The purpose of image analysis as a special type of signal analysis is to obtain relevant information from the physical world for decision making, like in industrial inspection, verification, alarm generation, for taking actions, like control of production systems, vehicle control, or for data transformation, like 3D-reconstruction, image coding, image rectification, etc. Any type of image analysis involves data grouping and data interpretation. The classical approach is the bottom-up strategy which is very efficient but requires extra efforts to obtain a high image quality and is quite sensitive even to slight changes in the scene setup, noise, disturbances, illumination effects, etc. The current trend in image analysis is to cope with more complex situations, like time varying scenes, spatial scenes, where the image depends on the viewing direction, or cases where the quality in one single image is too low to permit the extraction of reliable information. In these situations image analysis requires support from other sensors at different viewing angles, recordings form different time instances or the exploitation of different physical principles for image generation, i.e. multisensor data and the systematic use of knowledge. More flexibility in the analysis method is obtained by combining the classical data driven bottom-up strategy with the expectation driven top-down strategy. These new approaches will be illustrated in the paper by three examples, the analysis-by-synthesis strategy, multisensory analysis and knowledge based analysis.

This paper deals with the discussion of several problems in optical metrology which can be solved better by an active approach - the so-called active optical metrology. As an important difference in comparison to classical passive procedures the role of the model of the image formation/measuring process and its implementation into an active controlled feedback loop is analyzed. On example of phase reconstruction from 2D fringe patterns the necessity and the advantages of the active approach are explained first. Finally three examples are given where the solutions of complex measuring problems in HNDT and shape measurement are found by the implementation of active controlled feedback loops.

A very powerful technique for solving the kind of inverse problems that often arise in the processing of fringe pattern images is based on Bayesian Estimation with prior Markov Random Field models. In this approach, the solution of a processing problem is characterized as the minimizer of a cost function which has two types of terms: terms that specify that the solution should be compatible with the available observations and terms that impose certain constraints on the solution. In this paper we show that by the appropriate choice of these terms, one can use this approach in almost every processing step for accurate interferogram demodulation. Specifically, one can construct: robust smoothing filters that are almost insensitive to edge effects; operators that automatically determine a mask that indicates the shape of the region where valid fringes are available; adaptive quadrature filters for phase recovery from single and multi-phase stepping interferograms and robust phase unwrapping algorithms.

In sinusoidal phase-modulating interferometry an optical path length (OPD) larger than a wavelength is measured by detecting sinusoidal phase-modulation amplitude of the interference signal. This interference signal is produced by scanning sinusoidally wavelength of a light source. If the measurement accuracy in POD is higher than half of the central wavelength, this measured value is combined with a fractional value of the OPD which is obtained from the conventional phase of the interference signal. The measurement accuracy in POD is higher as the scanning width of wavelength is larger. We propose two different methods to create a light source with a large scanning width of wavelength by using superluminenscent laser diode and external-cavity tunable laser diode. Experimental results clearly show that sinusoidal wavelength-scanning interferometers using these light sources measure an OPD over a few tens of microns with a high accuracy of a few nm.

Fresnel or Fraunhofer hologram s can be recorded by CCD arrays as long as the sampling theorem is fulfilled. The numerical reconstruction of the wavefields is performed either by the discrete finite Fresnel transform or by solving the diffraction integral using the convolution theorem. The availability of the digitally evaluated complex wavefield instead of only the intensity field in optical reconstruction allows the subtraction of the phase distributions belonging to two states of the object to yield the sign-correct interference phase distribution with high accuracy. A numerical compensation for excess motion as well as effective filtering of the interference phase modulo 2(pi) are feasible.

A white light interferometer based on a single beamsplitter is described for direct group delay measurements. The arms of a Mach-Zehnder interferometer are folded in such a manner that a single beamsplitter could be used for splitting the incoming beam and combining the outgoing beams. This method offers a two-fold advantage: the measuring range of this interferometer is twice as large as that of the Michelson interferometer and the systematic error associated with the beamsplitter is minimized due to its configuration. We report the result of measurements on optical components performed in the 560nm to 630nm spectral region and propose a scheme for the processing of the experimental data. The principle of this group delay measurement procedure is then applied to construct a dispersive interferometric 3D profilometer. By adding the dispersion optics in one of the arms in the profilometer head, which consists of a Michelson interferometer, the practical dynamic range of the profilometer can be easily extended beyond one hundred micrometers.

