recognized, false objects, and a background to be rejected is utilized in an iterative training procedure to design a correlation filter with a given value of discrimination capability. Computer simulation results obtained with the proposed adaptive filter in test scenes are discussed and compared with those of various correlation filters in terms of discrimination capability, tolerance to input additive noise that is always present in image sensors, and to small geometric image distortions.

An efficient moving-object segmentation algorithm suitable for implementing on a chip is proposed. The basic idea is to use simultaneously a novel spatial segmentation algorithm and an effective temporal algorithm based on the accumulative information technique to produce the video objects. First, the spatial and the temporal segmentation algorithms are used simultaneously to produce the edges and the region of a moving object, respectively. Then, we make use of the edges with the region to obtain the object. It is found that the number of time-consuming motion estimation computations can be reduced dramatically. Hence, the overall processing speed is significantly accelerated to meet the hardware implementation requirement. Finally, a postprocessing step is applied to the object to smooth the object boundary. Good performance of this algorithm is demonstrated by experimental results.

The gain of a transmitter for intersatellite communications is closely related to the performance of all the links. We calculate the transmitter telescope's gain with the help of the rigorous scalar diffraction theory and equivalent optical layout method. Furthermore, a comparison is performed with the conventional imaging method. The results show that the stop inside the telescope can affect the gain of the telescope. Finally, the gain is calculated under the condition of the aberrations. We find that different aberrations cause different effects.

The development of a simple particle redistribution model for estimating the effect on surface obscuration after particle shed from a neighboring surface during random vibration is discussed. The model uses both spherical and elliptical particles and existing failure data of glass spheres on a metal surface to estimate the critical body force to cause the particles to release from the surface. The resulting obscuration from shedding particles on the shedding surface can then be added to the receiving surface. The model assumes that the force due to gravity exceeds the buoyancy force from venting. Because the redistribution analysis shows that particles 80 µm and larger will shed, and particles 60 µm and larger are verifiable using Visually Clean-II (VC-II) conditions, highly reflective surfaces cleaned to a VC-II level will pose little threat to neighboring surfaces from redistribution at 6-g quasi-static loading.