In August 1982 a conference on Robotics and Industrial Automation (Proc. SPIE 360, D. P. Casasent, ed.) elicited a tremendous response, with standing room only at nearly all presentations. This was followed in August 1983 by a Critical Review of Technology conference on Robotics and Robot Sensing Sys-tems (Proc. SPIE 442, D. Casasent and E. L. Hall, eds.). Beginning in November 1983 a permanent conference time and site were established. Future annual SPIE meetings in this field will be held in the fall in Cambridge, Massachusetts.

The use of Fourier descriptors for rapid recognition of complete shapes is discussed. A Fourier-Mellin correlation procedure for recognition of partial shapes is also presented. Some example recognition experiments, including industrial parts inspection and aircraft recognition, are shown.

Various feature extractors/classifiers for a hierarchical feature-space pattern recognition system are described. The system is intended to achieve multiclass distortion-invariant object identification. Although only a Fourier transform feature space is used, our basic hierarchical concepts, our theoretical analysis, and our general conclusions are applicable to other feature spaces. The performance using intensity and phase Fourier transform features and the performance in the presence of noise are studied and quantified for two different two-class pattern recognition data bases.

We show that by first measuring the line integrals of a two-dimensional picture f(x, y) via the Radon transform, certain feature-extraction operations useful in pattern recognition may be computed very easily; that is, the computational overhead for these feature-extraction operations is much less in the Radon space than in the direct space. In particular, we consider the following features: (1) moments of f(x, y) invariant to translation, rotation, geometric scaling, and linear contrast scaling; (2) two geometric features, polar projections and convex hull, that have similar invariance properties; (3) the Fourier power spectrum of f(x, y) integrated along radial piewedge and annular bins in the Fourier space; and (4) the Hough transform for detection of straight edges. Much of the motivation for this work lies in its implementation as an optical pattern recognition system. We show an optical-digital hardware implementation for the rapid computation of both the Radon transform and the feature extractions. By "rapid," we mean that the transform and feature-extrac-tion operations on a 512 X 512 image may be accomplished at video rates (1 /30 s per image). We point out advantages of this system over more traditional optical pattern recognition schemes that rely on the use of Fourier optics. Some experimental results are shown.

This paper deals with the state of the art and some development trends in Germany of sensor-controlled equipment for industrial automation. It gives a review of research and application work done at the Fraunhofer-Institut (IPA). The basis of this application work is a system- and hardware-independent software library that delivers structured and modular tools for efficient handling of picture data. One robot-sensor combination is discussed.

There are many real factory problems that can be solved by the use of robots equipped with computer vision. Typical of these tasks are the unpacking and assembly of loosely constrained objects. This paper describes a system in which TV deflection units are unpacked from a large carton and mounted onto the necks of picture tubes. The unpacking is performed by a cartesian gantry robot carrying a TV camera equipped with parallel-projection optics. The asso-ciated vision system is used to determine the position of the deflection units in the carton. Once a deflection unit has been unpacked, it is picked up by a PUMA 560 robot and then mounted in a specific orientation onto a picture tube. The mounting system is equipped with three TV cameras to locate the deflection unit and the neck of the tube. The paper describes the structure and operation of both systems, including gray-level picture processing, camera calibration with-out operator intervention, and the use of a general purpose, robot operating system, ROBOS, to control the two tasks.

Simplified 3-D vision schemes in a restricted bandpass of the infrared spectrum are used to fulfill welding adaptive functions in real time. A laboratory prototype able to seam track most of the 3-D joints encountered in welding is described, along with its performance as it applies to welding technology and to promoting better quality welds. Modules based on this prototype are of importance to expand the use of robotic arc welding since the latter can only be done reliably if real-time minute corrective actions on specific welding parameters (generalized torch coordinates and heat and mass balance) can be incorporated into a robotic welding station.

