This PDF file contains the editorial “All the News…” for OE Vol. 45 Issue 11

New all-plastic electrochromic devices have been manufactured using commercial PEDOT foils and classical polymer electrolyte electrodeposition techniques. Several devices with different areas have been electrically characterized by using an impedance spectroscopy technique. After a brief description of the manufacturing process, we discuss electrical properties with the size of the device. Real and imaginary parts of the impedance have been plotted as a function of frequency. Some interesting conclusions have been derived from those plots, and some improvements in manufacturing process of this kind of devices are also proposed.

We present an approach that incorporates multi-information, including intensity value, spatial relation, and local standard deviation information of the pixels in target region, into kernel density estimation for constructing the kernel-based infrared (IR) target model. The incorporated information can complement each other for a target-tracking task. This constructed target model is evaluated based on the relative entropy of the two classes and is applied in a mean shift tracking system for IR target tracking to verify the effectiveness.

We explore the application of photonic band gaps (PBGs) in photonic crystal structures to propose the design of an ultracompact PBG polarizer. The existence of complete PBGs in certain photonic crystal structures and the variation introduced in the PBGs by the creation of defects has been utilized to design a PBG polarizer at 1.55 μm with a degree of polarization equal to 1 leading to the formation of a super polarizer.

In recent years, it has become possible to fabricate complicated optical surfaces using multi-axis ultraprecision machines. Two diffractive optical designs were fabricated using an ultraprecision diamond turning machine equipped with four independent axes. Unlike the conventional clean-room-based micromachining process, this research demonstrates the development of two innovative diamond tool trajectories that allow the entire diffractive pattern to be machined in a single operation directly, without going through multiple steps, as commonly used in conventional lithography processes. The machined diffractive optical elements were measured for curve geometry and surface roughness. In addition, the optical performance was also evaluated. Finally, a simple welding test setup was utilized to test the 256-level diffractive optical elements (DOEs). Compared to conventional approaches where feature indexing is difficult and unreliable, the slow tool servo (STS) process can be utilized to produce DOEs with accurate geometry and optical surface finish; therefore, the process may be called non-clean-room or maskless micromachining. Unlike its predecessors, this micromachining process which is based on ultraprecision diamond machining can be used to produce true three-dimensional (3D) features in a single operation, thus making it a promising technology for micro-optical, electromechanical component fabrication. Moreover, the 3D micro features can be readily applied to a freeform substrate, making this process a unique approach for fabrication of complicated micro-optical devices.

Phase-only pupil-filtering differential confocal measurement, a new approach, is proposed to improve the spatial resolution of a laser probe measurement system (LPMS) for ultraprecise measurement of microstructural workpieces. The proposed approach uses a lateral superresolution pupil filter for sharpening the main lobe of the Airy spot to improve the LPMS lateral resolution and uses the differential confocal measurement method to improve the LPMS axial resolution, thereby improving the LPMS spatial resolution. In addition to improving the spatial resolution, linearity, and antiinterference capability of a confocal measurement system, the proposed approach can be used for bipolar absolute measurement and improvement of the measurement range. Experimental comparison and analyses indicate that the lateral resolution of a phase-only pupil-filtering differential confocal system can be improved by 50% over that of an LPMS with the same parameters, and a lateral resolution better than 0.27 μm and an axial resolution better than 3 nm can be achieved when the wavelength of the incident beam is λ=632.8 nm, the numerical aperture of the measuring lens is NA=0.65, and μ_M=4. It is therefore concluded that the phase-only pupil filtering differential confocal measurement method is a new approach to a higher spatial resolution of LPMSs and can be used for ultraprecise measurement of surface microcontours and microdimensions.

