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In this paper, we will derive a phenomenological model of the bidirectional reflectance distribution function of non-Lambertian metallic materials typically used in industrial inspection. We will show, how the model can be fitted to measured reflectance values and how the fitted model can be used to determine a suitable illumination position. Together with a given sensor pose, this illumination position can be used to calculate the necessary shutter time, aperture, focus setting and expected gray value to successfully perform a given visual inspection task. The paper concludes with several example inspection tasks.

With the recent technological advances, there is an increasing need for measurement systems providing interferometer resolution for inspection of large quantities of individual samples in manufacturing environments.. Such applications require high measurement rates, robustness, ease of use, and non-contact systems. We show here that Digital Holographic Microscopy (DIM), a new method that implements digitally the principle of holography, is particularly well suited for such industrial applications. With the present computers power and the developments of digital cameras, holograms can be numerically interpreted within a tenth of second to provide simultaneously: the phase information, which reveals object surface with vertical resolution at the nanometer scale along the optical axis, and intensity images, as obtained by conventional optical microscope. The strength of DHM lies in particular on the use of the so-called off-axis configuration, which enables to capture the whole information by a single image acquisition, i.e. typically during a few ten of microseconds. These extremely short acquisition times make DHM systems insensitive to vibrations. These instruments can operate without vibration insulation means, making them a cost effective solution not only for R&D, but also especially for an implementation on production lines. Numerous application examples are presented in this paper such as shape and surface characterization of high aspect ratio micro-optics, surface nanostructures, and surface roughness.

Building of three-dimensional models is an important topic in computer vision. Range finders only let to reconstruct a partial view of the object. However, in most part of applications a full reconstruction is required. Many authors have proposed several techniques to register 3D surfaces from multiple views. In this paper, a survey of the most common techniques is presented. Furthermore experimental results are performed, and a 3D model is obtained.

Vision systems for color measurement should be designed with the basic principles of colorimetry in mind. A lack of understanding that a vision based color measurement system could fall if it ignores the basic principles of colorimetry is the main reason for some earlier color vision system failures. The purpose of this paper is to clarify how the color measurement principles have to be applied to vision systems and how the electro-optical design features of colorimeters have to be modified in order to implement them for vision systems. Despite their considerable advantages color vision systems are not capable of solving all color and appearance problems. Not understanding the limitations of this new technology is another reason for the slow progress of color vision systems. Sometimes color vision systems have been used for solving problems which, for a variety of reasons cannot be successfully resolved with them. A critical overview of the major areas of applications for color vision systems will be presented.

We propose a new technique of AHI which combines the high speed operation advantages of dynamic holographic interferometry and a real- time, high resolution, high stability, Denisyuk's holograms. Based on a new high sensitive phototerfractive reversible crystals group 23 doped (P and Cu) a small power CW laser was used for continuously hologram read and read-out processing. Portable wariant of a small size AHI sensor and practical demonstration of this technique are described.

Optical inspection systems require fast image acquisition at significantly enhanced resolution when utilized for advanced machine vision tasks. Examples are quality assurance in print inspection, printed circuit board inspection, wafer inspection, real-time surveillance of railroad tracks, and in-line monitoring in flat panel fabrication lines. Ultra-highspeed is an often demanded feature in modern industrial production facilities, especially, where it comes to high volume production. A novel technology in this context is the new high-speed sensor for line-scan camera applications with unmatched line rates up to 200 kHz (tri-linear RGB) and 600 kHz (b/w), presented in this paper. At this speed, the multiline- scan sensor provides full color images with, e.g., a spatial resolution of 50 μm at a transport speed of 10 m/s. In contrast to conventional Bayer pattern or three-chip approaches, the sensor presented here utilizes the tri-linear principle, where the color filters are organized line-wise on the chip. With almost 100% fill-factor, the tri-linear technology assures high image quality because of its robustness against aliasing and Moire effects leading to improved inspection quality, less false positives and thus less waste in the production lines.

Surface parameterisation using phase measurement of interferometric fringe patterns is supported by a strong theoretical basis. However, little work has been published with regard to the practical implementation of the available methods as tools for industrial inspection. This paper attempts to justify the choice of Fourier Fringe Analysis for this purpose and addresses some aspects of its implementation.

