This PDF file contains the editorial “Correcting the Record II: Errors” for OE Vol. 46 Issue 11

The Fisherface method suffers from the problem of using all training face images to recognize a test face image. To tackle this problem, we propose combining a novel clustering method, affinity propagation (AP), recently reported in the journal Science, with linear discriminant analysis (LDA) to form a new method, AP-LDA, for face recognition. By using AP, a representative face image for each subject can be obtained. Our AP-LDA method uses only these representative face images rather than all training images for recognition. Thus, it is more computationally efficient than Fisherface. Experimental results on several benchmark face databases also show that AP-LDA outperforms Fisherface in terms of recognition rate.

A novel detection method for infrared (IR) point targets based on eigentargets is presented. The conception of eigentargets is proposed by making reference to eigenfaces in the field of face recognition. After creating the target training images using the Gaussian intensity function, we refine our method and obtain eigentargets that are a group of eigenvectors of the training set. These eigenvectors are then used to calculate the target map, defined by a target map function, at every location in the image to be detected. The large values in the target map image indicate the presence of targets. In comparison with other commonly used detection methods, our method has better performance with better receiver operating characteristics, and larger signal-to-noise ratio (SNR) and background suppression factor.

A two-rotating-prism system is an inexpensive lightweight two-dimensional beam steering device. It can be designed to be achromatic over a wide spectral range. However, the current two-prism achromatic design has a singularity problem at the center of the "field of view": if a beam is to be steered through the center, one of the prisms must make an instantaneous 90° flip. In our work we proposed a solution to this problem by adding a third prism to the system. The main thrust of this study was optimization of the apparatus by minimizing dispersion effects as well as predicting the theoretical speed and manner in which the beam may be steered.

Bidirectional reflectance distribution function measurements of optical surfaces both before and after molecular contamination have been done using UV, VUV, and visible light. Molecular contamination of optical surfaces from outgassed material has been shown in many cases to proceed from acclimation centers, and to produce many roughly hemispherical "islands" of contamination on the surface. The products of this outgassing will inevitably migrate throughout the surrounding area and adhere to any convenient surface, including optical elements in the system.

A new type of position sensing device (PSD) is proposed in this paper. The proposed PSDs are composed of two-dimensional grating dots. The grating dots of a new PSD can diffract an incident laser beam into many spots. By identifying the maximum and minimum values of the designed numbers of the diffracted spots, the one- or two-dimensional position of the center of the laser beam can be precisely determined. Because the operations are very easy and the mass-production costs are cheap for the proposed PSDs, the PSDs are useful.

This paper describes a high-resolution, real-time, three-dimensional shape measurement system using the modified two-plus-one phase-shifting algorithm. The data acquisition speed is as high as 60 frames/s with an image resolution of 640×480 pixels per frame. Experiments demonstrated that the system was able to acquire the dynamic changing objects such as facial geometric shape changes when the subject is speaking, and the modified two-plus-one phase-shifting algorithm can further alleviate the error due to motion. Applications of this system include manufacturing, online inspection, medical imaging, compute vision, and computer graphics.

To improve upon and provide a methodological alternative to published optoelectronic angle measurement systems, the paper performs high-accuracy angle measurement by use of laser diodes, dual-axis position sensing detectors, and a series of reflections between two first-surface mirrors. Measurement accuracy improves from 0.5 to 0.05 arc sec as the light ray is reflected back and forth several times between the mirrors. Analytic ray tracing is used to model the reflected light ray so as to determine the system equations implicitly in terms of the measured angles. The first-order Taylor series expansion provides a linear form of the system equations. To validate the system, a prototype is built. Calibration and stability experiments are performed. Experimental results show the resolution, accuracy, and measurement range are, respectively, 0.008, 0.05, and ±250 arc sec. Compared with traditional optical angle measurement systems, this method has many merits such as low cost, simple configuration, high sensitivity, and high linearity.

A simple method is presented to determine small wavelength differences based on the dispersion properties of a uniaxial crystal and circularly polarized heterodyne interferometry. A circularly polarized heterodyne light beam is incident on a uniaxial crystal at the Brewster's angle, and the reflected light beam passes through an analyzer for interference. Owing to proper azimuth angles of the transmission axis of the analyzer and the optical axis of the crystal, the variation of the phase difference determined with the heterodyne interferometric technique of the interference signal is significantly enhanced, resulting in an accurate wavelength variation. The feasibility of this method was demonstrated, and the sensitivity of wavelength differences is about 0.001 nm. The proposed approach has a simple structure, straightforward operation, high stability, and high sensitivity.