Optimizing view planning achieves the goal of minimum occlusion and minimum rotation to insure complete inspection of an object, and not only satisfies the goal of view planning, but also automatically maximizes the number of surfaces to which adaptive sampling can most fully be applied. The best view based on visible edge length can usually not only minimize the number of rotations needed to inspect an entire object, but can also provide the maximum amount of information for integration with nonuniform sampling techniques for a variety of parts and manufacturing processes. This new integration approach of first viewing then sampling establishes that the optimization criterion of maximum edge length is more robust than anticipated in its original role for view planning alone. The best view based on the number of visible faces and the face area has proven applicable to integrating the finite element (FEM) centroid sampling and indirect adaptive sampling techniques, respectively, for the inspection of sculptured surface products. Experimental work has verified various theories proposed. The verified view planning criteria include both the edge length and the number of visible faces criterion. Of them, the number of visible faces criterion not only maximizes the number of visible meshes for centroid sampling, but also reveals the maximum amount of high curvature regions of an object.

We developed a fast data-acquisition rate terahertz (THz)–wave spectrometer based on an all-solid-state achromatically injection-seeded THz-wave parametric generator (is-TPG). It takes only seconds to smoothly sweep the frequency range from 0.9 THz to 2.4 THz. This system has been used successfully in THz-wave absorption spectrum measurement with high brightness, a fast data-acquisition rate, and ease of handling.

A new x-cube prism with small polarizing dichroic filters was made for an optical projection system. The x-cube prism was used to combine the three primary colors, which were divided by the preset dichroic mirrors. A coating was designed and fabricated such that s- and p-polarized light was shifted to be obliquely incident in the x-cube prism: the shift was the same as that at the dividing dichroic mirrors. Hence, energy loss was lower than that associated with the conventional x-cube prism, and the brightness of the projection system was 33.2% higher and the color temperature was 18.2% higher than those of the conventional x-cube prism.

A review of the authors' work on orthogonal polarization of optical feedback in He–Ne and microchip Nd:YAG lasers is presented. Orthogonally polarized optical feedback has been applied to dual-frequency lasers and to monomode lasers with birefringent external cavity. The greatest advantage of the technique is that two modulated beams can be obtained with only one optical feedback path, so more information can be obtained than with conventional optical feedback. Polarization flipping with hysteresis and intensity transfer between the two eigenstates of the laser, the characteristics of intensity tuning, subdivision of the laser emission bandwidth, the phase relationship of the two orthogonally polarized intensity modulation curves, mode competition, signal frequency doubling through optical feedback, measurement of the small intracavity phase anisotropy in lasers, and antiphase intensity modulation of orthogonal polarization are experimentally and theoretically demonstrated. Possible applications are also discussed.

The standard two-mode rate equations are extended to discuss polarization behavior of vertical-cavity surface-emitting lasers (VCSELs) with optical feedback. In the rate equations, a logarithmic gain formula and unit step function are used to simulate the experimental conditions more truly. Our simulation results show that weak polarization-preserving feedback will cause multiple polarization switches (PSs) with increasing bias current; strong feedback can suppress PSs and make the VCSEL work in a single polarized mode. The case is similar when y-polarized feedback is considered. The PS point does not disappear even under strong x-polarized feedback. Bifurcation diagrams show that the interplay of PSs and delayed feedback makes the nonlinear dynamics of the two polarized modes more complex. If the feedback is large enough, both chaotic pulses due to feedback and low-frequency fluctuations due to gain competition emerge in the time traces of the two modes. Polarization modulation is also demonstrated when a quarterwave plate is added to the external cavity, which agrees with the experimental observations.

We experimentally studied a functional multiwavelength erbium-doped fiber (EDF) laser at room temperature incorporating a commercial highly nonlinear fiber (HNLF) and a comb filter based on a first-order polarization mode dispersion emulator (PMDE). The tunability of the lasing wavelength, the wavelength spacing, and the number of channels were investigated. It is found that the tuning of the three parameters can be achieved by changing the setting of the first-order PMDE and varying the pump current of the EDF amplifier. This feature is very important to make the fiber laser practicable in many applications

