This is my last editorial as your editor. I thank you all for the opportunity that you have afforded me during the last seven years to be your editor. It has been an interesting time for us all in optical science and engineering as the field has developed into a discipline that provides enabling technologies to a wide variety of current and future devices and systems.

A laser transmitter/receiver system using a retroreflector in space (RIS) to experiment with earth-satellite-earth laser long-path absorption measurements of atmospheric trace species is described. The system employs two single-longitudinal-mode pulsed CO2 lasers to measure the atmospheric spectrum and a second-harmonic Nd:YAG laser for active satellite tracking using the image of the RIS reflection. Details of the laser system and the initial experiment are reported.

Accurate, low-noise, wideband phased array radar antennas depend on the use of true time delays between microwave elements. A photonic means of generating the required element-to-element phase shifts was developed by Toughlian and Zmuda for systems operating in the VHF frequency range, and extended by Monsay and Caccuitto for operation in the radar C band. The photonic beamformer is based on a heterodyne optical system, in which the reference beam acts as a probe of the acoustic wave in the acousto-optic (AO) cell. It is apparent that the benefits of this photonic system rely greatly on the ability of the probe beam to pick out just the right phase shift/time delay from the acoustic waveform in the AO cell. A basic limitation to system performance could come from intrinsic diffraction effects due to the finite beamwidth of the probe in the AO cell. In addition, the finite size of the photodetector in the system will have an effect on the final SNR. These effects have been studied in detail and their implications for design and performance of the photonic beamformer are discussed.

A photonic means of generating the element-to-element phase shifts required for the operation of a true time delay radar beamformer was developed previously by Toughlian and Zmuda for systems operating in the VHF frequency range, and extended by Monsay for operation in the radar C band. The photonic beamformer is based on an acousto-optic (AO), heterodyne optical system in which the reference beam acts as a probe of the acoustic wave in the AO cell. The time delay of the acoustic waveform readout by the optical probe from various locations along the length of the AO cell can then be imposed directly on the microwave elements of the radar beamformer, providing the correct phase for each element at whatever frequency drives the AO cell. Fundamental systems-oriented calculations are reported. Results for both optical specifications and radar performance specifications are obtained based on a mathematical model of the photonic delay line previously developed by the author. These results address the use of the photonic delay line in a standard radar beamformer.

A chemiluminescent-based optical fiber immunosensor is developed to detect the presence of jejunal cholera antitoxin IgA immunoglobulins. This was accomplished using optical fiber tips, conjugated with the cholera toxin B subunit. The cholera antitoxin analyte is marked by a secondary antibody labeled with horseradish peroxidase. A photoelectronic setup is designed specifically to monitor the signal. This immunosensor system is shown to be specific, sensitive, and fast to run, without requiring a purification step. The lowest titer detected was 1:1,310,720. When the luminol-containing buffer solution was replaced by air, thus dramatically lowering the index of refraction of the surrounding medium, sensitivity increased and cholera antitoxin was detected at an additional titer dilution at 1:2,621,440.

Vector quantization (VQ) is an effective method of data compression. Its decoding process is very simple and a high compression ratio can be obtained. Thus VQ has been extensively used in image and speech compression. However, VQ has some difficulties such as the efficiency of codebook design process and the degradation of edges. In the codebook design and encoding phases, searching for the closest code word is a highly computational process, especially for high dimensional vectors. Our efforts are to design a fast algorithm to generate a better codebook and to reduce the computation time compared with the previous algorithms in codebook generation. Our algorithm is a top-down algorithm and is based on the longest distance first concept. Some experiments are shown to illustrate that our algorithm is superior to the previous algorithms.

A new block-based motion estimation algorithm for image sequence coding is proposed. The motion vectors between neighboring blocks are highly correlated, and the correlation exists in two dimensions in general. We model the 2-D motion correlation with two separate 1-D models in the horizontal and vertical directions, respectively. The 1-D Kalman filtering is then used to obtain the estimates in the two directions. By linearly combining the two estimates, we develop a motion estimation algorithm that exploits the motion correlation in two dimensions in a simple manner. The algorithm overcomes the difficulty of the general 2-D Kalman filter, which is very complicated and computationally intensive. The results indicate that the proposed algorithm achieves a significant reduction in computation with better performance as compared with the conventional full search algorithm.