Time delay and integration (TDI) imaging was first applied in the early 1970's to aerial photoreconnaissance as an electronic replacement for photographic film. Since that time, TDI has been applied elsewhere infrequently with bare printed circuit board inspection and document digitizing as the only well-known recent applications. Now, TDI has been effectively brought to bear on an ubiquitous problem, that of inspection of moving webs. Although other imaging techniques have been and are being used for web inspection, none shows the broad adaptability and ease of use of TDI-based imaging. Herein is a review of the TDI technique, a specific implementation of TDI in a unique web-imaging-compatible camera and a comparison of the TDI technique with other current technologies.

The methodology of phase encoded reflection measurements has become a valuable tool for the industrial inspection of components with glossy surfaces. The measuring principle provides outstanding sensitivity for tiny variations of surface curvature so that sub-micron waviness and flaws are reliably detected. Quantitative curvature measurements can be obtained from a simple approach if the object is almost flat. 3D-objects with a high aspect ratio require more effort to determine both coordinates and normal direction of a surface point unambiguously. Stereoscopic solutions have been reported using more than one camera for a certain surface area. This paper will describe the combined double camera steady surface approach (DCSS) that is well suited for the implementation in industrial testing stations

Monitoring biological relevant reactions on the single molecule level by the use of fluorescent probes has become one of the most promising approaches for understanding a variety of phenomena in living organisms. By applying techniques of fluorescence spectroscopy to labelled molecules a manifold of different parameters becomes accessible i.e. molecular dynamics, energy transfer, DNA fingerprinting, etc... can be monitored at the molecular level. However, many of these optical methods rely on oversimplified assumptions, for example a three-dimensional Gaussian observation volume, perfect overlap volume for different wavelength, etc. which are not valid approximations under many common measurement conditions. As a result, these measurements will contain significant, systematic artifacts, which limit their performance and information content. Based on Fluorescence Correlation Spectroscopy (FCS) and Fluorescence Lifetime Spectroscopy we will present representative examples including a thorough signal analysis with a strong emphasis on the underlying optical principles and limitations. An outlook to biochip applications, parallel FCS and parallel Lifetime measurements will be given with cross links to optical concepts and technologies used in industrial inspection.

This article deals with the problem of the determination of characteristics of imperfect circular objects on discrete images mainly the radius and center's coordinates. Imperfections are provided by discretization, noise and interior distortions present in some production processes. To this end, a multi-level method based on active contours was developed and tested on, noisy or not, misshaped or not, simulated circles whom centers and radius were known. The adequacy of this approach was tested with several methods, among them several Radon based ones. More particularly, this study indicates the relevance of the use of active contours combined with a Radon transform based method, using a description of circles from their tangents, improved thanks to a fitting considering the discrete implementation of Radon transform. Through this study, an active region algorithm based on stationary states of a non linear diffusion principle is proposed. Its originality is to obtain a set of geometric envelopes in one pass, with a correspondence between level threshold of the grayscale result and a regularity scale, more or less close to the original shape. This set of geometric envelopes gives a multiscale representation, from a very regular approximation to a full detailed and roughest representation. Then, a more robust measure of the circle parameters can be computed.

Non-intrusive inspection and non-destructive testing of manufactured objects with complex internal structures typically requires the enhancement, analysis and visualization of high-resolution volumetric data. Given the increasing availability of fast 3D scanning technology (e.g. cone-beam CT), enabling on-line detection and accurate discrimination of components or sub-structures, the inherent complexity of classification algorithms inevitably leads to throughput bottlenecks. Indeed, whereas typical inspection throughput requirements range from 1 to 1000 volumes per hour, depending on density and resolution, current computational capability is one to two orders-of-magnitude less. Accordingly, speeding up classification algorithms requires both reduction of algorithm complexity and acceleration of computer performance. A shape-based classification algorithm, offering algorithm complexity reduction, by using ellipses as generic descriptors of solids-of-revolution, and supporting performance-scalability, by exploiting the inherent parallelism of volumetric data, is presented. A two-stage variant of the classical Hough transform is used for ellipse detection and correlation of the detected ellipses facilitates position-, scale- and orientation-invariant component classification. Performance-scalability is achieved cost-effectively by accelerating a PC host with one or more COTS (Commercial-Off-The-Shelf) PCI multiprocessor cards. Experimental results are reported to demonstrate the feasibility and cost-effectiveness of the data-parallel classification algorithm for on-line industrial inspection applications.