Triangular slabs made of Nd:YAG or Nd:YAP crystals were tested as active media for diode-pumped lasers. The resonator arrangements for the Q-switched regime were prepared for emission corresponding to the Nd³⁺ ion transition ⁴F_3/2→⁴I_13/2in each crystal (λ=1318 nm for Nd:YAG, and λ=1342 nm for Nd:YAP). Optical pumping was accomplished by a fast-axis collimated quasi-cw diode laser stack with peak power of 600 W delivering up to 150 mJ of pump energy. In free-running regime, the maximum reached energies were 24 and 27.5 mJ for Nd:YAG and Nd:YAP crystals, respectively. The corresponding slope efficiencies were 19.9% and 23.7% for Nd:YAG and Nd:YAP laser oscillators, respectively. The passive Q switching for 1.3-μm wavelength was accomplished by means of a saturable absorber made of V³⁺:YAG crystal, whose initial transmission was optimized for the shortest possible pulse length. The 6-ns-duration giant pulses were obtained with energies of 740 and 432 μJ for Nd:YAG and Nd:YAP, respectively. These results correspond to attained peak powers of 125 kW (Nd:YAG) and 77 kW (Nd:YAP) in the fundamental TEM₀₀ mode, which allows this laser to be used as an efficient source for further nonlinear conversion or other applications.

A novel partial-discharge positioning system was demonstrated using an acoustic sensor array composed of four fiber acoustic sensors and a signal-processing unit. A hyperbolic position-fixing algorithm was employed to locate partial discharges. Convolution, correlation, and leading edge with finite impulse response filtering were used to determine time differences of arrival (TDOAs). Partial-discharge positioning was demonstrated in a 500-gallon tank. The positioning results showed that the correlation and leading edge methods are more robust and accurate in determining the TDOAs than the convolution method. A positioning accuracy of 3.0% was achieved using the leading edge method with a sensing range of 755 mm. These positioning results also indicated that the best sensor array layout is to spread the sensors in the tank in order to achieve high positioning accuracy.

In terms of the coupled mode theory, novel formulas of the transfer functions are presented for a microring resonator array, which consists of multiple series-cascaded filter elements, and each of them contains double parallel-cascaded identical microrings. By using these formulas, we can analyze transmission characteristics for such a polymer device. Simulated results show that when some parameters are selected properly, the box-like spectral response can be formed, which is flat and steep, and the sidelobes and the cross talk can be dropped efficiently. The effects of manufacturing tolerances on the transmittance are discussed, which result in the shift of the transmission spectrum of the device.

Transfer of light energy from one fiber to another due to a direct coupling mechanism can be used in various applications in all-optical data communication. We report an analytical approach for finding the exact amount of coupled light from one waveguide to other, if the nonlinearity of the guiding media is considered in this coupling. The significant difference of this coupling phenomenon (effected by the nonlinearity of the waveguide) with the conventional coupling mechanism obtained as coupled optical output is also discussed.

A passive instrument based on a Fabry-Perot interferometer was designed and used for oxygen atmospheric column absorption measurements. The instrument operates in the oxygen A-band spectral region from 759 to 771 nm. Surface solar irradiation reflected off the Earth is detected using two channels at two wavelengths-one for pressure sensing and the other for temperature sensing. Each channel of the O₂ column measurement system consists of two subchannels-Fabry-Perot and reference. Solid Fabry-Perot etalons were designed and used to confine the response to the O₂ absorption bands. The etalons have free spectral ranges of 0.575, 0.802, and 2.212 nm. Two narrow bandpass filters (760 to 764 and 767 to 771 nm) were also used. The instrument is sensitive to changes in oxygen column as small as 0.88 mbar for ground-based experiments and 5 mbar for airborne measurements. The major advantages of the optical setup are its compactness, high sensitivity, high signal-to-noise ratio, and stability for both ground and airborne experiments.

We propose an online, wide-band, adaptive, and no data-traffic interruption polarization mode dispersion (PMD) monitoring system using acousto-optic tunable filters (AOTFs). With the nonsignal carrying amplified spontaneous emission (ASE) noise as the reference signal, without interrupting the signal-carrying data traffic, multiple cascaded AOTFs are used at the optic receiver side to scan the spectrum of the ASE noise. Using the fixed-analyzer method, PMDs of different wavelength bands, which ranges from 120-1700 nm of an optic-fiber communication system, can be found by adaptively changing the radio frequency of AOTFs. The monitoring range of the PMD value can be up to several hundred ps by properly increasing the cascading number of AOTFs.