In this paper we give quantitative evidence for the electrical origin of two optical phenomena exhibited by commercial liquid crystal displays (LCDs) which affect its performance in spatial light modulation applications such as programmable diffractive optical elements (DOEs). These two optical phenomena are associated with a degradation of the spatial frequency response of the LCD. The first optical effect is the existence of spurious diffraction orders located halfway between the vertical diffraction orders produced by the pixelation of the LCD. The second is the dependence of the phase modulation depth on the horizontal local spatial frequency when displaying phase-only DOEs. Electrical measurements for the signal addressed to the LCDs are shown which demonstrate that they are directly related with these two optical phenomena. We also show how the spurious orders can be eliminated with a proper balance of the electrical signal, and we discuss strategies to compensate for the effects of the anamorphic and frequency dependent phase modulation depth.

In this paper, we present a floating image system that consists of a stereoscopic display and a two-lens system. A 3-D image is produced inside of the stereoscopic display and that image is projected into the air by the two-lens system. From the experimental results, our proposed system successfully produces the 3-D image, without the distortion and the defects, in midair so that image is a 3-D floating image.

Lenticular displays are a promising form of autostereoscopic technology and several products have recently been commercialized. For lenticular displays, typically several views of a scene are acquired from different viewpoints, or are generated by using depth information. If the depth information of a scene is known, then it is possible to easily generate several intermediate views simply by using the stereo image pair and depth information. The paper presents a simple method to correct the lenticular alignment error by compensating the correction coefficients to the viewpoint determination formula. For the realization of a fast lenticular display and removal of image distortion and artifacts, the proposed algorithm simultaneously performs intermediate floating-pointview interpolation and multiplexing on the scanline using the left-view and right-view images and depth information. Experimental results show that lenticular images having considerably reduced distortion and artifacts are generated by using the proposed algorithm.

Laser beams containing singularities are gaining increased interest for applications in metrology, particle manipulation and other technological paradigms. While these beams are usually generated by external modulation of a fundamental Gaussian laser beam, it is advantageous to generate them directly within the laser resonator whenever possible. In this paper we propose and investigate the mechanism of selecting a mode possessing a linear singularity using strong diffraction coupling of two adjacent resonators using a bi-prism-like element.

A liquid level sensor based on etched D-shaped silica optical fibers is presented. The optical transmission of the sensor depends on the liquid level. The sensor can be realized as a continuous level sensor with a high resolution and requires only one fiber and one optical source and detector. We have demonstrated a sensor with a resolution of ~1 mm. The sensor works for liquids with refractive indices greater than ~1.45. We show that the sensor response is the same for increasing and decreasing liquid levels.

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

We demonstrate a tunable multiwavelength fiber laser in this paper. The multiwavelength comb is produced by a self-seeded Brillouin-erbium fiber laser (BEFL). The self-seeded Brilllouin pump is achieved by incorporation of a transmissive Sagnac loop filter and 2 km single mode fiber. We study the influence of the transmissive Sagnac loop filter on the BEFL in detail, include the tunable characteristics of the BEFL, and the influence of the Sagnac loop bandwidth on the multiwavelength band. A multiwavelength band with 52 lines is achieved when the bandwidth of the Sagnac loop filter is 83.3 nm. At the same time, we observed dual Brillouin bands exciting.

Banyan optical networks play an important role in free-spatial photonic networks and optical communications. Based on previous research on the one-dimensional (1-D) Banyan network, the characteristics and structures of three-dimensional (3-D) Banyan networks are introduced and analyzed. Simultaneously, the experimental module of a 3-D Banyan network, which is integrated with a polarizing beam-splitter, 4×4 micro blazed-grating array plane, half-silvered mirror, 4×4 spatial light modulator, and mirror, is proposed and demonstrated. The 4×4 micro blazed-grating array plane can fulfill the vertical and horizontal connections of the 3-D Banyan network, and the mirror provides the straight connections. The theoretical analysis shows that the experimental setup can accomplish some functions such as optical signal switch, multicast, broadcast, and the 4×4 matrix conversion, and has advantages of compact in structure, low crosstalk, high speed, and efficient performance. Therefore, the designed experimental module of 3-D Banyan network can be implemented in free-spatial optical interconnection networks and optical signal processing.

