A 1-inch HDTV super-HARP camera tube with excellent compatibility between super sensitivity and high picture quality was developed using a newly devised super-HARP target and all-electrostatic electron optical system. A new camera equipped with the tubes demonstrated sensitivity 80 times higher than that of conventional Saticon cameras and an AR response of 45% at 800 TV lines with excellent uniformity over the entire picture area.

A study has been made of some of the factors affecting the quality of the recorded image when using a large format 2K X 2K Kodak CCD imager. The optimal means for removing the dc offset, often referred to as the bias, is to sample many such frames and take a median at each pixel. The effects of external noise from electronics and cosmic rays are then removed well. The remaining noise in the frame appears to have a Gaussian form. The effect of pixels that accumulate signal due to a high thermal current can be significantly reduced by cooling. To remove the non-uniformity across the array due to the variation in responsivity from pixel to pixel it is extremely important to acquire images of uniform fields at the wavelength at which the observations of interest were made. This is especially important when image acquisition is over wavelength ranges outside the normal visual. For highly accurate photometric applications residual image effects needed to be considered.

In order to reach the best possible quality for HDTV pictures, there is a need to reconsider the concepts upon which existing standards are based. In particular, the scanning mode for scene analysis, signal processing and display can be progressive instead of interlaced as used in conventional TV standards. This technique improves notably the vertical and the temporal resolution but video bandwidth, bit rate and thus signal processing speeds are twice as big with interlaced mode. However, by using diagonal filtering, it is possible to make a quincunx progressive signal with half the bit rate (1,15 Gbit/s) of the primary digital signal. Then, this signal can be mixed in a HDTV studio or recorded with a digital VTR. This article describes the realization of a new progressive scanning high definition camera working in 1250/50/1 standard. This camera offers the facilities of broadcast cameras and is coupled to the experimental HDP/HDQ mixer developed in the RACE 1080 program by THOMSON-CSF LER allowing the operation ability of a HDTV progressive studio.

A novel active vision system for CIM production and inspection applications has been developed in the framework of ESPRIT II project No. 5194 (CIVIS). The system consists of a unique, integrated combination of novel components: camera head, data acquisition electronics, a custom digital image processor, control hardware and a commercial framestore, all under the direction of control and processing software on a PC-486 platform. The camera head incorporates a fast zoom lens in combination with a pan/tilt mirror system, allowing region-of-interest acquisition. The special 256 X 256 MOS image sensor offers programmable resolution and random pixel access. The unique combination of optics, optomechanics and versatile image sensor has a high `virtual resolution,' corresponding to more than 1k X 1k pixels but without the overhead of a high pixel transfer rate. The fast computation of the algorithm employed for the fractal inspection of surfaces is realized with an unusual combination of an electrically switchable hologram (for performing all linear operations at the speed of light in the optical domain), a module-based digital processor and the host computer. In this way, active vision for the inspection of concrete tile surfaces has been implemented by acquiring only relevant image data and elegantly processing them in the most appropriate domain.

At RJM two different image scanners with very high spatial resolution have been developed: The metric camera `JenScan 4500 MC' (4500 X 3450 pixels in 3 seconds) based on a novel microscanning subsystem and the Scan-Bank unit `UMK-HighScan' (14.000 X 11.000 pixels in 5 minutes) for the photogrammetrical camera system UMK 1318/1320. The JenScan-camera is completed by a set of special designed lenses with highest resolution and lowest distortion (< 0.05%).

In the course of ESPRIT II project No. 2103 (MASCOT) a high performance color CCD camera was developed. It is based on a 1K X 1K frame-transfer CCD imager whose pixels are covered with an optimized dielectric filter stripe pattern. A microscanning optical unit is employed to displace the image, with a reproducibility of 1/200th of the pixel period, for programmable color image acquisition with a maximum resolution of 3K X 3K color (RGB, XYZ, etc.) pixels. The CCD's output is immediately digitized to 10 bits using an in- house developed ADC subsystem whose performance of 67 dB S/N at 20 MHz is ideal for this application. The data is stored in one of three fast framestores. The raw data is read out simultaneously from these three framestores at a data rate of 30 MBytes per second and processed, fully digitally, in a special color processor. After non-linear transformations to compensate for detector non-linearities, color matrixing is carried out using one set of 16 matrix parameters which have been optimized for different illumination conditions and color temperatures. They also enable the selection of the type of output data to be generated e.g., RGB for specific phosphors, CIE XYZ tristimulus values, etc. After matrixing, a non-linear table-lookup can be used to introduce gamma correction or other calibration functions. The color processor produces 8-bit color pixels at a rate of 20 MBytes per second, writing these data directly into an 8 MBytes commercial framestore plugged into a PC/AT.