This paper describes a high-speed 3D shape measurement system for in-line semiconductor package inspections. The system consists of three parts. One is an optics and sensor for confocal imaging, which we call a non-scanning multiple- beam confocal microscope. The microscope can get a confocal image within very short time because XY-scanning, which is required in conventional confocal microscopes, is not needed. Another is the algorithm that performs reconstructing the object surfaces accurately from a few confocal images. The last is a mechanism that performs shifting the focused plane of the microscope very quickly. This experimental system can measure objects having a space of 9.6 X 9.6 X 0.64 mm in less than 0.4 s with an accuracy in the order of 1 micrometers .

A low coherence speckle interferometer implemented using single mode optical fiber and a multimode laser diode as a pseudo-low coherence source is described. The design of the interferometer is presented and demonstrated on simple test objects. Signal processing techniques to improve the performance of the system are discussed.

A low-cost compact self-aligned optical sensor using the self-mixing effect inside a cw single-mode near IR laser diode has been developed for distance, velocity and displacement measurements. The optical beam back-scattered by a rough target into the laser diode cavity causes strong variations of the optical output power, the laser and the external target acting as a 3-mirror Fabry-Perot cavity. As each period of the optical power variations of the sawtooth- like self-mixing interference is due to a target displacement of a half-wavelength (lambda) /2, the motion law of this target can be represented by the addition of such small displacements. This sensor has also been used for velocity measurement up to several meters per second by applying a FFT directly on the self-mixing signal to reduce the influence of the speckle. By modifying the shape of the injection current, this sensor can be used as a laser range finder to measure distances from 1 m to 2 m with an accuracy of +/- 1.5 mm. In order to improve the accuracy of the range finder, the choice of the optical source is also discussed.

In phase shifting interferometers, spatial non-uniformity of the phase modulation often happens and affects high- precision phase measurement. Many phase measuring algorithms have been reported which compensate for nonlinear sensitivities of the phase shifter. This nonlinearity of the phase shifter usually gives only a constant bias to the measured phase in these algorithms. However, when the phase shift is spatially nonuniform, the measured phase is shown to suffer significant errors from these bias phase. We have shown that if we add a new symmetry to an algorithm we can remove the errors caused by the spatial nonuniformity of the phase shift. The algorithm needs at least one more image frame to acquire the symmetry. The lowest-order algorithm that compensates for a quadratic and spatially nonuniform phase shift consists of six frames. We have compared the performance of the new algorithm on several types of phase nonuniformity to the conventional error-compensating algorithms.

In this paper, a new 7-sample algorithm is derived based on the Surrel 6-sample algorithm by using the averaging technique. The Surrel 6-sample algorithm and the new 7- sample algorithm are analyzed using the Fourier description method and it is shown that the new 7-sample is more insensitive to linear phase-shift miscalibration than the Surrel 6-sample algorithm. By computer simulation, it is found that the linear phase-shift miscalibration produces the periodic phase error at three times the fringe frequency when the fringe signal contains a second-harmonic component. P-V phase error plots show that the new 7-sample algorithm is the least sensitive to the linear phase-shift miscalibration of the five phase-shifting algorithms considered in this paper when the fringe signal contains the second-harmonic component. A 3D fringe projection phase- shifting profilometry is constructed using a white light source and projecting a quasi-sinusoidal grating. The fringe pattern is captured by a CCD camera connected to a frame grabber in a PC computer. The new 7-sample algorithm is used and the experimental results are presented.

Fringe projection and passive photogrammetry for measuring range to remote points are both based on triangulation. Applying the phase-shift technique to fringe projection, point clouds with high spatial resolution and limited accuracy can be generated. Because of the 1D phase information, the geometric sensor calibration is needed for object point determination. In photogrammetry, highly accurate image operators are applied in order to solve the problem of image correspondence for structures like circles, crosses or natural patterns with a limited spatial resolution. Based on the image point coordinates, object point determination can be performed as well as sensor calibrations. In this paper two approaches are presented to combine the advantages of both strategies. The image correspondence problem is solved by using projected fringes with different orientations. High spatial resolution is obtained by the phase-shifting technique. Systematical error sources like phase-shifting errors or nonsinusoidal waveforms will be eliminated by applying special algorithms in addition to a passive setup. Redundancy will be improved by increasing the number of sample points.