We developed an analog optical transmitter module with rf gain for 60 GHz radio-over-fiber (RoF) application narrow band. It consists of an electroabsorption modulator (EAM), a filter, and amplifier. The frequency response increased about 20 dB from the noise level around 60 GHz with the EAM bias voltage of -1.6 V. The 3 dB bandwidth was about 2.2 GHz. The signal-to-noise ratio of the RoF link with transmitter module was measured and the noise figure was obtained, which were compared with those of narrow band EAM module with an additional amplifier. A 16 quadrature-amplitude-modulation data signal could be transmitted with the signal-to-noise ratio of 15.9 dB. The noise figure of the RoF link with the transmitter module was calculated 19.2 dB, which is about 7.5 dB larger than that of the EAM module with rf amplifier at the bias voltage -2.0 V.

A numerical study of femtosecond soliton switching by the relative phase change of a weak control pulse is carried out for a Kerr coupler with the simultaneous presence of intermodal dispersion, cross-phase modulation, third-order dispersion, self-steepening, and intrapulse Raman scattering. It is shown (numerically) that cross-phase modulation, though it appears as a very tiny parameter, plays a positive role in this mode of soliton switching and that these perturbative effects may lead to useful soliton switching if the relative phase of the control pulse is monitored judiciously.

A 40 Gbit/s hybrid optical code-division multiplexing (OCDM)/ wavelength-division multiplexing (WDM) system is experimentally demonstrated and simultaneous multiwavelength optical encoding of a single supercontinuum source using superstructured fiber Bragg grating is achieved. The interchannel interference and noise of the OCDM/WDM system is suppressed apparently by incorporating a nonlinear amplifying loop mirror, both the sidelobe and the pedestal are reduced, the waveform quality of decoded signal is improved, and the original 8.2 ps autocorrelation peak of decoded pulse is compressed to 4.8 ps.

The impact on the performance of the direct-sequence optical code-division multiple-access (DS-OCDMA) system due to wavelength mismatch between encoder and decoder is investigated. Simulation results show that the encoder-decoder wavelength mismatch will degrade the bit-error-rate performance of the DS-OCDMA system drastically by decreasing the contrast ratio of the correctly and incorrectly decoded signals and lower data rate systems are more vulnerable to wavelength mismatch than higher data rate systems. In practical DS-OCDMA systems, the wavelength mismatch between encoder and decoder should be minimized, and some protective measures, such as temperature stabilization and fiber Bragg grating (FBG) packaging, should be taken to enhance the immunity of the superstructured FBG encoder/decoder to ambient conditions.

A remnant chromatic dispersion monitoring method based on spectral shift of a semiconductor optical amplifier is proposed for a high speed optical communication system with carrier suppressed return to zero format and single-channel speed of 40 Gbit/s. The monitoring performance can be optimized by carefully selecting the bandwidth and center wavelength of the optical filter. The dynamical monitoring range is ±60 ps/nm and the monitoring precision is about 5 ps/nm. This method is suitable for application in dynamical chromatic dispersion compensation of high speed optical communication systems.

Based on the theory of Mueller matrix of optical devices with both polarization dependent loss (PDL) and birefringence, the definition of polarization loss (PDL) is analyzed. The newly formulated equations for PDL are generalized for input light with arbitrary degree of polarization (DOP). Theoretical derivation shows that the overall polarization states should contain all the polarization states with random DOP. The magnitude of PDL has connection with the input DOP. The direction of PDL vector is only decided by the Mueller matrix.

In this paper we present a novel optoelectronic device, called a photonic transistor, and we investigate its properties as they pertain to digital electronic applications. The photonic transistor design is based on a heterojunction configuration similar to a semiconductor optical amplifier, and can be used to construct either N-nary digital logic gates or binary Boolean logic gates. The properties of the photonic transistor are investigated using computer simulations, and the numerical results indicate that such a device can be successfully used in digital optoelectronic applications.

This paper presents the evaluation of a removal method to cancel the thermal convection effect that is generated in vertically positioned metal plates loaded by thermal waves when a lock-in temporal speckle pattern interferometry technique is used to detect hidden flaws. Additionally, the resolution of this technique to detect two nearby flaws is also analyzed.

We introduce our latest research of the computed tomography Fourier transform imaging spectrometer that combines the advantages of both the computed tomography imaging spectrometer and the Fourier transform imaging spectrometer. In our previous work, there were still some problems such as the optical aberration in the optical system. Therefore, some significant improvements are made on the optical configuration of our new system. In this paper, the computational simulation of our new system is introduced. Both the interferogram-projection cube and the spectrum-projection cube are generated in the simulation experiment, and the filtered back projection algorithm is adopted in the image reconstruction. The results of the simulation demonstrate the feasibility of our new system.