A flexible, adaptive, and programmable sensory control system for robotic acquisition of jumbled parts is described. The system consists of inde-pendent modules for vision and gripper control that guide a robot to acquire unoriented parts from a bin. The acquired parts are transported to a fixture and placed according to a desired alignment. The parts in the bin have either elongated or spherical symmetry, and all these parts are identical except for minor dimensional and textural variations. These objects may be colored or contain graphics, possess variable cross sections across their length, and have mixed material content and reflectivities. The system operates by taking a high resolution gray-scale image of the bin of parts using an overhead camera under ambient illumination. The overlapping parts in the image are separated by selectively removing the high spatial frequencies at the touching or occluding edges. These portions of the image are removed by dynamic range expansion, histogram-based adaptive image enhancement, and nonlinear homomorphic filtering. Algorithms are developed for fast and iterative data compression and segmentation and for estimation of the location and orientation of a cluster, irrespective of its shape. The photobeam, collision, and pressure sensors on the parallel jaw gripper are monitored during the process of parts acquisition and transport of experimental workpieces such as fuel filters, curved plier blanks, multicolored felt pens, L-shaped fuel links, ball bearings, and a mixture of shiny, semirusted, threaded, and unthreaded bolts of various lengths. In one image-processing cycle of 2 s or less, this system can compute locations and orientations of three objects at a successful acquisition rate of approximately 95%.

This paper describes the volumetric decomposition of an object into a hierarchy of hexagonal cylinders. The representation results in a tree of degree 7, called septree. A hierarchical addressing system, the generalized balanced ternary (GBT), is employed for the cylinders. The objective of this paper is to present efficient computational algorithms for manipulating the tree representation as the object undergoes translation and limited rotation through space.

A binocular-stereo-matching algorithm for making rapid visual range measurements in noisy images is described. This technique is developed for application to problems in robotics where noise tolerance, reliability, and speed are predominant issues. A high speed pipelined convolver for preprocessing images and an unstructured light technique for improving signal quality are introduced to help enhance performance to meet the demands of this task domain. These optimizations, however, are not sufficient. A closer examination of the problems encountered suggests that broader interpretations of both the objective of binocular stereo and of the zero-crossing theory of Marr and Poggio [Proc. R. Soc. Lond. B 204, 301 (1979)] are required. In this paper, we restrict ourselves to the problem of making a single primitive surface measurement for example, to determine whether or not a specified volume of space is occupied, to measure the range to a surface at an indicated image location, or to determine the elevation gradient at that position. In this framework we make a subtle but important shift from the explicit use of zero-crossing contours (in bandpass-filtered images) as the elements matched between left and right images, to the use of the signs between zero crossings. With this change, we obtain a simpler algorithm with a reduced sensitivity to noise and a more predictable behavior. The practical real-time imaging stereo matcher (PRISM) system incorporates this algorithm with the unstructured light technique and a high speed digital convolver. It has been used successfully by others as a sensor in a path-planning system and a bin-picking system.

A noncontact multilight source optical proximity sensor that can measure the distance, orientation, and curvature of a surface has been developed. Beams of light are sequentially focused from the ends of fiber optic cables onto a target surface. An analog light sensor a planar pin diode area sensor chip measures the position of the spots of light on the surface, and the 3-D locations of the spots are computed by triangulation. By fitting a surface to a set of points, the distance, orientation, and curvature of the target surface are calculated. The number of light sources and their positions and orientations were chosen so that the uncertainty in the measurement of distance would be within 0.05 mm and the uncertainty in surface orientation would be within 1.0 °. Since there are no moving parts and the spot position sensor chip outputs the position of the spot directly without scanning its field of view, fast opera-tion of the proximity sensor can be realized. Earlier prototype versions of the sensor can give approximately 1000 measurements of distance and orientation per second with precision of 0.07 mm for distance and 1.5 ° for surface orientation. This proximity sensor will be useful for such applications as tracing an object surface by a robot manipulator with a specified distance and orientation relative to the surface.

