We discuss how one optical processor (a correlator) can be used for all levels of scene analysis (low, medium, and high-level computer vision). This is achieved by the use of different filter functions for the different levels of a hierarchical inference system. New optical processor filter research that allows such flexibility is advanced and examples of each of these filters are provided. For large class problems, features extracted from each region of interest in a scene are fed to a neural net processor which performs recognition. New algorithms for optical neural net classifiers are also required. We conclude that present hardware optical correlator advances can significantly benefit from such processing.

This paper presents the optical Fourier analysis of human corneal endothelial cell patterns. The quantitative analysis of human corneal endothelial cells patterns is analyzed with Fourier transform methods. The optical Fourier transform of the pattern of endothelial cell borders is analyzed to yield the average cell area and the coefficient of variation of the average cell area. The advantage of the Fourier transform analysis is the parallel processing of the optical Fourier transform and the potential development of a hybrid digital-optical device for the rapid analysis of large numbers of endothelial specular photomicrographs. The intensity distribution of the Fourier transform of binary images of endothelial cell patterns is detected with a wedge- ring detector. The radial and the angular distribution of intensity is analyzed and related to the cell size distribution in the input image.

Articular cartilage is the bearing surface within human joints and as such is a subject of much interest among orthopaedic specialists. Diseases such as osteoarthritis are characterized by a deterioration in the cartilage surface and thus early detection and quantification of surface changes would be advantageous in the study and treatment of such disorders. Differential light scattering was studied as a technique for measuring the roughness of articular cartilage with the aim of developing a minimally invasive measurement method for use in-vivo. The method was established using a range of metal rough surfaces and cartilage surfaces. The results were correlated with stylus measurements. Samples were illuminated, using a helium-neon laser, at an incident angle of 45 degree(s) and the intensity of scattered light measured every 0.5 degree(s) over a 25 degree(s) range. For the cartilage surfaces the best correlation existed between optical parameters, based on a one dimensional moment of light intensity, and the roughness, calculated at a sampling length of 0.1 mm, the accuracy being 67%. The method was sensitive to surface changes during specimen preparation for SEM and was quick and easily interpreted. Differential light scattering is therefore a viable method of measuring the surface quality of articular cartilage.

Electron holography has a potential to overcome the resolution limitation of transmission electron microscopes imposed by a spherical aberration of an electron objective lens. This paper describes a new optical system a liquid-crystal spatial-light modulator (LC-SLM) to correct a spherical aberration from an off-axis electron hologram. The effective refractive index of the liquid crystals changed by the applied electric field can flexibly compensate for a wave aberration. Some experimental results involving the correction of the spherical aberration in an off-axis image electron hologram are presented. Zernike phase contrast method is also realized by the LC-SLM to visualize the phase distribution of a corrected object wave.

A confocal scanning fluorescent microscope (FCSM) changes parallel imaging, which is usually done with a conventional fluorescent microscope, to series-imaging. Because of this unique feature of imaging mean, the FCSM has the longitudinal discrimination ability a conventional fluorescent microscope does not have. The imaging principles of a FCSM are described briefly. Through an established mathematical model of system transfer function, the depth resolutions are calculated numerically. In biology science, the aberrations are introduced when an oil-immersion objective is used to study thick specimens, such as tissues and living cells, whose reflective indexes are significantly different from that of the immersion oil used in the experiment. Finally, after numerical calculation, a set of optimization curves for compensating the aberrations are given graphically under the different conditions, the compensation method proposed in this paper is suitable both for oil-immersion and non- immersion objectives.

The spectrophotometric technique used in pulse oximetry makes it possible to measure the oxygen saturation of arterial blood noninvasively and continuously. The accuracy of pulse oximeters tends to decrease during extreme hypoxemia, and so the lowest values of the oxygen saturation can not be evaluated with known error, as yet. Furthermore, it is mostly in this range that many undesirable influences interfere with the measurement reliability. Thus, it can be helpful to observe and analyze what factors and to what extent they affect the applied processing procedures. The author of this paper describes the main results of her studies with the focus on the performances of the device specially made for her research.