We report a relatively innovative method for automated fringe counting of a dual-cavity extrinsic fiber Fabry-Perot interferometer for vibration measurements based on the adaptation of the conventional zero-crossing technique to take into consideration two interdependent series of interference fringes. Two sets of interference signals generated by the fiber interferometric vibrometer are quadrature phase-shifted using phase retarding optics and exploited in the fringe counting process to generate the desired crossing-over signals. Each time period of the individual set of interference signal is subdivided into 16 crossing points via the modified fringe-counting method. A program written in MATLAB® is next developed for calculating the number of crossing points and plotting the displacement curve. This method has been found to be capable of automatically processing the two sets of interference fringes reliably. In addition, the program also calculates the displacement amplitudes of a vibrating target measured by the sensor to a resolution of λ/64. A reference displacement sensor has been used for comparison with output data from the interferometer, resulting in a percentage error of approximately 0.41% in the measured displacement.

An area scan digital camera is used to record the full-field heterodyne interference signals, and the processes to derive the associated phases from the data of the recorded frames under a convenient condition are described. By calculating the possible errors under several different cases, an optimal condition to get better results is proposed.

An effective method for reducing speckle noise in digital holography is proposed in this paper. The proposed method does not require classical filtering technique; instead it utilizes multiple holograms of an object generated by rotating an illuminating light continuously. The reconstructed hologram intensity fields possess different speckle patterns, and by properly averaging the intensity fields, speckle noise in the reconstructed images is reduced significantly. A merlion sculpture is evaluated and experimental results show that the proposed method is simple and effective in reducing speckle noise in digital holography.

The operating principle of atmospheric Rayleigh LIDAR (light detection and ranging) systems is that the range-corrected return-backscatter signal is directly related to atmospheric density. For this to be the case full overlap is required between the backscattered laser signal and the field of view of the receive telescope. Time-dependent errors in this alignment compromise the experimental method, and confuse the interpretation of geophysical signals present in the data. We describe a means of locking the alignment of a small LIDAR telescope to the backscattered laser beam, using images obtained with a commercial charge-coupled device camera, to reduce the effects of relative movement of telescope and laser on field overlap. This "autoguiding" system is implemented on a biaxial Rayleigh LIDAR in operation in Antarctica. We achieve a positional precision near 3 camera pixels (1 pixel~1 arc second) across the beam, and 7 camera pixels along the beam. Positional corrections are generated once per minute. The system is capable of removing medium- and long-term drifts in the relative alignment of our telescope and laser during an observing run.

We presented a method of remote-operated-vehicle (ROV) based image processing to restore underwater blurry images here. Because of the attenuating and scattering properties of water, underwater images observed by the conventional imaging system are always blurry. In this paper we introduced a simplified imaging model by considering the camera parameters, the inherent, and apparent optical properties of propagation of light in the sea to process the blurred underwater images. We set up an image system based on ROV and experiments were done on the coast of Qingdao. By comparing the original blurry images and the images restored by the suggested model we can see that the image's quality is obviously improved.

Airborne infrared limb-viewing detectors may be used as surveillance sensors in order to detect dim military targets. These systems' performances are limited by the inhomogeneous background in the sensor field of view which impacts strongly on target detection probability. SAMM-2 is an existing code able to model atmospheric structures and their impact on infrared limb-observed radiance. The AFRL background radiance code can be used to predict the radiance fluctuation as a result of a normalized temperature fluctuation, along a given line of sight (LOS). The existing code SIG was designed to compute the cluttered background which would be observed from a spaceborne sensor. However, this code was not able to compute accurate scenes as seen by an airborne sensor especially for LOS close to the horizon. Recently, we developed a new code called BRUTE3D adapted to airborne viewing conditions. This BRUTE3D code inputs a three-dimensional grid of temperature fluctuations and SAMM-2 transfer functions to synthesize an image of the atmospheric background clutter according to the sensor characteristics. This paper details the working principles of the code and presents some output results. The effects of the small-scale temperature fluctuations on infrared limb radiance as seen by an airborne sensor are highlighted.