The measurement of particle size and velocity in particle laden flows is a subject of interest in a variety of industrial applications. In combustion systems for electricity generation, industrial processes and heating, and transportation, where liquid and solid fuels are injected into air streams for burning in furnaces, boilers, and gas turbine and diesel engines, the initial size and velocity distributions of particles are determining factors in the overall combustion efficiency and the emission of pollutants and particulates. In the design of injectors and burners for the atomization of liquid fuels, a great deal of attention is being focused on developing instrumentation for the accurate measurement of size and velocity distributions in sprays as a function of space and time. Most recent advances in optical engineering techniques using lasers for particle measurement have focused on detailed spray characterization, where there is a major concern with spherical liquid droplets within the size range of 1 to 500µm in diameter, with droplet velocities within the range of 1 to 100 m/s, and the requirement for making in situ measurements of moving particles by nonintrusive optical probes. The instruments being developed for spray analysis have much wider applications. These include measurement in particle laden flows encountered in a variety of industrial processes with solid particles in gas and liquid streams and liquid particles in gas streams. Sprays used in agriculture, drying, food processing, coating of materials, chemical processing, clean rooms, pharmaceuticals, plasma spraying, and icing wind tunnels are examples of systems for which information is being sought on particle and fluid dynamic interactions in which there is heat, mass, and momentum transfer in turbulent reacting flows.

The task of sizing droplets in sprays has confounded optical diagnosticians even though measurement techniques for sizing individual particles under laboratory conditions have been successfully developed. Difficulties with such measurement techniques result from incompatibilities between instru-mental capability and the physicochemical processes within sprays and the lack of standard practices for sampling of sprays, processing the associated data, and describing the results in precise terminology. An additional deficiency that hinders spray characterization is the lack of a calibration standard. Subcommittees of the American Society for Testing and Materials have undertaken activi-ties to relieve these shortcomings through the formulation of standards for the use of instrumentation, sampling, data processing, and terminology and the development of standard reference materials for calibration. Each of these tasks can profoundly affect the accuracy of spray measurement. Through partic-ipation in these task activities the optical engineer can become acquainted with the needs of the spray technologist. This interaction offers the hope that future measurement capability will possess both credibility and relevance to nonideal testing conditions.

This paper describes the development of a fully automated instrument that measures critical spray characteristics of liquid atomizers via an optical, direct-imaging method. The system uses a gas laser as the illumination source to backlight a liquid spray and a lens system to project an image of silhouetted droplets on a vidicon tube. A microcomputer performs all system control and data analysis as well as diagnostic functions. A data acquisition front-end supplies droplet data to the computer in real time. Pertinent system design issues are discussed, and the resulting design choices are described. When fully operational, the cycle time for sample hardware testing, data analysis, and report preparation is expected to be under 30 min. The optical portion of the system has already been used successfully to visualize and videotape numerous sprays.

A method of measuring particle displacements and velocities in the optical Fourier transform plane of an in-line far-field hologram is examined. The Fourier transform of a doubly exposed hologram is calculated, and it is shown that each particle pair related by translation contributes a set of cosine fringes to the total diffraction pattern. The fringe frequency and orientation are related to the magnitude and direc-tion of a given particle's displacement or velocity. The intensity in the optical transform plane is detected with a TV camera whose output is digitized and then linked to a computer for analysis. Particle velocities in one and two dimensions are measured, and experimental results are presented. Also, resolution limits are established by evaluating the minimum detectable difference in particle displacement.

Although the advantages of holography for particle measurements have long been recognized, practical application of the technique has awaited the development of automatic systems for image data analysis. An automated holographic diagnostic is ideally suited for the simultaneous measurement of drop-size distributions, trajectories, and velocities in combustion systems, for example, liquid fuel sprays. We propose an approach for automatic analysis of holograms of spherical droplets that is based on analysis of patterns in two or more nonimage planes. With this method, we have found that both the particle size and location can be recovered with an accuracy greater than that obtained by the time-consuming plane-by-plane search for sharpest focus. Thus, this simple approach represents a significant economy in image analysis and greatly enhances the prospects for development of automated systems for holographic particle measurement.