A new method for derivation of phase-shifting algorithms is presented. The cost function is defined and it is minimized using descending gradient method. The family of algorithms is derived as the result. The properties of the algorithms do not change within the family. Examples of algorithms for constant phase-step as well as for randomly disturbed phase- steps are given and analyzed.

The paper describes a new algorithm that uses only two mutually phase-stepped interferograms per deformation state in order to retrieve modulo 2(pi) the phase signal due to deformation. It is suited for use in ESPI where the initial phase in the interference term is the phase of speckle that varies randomly over the imaging sensor. Any phase step value except those close to multiples of (pi) can be applied. Practical advantages of the algorithm are outlined. An analysis of phase measurement uncertainty is presented, results are discussed and compared with those from standard phase-shifting algorithms. Obtained results prove that measurement uncertainties smaller 2(pi) /20 are feasible.

Noting the analogy between electro-magnetic fields and the vector fields of phase gradients obtained by heterodyne techniques, we propose a new algorithm for least-squares phase unwrapping. Instead of solving a Poisson equation for the unwrapped phase map or using the Green's formulation, we directly remove singular points or residues from the measured phase map by superposing sign-reversed vortex fields which cancel out the rotational vector fields associated with the phase singular points.

The performance of a minimum L⁰-norm unwrapping algorithm is investigated using computer-simulated digital speckle pattern interferometry (DSPI) wrapped phase maps. This algorithm estimates its own weights in order to mask inconsistent pixels. Particular features usually included in DSPI wrapped phase maps such as shears, speckle noise, fringe cuts, object physical limits, and superimposed fringe patterns are analyzed. Some adequate approaches to solve these features are discussed. It is shown that a complex case in which shears and fringe cuts coexist in the wrapped phase map cannot be successfully solved by the minimum L⁰-norm algorithm on its own. In order to cope with this problem, a new scheme is proposed.

In several applications of interferogram analysis, e.g. automated nondestructive testing, it is necessary to detect irregular interference phase distributions or to compare interference phase distributions with each other. For that purpose it is useful to represent the essential information of phase distributions by characteristic features. We propose features which can be extracted both from interferograms as well as from phase distributions. For feature extraction we developed new image processing methods analyzing the local structure of gray-level images. The feature extraction is demonstrated with examples of a cantilever beam and a pressure vessel using holographic interferometry. Finally we show the use of the features for defect detection and phase distribution comparison.

This paper presents an extension of generalized boundary- fitted coordinate systems to image and fringe processing. Through a non-linear boundary-fitted coordinate system, it is possible to apply a very convenient geometrical transformation in an image in order to map a non-regular domain into a rectangular domain. The approach is very flexible and it can be used to map a very large variety of shapes, including shapes with discontinuities, voids or holes, into a rectangular area. That can be used to handle image processing task where the shape of the area that contains the fringe patterns is non regular: a one by one image mapping is applied, and the fringe processing can very comfortably be accomplished in a rectangular domain. The measurement data can very easily be digitized in a naturally defined boundary-fitted digitizing mesh. A computationally efficient algorithm is also presented to allow very fast image mapping. Some application examples are given.

To improve the resolution and the sensitivity of optical metrology an interferometer for VUV wavelengths was realized. To examine the influence of the wavelength especially with regard to the period of the object structure, an apochromatic design was chosen. This means an object can be measured with wavelength from 157nm up to 900nm without changing the optical setup. The design of this interferometer will be presented. The benefits and also the technological problems which come along with the use of VUV wavelengths are discussed. Further problems occur when deep binary structures are measured. An overview of those problems will be given and the use of white light interferometric methods to overcome those problems will be discussed. Measurements have been performed with different light sources. The wavelength scale is extended from the visible to the deep UV, the coherence properties of the sources are very dissimilar and the interferograms are evaluated with different techniques. The experimental results will be presented and discussed.