As part of the ESPRIT II project No. 2103 (MASCOT) a high performance prototype color CCD still video camera was developed. Intended for professional usage such as in the graphic arts, the camera provides a maximum resolution of 3k X 3k full color pixels. A high colorimetric performance was achieved through specially designed dielectric filters and optimized matrixing. The color transformation was obtained by computer simulation of the camera system and non-linear optimization which minimized the perceivable color errors as measured in the 1976 CIELUV uniform color space for a set of about 200 carefully selected test colors. The color filters were designed to allow perfect colorimetric reproduction in principle and at the same time with imperceptible color noise and with special attention to fabrication tolerances. The camera system includes a special real-time digital color processor which carries out the color transformation. The transformation can be selected from a set of sixteen matrices optimized for different illuminants and output devices. Because the actual filter design was based on slightly incorrect data the prototype camera showed a mean colorimetric error of 2.7 j.n.d. (CIELUV) in experiments. Using correct input data in the redesign of the filters, a mean colorimetric error of only 1 j.n.d. (CIELUV) seems to be feasible, implying that it is possible with such an optimized color camera to achieve such a high colorimetric performance that the reproduced colors in an image cannot be distinguished from the original colors in a scene, even in direct comparison.

The color fidelity of printed images depends upon the complete image reproduction chain. Factors include the spectral response of the color filters in the scanner, the color space chosen for digital encoding, image processing operations including corrections to tone curve, hue, and colorfulness, printer/press characteristics, and the color gamut of the printing inks. The criteria for fidelity of color reproduction depend on the objectives of the reproduction and the method of visual assessment.

Moire patterns can be formed when the spatial frequencies in a half-tone screened picture beat against the frequencies in a scanning raster. Very small periodic defects in the scanning raster can produce regular irregular bands and patterns which can spoil the quality of the printed result. Consideration of the factors which cause the patterns, and the sensitivity of the visual response, allow engineering tolerances to be placed on the raster scanning mechanism.

The M.T.F. of an image capture system is a good measure of a system's ability to reproduce sharp pictures. Post image capture processing will enhance the sharpness of the picture but the amount and type of processing required to produce a sharp picture is affected strongly the the M.T.F. of the image capture system. A simple and cheap method for measuring the M.T.F. in these circumstances is to measure the response of the imaging system to low modulation white noise. One such source of low modulation white noise is grain noise present in photographic transparencies. If the grain noise is captured with the image capture system and then Fourier transformed a M.T.F. response is produced. Presented is a practical example of this technique, from obtaining the test targets to producing the M.T.F. graphs. Also presented are some of the pitfalls that can be encountered using the technique.

Nowadays high-resolution cameras are used more frequently for solving measuring problems. Applications range from 2D- to complex photogrammetric 3D-measurements. Using a digital image recording system for measuring purposes however requires an exact knowledge about the reachable accuracy, taking into account the different modules like lenses, sensor, analog- to-digital converter and components, which in most cases are necessary to get a higher resolution (for example shifting devices or reseau plates). At the IPB a photogrammetric procedure was developed, which allows a fast determination of the geometrical efficiency and a calibration of any digital image recording device. A testfield with points, which 3D- coordinates must be known only approximately, is recorded in different images, which defines a geometrically stable photogrammetric network. All measured image points are used to compute a bundle adjustment. The results of the computation show the overall geometric accuracy of the system and the effect of different system parameters (for example lens distortion and pixel affinity). The paper gives a detailed description of the method and shows results of the evaluation and calibration of different high resolution camera systems.

This paper proposes a new approach to monitor the condition of a painting. That is the acquisition of the surface structure of the painting. As transportation damages are known to affect the crack pattern, very detailed images (cracks < 0.1 mm) are required. A compromise between this requirement and today's feasibility consists in using resolutions of about 20 pixel/mm with 8 bit, meaning images of 20k X 20k for a painting of 1 m X 1 m. A Kontron ProgRes 3000 on a high precision 3D motorized frame (repositioning accuracy < 0.01 mm) is used for the acquisitions before and after transportation. Each pair of images is resampled to compensate for geometrical distortions. The crack network is then detected by using line detection algorithms derived from mathematical morphology. The images are finally superimposed and changes can be detected manually or automatically. While the main focus of this contribution is spent on technical details, case studies are used to discuss recent applications.