Research was conducted on a laser light scatter detection method for measuring the size and velocity of spherical particles. The method is based upon the measurement of the interference fringe pattern produced by spheres passing through the intersection of two laser beams. A theoretical analysis of the method was carried out using the geometrical optics theory. The instrument response function was determined to be linear with drop size. Experimental verification of the theory was obtained by using monodisperse droplet streams. Several optical configurations were tested to identify all of the parametric effects upon the size measurements. Both off-axis forward-scatter and back-scatter light detection were utilized. Simulated spray environments and fuel spray nozzles were used in the evaluation of the method. The measurements of the monodisperse drops showed complete agreement with the theoretical predictions. The method was demonstrated to be independent of the beam intensity and extinction resulting from the surrounding drops. An instrument based on the concept has been developed.

In situ optical diagnostics have been more widely used in recent years for measurements in both research and industrial facilities. The subject of this paper is an in situ particle counting and sizing technique that uses the intensity deconvolution method. This technique is also capable of simultaneously measuring the velocity of a particle and therefore allows absolute particle concentrations to be obtained. The technique can be used in both the forward scatter and backscatter geometries. This paper first describes the technique and presents the theory of particle sizing by the intensity deconvolution method. An example of the successful measurement of particle size distributions in an industrial reactor using the backscatter configuration is given, and the results are discussed. Measurements using the forward scatter configuration of particle size distributions and velocities for coal/water slurry combustion are described. A discussion of the size resolution, accuracy, and error analysis of the technique is presented.

A technique to measure the size and velocity of particles is discussed, and results are presented. In this technique two small laser beams of one color identify the center of a laser beam of a different color. This defines a region of almost uniform intensity where the light scattered by the individual particles can be related to their sizes. A variation of this technique that uses two polarizations of the same color of laser beam is also presented. Results are presented for monodisperse, bimodal, trimodal, and polydisperse sprays produced by the Berglund-Liu droplet generator and a pressure nozzle. Size distributions obtained at three different ranges for the same spray show excellent self-consistency in the overlapping regions. Measurements of a spray of known characteristics exhibit errors in the order of 10%.

The response characteristics of laser diffraction particle sizing instruments were studied theoretically and experimentally. In particular, the extent of optical sample volume and the effects of receiving lens properties were investigated in detail. The experimental work was performed with a Malvern Instruments Ltd. Model 2200 particle size analyzer using a calibration reticle containing a two-dimensional array of opaque circular disks on a glass substrate. The calibration slide simulated the forward-scattering characteristics of a Rosin-Rammler droplet size dis-tribution. The reticle was analyzed with collection lenses of 63 mm, 100 mm, and 300 mm focal lengths using scattering inversion software that determined best-fit Rosin-Rammler size distribution parameters. The Malvern 2200 data differed from the predicted response for the reticle by about 10%. The discrepancies are attributed to nonideal effects in the detector elements and the lenses. A set of calibration factors for the detector elements was determined here that corrected for the nonideal response of the instrument. The response of the instrument was also measured as a function of reticle position, and the results confirmed a theoretical optical sample volume model presented here.

Holographic records of diesel sprays are produced for a range of conditions, with the object of finding the variation of droplet size with time, injection pressure, and fuel properties. Analysis of the holograms is by means of measurement in the Fraunhofer plane using a droplet sizing instrument. This rapid readout procedure has enabled the investigation of a large number of conditions. Factors influencing the measurement are discussed, and size results are presented as a function of time for high- and low-load conditions, as well as a function of viscosity for a range of heavy fuel/diesel fuel mixtures.

A calibration procedure for diffraction-based particle-sizing instru-ments using multielement detectors is briefly reviewed. The effects of multiple scattering due to dense sprays on the calibration of these instruments are then examined over a range of sprays with Sauter mean diameters from 20 to 55 um. An empirical scheme to correct for changes in calibration due to dense sprays or other scattering media is presented.

Recent advances in the theoretical background are presented. The optical sizing techniques currently used and/or under development at Rouen University are discussed, namely simultaneous sizing and velocimetry using a corrected laser beam system, holography and Malvern diffractometry, diffusion-broadening spectroscopy, and multiple-scattering media diagnosis. Examples of applications are reported.