Silicon wafers are widely used for semiconductors. Its flatness is very important in the inspection process. An oblique incidence interferometer with a one step phase- shifting technique using only one image was proposed for its inspection. This technique is developed for precise surface profile measurement even if the sample is mirror surface with multiple reflection between measurement and reference surface. To cover a large measurement area, the extension of the measurement area is archived to combine small area one after the another.

A novel optical diagnostic technique,namely, a dual hologram shearing interferometry with regulated sensitivity, is proposed for visualization and measuring the density gradients of compressible flows in wind tunnels. It has advantages over conventional shearing interferometry in both accuracy and sensitivity. The method is especially useful for strong turbulent or unsteady regions of the flows including shock flows. The interferometer proved to be insensitive to mechanical vibrations and allowed to record holograms during the noisy wind tunnel run. The proposed approach was demonstrated by its application to a supersonic flow over spherically blunted and sharp nose cone/cylinder models. It is believed that the technique will become an effective tool for receiving optical data in many flow facilities.

Centripetal forces in a rotating glass disk generate mechanical strains that are visible in polarized light. Dynamic stress birefringence in rotating disks has a practical effect on several classes of optical instruments, including flying-height testers for the data storage industry. We provide a model for stress-induced polarization effects, and describe an interferometric technique for mapping birefringence in a 100-nm diameter disk spinning at 12,000 rpm. The polarization interferometer employs a laser diode and a homodyne phase receiver to detect polarization- dependent phase shifts as small as 1 mrad at a data rate of 250 kHz.

Measurements of in-plane displacements of rough surfaces show strong influence of the sample structure on the registered signal. Rapid signal amplitude changes as function of sample position for various illumination angles introduce certain indeterminacy and can decrease the accuracy of the measurement system. To find measurements limits the experimental study of the flight diffracted on rough surfaces was performed. Experimental set-up with various illumination systems was built. To compensate environment influences the reference signal was applied. The notion of the probability of the heterodyne signal was introduced and determined for various illumination angles and surface treatments. A modification of heterodyne interferometry system for in-plane displacement measurements was proposed and discussed.

An improved method for measuring the refractive index of a medium is presented. First, the light coming form a circular heterodyne source is incident on the test medium. And, the reflected light passes through an analyzer with the transmission axis at a moderate azimuth angle. Then, the phase variation of the reflected light is measured by the heterodyne interferometric technique. Finally, substituting this phase variation into the equations derived from Fresnel's equations and Jones calculus, we can obtain the refractive index of the test medium.

We have proposed and studied a unique technique of synthesis of the optical coherence function. It has been demonstrated that the optical coherence function can be synthesized into desired shapes by appropriately modulating the optical frequency of the laser source and the phase difference in an interferometer. This technique has been used for photonic sensing and optical information processing applications. In this presentation, the principle of the technique is explained, the performance deterioration factors and the countermeasures are discussed, and then several application systems, including optical information processing, reflectometry, and distributed fiber-optic sensing, are introduced.

An intensity-based interrogation technique for arrays of fiber bragg grating (FBG) sensors is reported. The technique is based upon each FBG forming one mirror of a Michelson interferometer. Source wavelength modulation is combined with an unbalanced interferometer to produce a carrier signal. Carrier frequencies are characteristic of the optical path length imbalance and hence grating position within the array. The intensity of the carrier signal is directly related to the optical power reflected from the grating and hence the strain applied to the grating. Strain resolution of approximately 3 micrometers /m is demonstrated with an approximately 350micrometers /m sensor range. Multiplexing is demonstrated and techniques to extend the range are discussed.

A prototype of a compact vibrometer which allows to measure both, in- and out-of-plane vibration components has been developed, built and tested. The vibration component to be measured was selected by switching the electronics and without moving the measuring head. The optical system is based on a heterodyne interferometer and contains two laser diodes. The heterodyne frequency shift of 7 MHz was realized by using laser diodes with frequency modulation by changing the injection current and using optical delay lines. Several low-cost laser diodes have been examined. The authors used a near IR, 10 mW laser diode for out-of-plane and a red, 10 mW laser diode for in-plane measurement channel, examining rectangle and triangle modulation of the injection current and found significant differences in the necessary length of delay lines. Shorter delay lines allow to reduce phase noise and yield a compact setup. The minimum resolvable velocity at 10 Hz measurement bandwidth was 1,8 10^-6 m/s for out-of-plane and 1,4 10^-5 for in-plane measurements. The maximum vibration frequency that can be measured is 100 kHz.