This paper presents a method of building an image data retrieval system that can accept Japanese sentences and handle subjective expressions. A naive user who has little knowledge about objects in the database is likely to use subjective words to explain what he or she wants, for instance, ‘‘show me a cute one,’’ or ‘‘I would like to have a simpler one.’’ Objective interpretation of those expressions is difficult but is indispensable to retrieval systems. In this paper we propose a technique for matching subjective expressions with color features and discuss usability of our natural language interface.

Six specific defects in images captured on line-scan x-ray machines are discussed and software corrections are addressed. The corrections are intended to optimize the machine for the inspection of food products for hidden defects or contaminants. The defects include effects due to time constants in the preamplifier, decays (short and long term) of the phosphor in the detectors, gaps in the images at detector module boundaries, analog to digital converter (ADC) clipping of the photodiode signal, varying response between detectors to the low-energy end of the incident energy spectrum, and x-ray scattering. Of these, all but the long-term phosphor decay and scattering are corrected with software. While the long-term phosphor decay is of little consequence for food inspection, effects due to scattering are serious and must be addressed in the design of the detectors. The restored image is more suitable for image processing and thus for real-time sorting than the original image.

Regularization parameter estimation is an important issue in the overall optimization of image restoration systems. The parameter controls the relative weightings of the data- and model-conformance terms in the restoration cost function. In general, we should adopt small parameter values for highly textured image regions to emphasize detail and should use large values to suppress noise in smooth regions. In spite of this qualitative knowledge, the exact value of the parameter is normally difficult to estimate due to the nonintuitiveness of the parameter value as an indicator of the resulting image quality. In view of this problem, we propose a regionally adaptive regularization approach that first specifies the desired image regional quality in terms of a specific predictive filter mask and then establishes a correspondence between the filter mask and a regional regularization parameter value using a modelbased neural network. Due to the ease of tailoring local image quality using a filter mask by judiciously specifying the mask coefficients, we can define separate filter masks for different image regions to indicate different preferences for detail preservation. We can then relate the prediction given by each filter mask to a specific parameter value through the function approximation capability of the model-based neural network and fine-tune this value through training. As a result, the current assignment is more relevant in relation to the local spatial characteristics of the image than with the usual practice of using an arbitrary function of the SNR to determine the parameter value.

We present a machine vision inspection method that is specially devised to detect defects on shadow masks. This method incorporates Fourier optics to capture only irregular defects in real time by blocking out the periodically repetitive pattern of normal mask holes using a pinhole type spatial filter under coherent illumination. In addition, a fast defect-detection image processing algorithm efficiently suppresses undesirable background noisy images. Experimental results prove that this method provides a detection capability of 500 ?m2 for the least defect size.

Turbulence conditions affect video images in two ways. They cause local blur, and they distort the geometry of the scene. A video sequence of a still scene recorded under turbulence appears to contain local random motion of small neighborhoods in the images. The blur is an accumulated result of the imaging point spread function and the local motion. The geometric distortion is due to the fact that small neighborhoods move in different directions. The restoration scheme reported takes care of the geometric distortion as well as the blur. The geometric distortion is reduced by averaging the gray levels of relatively long (a few hundred images) video segments. The averaging reduces the geometric distortion, but it increases the blur. The second stage is the estimation of the global point spread function. The blur in the average image is a combination of the effects of the imaging system transfer function, the turbulence, and the averaging of the sequence. The global nonisotropic point spread function is estimated based on edge responses in the average image. A Wiener filter is used for the restoration of the image. The presented experimental results are superior to the results obtained by a previously proposed majority-vote technique.