A confocal microscope system illuminates the specimen with a point light source and then collects the reflected light onto a point detector. Only when the specimen is exactly in focus will any significant amount of light fall onto the detector. This gives the height sectioning capability of the microscope. Obtaining 0.1 micron depth resolution is not difficult. A potential drawback of the confocal microscope is that only the in focus region of the specimen is visible. We can use this property to form both an extended focus image and a three dimensional topological map. This extended focus mode is useful for understanding three dimensional structures. By using a three dimensional topological map image, where each pixel has an accurate calibration in three dimension, one can calculate various parameters such as surface roughness, height, depth, and volume. The volume of a three dimensional structure can be defined as the integral of the individual pixel values lying under the reference plane. One can define this reference plane manually with a mouse and a screen cursor. The software finds the volume below the surface enclosed within that area, deriving the height of the surrounding, reference surface.

One of the challenges in designing a confocal microscope is choosing the scan system configuration. The selection is based largely on the microscope application and involves a few distinct schemes. One scheme, moving mirror using galvanometer and resonant scanners, has been shown to offer an excellent solution exhibited by the large number of commercial systems which utilize them. Perceived shortcomings, such as slow image acquisition, are being dispelled due to the advent of large angle, high frequency resonant scanners. These newer devices offer near video rate performance at good scan efficiency.

A compound resonator semiconductor laser is described that eliminates mode hops that would otherwise be present with modulation of the laser. The method is easy to implement and makes possible consideration of laser scanners using rotating gratings.

Simple, highly efficient and fast holographic technology on silver halide media is developed. New features of the technology are: quasi real-time producing of holograms, recording and photoprocessing of holograms in the presence of day light, and no wavelength shifts of reconstructions. Possible applications of obtained results to data scanning and data storage are discussed.

The xerographic laser printing system is reviewed and the role that materials play in the seven xerographic subsystems is described. The functional performance of four major materials systems, photoreceptors, developers, fuser roll materials and paper, is defined and related to their respective composition and component properties. It is shown that the performance of the printing system and the quality of the output documents are almost exclusively dependent on the quality and reliability of these exceptional materials systems.

Intense optically stimulated luminescence (OSL) with a peak at about 420 nm is observed in ultraviolet (UV)-ray or x-ray irradiated europium-doped potassium chloride (KCl:Eu) crystals. The OSL intensity is increased with increasing UV-ray or x-ray irradiation dose. This suggests that KCl:Eu crystal is useful as a material for two-dimensional UV-ray or x-ray imaging sensor utilizing OSL phenomenon. The results obtained are consistent with the proposed emission mechanisms of the 420 nm OSL peak, based on the recombination of electrons released from the F centers with Eu³ ions. The excitation mechanism for the OSL in UV-ray irradiated KCl:Eu crystals is also discussed.

The Me-Chalcogenide glassy semiconductor-dielectric-semiconductor (Me-As₂S₃- SiO₂-Si) structure was formed and the writing and readout processes of the optical image with high resolution were studied. The structures make the positive and negative images possible. The device works in both accumulation of the small signals and real time. The space functional separation of the recording and readout allows us to carry out repetition readout of the image and other operations.

The results of the process of irreversible optical bit-by-bit recording on metal-polymeric films obtained by the method of plasma metal organic chemical vapor deposition are presented. The dependence between conditions of producing recording media and their properties has been established. The comparison of recording process on metal-polymeric antimony recording media with data recording on tellurium alloy films has been carried out.

Theoretic research and experimental investigations are showing the possibility of repeated information recording and read-out on new recording media with optically stimulated luminescence (OSL) effect. OSL concentration and spectral dependencies in Ca(Sr)S:Eu²⁺(Ce³⁺)-Sm³⁺ were determined. OSL in CaS films doped only by Sm³⁺ ions was detected.

This experimental study started over 13 years ago when a number of recordings were made in coherent light on fine grained silver-halide media. Some of them have not been photoprocessed yet. Using special photoprocessing bright and clear reconstructions were obtained from extremely faint latent images recorded over 10 years ago. Time dependent diffraction efficiency curves for Fresnel and Fourier holograms are given. Samples of holograms are presented. The results obtained seem to change present knowledge of silver- halide media capabilities.

Fluid lubricated bearings (ball or journal) exhibit problems of life and contamination in high speed polygonal scanners, particularly at speeds above 15,000 rpm. Grooved air bearings are limited to relatively high manufacturing cost, vertical only attitude, unidirectional rotation, and they tend to ingest debris. A plain journal air bearing is described which is bidirectional, any attitude operation, is free of whirl instability and has low manufacturing cost.