Image processing and recognition methods are useful in many fields. This paper presents the hybrid optical and digital method applied to recognition of pathological changes in bones involved by metabolic bone diseases. The trabecular bone structure, registered by x ray on the photographic film, is analyzed in the new type of computer controlled diffractometer. The set of image parameters, extracted from diffractogram, is evaluated by statistical analysis. The synthetic image descriptors in discriminant space, constructed on the base of 3 training groups of images (control, osteoporosis, and osteomalacia groups) by discriminant analysis, allow us to recognize bone samples with degraded bone structure and to recognize the disease. About 89% of the images were classified correctly. This method after optimization process will be verified in medical investigations.

Mass examinations of women should be carried out for early detection of cervical cancer. An automated system for selection of suspicious smears from a large number of negative cases has to be applied. Band-pass spatial frequency filtering technique may be used for the fast reduction of information in the image by converting dark stained nuclei into bright spots. Their intensities depend on the nuclei diameters. The enlarged nucleus is a symptom of the disease. However the filtering system suffers from false alarms produced by amplitude and phase artifacts. In this paper two alternative solutions have been presented. Both employ unequal spectral transmittance of the stain used for sample preparation which is high for infrared and low for the visible spectrum. The first solution consists in the nuclei contrast comparison in visible and infrared light in the direct images. In the second solution helium- neon and infrared diode lasers are used to perform the filtering process and the modified images are compared. The system has been successfully tested on the routine samples.

A new white light joint transform correlator (WLJTC) using LCLV in the Fourier plane is investigated. Appling the partial coherent light transmission mode ,we derive that the WI.JTC remains the linear computation of the complex amplitude. Correlation experiments show that the WLJTC can produce good auto correlation signal with rainbow color and can restrict coherent noise.

The coherent detection (and the consequent replay forward or backward in time emission) by an array of microphones (and loud speakers), in mutual phase, may mimic a dynamical acoustic hologram or a dynamical acoustic phase conjugate mirror (APCM). The ability of APCM to compensate distortions due to diffusing subjects (as part of living bodies) may in principle reverse in 3D detail (and with no hazard) the internal structure of anatomic components (tissue...) as well as absorbing ones (bones...). The resolution and the applications of APCM in medical inspections are discussed: megahertz frequencies are preferred. Anatomic subjects are generally optically opaque, but they are acoustically transparent. This is the reason to prefer APCM to optical PCM in medical as well as in geological inspections.

We used isolated radioulnar bones of subadult European moose collected in various environmental pollution areas of Finland. The bones were radiographed and outer dimensions measured. By using small caudo-cranial bending forces, the bones were tested by using HNDT. For bone mineral studies, samples were taken from the mandibles of the same animals. Results showed, that the bones obtained from the heavily polluted area showed biomechanical response comparable to the bones developed partially without mothers milk. Differences were also seen in morphometrical and radiological studies. The mineral contents studied did not differ significantly from randomly collected samples of the same age category. We therefore conclude that environmental factors may influence the bone matrix development.

Changes in molecular texture and structure of isolated radioulnar bones of subadult European moose collected in various environmental pollution areas of Finland were investigated by using HNDT and x-ray diffraction methods. By using small caudo-cranial bending forces, the bones were tested by using HNDT. For bone molecular texture and structure studies by using x-ray diffraction methods, samples were taken from the ulnar metaphyse (Olecranon). Results show that the bones obtained from the Harjavalta area and one from North Karelia showed changes in molecular texture and structure compared with samples from apparently normal animals.

There are a plethora of interference techniques which can be utilized for whole-field displacement and strain measurements. This paper contains a brief overview of some of the whole-field interference techniques which can be used for measurements in biomechanics. Rather than provide an exhaustive review of the applications of these techniques in biomechanics, however, two specific applications using holographic interferometry (HI) are presented. Although focused on HI, this discussion is pertinent to a range of whole-field interference techniques. The term whole-field is used to differentiate a class of interference techniques which provide information about displacement and strain over a large field of view, from point-by-point methods which require the repetition of the experimental protocol at an ensemble of points to produce similar information. Strain gauge measurements are a prime example of the latter class of techniques. Although whole-field methods often require an analysis at discrete points, the simultaneous acquisition of information at an ensemble of points is characteristic of these techniques.

We present a result of studying holographic grating focus both in theory and experiment. It is based on a geometric analysis of a point source grating, through a detailed study of a typical holographic grating we show the grating focus place and its possible application.