A coherent Doppler lidar at 2 μm wavelength has been built with higher output energy (100 mJ) than previously available. The laser transmitter is based on diode-pumped Ho:Tm:LuLiF, a recently developed laser material that allows more efficient energy extraction. Single-frequency operation is achieved by a ramp-and-fire injection seeding technique. An advanced photodetector architecture is used incorporating photodiodes in a dual-balanced configuration. A digital signal processing system has been built, allowing real-time display of wind and aerosol backscatter data products. The high pulse energy and receiver efficiency provides for measurement of wind fields to ranges not seen before with 2 μm lidars, and example wind measurements were made to show this capability.

Spectral-spatial independent component analysis (ICA) basis functions of visible color images are similar to some processing elements in the human visual systems in that they resemble Gabor filters and show color opponencies. In this research we studied combined spectral-spatial ICA basis functions of multispectral mid wave infrared (MWIR) images. These ICA spectral-spatial basis functions were then used as filters to extract features from multispectral MWIR images for classification. The images were captured in the 3.0–5.0 μm, 3.7–4.2 μm, and 4.0–4.5 μm bands using a multispectral MWIR camera. In the proposed algorithm, phase relationships between the basis functions indicate how the extracted features from the different spectral band images can be combined. We used classification performance to compare features obtained by filtering using multispectral ICA basis functions, multispectral principal component analysis basis functions, and Gabor filters.

The paper puts forward a fractal dimension algorithm that fuses mid-wave and long-wave infrared images and detects targets. Usually, the targets in infrared images are man-made, and their fractal dimensions are different from that of their natural background. In the fractal dimension algorithm, the source images are first decomposed by wavelet transformation. Then in the wavelet transformation domain, fractal dimensions are calculated and fusion rules that merge corresponding sub images of two matching source images are set up, and new sub images are created. Finally, the image is reconstructed by inverse wavelet transformation and a fused image is obtained. The fusion results have shown that the contrast between the targets and their background has changed significantly, and the targets can be easily detected by applying a contrast threshold. The experimental results have shown that the method using fractal dimension to fuse dualband infrared images and detect targets is superior to the one using mid-wave or longwave infrared images to detect targets alone.

Under oscillatory behavior of the net profit of transmission over time, heavy losses may be incurred in the form of foregone opportunities in the future if the transmission system prefers to transmit low-cost bit resources at this time over conserving for the future. This oscillatory behavior over time necessitates devising a stabilizing scheme for its optimal use in the transmission. Here we examine an optimal bit-saving path over time. During an initial period, the transmission system prioritizes exhaustible bit reserves of low transmission cost at the maximum available capacity and allocates gross transmission income partly to transmission and the rest is saved and invested to increase the degree of knowledge; and in the second period, once these low-cost bit reserves are exhausted, it is necessary to switch to a source of transmission solely from returns on current degree of knowledge, which initially includes highly insignificant bit streams. For knowledge-poor transmission systems the optimal bit-saving path differs sharply from that for region-based approaches with higher share of knowledge in the transmission's initial wealth. Also, the bit-saving path is highly dependent on the low-cost bitstreams life. We give a comparison in performance of the state of the art codec in progressive transmission against an algorithm which implements the saving path. It appears that the bit saving may be used with acceptable image fidelity.

The purpose of a steganalysis scheme is to distinguish the stego-image from suspicious images. A well-designed steganalysis scheme must distinguish stego-media from cover-media with a better probability rather than random guessing. Most steganalysis schemes belong to the embedding specific approach. However, Farid initially proposed universal steganalysis schemes to detect messages hidden by various embedding algorithms. Because detection accuracy is related to the trained characteristic database, the selection of statistical features will be more important. In 2006, Lyu and Farid indicated that some statistical features are less important than others and that they do not affect the classified results. The proposed universal steganalysis scheme focuses on the differences of statistical features formed by embedding algorithms and applies a support vector machine to distinguish the stego-image from suspicious images. The proposed scheme is more practical than Lyu and Farid's schemes and experimental results show the performance of the proposed universal steganalysis scheme is also superior to those of the above-mentioned schemes.

A new iris recognition scheme using multispectral iris images aimed for preventing the counterfeit attack is proposed. In the proposed system, multispectral infrared iris images are taken in order to utilize the spectral features of real iris. Rather than additionally deciding whether the enrolled iris is fake or not, the multispectral images are fused into a grayscale image to contain the complementary information among them by a gradient-based image fusion algorithm, and the iris region of the fused image is applied directly to the recognition procedure. Through the fusion process, the images which do not show multispectral variations result in a scrambled image that does not contain the exact features of the original iris. Because of the failure in the fusion process, the fused image of a fake iris does not match the original iris features in the database. Thus, they are simply rejected in the recognition step. Experimental results show that the proposed scheme successfully localizes the iris position of real irises and prevents possible counterfeit attacks while maintaining the performance of the authentication system.