Hydrodynamic fluid film bearings are preferred by today's electronic imaging industry because of their high accuracy, high speed capability, long service life, and low maintenance. In this paper, various performance aspects of hydrodynamic fluid film bearings are discussed in relation to the special requirements of the laser scanner application. Emphasis is placed on the non-repeatable wobble (NRW) of the laser beam deflected by the scanner spindle, since NRW has the most significant effect on image quality. Major factors affecting the laser beam's NRW are analyzed both experimentally and theoretically. Testing methods for bearing performance evaluation are also discussed. It is found that unlike the non-repeatable wobble of the spindle rotor, the non-repeatable wobble of the deflected laser beam is not a purely mechanical property of the bearings and the rotor, but rather a system property affected by many factors, one of the most important being the thermal/turbulence distortion. Based on these results, methods of optimizing bearing and system design to achieve sub-arc second laser bean NRW performance in various speed ranges are suggested.

Advances in lasers, solid state detectors, electronics, and computational and display capabilities have made a reality of filmless recording, precision dynamic testing, and real-time processing of optical interference fringe patterns. Stroboscopically produced fringe patterns of the mirror-facet surface of a cylindrically shaped and a conically shaped scanner heat for `monogonal' scanners correlate with the predicted dynamic deformations from finite element analysis (FEA) at rotational speeds of 10 krpm and 20 krpm.

Reflective scanning devices have plane mirrors that deflect a light beam. When the mirror surface is coincident with the axis of rotation and when the incident beam passes through the axis of rotation, the instantaneous center-of-scan (ICS) is a single point for all angular positions of the mirror. If these two conditions are not met, the ICS moves with respect to the rotational axis and is, therefore, a locus. This paper illustrates the ICS for a six-facet and a twelve-facet prismatic polygonal scanner, and the relationship between the limiting off-set angle of the incident beam to the scan axis and the number of facets. This paper also illustrates the relationship between the range of the off-set angles of the incident beam from the scan axis and the number of facets. These aspects provide useful insights for consideration when undertaking the system design or detail design of an optical scanning system.

Servo-actuated limited rotation motors of the moving iron type have been used for many years to meet a great number of laser scanning requirements. More recent scanning applications have needed a greater level of accuracy, which has stimulated the creation of an entirely new kind of scanning device: the moving magnet scanner. This paper provides the information needed by design engineers to help them predict the performance of systems that incorporate such scanners.

A novel method for digitization of hand-written and hand-drawn information is presented. Two or more resonant laser scanners sweep out a plane, the interruption of these laser beams by a hand-held stylus and the beams' angular positions are detected. These data can be used to digitize coordinates along the hand-drawn lines with high precision (approximately 1 part in 10,000) and digitization rates (> 150 HZ). The data input surface can vary from small to large (permitting digitization on wall-sized writing surfaces), thus enabling a new family of applications. We discuss a novel application of this laser digitizing system, in conjunction with emerging radio modem and pen-computer technology, to the automation of class or conference room note-taking.

Scanning performance defines mainly capabilities of laser display systems. The use of mirror galvanometers provides simple reliable and inexpensive devices for the laser beam scanning. Maximal deflections of mirrors and a frequency band depend on both the mirrors' dimensions and the magnetic system's features. On the other hand the mirrors' areas, their deflections, and frequency band determine the laser beam image performance. An amplitude response of the galvanometers under various mirror designs and different kinds of magnetic materials has been studied over the frequency range from 0 to 6000 Hz and angles of deflection to +/- 7 degrees. Our results demonstrated a small cross-section laser beam's successful control over a frequency range to 3500 Hz without any feedback. The investigation allowed us to develop improved wideband scanners with light-weight mirrors and high residual magnetization magnetic systems.

Flying spot scanning technologies providing a constant velocity were presented in 1963 and in 1969, although the concept of `f-0' was not yet explained definitely. After the middle of the 1970s, laser diodes became worthy of notice and a compact-sized laser beam printer was developed. Along with that development, the `f-0 lens' was defined based on the optical design theory in 1979 and also popular-type `f-0 lenses' were developed through the analytical design method. On the other hand, the author and colleagues worked out the best way of enabling metal light deflectors to apply in a popular-type system in 1984; which means the optical system of `deflection error compensation' with the simple composition including a toric lens. The epoch-making optical system raised the productivity of laser beam printers and also has been providing high-definition image printing. As for recent trends, low-priced and compact- sized printers are expanding their share of the market. The author predicts that future laser scanning technologies will be focused in low-priced and process-simplified printers looking closely into high-definition image quality.