An optical arrangement using a wedge-plate shearing interferometer and a digital image processing system are devised for laser beam collimation. A modification of Xu and Rosenbruch’s method is presented that involves the rotation of a large-angle wedge plate by 180 deg and taking the absolute value of the result of the digital subtraction between the two shearing interferometric fringe patterns. The use of digital moire´ fringes for collimation testing is analyzed and the principle is verified experimentally. The defocusing errors in obtaining the perfect collimation by this method are calculated. It is found that the rotating wedgeplate method for obtaining digital moire´ fringes in collimation testing is twice as sensitive as the plane-parallel-plate method and also this method is a self-referencing collimation testing method, i.e., it does not require a horizontal reference mark and calibration of the position of the wedge direction. The laser beam divergence can be calculated directly by measuring the digital moire´ fringe spacing in this optodigital arrangement.

In this paper a new comparative speckle interferometric technique is presented: we call it the difference digital speckle pattern interferometric (DDSPI) method. The technique uses the two holographically reconstructed virtual images of the (unloaded and loaded) master object as references to detect the difference in displacement profiles of two macroscopically similar but microscopically different object surfaces. The two images corresponding to the two different states of the master object are recorded holographically on one holographic plate or on a thermoplastic film. So, the method does not require the real presence of the master object in the comparison process: the master object does not need to be subjected to repeated stresses, and each test object can be compared with the very same two states of the master object, which makes the method more precise and faster than conventional techniques.

High-resolution adaptive phase distortion suppression is experimentally demonstrated for laser interferometers using a liquid crystal television as a phase modulator and an optoelectronic feedback loop. The experiments are carried out for both amplitude division (Mach- Zehnder) and rotational shear types of interferometers. The suggested iterative control algorithm is based solely on interference pattern information. The results of numerical simulations of a high-resolution adaptive system based on rotational shear type interferometers show the system’s potential for atmospheric turbulence phase distortion suppression.

A powerful new optical method that utilizes diffractive optic interferometry (DOI) to measure both in-plane and out-of-plane displacement with variable sensitivity using the same optical system is introduced. Sensitivity is varied utilizing various combinations of the different wavefronts produced by a conjugate pair of binary optical elements; a transmission grating is used to produce several illumination beams, while a reflective grating, replicated on the surface of a specimen, provides the reference for the undeformed state. A derivation of the equations that govern the method is included along with a discussion of the experimental tests conducted to verify the theory. Overall, the results are excellent, with experimental data agreeing to within a few percent of the theoretical predictions.

A time-sharing collimation (TSC) method is developed to measure the beating force of an insect. In this method, a rod with a square cross section is used as a sensor block to transform the force variation to tilt angle variation, and an acousto-optic deflector is used as a diffractive scanner to measure these angle variations in two directions. We first calibrate the force variation with respect to the tilt angle variation and find that the uncertainty in force measurement for the TSC system is 8.8×10-4 N. We then apply the method to measure the dynamic angle variations and the beating force of a bumblebee. ©

A high-resolution distance meter is fabricated using optical waveguide modulators. The modulation frequencies of the optical modulators are around 3.5 GHz, while the modulation frequencies of the optical intensity are around 7 GHz because the modulation bias voltages are set at the peaks of the electrooptic characteristics. The distance meter was evaluated in the National Research Laboratory of Metrology (NRLM) tunnel, which is a semiunderground tunnel. The measurement resolution has a standard deviation of 12 ?m for a distance range of 0.5 to 5 m after correction of the cyclic error.

The feasibility of using bi-detectors or quad-detectors for ultra-high-resolution position-monitoring systems is explored. Factors that can affect the resolution of this kind of detection system are examined. We find that one of the major limiting factors is the shifting of the laser beam. A noise cancellation technique is developed successfully to suppress this noise. Using this noise cancellation system together with a thermally compensated laser and a pinhole spatial filter in a temperatureand vibration-controlled environment, the feasibility of ultrahigh resolution (< 20 Å) for displacement monitoring is demonstrated using off-theshelf components.

An optical probe for profile measurement of mirror surfaces is developed. This probe, consisting of a displacement meter and an angle meter, can detect the displacement and surface slope at one point simultaneously. Both the displacement meter and the angle meter of the probe employ position-sensing detectors (PSDs) as detecting devices. An optical fiber output is used as the light source so that the probe is made compact and has good characteristics. To eliminate influences of light disturbance the light intensity of the light source is modulated by a sine wave of 20 kHz, and only the position signal is removed from signals obtained from the PSDs. Calibration results show that the displacement meter and the angle meter can measure larger than ±500?m and ±60 arcmin with good linearity, respectively. Estimating from the SNR of the system, the displacement resolution and angle resolution are ±10 nm and ±0.1 arcsec, respectively.

