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We consider the feasibility of performing logic with optical fibers at low powers. A Mach-Zehnder interferometer consists of two optical fibers. We consider the circular interference fringes between the outputs of the two fibers. A laser beam with a different wavelength is coupled into one of the two fibers to provide an increased intensity in that fiber. This effect will cause the index of refraction to change in that fiber because of nonlinearity. Since the interference fringes are very sensitive, a small change due to phase modulation will cause the pattern to move. Therefore, we do not need high power. The different combinations of the input presence and absence for the two laser beams will give different interference patterns at the output. Logical operations are obtained if a detector is placed at a particular position in the output.

Previously, we showed experimental results using spatial light rebroadcasters (SLRs) for orthogonal associative memory and for key word addressable memory. The SLR is suitable for memory because it may be written and then read later. In this paper, a parallel set of half adders is constructed using a single spatial light rebroadcaster together with an image intensifier and optically addressable liquid crystal light valve (LCLV). Experimental results using a 10 X 10 array show 100 additions in one step. We describe how to construct a parallel ripple-carry full adder and a bit-slice full adder with a single half adder.

Knowing the end-effector location (position and orientation) and the joint angles of the robot manipulator in real-time will assist the manipulator in negotiating around the obstacles when the manipulator is moving in a crowded environment. Thus, Forward and Inverse Kinematics Computations (FKC and IKC) play very important roles in robotic manipulators. The main objective of this paper is to demonstrate the capability of learning different trajectories of the robot reachable space by using the proposed PNN model. A software package has been developed for solving both FKC and IKC. The software can discover both the structure and the coefficients of a model to describe the dependent output variables in terms of the independent input variables identified by the users. The simulation is performed in a two degree-of-freedom manipulator. The solutions of the built FKC and IKC networks are compared with the analytic equations. The PNN learns successfully the indicated path. The simulation result shows that the PNN can interpolate the indicated path better than 99.87% of accuracy by only training the built PNN network 361 data pairs (out of 2D space point). The approach presented here can be expanded to six degree-of-freedom type of manipulators. Detailed algorithms of the GMDH to construct the PNN kinematics models will be discussed.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Conventional or phase-only correlators suffer from the requirement of fabrication and accurate alignment of the complex filter in the Fourier plane. A joint transform correlator, on the other hand, does not require fabrication of any complex filter and therefore is more attractive for real-time uses. In a JFT setup, the joint transform power spectrum of the input objects (i.e., the reference object and the input object) is generated and then, by performing subsequent an inverse Fourier transform on these interference fringes, the cross-correlations between these objects are produced.1 In our setup, the LCLV is used to generate the intensity fringes, and then used to provide gain. Unlike other methods no optic-to-electronic conversion is performed, since the function of the square law detector is preformed by the LCLV as required by the JFT. Therefore this system is an all-optical setup. Nonlinear operation is then achieved by changing the power of the write beam. The correlation output is fed back to observe its effect on the correlation peak.2

In signal processing, optical computing, communication, holographic memory lookup, pattern recognition, capability of reconfigurable interconnection is an extremely desirable feature. Optics can offer very high bandwidth, high propagation speed, noninterfering, high density, parallelism, and also dynamic reconfigurability. Multiple correlation can be achieved using an interconnections1,2 network. Recording interferometer patterns generated by a multiple source of light, an interconnection grating may be designed. A collimating beam can be split and then reflected by plane mirrors. The reflected beams are allowed to interfere with one another and then the interference pattern is recorded on a recording device such as a liquid crystal light valve. The interference pattern, if illuminated by a plane wave, will result in providing interconnection between the read beam and different locations of the output. For reconfigurability, the angular orientation of the mirrors can be controlled by changing the actuation input to the piezoelectric mirrors or certain beams may be prohibited from interfering using electronic shutters.