A new technique for processing of noisy fringe patterns with complex fringe shapes is presented . The technique is based in exploiting the capabilities of digital filters, treating the fringe-pattern as a signal to be processed. The main parameters required for designing the filter, and the application of the design methodology to a particular experimental fringe pattern are described in detail. To conclude, the designed filter is applied to experimental noisy fringe-patterns both from complex and simple wavefronts, which are processed without a single change in the parameters of the algorithms. The procedure is completely general, with a very small computational cost, and may be extended to any noisy fringe-pattern to be processed given the fringes are still visible.

Many industrial inspection such visual quality control of metal laminates require billions of operations per second. Analog CNN array computer arises as an alternative to traditional digital processors, capable of make in a single chip Tera equivalent operations per second. A 4096 analog CNN processor array is able to perform complex space-time image analysis, being much faster than a camera-computer system in continuous inspection applications. Both chips have been implemented in CMOS technology and they are managed by a 32- bit high-performance low-cost micro-controller that closes the pan, tilt, lighting, focus and zoom loops required in the implementation of the active vision strategies. Several convolution masks for the Cellular Processors has been selected to detect particular changes in the texture, size, direction or orientation of the image entities, reprogramming 'on the fly' the pixel resolution or shape when necessary. Laboratory results present these Cellular Processors and multiple resolution imager circuits as a promising architecture for visual inspection of industrial processes in real time.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this paper, we present several methods to improve the processing speed of an optoelectronic morphologicalindustrial inspection processor, which uses an incoherent correlator as its optical hardware and the extensive complementaryencoding morphological hit-or-miss transform as its detection algorithm. The first method is using a multi-channelcorrelation scheme, in which four database images are processed simultaneously so that the LCD panel needs only update 25times for a set of 100 images, for instance. The second method is using a postprocessing method for the optical correlationoutput plane. An absolute difference measurement (ADM) algorithm is applied for measuring the similarity of the opticalcorrelation resultant images, and then the similarity between the tested and the reference image can be deduced. By thismethod, the complicated preprocessing procedure including the extensive complementary encoding can be simplifiedbecause we can directly deal with the gray-scale images. The third method is using a photorefractive correlator instead of theincoherent correlator so that there is no the update rate limitation of the LCD panel, which was a main problem facing anyoptoelectronic hybrid system.Keywords: industrial inspection, morphological, processing speed, multi-channel correlation, postprocessing, similaritymeasure, photorefractive correlators

The image reference approach is very popular in industrial inspection due to its generality for different inspection tasks. Unfortunately, this approach is sensitive to illumination variations. A novel illumination compensation algorithm is proposed in this paper for correcting smooth intensity variations due to illumination changes. By using the proposed algorithm as a preprocessing step in the image reference based inspection or localization, we can make the image inspection or localization algorithm robust against spatially smooth illumination changes. This technique is very useful to achieve a reliable automated visual inspection system under different illumination conditions. The proposed illumination compensation algorithm is based on the assumption that the underlining image reflectance function is approximately piecewise constant and the image irradiance function is spatially smooth. Reliable gradient constraints on the smooth irradiance function are computed and selected from the image brightness function by using a local uniformity test. Two surface fitting algorithms are presented to recover the smooth image irradiance function from the selected reliable gradient constraints. One is a polynomial surface fitting algorithm and the other is a spline surface fitting algorithm. The spline surface fitting formulation leads to solving a large linear system, which is accomplished by an efficient preconditioned conjugate gradient algorithm. Once the image irradiance function is estimated, the spatial intensity inhomogeneities can be easily compensated. Some experimental results are shown to demonstrate the usefulness of the proposed algorithm.

The past decade has seen the development of multispectral and hyperspectral imaging spectrometers for use in remote sensing applications in the aerospace business. Correspondingly, advanced electronic imaging techniques have been exploited for use in industrial inspection and manufacturing process control. TRW has been involved in hyperspectral imaging since 1989 for use in remote sensing of earth resources and has developed many instruments and related technologies which can easily be re-applied to unique industrial inspection applications. These instruments operate in the visible, near-infrared and short-wave infrared wavebands covering the range from 0.4 microns to 2.5 microns depending on the application. The exploitation of hyperspectral imagers for remote sensing has shown the power of spectral imaging for typing and discrimination tasks, which can be readily applied to industrial applications. In this paper we explain the relevant fundamentals of hyperspectral imaging and how it can be exploited for industrial inspection and process control tasks, particularly those that require color or spectral typing and discrimination. The associated technologies used to perform measurements and reduce the data also are described.