Results of millimeter wave (MMW) radiation action upon a refraction index of 2 - 10% water solutions of human blood plasma are presented in the paper. Investigations were carried out by holographic interferometry. Incident power density of MMW radiation applied was about 100 W/m². Under MMW irradiation a refraction index of 2% solution of human blood plasma was detected to increase by 2.52 (DOT) 10^-4. Field effect leading to refraction index changes was opposite to temperature effect. Millimeter wave effect was manifested immediately after the start of irradiation with its maximum reached after 6 - 7 min exposition. The initial refraction index was restored 10 min after the generator was switched off. In this paper the phenomena are explained from the point of view of the collective states whose changes take place under MMW field action on biomolecule containing water solutions.

Reflectometers based on low-coherence interferometry are potentially useful tools for probing superficial biological structures. In this paper, we present results of theoretical and experimental investigations of the variables that affect the backscattered signals measured by low-coherence reflectometers from dense tissues. Using a single-backscatter model of a turbid biological sample, we examine the effects of the focal spot size and collection angle on the heterodyne efficiency for light backscattered over a range of sampling depths. Coherence losses resulting from multiple scattering are studied using a simple analytical model augmented by numerical simulations. Our results suggest that the single-backscatter model, which has been applied previously in atmospheric lidar and ultrasound studies, provides a good description of the relationship between the shape of the reflectance-vs-depth profiles and the optical properties of a turbid sample under certain conditions. Model predictions were tested by measuring reflectance profiles from dense suspensions of particles using a low-coherence reflectometer built in our laboratory and a commercially available fiber-optic reflectometer. Results of these measurements are compared with others obtained in vivo from human skin. To demonstrate that small structures located at depths of several hundred microns can be probed without contacting a biological specimen, we show an image of bone specimen obtained with the laboratory reflectometer.

A new holographic technique based on a numerical reconstruction method is presented and applied to endoscopic holograms. The hologram is obtained by the interference between the light reflected by the object and a reference beam taken as a plane wave travelling back along the axis of the multimode fiber bundle (MMB). The reconstruction of the image is computed numerically, using a fast algorithm to perform the Fresnel transform of the illuminated hologram. The quality of the reconstructed image has been evaluated by simulation and the limitations of the microendoscopic process enlightened: reduced aperture, sampling through the MMB. The resolution limit reachable by a miniaturized endoscope has been predicted by deriving the pseudo 3-D amplitude modulation transfer function (AMTF) of the system, and the noise originating from the twin image. Both AMTF (contrast included) and noise allow the calculation of the SNR (signal to noise ratio) of the reconstructed object. The size of the smallest object observable from the hologram can be established. This size is taken as an image quality index (IQI). Our simulations have shown that this IQI is good enough to identify small size objects (100 micrometers or less) from a small aperture (0.31 mm) endoscopic hologram. The sampling of the on-axis hologram on the tip of the MMB has been shown not to significantly degrade the image.

Endoscopy has become established as a technique for visual inspection in difficult to access environments. So far it has not exceeded beyond the observation purpose. When a three- dimensional object is imaged by means of an endoscope, only a two-dimensional display is possible. In modern diagnostics, however, it can be necessary to know the size and shape of the object under study or to perform some deformation analysis. The methods for reconstructing the 3-D object shape from a 2-D endoscopic image are described and illustrated with some examples. They exploit holographic and non-holographic techniques for contour generation. Endoscopic deformation analyses with internal and external holographic recording are demonstrated as well.

The oral health of the Swiss population was significantly improved by the successful prevention of dental caries and periodontitis. Along with the healthy dentition the demand for aesthetic dentistry is increasing. Removable partial dentures are becoming less accepted. Therefore, to substitute lost teeth by permanent fixed partial prosthesis (bridges), the often deformed alveolar ridge has to be operated, either to improve the aesthetic appearance or to make it possible to restore the missing teeth by a fixed cemented bridge. The aim of this paper is (1) to evaluate whether the moire technique is an appropriate and handy method, and (2) to validate the precision of the new method. The measuring system consisted of a moire projector with an integrated phase shift device and a moire viewer with a CCD video camera, connected to a frame grabber in a personal computer. a highly versatile software was allowed to control the system as well as to grab the moire images using the four-phase shift technique in order to compute the phase image of the actual object. The new technique was validated with one solid test object measured by a 3D coordination, high precision measuring machine.