In recent years, the OTDR-based method has become a familiar technique for measuring chromatic dispersion distribution along an optical-fiber transmission system. In this paper, a nondestructive measurement technique is presented. This technique uses a four-wavelength bidirectional optical time domain reflectometer (OTDR) to measure the chromatic dispersion distribution along an optical-fiber transmission system. A new formulation has been developed to enhance the correction factor, which leads to an improved and precise measurement. The obtained experimental results are in good agreement with those obtained by the interferometric technique.

Generally pair control architecture is adopted in telecommunication systems to save software processing time to setup both-way paths between a sender and a receiver. We have introduced this into a photonic switch fabric (PSF), which is a key instrument of a developed photonic label switch router (PLSR). The PLSR is to be operated as a photonic router in an optical Internet system to guarantee QoS (quality of service) and the transmission bandwidth by providing end-to-end wavelength LSPs (label switched paths). In contrast to conventional PSFs for both-way communications that do not have the capability to save switching elements and its control circuits, the proposed architecture enables us to save them drastically. General configuration of an N×N PSF is described in addition to the developed 3×3 PSF.

A comprehensive theoretical model of the semiconductor optical amplifier (SOA)-based ultrafast nonlinear interferometer (UNI) in counter-propagating configuration is presented. The model consists of a set of equations that describe the gain and phase dynamics of an SOA deployed as the nonlinear element in an interferometric switch. By undertaking an extensive numerical analysis, the transmission response of the UNI is calculated with respect to the key temporal parameters of the SOA transit time, the time delay between the two copies of the clock signal to be switched, and the width of the control pulses that alter the SOA properties. The obtained simulation results allow us to investigate the simultaneous influence of these parameters on the switching window and effectively correlate them to derive an operational condition that must necessarily hold in order to achieve satisfactory operation. The thorough study of this condition enables us to specify the restrictions imposed on each involved parameter and extract useful design rules concerning their proper selection and combination so as to ensure optimum performance. The proposed model can provide the framework for studying more complex, combinatorial all-optical circuits of enhanced functionality in which the UNI is the core switching module.

The impact of cascaded CFBGs delay ripple for dispersion compensation has been analyzed. The experimental results show that the overall penalty was proportional either to the number or to the square root of the number of CFBGs employed along the link. The delay ripple of the overall CFBGs fluctuates, and the overall CFBGs reflectivity was not simply additive but was related to the placement of the CFBG and line amplifier gain. For the first time, the experimental results of dispersion compensation for a 2-×10-Gb/s, 1000-km WDM system using self-made CFBGs with less than 1-dB power penalty for each channel have been achieved.

In this contribution, we measure and compare the polarization properties of 3-D photonic crystal fibers and of a classic single-mode polarization maintaining fiber. The polarization-maintaining property depends on the cross-section geometry of the fiber and is therefore related to the strong intrinsic birefringence and to the well-defined principal axis of the fiber.

Optical crosstalk imposes a major limit to the practical implementation of optical cross-connects (OXCs). Intraband crosstalk characteristics of OXCs based on the dilated Benes (DB) and generally modified DB (GMDB) networks are investigated and compared. Numerical simulation and experimental results confirm that OXCs based on GMDB networks can eliminate intraband crosstalk influence effectively compared with OXCs based on DB networks.

We propose an all-optical technique for decoding of ASCII-coded data. This method accommodates a decoding system using an all-optical AND logic gate. Optical switching with a nonlinear material is exploited here for the decoding.

High-étendue Fourier transform imaging spectrometers can be useful tools for acquiring airborne hyperspectral images, since they do not need moving parts and, as Fourier transform spectrometers, they benefit from the Felgett advantage. The Sagnac interferometer and the Michelson interferometer with dihedrons can be used in such an instrument. These two interferometers act very similarly on the entering beam, and in particular they both work with fringes of equal inclination. This property enables them to benefit from the Jacquinot advantage, too. Nevertheless, to fully benefit from this advantage, it is necessary to maximize the geometrical étendue accepted by the interferometer. From this point of view, the Michelson interferometer with dihedrons appears to be much more interesting than the Sagnac interferometer. Indeed, calculation shows that, in the optimal symmetric configuration, and for the same beamsplitter diameter, the étendue accepted without vignetting by the Michelson interferometer is more than five times greater than the étendue accepted by the Sagnac interferometer. Even if, in a real instrument, the optical scheme cannot be exactly this optimal configuration, this result is a strong argument in support of the Michelson interferometer with dihedrons.