Optics has been successfully utilized to perform analog matrix-vector multiplication. It can be shown that any general purpose digital logic can be expressed in terms of two-stage binary matrix- vector multiplication or single-stage multiplication followed by a logical NOR operation. A logical inversion can be performed by the LCLV or the spatial light rebroadcaster material by multiwavelength exposure. The OR operation is then performed by a cylindrical lens. The complete process is then performed optically. Experimental results, future prospects, and related problems are discussed.1-3

Optical computers may be constructed from memory, logic, and interconnection modules.1 A module is proposed in which the output of a spatial light rebroadcaster (SLR) is fed into an image intensifier, followed by an optically addressable liquid crystal light valve (LCLV). Experimental characterization of the devices is provided. The cascadability of the module is demonstrated experimentally. First, an 8 × 8 array is stored onto the SLR by writing the argon light. Later, infrared is used to read out the stored pattern from the SLR. The orange output is amplified by the image intensifier and the output of the image intensifier illuminates the photoconductive side of the LCLV. Argon light reads the information off the other side of the LCLV. The output pattern is seen to be identical to the original input. Storage is provided by the SLR and gain by the image intensifier and the LCLV. The LCLV also converts the frequency back to the original frequency for cascadability. The module is acting as a memory module or buffer that permits synchronization for a computing system. Further, two inputs may be merged using a polarizing beam splitter to provide a parallel logic module for performing OR or NOR. The module may be combined with an interconnection module to permit the construction of a digital optical computer.

A heteroassociative memory is proposed that allows a key word in a dictionary of key words to be used to recall an associated holographic image in a database of images. Symbolic substitution search finds the word sought in a dictionary of key words and generates a beam that selects the corresponding holographic image from a directory of images. In this case, symbolic substitution is used to orthogonalize the key words. Spatial light rebroadcasters are proposed for the key word database. Experimental results demonstrate that symbolic substitution will enable a holographic image to be selected and reconstructed. In the case considered, a holographic image having over 40,000-bits is selected out of eight by using a key word from a dictionary of eight words.

A user friendly flexible system for assembly line part inspection which learns good and bad parts is described. The system detects missing rivets and springs in clutch drivers. The system extracts features in a circular region of interest from a video image processes these using a Fast Fourier Transform for rotation invariance and uses this as inputs to a neural network trained with back-propagation. The advantage of a learning system is that expensive reprogramming and delays are avoided when a part is modified. Two cases were considered. The first one could use back lighting in that surface effects could be ignored. The second case required front lighting because the part had a cover which prevented light from passing through the parts. 100 percent classification of good and bad parts was achieved for both back-lit and front-lit cases with a limited number of training parts available. 1. BACKGROUND A vision system to inspect clutch drivers for missing rivets and springs at the Harrison Radiator Plant of General Motors (GM) works only on parts without covers Fig. 1 and is expensive. The system does not work when there are cover plates Fig. 2 that rule out back light passing through the area of missing rivets and springs. Also the system like all such systems must be reprogrammed at significant time and cost when the system needs to classify a different fault or a

Optical shadow-casting based edge detection is hardware implemented using the spatial light rebroadcasting (SLR) materials. The digitized input image is encoded in accordance to the polarization-encoded optical shadow-casting design algorithm. An edge-detection operation of the coded image is performed using the SLR material both asspatial light modulator and logical device.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

An optical implementation is considered for a novel system, recently invented by the author, for accurately locating objects relatively close to an array from distributed backscatter. Processing is partitioned into handling scatterers in annuli rather than in pie shaped regions as in conventional systems which use beamforming followed by matched filtering. The advantages of the new design are discussed. Precomputing a matrix containing geometric and transmission pulse information leaves only a matrix-vector computation to be performed in real-time. Experimental results are shown for a 100 by 100 matrix-vector multiplication with a new device, a spatial light rebroadcaster (SLR). A method of constructing an optical sonar or radar is proposed using the new concept and the optical matrix-vector multiplier.