Developers and users of industrial inspection systems can choose from a variety of CCD—cameras with large differences in performance and price. Many industrial inspection tasks require the extraction of metric information and ever more frequently of accurate three- dimensional metric information. The performance of CCD-cameras for metric inspection tasksis influenced by a large number of factors such as illumination, sensor characteristics, signaltransmission and frame grabbing, calibration techniques, and algorithms. Recent advancesin characterization and calibration of CCD-cameras are presented. Measurement accuraciesexceeding 1/50th of the pixel spacing were attained with off-the-shelf equipment in controlledlaboratory tests. Selection criteria of cameras as a factor of resolution and accuracy require-ments are discussed. 1 INTRODUCTION Machine vision systems have gained acceptance in industry and are used for a wide range of applica- tions. An increasing number of tasks require the determination of highly accurate three-dimensionalmetric information. Examples are the installation and control of manufacturing systems (fixtures,robots, etc.), and dimensional quality control of goods at various production states. Accuracy andmeasuring range are one of the factors determining the economic viability of 3D machine visionsystems. Doubling the accuracy of sup-pixel positioning allows to increase the measurement volumeby a factor of 8.Improving the metric accuracy performance of machine vision systems is a complicated task asit is influenced by a large number of factors. Most prominent among these are the environmentalconditions, the performance of the imaging system, the measurement arrangement, and algorithms(e.g. sub-pixel location, calibration, positioning). The development of accurate 3D machine vision

Airborne optical remote sensing has recently seen an evolution from limited spectral discrimination into high spectral resolution imagery. Hyperspectral imagers now have the ability to sample a scene at both high spatial and high spectral resolution, permitting optimal selection from the available information to meet specific applications. Techniques have been developed which provide for high speed acquisition, radiometric calibration, conversion to spectral reflectances, geometric correction and interpretation of airborne hyperspectral data. The same technology currently in use for discrimination of subtle features in airborne scenes is available for industrial inspection applications which can benefit from combined spectral reflectance and imaging information.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper describes a low-cost industrial inspection system (MAQVIS) developed by the authors and based on a personal computer equipped with a simple frame grabber and a digital input/output controller. Originally developed under a contract with an industrial partner for inspecting text and symbols printed on electronic components, MAQVIS can be applied to many inspection tasks since it is based on a generic template matching algorithm. The task of inspection is broken down into two steps; first, location of the symbols that must be verified in the image and second, verification of the symbols using criteria previously defined by the operator during the set-up phase. The first step is important in many applications where it is impossible, due to lack of mechanical precision, to guarantee that the object being inspected (or the symbols printed upon it) will always appear in the same position relative to the camera. The second step produces a pass/fail result for each symbol and finally for the component itself. MAQVIS can be programmed to display failed symbols on-screen and indicate the reason for the failure, or simply divert the offending component to the reject bin. Both the location and the verification steps are performed on gray-level images using algorithms specifically developed for this application. Statistical information about the number of failed components and the failure rate of individual symbols is generated and can be used to trace problems in the manufacturing process. The paper describes the system in general, and specifically the template matching algorithm used to locate symbols in the image and also the verification algorithm that validates each symbol as it is found. Results of tests performed using the system on the production line of an electronic components manufacturer are also presented.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A research group at the University of Stuttgart has set up an experimental measurement robot for industrial close range inspection. During a test run, the feasibility of a multi- sensor/actor system has been shown. The system uses optical sensors to perform different tasks including object recognition, localization and gauging. It is a step towards systems which are able to inspect and gauge several parts from a set of parts stored in a 3D model database. This paper describes the results which have been obtained so far and were demonstrated during a test run. It then focuses on our latest developments concerning 3D data acquisition, registration, segmentation, model generation from CAD data and object recognition.