We show how an eight-step algorithm with a high tolerance for phase-shift miscalibration can be used with a conventional Mirau interferometer, with only minor modifications to the software, for two-wavelength interferometric profilometry of surfaces exhibiting steps and discontinuities.

We introduce reconfigurable image projection (RIP) holograms and a method for computing RIP holograms of three-dimensional (3-D) scenes. RIP holograms project one or more series of parallax views of a 3-D scene through one or more holographically reconstructed projection surfaces. Projection surfaces are defined at locations at which the hologram reconstructs a variable number of real or virtual images, called holographic primitives, which collectively compose the surface and constitute exit pupils for the view pixel information. RIP holograms are efficiently assembled by combining a sweep of 2-D parallax views of a scene with instances of one or more precomputed diffractive elements, which are permitted to overlap on the hologram, and which reconstruct the holographic primitives. The technique improves on the image quality of conventional stereograms while affording similar efficient computation: it incorporates realistic computer graphic rendering or high-quality optical capture of a scene, it eliminates some artifacts often present in conventional computed stereograms, and its basic multiply-and-accumulate operations are suitable for hardware implementation. The RIP approach offers flexible tuning of capture and projection together, according to the sampling requirements of the scene and the constraints of a given display architecture.

Phase-shifting digital holography is applied to record the caustics of a stationary crack at arbitrary distances. The stress intensity factors of the crack are measured from the reconstructed images of the caustics. The measurement results show that the stress intensity factors are almost constant in the region where the initial curve radius, i.e., distance from the crack tip, is greater than half the specimen thickness. In addition, the stress intensity factors decrease in a three-dimensional stress field. These results correspond to those by Rosakis and Ravi-Chandar. This confirms that this method is applicable to measure the stress intensity factor of cracks.

Gated laser radar imaging systems hold unique promise for long-distance remote sensing applications. Short-exposure speckle imagery from wide field-of-view (FOV) systems may be used to jointly estimate maximum likelihood estimates of the remote scene together with the atmospheric seeing condition parameterized by Fried's parameter. Previous research has indicated that employment of the short-exposure optical transfer function (OTF) within the deconvolution algorithm yields slightly pessimistic estimates of Fried's parameter. It was postulated that the short-exposure OTF included excessive high spatial frequency components when applied to wide FOV systems, yielding seeing condition estimates of the imaging scenario that were slightly lower than if the atmospheric conditions admitted an anisoplanatic system imaging model. To better estimate Fried's parameter, an anisoplanatic OTF (AOTF) was developed using a tilt-only phase correlation approximation. This AOTF was used together with the short-exposure OTF within the MAP algorithm, and estimated seeing conditions were compared for both simulated and experimental wide FOV scenarios. It was found that the additional anisoplanatic blur components modeled by the AOTF increased the accuracy of the estimation of Fried's parameter from 5% to within 2% using simulated imagery, and from 8.6% to within 2.9% using experimentally collected image data.

This article describes measurements of snow reflection using laser radar. There seem to be few publications on this subject. This article reports measurements on reflection from different kinds of snow, including the angular reflection properties. Reflectance information obtained from two commercial scanning laser radars working at the wavelengths 0.9 and 1.5 μm is shown and discussed. Data are mainly be presented at the eye-safe wavelength 1.5 μm, but some measurements were also performed at 0.9 μm. We have measured snow reflection during a part of a winter season that gave us opportunities to investigate different types of snow and different meteorological conditions. The reflection values tend to decrease during the first couple of hours after a snowfall. The structure of the snow seems to be more important for the reflection than its age. In general the reflection at 1.5 μm is rather low; the reflectivity can vary between 0.5% and 10% for oblique incidence, depending on the structure of the snow, which in turn depends on its age, the air temperature, the humidity, etc. The reflectivity at the 0.9-μm wavelength is much higher: more than 50% for fresh snow. Images of snow-covered scenes are shown together with reflection data, including bidirectional reflectance distribution functions.