All-optical digital sequential logic reduces the expense and bit rate constraints associated with optical-electronic-optical (OEO) conversion in telecommunications. Two semiconductor optical amplifiers (SOAs) are directly coupled by connecting the output of each to the input of the other. This new configuration provides positive feedback to create a logical NOT or inverse for complete logic. An inverted optical threshold improves the quality of bit modulation. At the same time, frequency shifting allows improvement in the quality of the optical carrier. The SOA pair is analyzed in closed form to show that the positive feedback provides an output-input slope steeper than –1, allowing connection of two pairs to form a flip-flop. Two SOA pairs are cross-connected by connecting the output of each pair to the input of the other, to construct a novel R-S flip-flop. Closed form analysis shows, for the first time, that there is an unstable state and two stable states forming bistability for this configuration. Simulation demonstrates setting and resetting the reset-set (R-S) flip-flop at more than 5 Gbps. Agreement between closed form analysis and numerical simulation provides verification of the validity of the results obtained.

Novel real-time joint transform, Hilbert transform optical correlators are proposed in which only a half or a quarter of the Fourier plane is written onto an optically addressable spatial light modulator. A point source is used to recover the result for the whole plane. As a result, images with a two- or four-times larger space–bandwidth product can be matched in amplitude and phase. The effect of truncating the transform plane is explained with two- and one-dimensional Hilbert transform analysis. Results of computer simulation are shown.

Two novel full adder architectures are proposed that can be implemented with optical couplers using fiber optics or integrated optics. The first adder has the advantage over other proposed approaches by requiring only three different component devices: optical logical OR, op- tical logical NOT, and optical couplers. Configurations of the three com- ponents are described that are relatively simple to implement and are expected to function at greater than gigabit per second rates. The sec- ond adder requires fewer gates by using additional different gates: ana- log ADD and thresholding. Methods of implementing in fiber optics and with integrated optics are suggested including the synchronization of the lasers and methods for changing phase. The optical full adder can be used to provide high speed word addition by multiplexing independent additions. The pros and cons of fiber optics versus integrated optics for one architecture versus the other are discussed. © 1999 Society of Photo- Optical Instrumentation Engineers. (S0091-3286(99)00603-0)

An optical diffraction method is described for inspecting peri- odic structures such as combs or semiconductor leads. Coherent light passing between the prongs of the structure self-interfere at the frac- tional Talbot plane to provide a simple method of inspection. Computer simulation and laboratory experiments show the viability of this ap- proach. The theory assumes infinite structures. In practice, large end effect signals arise due to the finiteness of the periodic structure. A neu- ral network is demonstrated that learns to distinguish end effect signals from prong damage signals. The variability of the measuring process in a production environment makes neural networks an appropriate approach for this task. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)02303-4)

An alarm system was constructed and tested to demonstrate for the first time an all-optical system that uses electron trapping material with unsupervised learning. The alarm system provides an output when there is a deviation from a time weighted average of a 2-D input image. Classic Hebbian unsupervised learning is used to update the 2-D time weighted average weight array recursively with an all-optical loop. The fabrication of micrometer resolution nanosecond response electron trapping material is described and equations derived to show for the first time that electron trapping materials correctly multiply in parallel elements in a 2-D input image with corresponding elements in a second 2-D weight array. The alarm system equations and associated optic implementation are modified for a binary system instead of a bipolar one because of positivity of intensity. The system uses two electron trapping spatial light rebroadcasters (SLRs), one stores the 2-D weight array and the other the scalar output for synchronization and delay of the all-optical loop. The experiment uses a folded configuration to save cost by using only one image intensifier and liquid crystal light valve for both SLRs. Optical experimental results show the correct functioning of the system.

A wavelet transform is used to transform data so as to improve discrimination between objects for classification. The wavelet transform is implemented in optics using the Fourier transform of the wavelets. Further, the wavelet chosen has a Fourier transform that is real and positive to avoid the use of holographic techniques. An optical setup is described in which an electronic analog sensor signal drives an acousto-optic cell that controls the intensity of an argon laser. A mechanical scanner writes the information as a line onto a spatial light rebroadcaster module containing an optical liquid crystal light valve. A lens system expands the line into a 2-D array. A real positive Fourier transform wavelet filter is placed in the Fourier transform plane of a 4- f correlator. An optical demonstration shows the formation of a wavelet transform and agreement with computer simulations. An approximation of the inverse wavelet transform is possible using only a real filter, and this is demonstrated in an optical experiment.