Development of pressure sensor for the instrumentation of experimental aerodynamic facilities has traditionally concentrated on electrical techniques. Such transducers have temporal and spatial resolutions that are currently insufficient to provide the accurate measurement of turbulent flows behind turbine rotor stages, for example. We present result obtained in a turbine test rig form a simple fiber optic pressure sensor based upon the interferometric response of an extrinsic cavity formed between the interrogation fiber and a reflective diaphragm. We discuss the design trade-offs, optical interrogation and temperature sensitivity of such a configuration, and demonstrate the success of the design in small-scale shock tube experiments. We then describe the application of the sensor in a full scale turbine test facility.

The introduction of laser beam welding into industry requires an extended knowledge about the weld seam properties. This is a standard procedure for all welding methods. However, the geometry of laser welds significantly differs from the geometry of conventional welds. Narrow dimensions of the heat affected zone and the weld material are characteristic for laser welds and cause high gradients of the laser weld properties, e.g. the yield strength. In order to determine experimentally the real local material properties of each zone of the laser weld an adapted measurement technique with a high lateral resolution is required. Conventional methods, like strain gauges, are not able to provide this information due to the lack of local resolution. The digital speckle photography, presented in this work, is a rather new optical measurement technique that fulfills the resolution requirement. Furthermore, this method evaluates electronically displacements and strains in a wide measurement range up to the failure of the investigated sample. Experimental results obtained by means of digital speckle photography show that this is an excellent method for fieldwise displacement and strain determination, respectively. The characteristic 'overmatching' effect of laser welded steel samples, that is the significantly higher yield strength of the weld material in comparison to the base material, is presented on the basis of experimentally determined stress/strain diagrams.

Speckle interferometry has been successfully used in many cases where a non-contact analysis of a surface's deformation state was required. This technique has been mostly applied in favorable environment, where the absence of vibrations and a reduced ambient illumination could be assured, and for the observation of areas being not in excess of some dm². When inspecting larger surfaces, all the problems related to the spatial resolution, to the limited sensitivity of the acquisition system, to the amount of illumination and to the extension of the observed area, should be taken into account. If the observed surface belongs to a structure directly positioned in-situ, problems of vibration, air turbulence, or ambient light saturation, become very restrictive for the application of the method. After a brief introduction about the theoretical principles of speckle interferometry, some main problems related to the inspection on quite large surfaces in-situ discussed. The problem is treated with the help of some simulations, possible solutions are proposed and some applications are presented. This work is the result of a joint collaboration between may institutes and research centers in the framework of a European project named VISILAS. Special fields of application foreseen for this project are civil engineering, aircraft industry, ship building and power plants for energy production.

A real-time two-color laser speckle-shift strain measurement system based on Yamaguchi's technique was designed, built, and tested at room temperature. This non-contact 1D system detects surface strain in a structural fiber as it is pulled in a tensile test machine. Interference or speckle patterns from the laser illuminated fiber test specimen are recorded. As the fiber is pulled, its speckle patterns shift in proportion to the strain, translation, and rotation components of the sample deformation. Shifting speckle patterns are detected at real-time rates using 2 linear CCD arrays with image processing performed by a hardware correlator. Surface strain detected in fibers with diameters on the order of 100 micrometers can be resolved to 19 microstrain. This system was designed to be compact and robust and generally does not require surface preparation of the structural fibers.