A manufacturing error in the orientation of the working planes of a reflecting prism, such as an angle error or an edge error, will cause the optical axis to deviate and the image to lean. So does an adjustment (position error) of a reflecting prism. A universal method to be used to calculate the optical axis deviation and the image lean caused by the manufacturing error of a reflecting prism is presented. It is suited to all types of reflecting prisms. A means to offset the position error against the manufacturing error of a reflecting prism and the changes of image orientation is discussed. For the calculation to be feasible, a surface named the ‘‘separating surface’’ is introduced just in front of the real exit face of a real prism. It is the image of the entrance face formed by all reflecting surfaces of the real prism. It can be used to separate the image orientation change caused by the error of the prism’s reflecting surfaces from the image orientation change caused by the error of the prism’s refracting surface. Based on ray tracing, a set of simple and explicit formulas of the optical axis deviation and the image lean for a general optical wedge is derived.

A stereo microscope arrangement used for visual quality inspection is extended to a fast 3-D topometer using the fringe projection technique. With specially designed binary gratings, an ideal sinusoidal intensity distribution can be achieved for an optimized illumination. Using a two-grating technique, the unambiguity range can be increased significantly. Thus, various applications can be solved with this method as is discussed. The resolution that can be achieved depends on the field of view, which at a large magnification is below 0.2 ?m.

Relaxation matching is one of the most relevant methods for image matching. The original relaxation matching technique using point patterns is sensitive to rotations and scale changes. We improve the original point pattern relaxation matching technique to be invariant to rotations and scale changes. A method that makes the Hopfield neural network perform this matching process is discussed. An advantage of this is that the relaxation matching process can be performed in real time with the neural network’s massively parallel capability to process information. Experimental results with large simulated images demonstrate the effectiveness and feasibility of the method to perform point pattern relaxation matching invariant to rotations and scale changes and the method to perform this matching by the Hopfield neural network. In addition, we show that the method presented can be tolerant to small random error.

A quantitative expression for residual errors and mid-spatialfrequency errors of the aspherical surface finished by computer controlled polishing (CCP) is discussed in terms of the power spectral density model. The relationship between the magnitude of these errors and the CCP parameters is investigated using experimentation. An optimized CCP process is presented to reduce the residual surface errors. By properly choosing the polishing parameters such as tool size and lap material the residual errors can be removed. The final surface error of a hyperbolic mirror has reached 0.038 wave rms with residual errors less than 0.018 wave rms.

We propose a pipelined asynchronous time-division multiplexing optical bus. Such a bus can use one of two hardwared priority schemes: the linear priority scheme and the round-robin priority scheme. Our simulation results show that the performance of the proposed bus is significantly better than the performances of known pipelined synchronous time-division multiplexing optical buses. The possibilities of using our buses to construct multichannel switches and multidimensional processor arrays are also discussed.

We present an optical surface description that is more suitable for designing annular field systems than the standard aspheric surface representation. The use of this novel surface description leads to shorter design times and improved systems.

A simple model based on diffraction and geometrical optics relates the field-of-view dependent lidar signal returns from clouds to the size density distribution of their water droplets. The relation is written in a matrix form. The apparent size density distribution is obtained via matrix inversion with a constraint technique. The perturbation caused by the geometrical optics is interpreted in terms of small-particle diffraction. The apparent size density distribution is corrected for multiple scattering a posteriori. The correction is established by calculating the relative contribution of the different scattering orders to the broadening of the scattering phase function. The validity of the model is supported by Monte Carlo simulations and by experimental data performed under controlled conditions. Finally the inversion technique is applied to multiple-field-ofview (MFOV) lidar measurements from real clouds.