In this paper a High-speed Opto-electric Image Processing Unit (HSOEIPU) based on an incoherent correlator is constructed, which can do two main processing works. One is digital filtering; the other is object recognition. Using HSOEIPU a Lapalace filter is realized to extract the edge characteristic from the images. Then the preprocessed images are sent into the object recognition unit for identifying the important areas or targets. A novel template-matching method is proposed for gray-tone image recognition. A changeable cycle-encoding method is introduced to realize the fuzzy relation pixel-matching on a correlator structure. The system has good fault-tolerance ability for rotation distortion, gaussian noise disturbance or information losing. In the experiments photographs of workpieces are sent into HSOEIPU for processing.

This paper presents an overview of past and current activities in the field of computer vision at Joanneum Research. Joanneum Research is a non-profit research organization covering mostof its revenues from contract research with industrial partners and international agencies in the area of space research (e.g., the European Space Agency). The focus on industrial real-time image processing started with the development of a 2D inspection system for wooden surfaces, and has expanded to the development of a 3D vision system for spacecraft navigation and elevation modeling.In this presentation the major projects in this area of research will be outlined. 1 . INTRODUCTION Our work in real-time image processing typically deals with inspection problems for industrialautomation. The systems developed can handle data rates of 4Mpixel/sec and up using scaleable multiprocessor systems. Projects completed include automatic inspection of • Profiled boards and textured surfaces;• bearing shells;• wet blue hides

This paper describes a flexible 3D sensor developed by British Aerospace as part of a collaborative project, LAIRD (IED 1551), which aims to meet the inspection needs of high technology manufacturing. By combining the principles of computer vision and robotics it has been possible to produce a visual inspection system where both the cameras and object can be automatically orientated to suit specific applications. A method for calibrating such a system is detailed as is a strategy for determining how best to orientate the cameras and the object.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes an image-based inspection system for surface defects, implemented on a transputer system with a high- performance transfer bus to provide fast access to large blocks of data. Data-level parallelism (the image pixel data is partitioned horizontally into slices) and task-level parallelism (the algorithms themselves can be parallelized) are utilized. Surface defects and anomalies are detected by a texture-based segmentation procedure. In the training phase the objects of interest are marked and all feature vectors implemented in the system are computed. The system uses simple statistical features, features calculated from the cooccurrence matrix, features based on texture spectrum and the fractal dimension. The time critical run phase is realized on a parallel computer. The implementation is done fully in software, allowing flexibility in the use of features and window sizes for pixel descriptors and freedom in the use of various classifier-methods. The processing speed of the segmentation system is easily scalable with the number of processing units. The performance of the system is demonstrated on an industrial visual inspection task, the recognition of surface defects of aluminium cast workpieces, where a connectionist classifier is used for pixel classification.

High development costs of machine vision systems can be reduced by designing more general algorithms that can be used in a wide range of applications, by using modular system architectures in which new algorithms and more computational power can be added easily, depending on the needs of the given applications, and by using powerful tools for the design of, for example, new algorithms, hardware, software, optics, and illumination. This paper overviews the related research in progress at the University of Oulu. The topics to be discussed include hybrid computer architecture for machine vision, a color segmentation algorithm based on hierarchical connected components analysis, an interactive tool for performance analysis of parallel vision programs, and an object-oriented image processing library.

The quality of a manufactured part may depend upon the either the chemical integrity or relative quantity of son characteristic substance; either as part of the fmal product or a chemical used sonwhere in the process. Examples are traces of oxidation on a machined metal surface, cuthng fluid used in machining, water content in a food product or pignnt differences on paperboard. Often the effects are not noticed in process until it is too late or contaminants in a product are not reliably detected by off-line human visual inspection. Problems of this type are candidates for on-line spectral analysis. In this paper, spectral signature analysis is shown as a viable tool for many industrial problems. We present several real.world indusirial spectral inspection examples using a laboratory prototype spectrometer/statistical signature classifier.