The widely used liquid crystal (LC) projection display based on rotation of polarization has some disadvantages, such as significant (about 50%) loss of the unpolarized light on an input polarizer and a limited contrast ratio. The drivable LC phase diffraction grating, embedded in the Schlieren system as a spatial light modulator, is introduced as the alternative to a conventional LC light valve. The phase grating produced by a pattern alignment of the LC enables the construction of an LC diffractive modulator, which is independent from the polarization of the incident light. The LC phase diffraction grating redirects light passing through rather than absorbing light. The LC phase diffractive grating is potentially able to transform all incident light, at the ON state of the modulator, into diffractive maximums with no light in the zero-diffraction order. This enables the construction of an LC diffractive modulator with more modulation efficiency than the conventional LC light valve. Therefore, a model of the nematic LC diffractive phase grating is proposed. This model is based on an approximation for a retarded electrical field of diffracted radiation. The presented model is developed to optimize parameters of the LC light diffractive modulator to achieve maximum efficiency.

Simultaneous detection and classification of single/multiple identical and dissimilar targets is very important in automatic target recognition applications. A new approach is proposed for this purpose using a combination of maximum average correlation height (MACH) filter and polynomial distance classifier correlation filter (PDCCF). In this technique, full-resolution MACH filters are applied to the input scene, and the regions of interest (ROIs) containing the probable targets are selected from the input scene based on the ROIs with higher-correlation peak values in the correlation output. Then a multiclass PDCCF is applied to these ROIs to identify target types and reject clutters and/or backgrounds. To increase the robustness of the proposed technique, multiple filters are formulated for multiple ranges of target size and/or orientation variations. The simulation results using real-life imagery indicate the effectiveness of the proposed technique for target detection and classification in the presence of distortion, clutter, and other artifacts.

We propose a novel interpretation of stray light, which is modeled using a scattering process. For this, a description and simulations based on the bidirectional scattering distribution function (BSDF) are developed. We focus on the particular example of a window closing an optical cavity. Such a window is known to introduce a stray light component that is experimentally very subtle to handle. Our idea is motivated by the uncomfortable observation that for years, the usual estimation of this parasitic contribution (be it for absolute or relative measurements, for visible or IR applications, for field or laboratory experiments, etc.) was based on the rather imprecise and obviously incorrect assumption (nevertheless today a widely used rule of thumb) that the optical window can be approximated by a graybody emitting in its transparency range. This statement obviously goes against Kirchhoff's law of radiation, and can thus not be physically sound. Various typical experimental situations are explored with our model, and a comparison is made with results given by the rule of thumb. This shows some cases of relative concordance. However, the scatter-based model should provide an individually more accurate estimation, as shown by some examples.

Recently, an algebraic reconstruction method has been presented for generation of three-dimensional (3D) maps of the grain boundaries within polycrystals. The grains are mapped layer by layer in a nondestructive way by diffraction with hard x rays. We optimize the algorithm by means of simulations and discuss ways to automate the analysis. The use of generalized Kaiser-Bessel functions as basis functions is shown to be superior to a conventional discretization in terms of square pixels. The algorithm is reformulated as a block-iterative method in order to incorporate the instrumental point-spread function and, at the same time, to avoid the need to store the set of equations. The first reconstruction of a full layer and two neighboring 3D grains from experimental data are demonstrated.

We propose a method called the base-oriented algorithm for image hiding. The method classifies each block of the host image H according to the base value (BV) that represents the block's variation. The classified blocks then either uses BV embedding or module substitution to hide data. The hiding capability of the proposed method is high, whereas the visual performance is also good. The lossless extraction of the confidential image from the mixed image is simple and uses no look-up table. The method can be used as an economic tool to hide and store confidential data in images.

A new iterative reconstruction algorithm is developed and applied to moiré deflection tomography for flow field measurements. The algorithm is derived from the basic deflection formula and based on a modified algebraic reconstruction technique. The precision and convergence of the algorithm are analyzed through a numerical simulation. To capture multidirectional projection data, a rotatable deflectometric system is developed. The efficacy of the new algorithm is assessed by reconstructing an asymmetric temperature field. Furthermore, the algorithm is employed to investigate the image of a cross section of a free jet containing steep gradients and to reconstruct the density field of the rocket exhausted jet.