An optical model for contamination effects has been developed for the Stratospheric Aerosol and Gas Experiment II/Earth Radiation Budget Satellite (SAGE II/ERBS) instrument. This model describes throughput efficiency and response characteristics as a function of molecular contamination thick-ness for indexes of refraction representative of Shuttle/ERBS/SAGE II contam-inants at seven spectral wavelengths between 0.385 and 1.02 Am. Con-tamination effects are treated as thin-film coatings on selected optical elements that cause changes in those elements' reflection/transmission/absorption characteristics. SAGE/Applications Explorer Mission (AEM) in-orbit perfor-mance data were used to estimate the optical constants for the contaminants. SAGE and SAGE II are radiometers that spatially scan the sun through the earth's atmosphere with a narrow field of view in spectral intervals from visible to the near-infrared.

Simple interferometric configurations are considered in which the beam splitter is made of a diffraction grating placed at the Fourier plane of the source system. Under coherent illumination, interference patterns are produced that account for the phase difference between the source wavefront and the back-reflected probe wavefront. A practical laser unequal path interferome-ter (LUPI) setup is presented, along with calibration results from comparison with well-established interferometric configurations.

A computational model of the deterministic and stochastic processes involved in remote sensing is used to study and compare the performance of sensor spectral responses and data processing algorithms for classifying spectral features. The simulated spectral responses include those of the U.S. Landsat Thematic Mapper (TM) and the French Systeme Probatoire d'Observation de la Terre (SPOT). The simulated data processing algorithms include the computationally simple boundary approximation method (BAM) to discriminate between general target categories such as vegetation, bare land, water, snow, and clouds, and the maximum likelihood (MLH) and mean-square distance (MSD) classifications to discriminate between specific targets such as various crop types.

We have measured the reflectivity of several multilayer dispersion elements between 80 and 500 eV. Two samples of ReW-C and one of Ni-C, with 2d spacing of approximately 70 and 150 A, were tested at angles of incidence between 10° and 80°. Measurements were made by fixing the incident and reflected (Bragg) angles and scanning the photon energy. Theoretical analyses of these multilayers also have been made, and the results are compared with the experimental measurements.

Analytical expressions for the polarization properties of a corner reflector are obtained. The elements of the Jones matrices of a corner reflector are calculated as functions of rotation-induced phase retardation and polarization phase shifts at total internal reflection. The polarization properties of laser resonators containing corner reflectors are also presented.

An extension to image processing of Van Cittert's iterative restoration technique for one-dimensional data is presented. A particular advantage of the algorithm given here is the ability to satisfy amplitude constraints. It is useful for presentation of high dynamic range imagery in a limited display environment.

Space radiation can increase the noise of photodiodes as a result of either a sustained ionizing dose rate effect or displacement damage. Elementary, straightforward models are presented for calculating radiation threshold levels and radiation hit susceptibility. Radiation effects experiments that verify these models are discussed. Calculations for room temperature silicon p-i-n photodetectors, an avalanche photodiode, and a hypothetical cooled staring detector indicate that this damage mechanism should not be ignored for space and nuclear environments.

We have fabricated monolithic four-element diode laser arrays of PbS09Se01, emitting 100 mW of cw power per array end at 4 A in the 4 to 5µm spectral region. Corresponding to an external quantum efficiency of 20%, these arrays demonstrate the feasibility of upscaling output power levels by the parallelization of stripe-geometry diode lasers on a single crystal wafer. Such high power arrays are useful in applications that require high illumination levels in very narrow spectral ranges. By varying the material type and composition, any emitting region between approximately 4 and 8µm can be obtained with this material system.

The Rudolf Kingslake Medal and Prize for the most noteworthy original paper to appear in Optical Engineering in 1983 (Volume 22) has been awarded to James R. Palmer of Comarco, Inc. for his paper, "Continuous wave laser damage on optical components," which appeared in the July/August 1983 issue on pages 435-446.