One of the major issues in recovering a high-resolution image from a sequence of low-resolution observations is the accuracy of the motion information. In most of the work in the literature, the motion information is assumed to be known with high accuracy. This is very often not the case, and therefore the accuracy of high-resolution image reconstruction suffers substantially, since it greatly depends on the motion information. To address these issues in this paper, we propose a high-resolution image reconstruction algorithm that reduces the distortion in the reconstructed high-resolution image due to the inaccuracy of the estimated motion. Towards this task, we analyze the reconstruction noise generated by the inaccurate motion information. Based on this analysis, we propose a new regularization functional and derive a sufficient condition for the convergence of the resulting iterative reconstruction algorithm. The proposed algorithm requires no prior information about the original image or the inaccuracy of the motion information. Experimental results illustrate the benefit of the proposed method when compared to conventional high-resolution image reconstruction methods in terms of both objective measurements and subjective evaluation.

We use physical considerations to show that an affine transformation can be used to model the effect of environmental changes on hyperspectral image distributions. This allows the generation of a vector of moment invariants that describes an image distribution but does not depend on the environmental conditions. These vectors maintain the invariant property after each image band is spatially filtered which allows the representation to capture spatial properties. We use the distribution invariants and the Fisher discriminant to reduce the size of the representation by selecting optimized spectral bands. We apply the methods developed in this work to the illumination-invariant classification and recognition of regions in airborne images. We also show that the distribution transformation model can be used for change detection in regions viewed under unknown conditions.

This paper proposes an incremental shape recovery and registration method based on weak perspective factorization and pairwise point cloud registration. While a camera is moving freely in unknown environments, point features are automatically extracted and tracked. The 3-D position of scene points is then estimated using the tracked features from four consecutive frames and the point set is immediately registered to the global point cloud. The advantage of the proposed incremental method is that the recovery and registration process relies only on past frames for estimating a global shape. Shape recovery and registration are unified into a single framework where all the internal steps are linear and non-iterative. An application can utilize intermediate results that are incrementally computed from past frames and thus the procedure is applicable to on-line interactive vision systems such as augmented reality applications. Experimental results on several real image sequences showing the feasibility of the proposed approach are also provided.

The motion imagery community would benefit from standard measures for assessing image interpretability. The National Imagery Interpretability Rating Scale (NIIRS) has served as a community standard for still imagery, but no comparable scale exists for motion imagery. Several considerations unique to motion imagery indicate that the standard methodology employed in the past for NIIRS development may not be applicable or, at a minimum, requires modifications. The dynamic nature of motion imagery introduces a number of factors that do not affect the perceived interpretability of still imagery—namely target motion and camera motion. We conducted a series of evaluations to understand and quantify the effects of critical factors. This paper presents key findings about the relationship of perceived interpretability to ground sample distance, target motion, camera motion, and frame rate. Based on these findings, we modified the scale development methodology and validated the approach. The methodology adapts the standard NIIRS development procedures to the softcopy exploitation environment and focuses on image interpretation tasks that target the dynamic nature of motion imagery. This paper describes the proposed methodology, presents the findings from a methodology assessment evaluation, and offers recommendations for the full development of a scale for motion imagery.

This work reviews the use of diffractive optics for beam-shaping of high-power lasers (50–100 W) for welding and microwelding of plastics. While the use of lasers to weld plastics is well known, the use of diffractive optics to reshape lasers for welding of plastics has not been previously reported. By using inverse Fourier transformations diffractive lenses were designed and fabricated. An 80 W fiber laser with a wavelength of 1084 nm was coupled in air to the diffractive optical element (DOE) to shape the beam into predetermined patterns. These patterns were then reduced with standard optics to a desired size. Weld quality was assessed in terms of fidelity and replication of the original bitmap image that was used to design the DOE. Good results were obtained for both image fidelity and replication. In many cases the weld image retained the individual bitmap elements of the original artwork used to encode the DOE. It was also found that the overall efficiencies of the system were as high as 59% and weld times were less than 1 s. Weld joints were also determined to be relatively strong and weld circles as small as a few hundreds of µm in diameter could be formed.

This PDF file contains a retraction notice for “OE Vol. 44 Issue 10 Paper 103601”