Segmentation of moving objects in image sequences by change detection has been a very important topic in multimedia and surveillance applications. One popular approach is to model the background of the scene and then threshold the differences between the background and the input images to detect the change caused by the moving object. Although this idea is simple and effective, the selection of a proper threshold value faces a trade-off between false alarms and misdetection. In this paper, a new method of thresholding for moving object segmentation in scenes without dynamic background and rapid variation of illumination is proposed to avoid misdetection while reducing false alarms. This new approach adopts the concept of thresholding-with-hysteresis, which utilizes a multiresolution and variable thresholding (MRVT) scheme to achieve improvements on the segmentation performance. Combined with a module of shadow removal, MRVT can generate accurate moving object masks. Segmentation results are evaluated qualitatively and quantitatively for indoor scenes, and the effectiveness of MRVT is encouraging. Compared with two other state-of-the-art approaches, our proposed method can achieve more accurate object boundary, fewer false alarms, and reduced fragmentation of objects.

A new enhanced-resolution computational integral imaging reconstruction method employing an intermediate-view reconstruction (IVR) technique is presented. In the proposed method, as many intermediate elemental images as required can be synthesized from the limited number of picked-up elemental images by using the IVR technique. With sufficient overlapping of this increased number of elemental images in the reconstruction image plane, an enhanced-resolution 3-D image can be displayed. To show the feasibility of the proposed scheme, some experiments were performed, and their results are presented.

A detection and tracking scheme of a dynamic contour based on image fusion is proposed. In the scheme, an image fusion based on a wavelet transform is applied, and for the hierarchical fused images, a novel multiresolution dynamic contour is applied. This scheme has three advantages. First, it not only retains the advantage of a monoresolution dynamic contour, but also decreases the strict requirement to an initial contour. Second, the relation formulas for a dynamic contour and the allowed target velocity in different resolutions are derived. According to these formulas, the allowed maximum target velocity is calculated quantitatively in monoresolution and multiresolution cases, proving that this scheme can track a fast target. Finally, more accurate image information of the fused image is applied in this scheme, which increases the detection and tracking accuracy of a dynamic contour.

Remotely sensed videos, captured by high-resolution imagers, are likely to be degraded by the atmosphere. In still images, the degradation sources, which include turbulence and aerosols, mainly cause blur. In video sequences, however, spatiotemporally varying distortions caused by turbulence also become important. These atmospheric degradations reduce image quality and therefore the ability of target acquisition by the observers. The effects of image quality and image restoration (deblurring) on target acquisition in still images were examined previously in several studies. Nevertheless, results obtained in static situations may not be appropriate for dynamic situations (with moving targets), which are frequently more realistic. This work examines the effect of image restoration on the ability of observers to acquire moving objects (such as humans and vehicles) in video sequences. This is done through perception experiments that compare acquisition probabilities in both restored and nonrestored video sequences captured by a remote-sensing thermal imaging system. Results show that image restoration can significantly improve the acquisition probability. These results correspond to the static case. However, unlike the static case, considerably smaller differences were obtained here between the probabilities of target detection and target recognition.

The selection of an image quality assessment criterion plays a key role when an illuminant of autoregulative intensity is designed for a vision measurement system. In this work eight image quality assessment functions were compared and analyzed with adjustment of the illumination intensity from weak to strong. Four different workpieces, each representing a typical spatial frequency, were used in the comparison. The experimental results show that the best two functions are the image variance function and the gray standard deviation function.

The far-field spectral characteristics of a space-time-dependent Gaussian pulsed beam passing through an annular aperture are studied. Based on the expansion of a hard aperture function into a finite sum of complex Gaussian functions and starting from the Fresnel diffraction integral, some analytical expressions for the spectral distribution of the diffraction field are derived. The expressions for a circular black screen and a circular aperture are given as special cases of the general results. The red and blue shifts of the spectral intensity maximum and the spectral intensity shape distortion and distribution are studied and illustrated with numerical calculations.