Vibration measurements by interferometry can be realized with continuous or pulsed lasers. A convenient and less expensive way to measure displacements relative to vibrating objects is to use an acousto-optic modulator in the object beam of an interferometer using a continuous laser. Stroboscopic illumination of vibrating objects can freeze moving speckle patterns when the stroboscopic and vibration frequencies are synchronous. This supposes a monofrequency excitation. We have developed a method for measuring the complex displacement response of vibrating objects at any frequency. The use of spatial phase-shifting and temporal phase-shifting allows consistent measurements of vibration amplitudes and phases without changing the phase of the excitation force. We call 'spatial phase-shifting' a method using the phase-shift of the reference beam in an interferometer and 'time phase-shifting' an original technique based on the relative change of phase between the stroboscopic illumination and the excitation force. Three spatial phase-shift steps and the impact of the choice of the phase-shift amounts in the developed algorithm is discussed. Recording of vibration amplitudes and phases at successive frequencies enabled us to measure the frequency response of objects and to analyze how eigenmodes appear.

A new in-plane ESPI displacement sensor will be proposed.It is suitable for high frequent 1D displacement measurement with high accuracy. For this measurement an on-line phase calculation is used. This technique is based on a standard phase shift algorithm and leads to the 1D displacement of one object point. Introducing a new simultaneous initialization the decorrelation limit of the present speckle measurement will be exceeded. This will realize a continuous displacement measurement.

The holographic and photoelastic method have been extensively applied for the analysis of the transient vibrations. Shearography as a relative new technique compared with holography and photoelasticity, provides an alternative method for the measurement of the transient vibration. The special appeal of the shearography is that (a) it can measure strain waves directly on the object surface to be studied, and (b) it is relatively immune to ambient interruptions and provides a wider and more controllable range of sensitivity. Although the ambient interruption is not a critical problem for the transient vibration measurement due to the application of the double pulse technique, the wider and more controllable range of sensitivity makes it possible to measure the relative large vibration which is beyond the measuring range of holography. In this paper, these measuring methods are compared and the developmental steps of shearography for the transient vibration measurement are represented.

We report on a novel technique for the evaluation of transient phase in double-pulsed electronic speckle-shearing pattern interferometry. Our technique requires the acquisition of just two speckle-shear interferograms which are correlated by subtraction to obtain a fringe pattern. A spatial carrier is generated by means of an original optical setup based on the separation and later recombination of the two beams produced by a Nd:YAG twin pulsed laser. One introduces an optical path difference in the curvature radii of the illumination beams by mismatching the distances from two diverging lenses to a beam combiner. This procedure gives rise to a linear phase term in the second speckle- shear interferogram that plays the role of a spatial carrier and allows the use of spatial phase measurement methods to analyze the fringe pattern. We present the theoretical aspects of the technique as well as its experimental implementation.

Instrumentation and data postprocessing problems connected with local measurements of high gradient in-plane displacement/strain fields by automated grating interferometer are considered. A new version of waveguide grating microinterferometer is proposed. Various paths of postprocessing are investigated and data reduction and interpolation technique with adaptive size of elementary sampling area is recommended for strain and local material constant determination. The usefulness of the technique is shown on the base of ceramic-to-metal joint investigation.

The vibration analysis using a holographic interferometer is a very useful method for analyzing the dynamic characteristics of machine elements. However, there is the limitation that the method cannot measure large deformation. On the other hand, the method based on the moire topography has been proposed for solving this problem. However, there are also some problems peculiar to optical measurements. Because the moire method is based on the shape measurement, the displacement of an object cannot be directly measured. We should grasp the trajectories of movement of the measuring points in the case of measuring displacement of the vibrating object with large amplitude. Consequently, the nodal lines of the object at each mode can be drawn using the displacement. Then, the modal analysis can be performed against the vibration with large amplitude using the nodal lines. In this paper, a system that can measure the displacement of the vibrating object with large amplitude is proposed using the inverse-transformation for the central projection and estimating geometrically the trajectories of the corresponding points. The experiment results show that this method is useful for the measurement of the object's displacement and the vibration analysis in the case that the object is vibrated with large amplitude.

We propose tow new methods to stabilize both the frequency and power of a two-longitudinal-mode He-Ne laser by using the frequency dependence of beat-noise power spectral density of the two-mode laser. The frequency and power stability of two methods are analyzed and compared briefly. Our study shows that the theoretical frequency and power stability could be achieved to 4.8 X (10^-10 - 10^-11) and 1.3 X (10^-3 - 10^-4), respectively.