The aim of this paper was to measure the volume differences of operated alveolar ridge defects before and until 3 months post-surgically. Ten patients with ten localized alveolar ridge defects were operated on. Five alveolar ridge defects were corrected by using the full thickness onlay graft technique and the other five defects were operated by the subepithelial connective tissue graft technique. A strict standardized operation protocol was followed and all alveolar ridge defects were operated on by the same dental surgeon. Before as well as 1, 2, and 3 months after surgery the corrected defect was photographed and an impression was made by using an A-silicon material to produce a gypsum-cast model. The form of all these cast models was then measured using the moire technique. The three months result of ten cases shows that the form of the operated alveolar ridge defects, which were corrected by the subepithelial connective tissue graft technique are more stable compared to those which were operated on by the full thickness onlay graft technique. Localized alveolar ridge defects using the latter method does not show a form stability after 3 months post-surgically.

A collaborative project between NEL and St George's Hospital to investigate the measurement of the human face has resulted in the development of a 3-D clinical facial imager. The system utilizes the projection moire fringe contouring method developed at NEL to acquire accurate 3-D coordinates from the surface of a patient's face. In order that data can be obtained from the full facial area, two moire measuring units are employed, positioned symmetrically to each side of the face. The phase-stepping technique is used to improve the accuracy of interpolation between fringe centers and to distinguish automatically between surface concavity and convexity. Digitization and analysis of the resulting fringe patterns is performed using CCD cameras linked to a PC-hosted transputer image processing board which also controls the operation of the measuring units. Output is in the form of a dense mesh of 3-D coordinates which are transferred to a graphics workstation for image display, manipulation, and interrogation using specially developed software. A detailed description of the facial imager is given, with particular emphasis on the design features and two-stage calibration method which ensure that the inherent accuracy of the data acquisition technique is realized and facilitate the reliable measurement of unrestrained patients.

Double exposure as well as real time holographic interferometry were used to evaluate changes of the central curvature of the bovine cornea in vitro under small intraocular pressure (IOP) differences. Double exposure holographic interferograms of expanding corneas were used to get the positions of dark interference fringes on the surface of the cornea. Real time holographic interferometry allows one to determine the absolute value of the displacement of the corneal center along the axis of the eye or the number of the fringe, which is located closest to the corneal center. A mathematical model is given for the radial distentions and displacement of the center of curvature in two mutually perpendicular planes of a longitudinal- section of the cornea along the axis of the eye. Examples of holographic interferograms of a bovine cornea recorded at an intraocular pressure of 1340 Pa and pressure differences of 10 Pa and 20 Pa, respectively, as well as resulting changes of the corneal curvature are presented.

The usual holographic interferometric techniques provide the possibility for deformation, shape, and refractive index change measurements of objects with diffuse reflection properties but do not allow their comparison in a direct interferometric way. To compare two different but similar objects (e.g., master and test objects, or the original object and the same one after some alterations or wear) two interferograms are made and evaluated numerically. Difference holographic interferometry (DHI) makes the direct interferometric way possible, and, in addition, DHI does work even if the individual interferograms to be compared would be invisible, dense, or badly localized. The present paper summarizes the idea, theory, and experimental evidences of DHI and points out its useful application possibilities in prosthesis development too.

In mammalian hearing, the frequency-dependent spatial pattern of movement in the basilar membrane (BM) forms the basis of frequency discrimination (tuning). This is not necessarily the case in lower vertebrates; the turtle, for example, has an electrical resonance mechanism in its auditory receptor cells that varies in best frequency from cell-to-cell along the underlying BM. But how much, if any, of the frequency separation by this reptile is done mechanically by its BM? In other animals, vibrational analyses were indirect in that they required the placement of nonphysiological objects on the BM (e.g., the radioactive source of the Mossbaurer technique or the mirror of traditional laser interferometry). Our attempt to find an alternative approach led to the rediscovery of laser-feedback interferometry (LFI), here applied for the first time to vibration analysis in a biological system. LFI is an ideal method to directly measure the nanometer motion (amplitude and phase) of diffuse scattering surfaces such as the BM because of its simple geometry, ease of alignment, and its ability to respond to surfaces with a broad range of reflectances (10^-6 to 1). Preliminary LFI investigations of BM motion in the turtle reveal that its BM is broadly tuned and mainly reflects middle ear filter characteristics. No evidence for frequency-selective spatial BM mechanical tuning was found.