The standard analysis of heat-camera measurements includes emitted as well as reflected radiation, but assumes the same emittance for these two contributions. This is not valid if the sample emittance has spectral structure, i.e., is nongray, in the working range of the detector and near the maximum of the Planck function. The temperature dependence of the averaged emittance is shown to cause a significant error in the emittance value. Two algorithms are derived, based on linearising the heat-camera emittance values as a function of sample temperature for correction of this error. They are demonstrated to be effective on a spectral step model as well as for experimental data. BeO has a steep emittance edge in the long wave atmospheric window, similar to the step model. As for the model calculations, the conventional heat-camera emittance was significantly different from the corresponding integrated average based on spectral, reflectance data. Heat-camera measurements are compared with integrated spectral reflectance of ceramic beryllium oxide to illustrate the corrections. The two correction algorithms improve the agreement significantly, and it is proposed that they should be used when the heat-camera emittance exhibits systematic temperature variation.

A practical and effective, alternative Monte Carlo formalism is presented that rapidly finds flux solutions to the radiative transport equation for a class of problems in biophotonics; namely, wide-beam irradiance of finite, optically anisotropic homogeneous or heterogeneous biomedias, which both strongly scatter and absorb light. Such biomedias include liver, tumors, blood, or highly blood perfused tissues. As Fermat rays comprising a wide coherent (laser) beam enter the tissue, they evolve into a bundle of random optical paths or trajectories due to scattering. Overall, this can be physically interpreted as a bundle of Markov trajectories traced out by a ‘‘gas’’ of Brownian-like point photons being successively scattered and absorbed. By considering the cumulative flow of a statistical bundle of trajectories through interior data planes, the effective equivalent information of the (generally unknown) analytical flux solutions of the transfer equation rapidly emerges. Unlike the standard Monte Carlo techniques, which evaluate scalar fluence, this technique is faster, more efficient, and simpler to apply for this specific class of optical situations. Other analytical or numerical techniques can either become unwieldy or lack viability or are simply more difficult to apply. Illustrative flux calculations are presented for liver, blood, and tissue-tumor-tissue systems.

The structural, microstructural, optical, and mechanical properties of MgF2, SiO2, and TiO2 films prepared by reactive electron-beam deposition (EBD) and reactive ion-assisted deposition (IAD) were systematically investigated using an x-ray diffractometer (XRD), a transmission electron microscope, a spectrophotometer, and a microhardness tester, respectively. A mixture gas of pure argon and pure oxygen was used as the reactant. The mean ion energy was about 90 eV for the IAD process. Results showed that the preferred orientation, refractive index, and hardness of the films were strongly influenced by ion bombardments, although the variations of the phases and grain sizes were insignificant. With the fixed x-ray incident angle of 2 deg, the measured preferred orientation of polycrystalline MgF2 films deposited on unheated glass substrate by IAD was [110], which was consistent with the powder XRD pattern of MgF2, whereas that of the film deposited by EBD at a substrate temperature of 280 °C was [111]. The refractive index and hardness of the films deposited by IAD were always higher than those of the respective films deposited by EBD at a substrate temperature of 280 °C, which were due to the higher packing density caused by energetic ion bombardments. A 24-layer near-IR cutoff filter of alternating SiO2 and TiO2 layers prepared by IAD was more efficient on near-IR isolation and more thermally stable than that prepared by EBD. The optical thickness variation for the filter prepared by IAD over a substrate holder radius of 30 cm was less than 1%.

A two-dimensional (2-D) very large scale integration (VLSI) architecture using a unified systolic array for fast computation of the discrete cosine transform (DCT), the discrete sine transform (DST), and the discrete Hartley transform (DHT) is proposed. The N-point discrete transform is decomposed into even- and odd-numbered frequency samples and they are computed independently at the same time. The proposed unified systolic array architecture can compute the DCT, the DST, and the DHT by defining different coefficient values specific for each transform. We also present another architecture for computation of the DHT, a modified version of the unified systolic array structure, which is faster than the unified architecture by a factor of 2. In addition, the proposed unified architecture can be employed for computation of the inverse DCT (IDCT), the inverse DST (IDST), and the inverse DHT (IDHT) with some modifications.