This paper reviews some of the activity in the UK directed towards realisation and exploitation of practical shop-floor automatic inspection systems. There are still considerable barriers to widespread applications because of the generally specialised nature of each situation, and the complexity and cost associated with achieving satisfactory solutions to image analysis problems. However, rugged solid-state imagers and microprocessor-based signal processing systems are beginning to advance the state-of-the-art to the point at which autonomous and robust equipment of moderate sophistication can be built at reasonable cost. The impact of microelectronics on performance and cost of equipment for inspection applications, and the problems of justifying and maintaining this equipment, are examined. Projects in which Sira Institute has been involved are referred to briefly to illustrate some of the points made.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The suitability of a number of systems architectures for use in industrial inspection machines is briefly reviewed. Two different pipe-line processors, a (linear) array processor, an array of transputers, a concurrent array of (non-interconnected) von Neumann machines are all discussed. Where possible, measured execution speeds are given. The article concludes that no one system yet available is able to fulfil anything approaching a significant proportion of all inspection requirements. However, a clear view of the short-term future emerges, in which a combination of certain current ideas is perceived as providing a basis for a far more cost-effective 'general purpose' image processing system for industrial inspection than we have yet enjoyed.© (1987) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A real-time Vander Lugt correlator for the automatic recognition, location and inspection of objects from direct imaging or TV camera input is described. Techniques to cope with changes due to scale and rotation are discussed. These include: (i) Image rotation with dove prisms. (ii) Multiple matched spatial filters by parallel addressing. (iii) Selective spatial filtering. Example results from an inspection task are presented.© (1986) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper describes an automated visual inspection system for complex industrial purposes. The system is composed of four main interacting divisions. These represent knowledge, processing modules, data structures and the master program. The knowledge division is composed of a model and a set of rules. The model describes geometrical, positional and relational properties of the items under test. Rules are further classified into representational, procedural and control rules. Representational rules are a set of design rules that should be followed by items under inspection. Procedural rules are the specific steps that should be executed to ensure the validity of representational rules. Control rules are respon-sible for the sequence of different levels of system activities. Processing modules are simple image processing, morphological and pattern recognition procedures, each assigned a particular job. They share data at different levels of representation. The master program, supervized by the procedural and control rules, chooses the appropriate processing module to continuously update the data or create a new pictorial structure in order to achieve specific goals. The seperation between the rules and the master program makes it a learning system in the sense that it can be taught new models, design rules and inspection algorithms. Thus, it can be easily adapted to different applications.

A flexible, reliable pattern recognition system has been developed that operates underthe difficult viewing conditions encountered in many industrial applications. The systemis flexible because it can be trained and retrained by an unskilled operator to recognize awide variety of pattern sets. The system is reliable because extensive pre -processing ofthe scanner signals is included to provide immunity to variations in lighting, surfacereflectivity, pattern distortion and pattern registration. The system has a number ofunique features. A different subset of the pattern set can be selected for recognition ineach position in a row of characters. A varying number of characters per row can be accom-modated. The patterns can be read a number of times before making a final decision. Thereject level can be set by the operator. Also, the operator may overide recognition withmanual input when necessary. Initial results achieved with this system indicate thatpractical solutions exist for the difficult pattern recognition problems that arise in anindustrial environment.IntroductionReading, recording and checking sequences of symbols is an important part of many industrialoperations. The consequences of an incorrectly recorded serial number on an engine part, amilitary weapon or a syringe may be far reaching. Frequently, high error rates occur evenwhen several people check each others work. Automatic equipment that can reduce errorrates and augment or relieve human operators can find immediate application in many areas.However, special pattern recognition equipment is required to process the low qualityimages that are frequently encountered. Such equipment must be readily adaptable to a widevariety of applications. It should also provide for sufficient interaction between operatorand machine to adjust to the variety of conditions that occur in a particular application.This paper examines the requirements of industrial automatic recognition equipment anddescribes a system designed to meet them.The paper opens with a discussion of some of the difficulties encountered in creatingimages of patterns on production parts. There follows a brief review of the hardware of anindustrial recognition system, a description of the pre -processing used in that system toextract useful information from the images of patterns, and the decision rules used in re-cognition. Then the operation of the system in the training, testing and running modes isdescribed and examples are presented of operator interaction with the machine through theteletype. Finally, some evidence is presented concerning the performance of the system inrecognizing two of the pattern sets to which this system has been applied.Pattern Images of Production PartsA reliable recognition system requires that the images of the patterns to be recognized beclear and consistent. The quality of the images created by a scanner is a function ofillumination, background conditions, positioning, and quality of reproduction of thepatterns. Consider, for example, reading serial numbers stamped around the rim of an auto-mobile distributor cap. Assume a scanning device that responds to light reflected from thecap's surface. Any of the following factors may be responsible for poor image contrast:non -uniform illumination caused by the curvature of the surface and shadows created byadjacent parts of the cap; variations in reflectivity produced by rust, abrasions and dis -colorations; variations in the position of the entire character string because of thedifficulties of fixturing an odd shaped part; variations in the position of individualcharacters caused by an imprecise stamping machine; and variations in character shape andstroke width produced by stampings that are non -uniform and inconsistent in depth.Many of the problems just described can be alleviated by improving other phases of the man-ufacturing process e.g., improving stamping machines, improving surface finishing and whereapplicable, use of computer controlled precision positioning tables for presenting thepatterns to the scanner. However, even when other factors have been optimized, a successfulrecognition system must be at once insensitive to variations in contrast, capable of findinginaccurately registered characters and relatively independent of the precise geometricdescription of the characters to be classified.