In the optical design of laser beam printers, it is very important to know the spread function of the beam across the photoconductors. With the usual method, however, we cannot determine the spread function directly, but rather we have to infer it from the optical aberration in the system and the shape of the beam assuming no aberrations. The fundamental method to simulate the point spread function has already been described. In it, the pupil function is defined assuming irregular illumination deviation of the wave front. Fraunhofer diffraction is then applied. A thorough investigation of the method has not yet been performed, however. We developed an algorithm based on the above method and created a program which determines the laser distribution over the photoconductors taking into consideration the influence of both optical aberrations and truncation by the optical pupil. Experimental values agree well with the calculated values, confirming the efficiency of the program. With this method and software, evaluation of the influence of the pupil and aberrations in the optical system on an elliptical Gaussian beam have become possible.

A two-beam laser scanning system using an acousto-optic deflector (AOD) has been developed. The lensing effect and the AOD nonlinearity were investigated, and were completely compensated for. In order to write a variety of masks, a servomotor-based auto- focus and an auto-revolver with up to three objective lenses were adopted.

In industrial robotics, laser scanners are mostly used to locate objects in all 6 degrees of freedom (6 dof), on- or off-line with respect to the robot process. Laser scanners are also well suited to characterize geometrical parameters of robot performance. We present examples of commercial weld-seam tracking sensors for robotic arc-welding, and of robot evaluation systems based on laser scanning.

On-line inspection of fast moving surfaces is one of the domains of laser scanning methods, especially whenever extremely small flaws are to be monitored on high quality products. Results of surface inspection on rolled aluminum based on several years' experience with several generations of inspection equipment are presented. Surface texture and characteristics of aluminum flaws require a problem related design of the laser scanner hardware for operation in the environment of a rolling mill plant. Fast intelligent data processing develops the inspection equipment to the center part of a plant-wide quality concept that strongly supports the idea of producing quality instead of only selecting quality.

Various systems for artificial 3-D imaging of real or hypothetical objects are described. All systems are divided into groups characterized with a similar way of forming and presenting 3- D images. Possibilities and limitations of each type are analyzed. Classification is given. Current systems utilizing laser scanning for 3-D imaging and their perspectives are discussed.

Various techniques are currently used to project video images. One of these, described in a previous paper by the author, operates by mechanical scanning of a laser beam with acousto- optic modulation, and has been proven suitable for high definition television and computer display scan rates by use of novel electronic and optical compensation methods. The requirement for improved image intensity with greater efficiency has led to a re-appraisal of the selection of the light source and the relationship between the light source, the form of the modulator, and the method of scanning. The electrical input to visible radiation output ratio of the Argon-ion lasers currently used in the projector shows efficiency to be as low as 0.001%, a factor limiting the commercial exploitation of the projector. Recent developments in acousto- optics can be applied to the projector's optical system allowing alternative light sources to be used. These help to reduce the complexity of both the optical and signal processing stages as well as improve efficiency.

We have developed a parallel Raster Image Processor that generates the laser beam control information on-the-fly, obviating the need for image storage, and in real-time. The system exhibits a nearly linear speedup in the number of processors used: It is therefore possible to achieve the very high pixel rates requested by the laser recorder. The system is composed of a variable number of processors and can hence be scaled, depending on the speed of the laser recorder. The software architecture of the system allows transparent execution of a large class of sequential algorithms on the parallel hardware.

Achieving good halftone reproduction in laser printing requires multi-level modulation of laser diodes. We proposed a hybrid modulation method that is basically pulse-width modulation (PWM) supplemented by intensity modulation (IM). This method is implemented as an IC, resulting in a small, high-speed LD controller module that can be mass produced at comparatively low cost.

The Xerox Docutech High-Speed Digital Copier achieves an output print speed of 135 (14 in X 8.5 in) pages/minute, at 600 dots/ inch resolution. Its digital optical image is generated by a laser scanner whose dual-channel modulation subsystem (AOM/D) enables this performance capability through crystal beam splitting/recombination optics, polygon facet tracking, pulse-imaging, and a dual-electrode Bragg cell. The AOM/D features: 86% throughput enabling the use of a standard 5 mW package size 633 nm Helium-Neon laser. Facet-tracking, enabling the use of a 63.5 mm diameter 18-facet polygon rotating at 22 KRPM. The splitting optics generate two cross-polarized beams which are then modulated independently by the dual-channel Bragg cell. The recombination optics enable tight separation control between the two adjacent scan line spots at the photoreceptor with excellent stability. Symmetrization of path lengths insures that the scan and cross-scan waists and image structures are imaged at the same plane. The Bragg cell and associated driving electronics accommodate modulation of 66 Mbits/sec per channel and >= 20:1 contrast ratio of pulse-imaged pixels. Design and manufacturing aspects are discussed.