As polarization-induced fading is commonly exists in interferometric fiber-optic sensors and their arrays. This paper proposed a method for input polarization control in interferometric fiber-optic sensor arrays. Here, the signal used to control the input polarization state of the multiplexing system is the weighted sum of each sensor's feedback signal for its optimum input control. The suitable feedback signal in a single fiber-optic sensor is presented, and the feasibility for arrays' input polarization control is discussed. The theoretical result of the lowest control visibility is approximate to the ideal value of sin[(pi) /(2N+2)].

Fourier transform technique for moire deflectogram is proposed to automatically map the phase object. The moire deflectogram is generate by conventional deflectometer and is analyzed by means of Fourier transform algorithm, in which the fringe phase is retrieved and phase object message is obtained automatically. Theoretical analysis, simulation calculation and application example are presented.

A new phase measurement algorithm without phase-unwrapping problem is presented. It is mainly applied in the interferograms of few and straight fringes with noise and corrupted regions. Existing phase-unwrapping algorithms for those interferograms are trivial and time-consuming. The new algorithm first searches N 'seeding pixels' in the interferograms according to the good modulation. The interferograms are then segmented into N parts by the 'seeding pixels'. The adjacent 'seeding pixels' phase difference is limited in the range. Because the phase measurement is relative, assuming one of the 'seeding pixels' phase is constant, other 'seeding pixels' phases can be easily obtained by the phase-stepping algorithm. Moreover, other pixels phases in the interferograms can be solved by the simple operation with the 'seeding pixels' phases by the phase-stepping algorithm. The procedure of calculating phase is straightforward. The operation of plus or minus 2(pi) is unnecessary. So the phase unwrapping problem is avoided. A smooth flat mirror is measured in a Linik interference microscope. The interferograms are corrupted with many dirty spots or regions. The experimental result confirm that our new algorithm is fast and robust.

Many phase-stepping algorithms have been developed for last decade. Some of them may be more attractive to practical measurement because of the insensitivity to phase-stepping errors. But it should be noticed that all existing phase- stepping algorithm need to know or calculate the phase steps. Why cannot we extract the measured phase without knowing or calculating phase steps. A new phase-stepping algorithm is proposed by our group. The algorithm can be implemented without knowing or calculating the phase steps. Actually, the new algorithm gives important improvements for the algorithms developed by C.T. Farrell and M.A. Player. Based on using Lissajous figures and ellipse fitting, the new algorithm introduces a simple transform for the intensity of the interferograms. New phase extraction expressions are derived. The simulating results indicate that the new algorithm is insensitive to phase-stepping errors and the accuracy of the new algorithm is only limited by the computation truncation errors.

The paper presents a configuration to record out-of-plane displacement component and slope simultaneously using electronic speckle pattern interferometry. The retrieval of information, however, is possible only by Fourier processing.

This paper presents results of initial studies on polarization interferometry in fiber optic smart structures. The smart structures based on highly birefringent fibers embedded in a specially prepared cylindrical epoxy cylinders were subjected to selected deformation effects mostly induced by hydrostatic pressure and temperature, whereas polarization properties of the transmitted optical signal have been investigated. The presence of the smart structure modifies the output characteristics of the highly birefringent fiber due to elastic properties of the structure. The applied experimental birefringent fibers influenced by the same deformation effects.

We present a complete system for building complex 3D models using multiple range views measured from a fiber-optic projected-fringe interferometry system, and from a structured light range scanner. For the interferometry images, the BLS phase unwrapping algorithm was used to obtain true depth values. A robust registration algorithm is proposed that uses randomly selected control points, and the interval least medium squares error estimator. It is not necessary to triangulate the raw data before the algorithm is applied. Also, a 'holes-and-gaps' filling algorithm is described to improve the display of the integrated 3D models. The experimental results show that the system robustly integrates different views into a single 3D model, and that the holes-and-gaps algorithm improves the visual results.