In this paper, a method is proposed for the integration of information which can be derived from the thermal infrared and visual modes based on the use of edge (dissimilarity) properties of the two types of images. The method involves the use of the Sobel operator to extract and classify edge points according to their strengths. A point-by-point comparison of edges from the visual and TIR images is made. Heuristics, supported by the physical processes affecting the image formation, are employed to give a probabilistic interpretation to each point in the images based on the strengths of edge points detected in the two images at the point. The validity of this approach is tested in a laboratory environment.

Optical coherence tomography (OCT), as an interferometric method, has been studied as a distance ranger. As a technology capable of producing high-resolution, depth-resolved images of biological tissue, OCT had been widely used for the application of ophthalmology and has been commercialized in the market today. Enlightened by the emerging research interest in biomedical domain, the applications of OCT in industrial inspection were rejuvenated by a few groups to explore its potential for characterizing new materials, imaging or inspecting industrial parts as a service solution[3]. Benefiting from novel photonics components and devices, the industrial application of the older concepts in OCT can be re-visited with respect to the unique performance and availability. Commercial OCT developers such as Michelson Diagnostics (MDL; Orpington, U.K.) and Thorlabs (Newton, NJ) are actively exploring the application of OCT to industrial applications and they have outlined meaningful path toward the metrology application in emerging industry[3]. In this chapter, we will introduce the fundamental concepts of OCT and discuss its current and potential industrial applications.

We present a polarization-controlled terahertz (THz) wave spectroscopic imaging modality to investigate the anisotropy of the detected materials. The polarization of the emitted THz wave is controlled to be horizontal and vertical by changing the relative phase of the fundamental and second-harmonic waves in the two-color laser-induced air plasma THz generation configuration. The anisotropy of the industrial sprayed-on-foam-insulation (SOFI) is characterized by measuring its azimuthal angle dependent THz polarization response. This work demonstrated that THz wave polarization-controlled imaging technique can be used for highly sensitive industrial inspection and biological related characterization.

Optical tools offer a route to increasing throughput and efficiency in industrial inspection operations, one of the most time-consuming and labour-intensive aspects of modern manufacturing. One prominent example in the medical device industry is inspection of drilled holes, particularly in narrow-bore tubes (precision-flow devices, such as catheters for drug delivery, radio-opaque contrast agents, etc). The products in which these holes feature are increasing in complexity (reduced dimensions, increasing number of drilled features- in some products now reaching into the hundreds). These trends present a number of technical challenges, not least to ensure that holes are completed and that no damage to the part occurs as a result of over-drilling, for example. This paper will present a novel sensor based on back-side illumination of the drilled hole using side-glowing optical fibers to detect, qualify and quantify drilled holes. The concept is based on inserting a laser-coupled side-glowing optical fiber into the lumen of the tube to be drilled, and imaging the light emitted from this fiber through a drilled hole using a vision system mounted external to the tube. The light from the fiber allows rapid determination of hole completion, shape and size, as well as quantity in the case of products with multiple holes. If the fiber is mounted in the tube prior to drilling, the light emitted from the fiber can be used as a real-time hole breakthrough sensor, preventing under or overdrilling of the tube.