An optical implementation is considered for a novel system, recently invented by the author, for accurately locating objects, relatively close to an array, from distributed backscatter. Processing is partitioned into handling scatterers in annuli rather than in pie-shaped regions as in conventional systems that use beamforming followed by matched filtering. The advantages of the new design are discussed. Precomputing a matrix containing geometric and transmission pulse information leaves only matrix-vector computations to be performed in real time. An optical processor is proposed because a large number of these computations must be performed in real time and because optics is well suited to matrix-vector computation. Experimental results are shown for 100 by 100 matrix-vector multiplication with a new device, a spatial light rebroadcaster (SLR). A method of constructing an optical sonar is proposed using the new concept and an optical matrix-vector multiplier. Much faster devices would be required for the method to be practical for a radar processor because of the much higher sampling rates.

The need for high performance analog to digital (AID) converters, the advantages of optics, and current approaches to AID conversion are reviewed. A novel method, for which a U.S. patent was recently awarded, is proposed that uses comparators, optical logic, and a table look-up to provide optical digital output from an optical analog input. The advantage of the new method is the ability to produce any digital code, optical input! output, and longer word lengths at high speed. Implementations of the optical logic are proposed that use 1-D spatial light modulator devices under development, including self-electro-optic effect devices (SEEDs), double heterostructure optoelectronic switch (DOES) devices, and spatial light rebroadcasters (SLRs). Optical AID converters could make digital multiplication by analog convolution competitive with electronic systems.

Experiments with synthetic data have indicated that generalized linear inversion may be used to estimate compressional velocities as a function of depth with high resolution directly from band‐limited, unstacked data. The ocean surface was not included in these experiments. In the presence of strong surface multiples, inversion is expected to take longer and be less accurate, because events from multiple surface reflections overlie primary events and normally have differing moveout. Existing velocity‐analysis techniques rely on the ability of an observer to make the difficult distinction between multiples and primaries. Equations are provided for adding the surface to the inversion procedure. This involves adding the surface effects to the Jacobian matrix as well as to the forward modeling procedure. To speed computation, the addition of the surface effects to the Jacobian matrix is delayed until after the matrix has been multiplied by a vector in the linear‐equation solution. Absorption is added to the inversion to represent the real world more closely and to improve computation speed by reducing sampling requirements. Realistic synthetic band‐limited data with high surface reverberation content were generated from a well‐log velocity profile. The inversion recovered the velocity profile to within 3 percent when a velocity increasing linearly with depth was used as a starting profile. The error in the model‐generated seismogram converges from 100 percent to within 2 percent of the reference data. The positions of interfaces are located more accurately at greater depths than at shallower depths because more sensors are observing deep strata than shallow strata. Convergence is to within 0.1 percent of that of the reference data at the maximum depth. The computation required 25 iterations and a total time of 66 hours on a DEC VAX 11/780. Reducing this time should be possible. In a preliminary study of the effects of noise, additive Gaussian noise was seen to limit the accuracy of the velocity estimate monotonically as the variance of the added noise was increased.

Prestack inversion with point‐source plane‐layer modeling has many advantages over poststack or normal incidence inversion. For example, it permits the determination of absolute compressional and shear velocities, density variations, and the accurate accounting of interbed and surface multiples. I neglect shear effects in this paper by assuming that they are adequately suppressed by velocity filtering. In the forward modeling step, a spherical wave expansion into plane waves is used to account for the point source. The plane‐wave reflection response for a set of plane layers is extended to the nonnormal incidence case. I use a Hankel transform to account for cylindrical symmetry. Generalized linear inversion is used because the fast recursive approaches available for normal incidence inversion are no longer applicable. I provide the derivation for the required derivative matrix, and I take into account the band‐limited nature of the data in frequency, time, and space. I demonstrate that moveout of events on realistic simulated prestack data enables the determination of absolute compressional velocity in the velocity‐depth profile, even though the data are band‐limited in frequency. I assume that preprocessing has adequately removed the shear and surface effects and that density is constant. Low frequencies in the velocity profile may be obtained more accurately than with velocity analysis used for stacking, because interbed multiples and other modeling phenomena are accounted for in the computation. Autoregressive modeling procedures that predict into the low frequencies of the velocity profile are also less accurate and cannot generate absolute velocity. I suggest future research leading to cost‐effective inversion of real data.