A three-dimensional camera calibration technique is developed by combining two, 2-D camera calibrations for an orthogonal stereo viewing geometry. The left camera view (YZ view) and the right camera view (XZ view) are calibrated separately and then combined to produce an XYZ (3-D) calibration routine. Our technique employs three parallel calibration planes. One is placed along the main diagonal of the cubic experimental chamber, and the other two planes are placed known distances in front of it and behind it within the chamber. Both cameras view the calibration points on the planes simultaneously. Given the coordinates of a number of points, we use a physical model to determine the exact pixel locations of the calibration points. After inverting the model equations, we input the absolute coordinates and measured pixel locations into a least-squares fitting algorithm to obtain the experimental camera parameters for each camera individually. We then combine the two camera views via a ray-tracing method. We calibrated 3-in.3 (7.62-|mm3), 4-in.3 (10.16-|mm3), 5-in.3 (12.70-|mm3), and 6-in.3 (15.24-|mm3) chambers with accuracies between 1.66 and 2.01 pixels (0.60 and 0.77% of full field), 1.26 and 1.86 pixels (0.43 and 0.63% of full field), 1.16 and 1.34 pixels (0.33 and 0.39% of full field), and 1.91 and 2.49 pixels (0.59 and 0.77% of full field), respectively, using our 3-D camera calibration routine.

A vision-based finger motion tracking approach is presented to gather quantitative data about breast palpation for cancer detection, such as finger positions, search pattern and coverage area, and this approach is used to develop a prototype palpation training system. Special color markers are used as features of interest because in breast palpation the background of the image is the breast itself which is similar to the fingers in color. This color similarity can hinder the ability or efficiency of other feature extraction methods if real-time performance is required. To simplify the feature extraction process, color space transform is utilized instead of directly using the original RGB values of the image. Although the clinical environment will be well illuminated, normalization of color attributes is applied to compensate for minor changes in illumination. A neighbor search is employed to ensure real-time performance, and a three-finger pattern topology is checked for the extracted features to avoid any possible false features. After detecting the features in the images, 3-D positions of the color marked fingers are calculated using the stereo vision principle. Experimental results with the prototype training system are given to show the performance and effectiveness of the proposed approach. This approach is expected to significantly improve the training quality of breast palpation, thus increasing the detection rate and accuracy of breast cancer.

A technique for finding the relative spatial pose between a robotic end effector and a target object to be grasped without a priori knowledge of the spatial relationship between the camera and the robot is presented. The transformation between the coordinate system of the camera and the coordinate system of the robot is computed dynamically using knowledge about the location of the end effector relative to both the camera and the robot. A previously developed computer vision technique is used to determine the pose of the end effector relative to the camera. The robot geometry and data from the robot controller is used to determine the pose of the end effector relative to the robot. The spatial transformation between the robot end effector and the target object is computed with respect to the robot’s coordinate system. The algorithm was demonstrated using a five-degree-of-freedom robot and an RGB camera system. The camera can be dynamically positioned without concern for an assumed spatial relationship between the camera and robot, enabling optimization of the view of the object and the end effector. Further, the iterative nature of the grasping algorithm reduces the effects of camera calibration errors.

A wavelet transform is efficient for multiresolution signal analysis. Difference-of-Gaussian (DOG) wavelets belong to a particular class of wavelets that extract the information of a specific frequency range in an image. Different DOG wavelets are produced by simple diffusion and subtraction processes by using diffusion network. We propose an optoelectronic DOG wavelet transform system using the point spread function of the combined system, which is similar to the Gaussian function. The experimental results show that the proposed system has potential applications to the systems that require DOG wavelet transforms in real time.

An important issue in the production of integrated optics and optoelectronics devices in semiconductors is coupling to optical fiber. The refractive index and size of singlemode fiber is quite different from that of semiconductor waveguides, and therefore direct coupling of the two is associated with very high coupling losses.

This PDF contains the communications section which includes "Process control for a SiO2 buffer layer of LiNbO3 modulators to obtain reduced dc drift performance"

I first became involved in laser processing in the mid-1970s, a time when there were relatively few books about the subject. Although the laser had been rapidly commercialized and implemented in manufacturing industries in the 1960s, most of the burgeoning information about machining processes was confined to internal company documents or scattered throughout miscellaneous conference proceedings and research journals.