To the best of our knowledge, proposed is a novel variable depth of field smart imager design using intelligent laser targeting for high productivity multiple barcodes reading applications. System smartness comes via the use of an Electronically Controlled Variable Focal-Length Lens (ECVFL) to provide an agile pixel (and/or pixel set) within the laser transmitter and optical imaging receiver. The ECVFL in the receiver gives a flexible depth of field that allows clear image capture over a range of barcode locations. Imaging of a 660 nm wavelength laser line illuminated 95-bit one dimensional barcode is experimentally demonstrated via the smart imager for barcode target distances ranging from 10 cm to 54 cm. The smart system captured barcode images are evaluated using a proposed barcode reading algorithm. Experimental results after computer-based post-processing show a nine-fold increase in barcode target distance variation range (i.e., range variation increased from 2.5 cm to 24.5 cm) when compared to a conventional fixed lens imager. Applications for the smart imager include industrial multiple product tracking, marking, and inspection systems.

Industrial inspection requires very fast and reliable measurements. One of the techniques, recently widely used for monitoring of engineering objects, is digital holographic interferometry (DHI). In the paper we present novel digital holographic cameras (DHC). Their configuration allows to provide high accuracy information about shape, out-of-plane and in-plane displacement distributions, through capture of digital hologram by CCD, numerical reconstruction of phases and their proper manipulation. Digital holographic systems presented have compact design, fibre optics light delivery system and automatic data acquisition and processing. The cameras capture data in real-time and have low sensitivity to environmental changes. In the paper several examples of engineering application of these cameras are presented.

We propose a novel structured light method, namely trapezoidal phase-shifting method, for 3-D shape measurement. This method uses three patterns coded with phase-shifted, trapezoidal-shaped gray levels. The 3-D information of the object is extracted by direct calculation of an intensity ratio. Theoretical analysis showed that this new method was significantly less sensitive to the defocusing effect of the captured images when compared to the traditional intensity-ratio based methods. This important advantage makes large-depth 3-D shape measurement possible. If compared to the sinusoidal phase-shifting method, the resolution is similar, but the processing speed is at least 4.5 times faster. The feasibility of this method was demonstrated in a previously developed real-time 3-D shape measurement system. The reconstructed 3-D results showed similar quality as those obtained by the sinusoidal phase-shifting method. However, since the processing speed was much faster, we were able to not only acquire the images in real time, but also reconstruct the 3-D shapes in real time (40 fps at a resolution of 532 x 500 pixels). This real-time capability allows us to measure dynamically changing objects, such as human faces. The potential applications of this new method include industrial inspection, reverse engineering, robotic vision, computer graphics, medical diagnosis, etc.

When it was first introduced two years ago, Indigo Systems Corporation's UL3 Alpha, a miniature uncooled infrared camera, set new standards for ultra-low size, weight and power within the thermal imaging industry. Now Omega, the next generation in Indigo's UL3 product line, takes advantage of novel algorithms and packaging concepts to further reduce size, weight, and power while still improving performance. These qualities make Omega an ideal candidate for many commercial and military applications, including fire-fighting, law enforcement, industrial inspection, remote surveillance, miniature unmanned aerial vehicles (UAVs), unmanned ground vehicles (UGV), and numerous other possibilities. This paper describes the design, performance and salient features of the Omega camera. Current and future applications of the UL3 product line are also discussed.

This paper will guide the first-time user toward proper selection and use of IR detectors for applications in industrial inspection, process control, and laser measurements.

Rochester, NY 14511ABSTRACTAutostereoscopy is finding acceptance in applications wherestereoscopic imaging is critical and where the use of stereoglasses and virtual reality head mounted displays (HMDs) isunacceptable. A wide variety of telerobotic activities arebeginning to rely on autostereoscopic displays for visual input.Experimental applications have been found in industrial inspectionand sign language learning/communication.Keywords: autostereoscopic, stereoscopic, 3D, display, virtualreality, yR1 telerobotics, industrial inspection, sign language.2. AN AUTOSTEREOSCOpIC VIDEO SYSTEM FOR INDUSTRIAL

In some applications, such as industrial inspection, it is often convenient or necessary to generate a stereo pair of images with a single photographic, X-ray, or video camera. The left and right views are created by moving the objects or the camera. This paper discusses this method of stereo image acquisition, illustrates some pitfalls, and shows how to overcome them. Examples images are presented that have come from applying the methods to the radiographic inspection of armament and tires.

Recent developments of interferometric techniques for industrial inspection in Japan are reviewed, with special emphasis on automatic fringe analysis, use of unique interferometers, use of advanced devices.