A finite element method is developed for investigating the propagation of high frequency electromagnetic waves along closed or open (surface) waveguides containing dissipative materials and having a cross section of arbitrary shape. The complex propagation constants and associated complex electromagnetic fields are determined as a function of frequency for possible modes of propagation. The method is verified by applying it to structures of simple shape for which analytical results may be calculated for comparison. Waveguides considered include a waveguide filled with dissipative material, a dissipative dielectric rod, a dielectric coated wire and a conducting wire.

A guided radar system is outlined which is suitable for collision avoidance and headway control in future high capacity systems, and a method is proposed in which the track is adapted for use as a radar waveguide. Present high-frequency methods are reviewed for comparison. A numerical procedure involving a generalization of the finite element method using the method of weighted residuals is developed for determining the complex propagation constants for surface waves along lossy waveguides of arbitrary shape such as the track waveguide. A strip of polystyrene attached to a rail was analyzed as a waveguide, and the results indicated that a 1.3 Gh/ wave would travel about 155 m before the attenuation had dropped to 1/e of the initial signal, even in wet track conditions. The phase constant was shown to be linear over several hundred khz.

A modet is described which consists of an aircraft with flux gate magnetometers mounted on the wing tips and a submarine containing a magnet to simulate the induced and permanent fields of an actual submarine. Equations are developed which enable a minicomputer sampling the magnetometers to calculate the location, depth, and heading of the submarine as the aircraft travels towards it. The real time plotted results are presented.

An examination of the newer courses of study for the social studies in the elementary school reveals a trend toward more complex content from a wider and more diffuse selection of social sciences.' True, for too long content from only history, geography, and some civics graced the skeletal framework of the social studies curriculum. It is as if seven years of famine are to be followed by seven years of overindulgence. In too many of the newer courses of study, content has squeezed out an emphasis on social living and adjustment, a democratic classroom environment and group responsibility which were so prevalent in the social studies syllabi of a decade ago. Yet, never has the need been greater for teaching and developing in young children the purpose of social responsibility and its behavioral techniques. Thirty-eight New York apartment dwellers witness a half hour murder scene but none calls for police rescue. In Atlantic City a crowd lets two nine year old boys drown despite cries for help. The bystanders, neutral respectable citizens, don't want to become involved to answer police questions or to appear in court. They don't want to commit themselves.

When does an individual decide to become a teacher and how did she decide are questions perhaps difficult to determine and somewhat unrealistic in form. One hundred elementary school teachers were so questioned, teachers from grades one through six. Superintendents, supervisors and principals were asked in conference to name from their personal acquaintance and knowledge, those teachers in the elementary schools of that system, who liked and were enthusiastic about teaching and not only said so but behaved as if they were. These teachers had indicated to the administration they were so satisfied with teaching in the elementary classroom they wouldn't accept any other type of position. The administration of eleven different school districts were so contacted and interviewed. The study covered an area of the state containing a population of approximately 1000 elementary school teachers.

(1960). Two Major Problems in the Teaching of the Social Studies. The Social Studies: Vol. 51, No. 4, pp. 135-139.