A multiple detector method was developed to extend the capabilities of phase stepped, real- time holographic interferometry to measure two components of a displacement vector simultaneously. To test the method, two experiments were performed which measured the cantilever bending of a piezoelectric ceramic bimorph due to an applied voltage. For the first experiment, the optical axis of one of the cameras was perpendicular to the surface of the bimorph while the optical axis of the second camera formed an angle of 48 degree(s) +/- 1 degree(s) with respect to the optical axis of the first camera. The bimorph was then rotated so that the angle between the optical axis of the first camera and the surface normal changed by 20 degree(s) +/- 1 degree(s). Both the out-of-plane (normal to the surface) and one of the in- plane (tangential) displacement components were resolved for each experiment and the results were compared with the known values.

The development of the single beam gradient force optical trap has improved the experimental capabilities available to cell biologists for noninvasive micromanipulation and mechanical measurement on living cells. Laser traps can be used not only to optically manipulate particles including bacteria, yeast cells, and intracellular organelles ranging in size from 25 nm to 25 micrometers with fine control of position (10 nm) but also to measure small (0.1 pN) forces in biological systems. For a given particle, trapping forces are linearly related to the laser power so that a relatively simple way of measuring force is to trap a particle at high power and gradually reduce it until the particle just escapes from the trap. The `escape' power, which is usually calibrated against the viscous drag of the aqueous medium at varying laser power levels, is a measure of the force.

Holographic interferornetry is a widely applied method for nondestructive, contactless testing of diffusely reflecting surfaces. For the investigation of very small objects it is necessary to use a magnifying imaging sy'stem for hologram recording. There are two principal setups of holographic microscopes': At first, the light wave front coming from the object surface is directly stored in a hologram, and the reconstructed image is observed through a usual microscope. At second, it is possible to store a magnified real image at or near by the intermediate image plane of a microscope and to observe the reconstructed image through an eyepiece. The first method is used, when a large angular aperture is required, but it suffers from a rather limited resolution. Though there are disturbing effects due to coherent noise (speckle effect), the second method provides resolution limits in the order of magnitude of conventional microscopes 2, and was chosen for our investigations. Two problems have to be taken into consider: At first, using the double-exposure technique for comparison and evaluation of two different object states, imaging errors of the magnifying system could be important. Following a proposal of Smith and Williams , these aberrations may be suppressed by conjugated reconstruction of the holographic interferogram. For this, the hologram is repositioned exactly and illuminated by the conjugated reference wave. In this way, deformation errors of the wave fronts due to the optical setup are cancelled, and the inuge nearly unaffected by lens aberrations can be observed at the original position of the object. At second, due to the coherence of the recording light, a holographic image is always superimposed by a subjective speckle pattern depending on the size and localion of the system aperture. Consequently, magnifying the image must result in magnifying the speckles. There have been some few publications concerning speckle reduction in holographic transmission microscopy, but the methods described do not apply to microscopic interferometry. So there must be found a cornpromise between speckle size and image magnification. To suppress speckle production by the reconstructing beam the hologram should be recorded as an image-plane type that can be reconstructed by incoherent light. A further important problem is the location and visibility of the interference fringe pattern. It is shown that the visibility of the fringe system is not influenced by conjugated reconstruction, but depends as well as its location on the size and the position of the aperture of the imaging system. Following these considerations, a holographic interference microscope was built up to record holographic double-exposure interferograms of surfaces of completely different objects: solder joints of surface mounted devices and germinating seeds.

Endoscope for stereoscopic vision is in great demand for medical field to diagnose and treat disease parts of patients more precisely. The authors are convinced that the silica-based imagefiber is suitable for making a thinner fiberscope for stereoscopic vision and have developed an ultrathin fiberscope with silica-based imagefibers for stereoscopic vision. The diameter of fiberscope is only 2 mm with two transmitting systems that consist of two imagefibers with 10000 pixels and lightguide for illumination and objective lenses. This fiberscope for stereoscopic vision can be used for the microsurgery, such as the laparoscopic surgery and the thoracoscopic surgery required for the thin diameter.

To develop methods of skin disease diagnostics and treatment monitoring, experimental investigations of the laser beam scattered by epidermis thin layers have been carried out. The coherent optical analyzer (COA) has been developed to analyze typical structures in the human upper skin layers. By means of the COA, the spatial distributions of epidermis strippings amplitude-phase transmission functions were investigated. The spatial power spectrum's instantaneous values registration for various spatial frequencies at the mechanical scanning of a direction, normal to the system's optical axis, was carried out. The registration was fulfilled by means of a specialized pulse- counting register of photoelectric signals.