The faculty of Southern Oregon College of Education initiated, during 1953, an evaluation of the curriculum which educates elementary teachers. An exploratory committee was organized-to investigate the essential qualifications which would seem desirable in a good teacher. These qualifications, once determined, would then serve as guiding criteria in reorganizing the sequence and content of courses and in the elimination or addition of experiences for the teacher education student. Administrators, parents, teachers and students were personally interviewed during the year and asked five specific questions. Some thirty school administrators were solicited, who hired graduates of the college. Five were superintendents of systems consisting of at least ten school plants, five were superintendents of smaller school systems, of ten school plants or less, five were supervisors of large school systems, five were supervisors of the smaller school systems, five were principals of elementary schools consisting of at least twenty teachers and five were principals of elementary schools of ten teachers or less. Thirty parents were also interviewed. Ten of these parents had children in the first and second grades, ten had children in grades three and four, and ten had children in the fifth and sixth grades. Thirty elementary teachers were contacted; five teachers from each grade, first through the sixth. Twelve classrooms of children were interviewed, two classrooms for each grade, one through the sixth, giving a total of four hundred elementary children questioned. In all some two hundred elementary school systems were contacted. Finally one hundred twenty college students were interviewed, thirty from each year in college.

One requirement of any profession is its ability to select or screen those individuals wishing to enter its ranks. But teaching, as a profession, has long been noted for its laxness in screening those persons wishing to prepare for its portals. Many institutions are attempting valiantly to set up screening procedures to examine and select those candidates desiring to enter teaching-although with the terrifying shortage of teachers, results of such procedures are somewhat discouraging. Many administrators of the public schools system set up their own screening procedures through a system of tenure and supervision. But supervision is not always adequate and the tenure system not fool-proof, so many children might suffer in the process of the screening operation. Perhaps the principal agency for the screening of teachers should be the institution preparing teachers. In determining an adequate instrument for the selection and screening of its teacher education candidates the education faculty of Southern Oregon College of Education conducted a study to determine (1) what attitudes and opinions have practicing teachers and student teachers on screening procedures, (2) what procedures are presently practiced by other teachers education institutions in this country and (3) what procedures are presently practiced by teacher education institutions in Canada. The general conclusions of this study would seem to be as follows.

(1968). Physical Geography In The Primary Grades. Journal of Geography: Vol. 67, No. 1, pp. 18-23.

(1966). Geography Understanding of the Primary Child. Journal of Geography: Vol. 65, No. 4, pp. 170-176.

An examination of the newer courses of study for the social studies in the elementary school reveals a trend toward more complex content from a wider and more diffuse selection of social sciences.' True, for too long content from only history, geography, and some civics graced the skeletal framework of the social studies curriculum. It is as if seven years of famine are to be followed by seven years of overindulgence. In too many of the newer courses of study, content has squeezed out an emphasis on social living and adjustment, a democratic classroom environment and group responsibility which were so prevalent in the social studies syllabi of a decade ago. Yet, never has the need been greater for teaching and developing in young children the purpose of social responsibility and its behavioral techniques. Thirty-eight New York apartment dwellers witness a half hour murder scene but none calls for police rescue. In Atlantic City a crowd lets two nine year old boys drown despite cries for help. The bystanders, neutral respectable citizens, don't want to become involved to answer police questions or to appear in court. They don't want to commit themselves.

In commuting a teacher's worth to a community in terms of the monetary compensation she should receive, many laymen use as a criteria the amount of time the teacher spends on her job. They cite the shortness of her working day, her lengthy weekend, the long and plentiful vacations she receives. This argument was used recently, in one county, to refute a salary schedule, presented by the local teachers. To test such an argument, a project was organized to determine the number of hours of professional work in the week of the average teacher. Ninety teachers from the elementary school were interviewed; fifteen teachers from each of the respective grades, one through six. Forty-five junior high school teachers were interviewed, fifteen from each grade, seven, eight and nine. In all one hundred and thirty-five teachers were interviewed from six different elementary schools and three different junior high schools, each situated in a separate community. The teachers of the first, second and third grades were studied as one group. The fourth, fifth and sixth grade teachers were studied as a second group, and the upper grade teachers of the seventh, eighth and ninth grades, formed the third group. Each teacher was asked to keep a diary of her teaching duties and responsibilities over the period of a school year and also a time sheet on each of the following arbitrarily selected duties extending over the same period of time of thirty-six weeks.