An introduction into the elements of diffraction theory of coherent scattering of vector waves for size and velocity measurements is proposed to discuss. In traditional approach, a square-law detection is to observe beating in optical signal consists of two components: scattered coherent vector waves with variable states of their vectors of polarization (coherent light beating scattering-CLBS). Vectorial optical signal of CLBS is considered in framework of Fraunhofer diffraction of two plane vector waves by a single particle in case of periodical modulation of vector of polarization described as Jones vector. The formalism of Jones matrix is proposed to describe CLBS by a distribution of particles to control their sizes and velocities. A portable CLBS-spectrometer for size and motility application in biology is described. In traditional spectroscopy of optical beating, a particle alone provides with one scattered component of scalar wave to mix with a narrow-band reference wave on a square-law photodetector. As a result, a community of particles in motion givers fluctuation of intensity available to next spectral analysis of electrical signal. By CLBS, in contrast, a single particle is to form two vectorial scattered coherent components to beat on photodetector that joints beating and scattering as the basis of a new active control of a distribution of particles with possibility of simultaneous k-spectroscopy of sizes and w-spectroscopy of velocities. The preliminary experimental results on control of several types of plankton and sperm are discussed in scope of using CLBS as a new optical standard to measure of bioactivity.

Current demanding engineering analysis and design applications require effective experimental methodologies for characterization of surface shape and deformation. Such characterization is of primary importance in many applications, because these quantities are related to the functionality, performance, and integrity of the objects of interest, especially in view of advances relating to concurrent engineering. In this paper, a new approach to characterization of surface shape and deformation using a simple optical setup is described. The approach consists of a fiber optic based electro-optic holography (EOH) system based on an IR, temperature tuned laser diode, a single mode fiber optic directional coupler assembly, and a video processing computer. The EOH can be arranged in multiple configurations which include, the three-camera, three- illumination, and speckle correlation modes.In particular, the three-camera mode is described, as well as a brief description of the procedures for obtaining quantitative 3D shape and deformation information. A representative application of the three-camera EOH system demonstrates the viability of the approach as an effective engineering tool. A particular feature of this system and the procedure described in this paper is that the 3D quantitative data are written to data files which can be readily interfaced to commercial CAD/CAM environments.

A moire method using phase shifting technique is proposed for a flatness measurement, with highly accurate and fast measurement time, especially of computer discs, wafers or glass substrates. Two methods are proposed for the expansion of measurement size and for the elimination of the reflected light from the back plane of the glass substrate. One is to joint small measured areas one another the flatness of which are measured in advance and the other is UV moire technique. Using these techniques, the proposed system realizes higher accuracy than conventional techniques without any limitation of the size in the glass substrate measurement.

A new ellipsometric configuration suitable for in-situ studying of fast processes is proposed. This configuration eliminates the use of mechanically the use of mechanically rotating components. The light beam from a Zeeman laser is directed to a sample. The reflected light passes through two subsequent Brewster prisms and a polarizer. The plane of incidence of the first Brewster prism is perpendicular to the sample and to the incidence plane of the second Brewster prism. The intensities of the beams reflected from the prisms are proportional to the amplitudes of s- and p-total reflection coefficients of the sample, and the intensity of the beam transmitted through both the prisms and the polarizer contains information on their phase difference. The light from a Zeeman laser emerges as linearly polarized light whose plane of polarization rotates with the frequency of 1.2 MHz, therefore the signal on the detectors contains DC and AC components. The ellipsometric angle (Psi) is obtained from the ratio of the amplitudes of the AC signals from two detectors, whereas the ellipsometric angle (Delta) is obtained from a third detector. This ellipsometric system is fully automatic and free of any moving parts. The ellipsometer has a time resolution of approximately 1 microsecond(s) ec, and is not sensitive to low frequency noise. Theoretical calculations based on Jones matrix approach are presented as well as experimental results for a SiO2 layer on Si.

In the paper a interferometric sensor for measuring temperature by means of liquid-core fiber is described. The experimental results and theoretical calculations show that a temperature variation of 10^-4 degrees C can be measured. We have developed a liquid-core multimode fiber. The liquid-core fiber are composed of hollow silica filled of chlorobenzene. High sensitivity is achieved by the interferometric measuring. It can profitably be employed in spectrum research and sensing.

The paper presents initial studies of the fiber flowmeter realized by polarimetric sensing with highly birefringent polarization-maintaining optical fibers. In the studied system one fiber is applied as the both bluff body and sensing element. The flow velocity is evaluated from the amplitude modulated signal of the frequency of vortex shedding. The polarimetric sensing based on polarization interference presents the advantage of sensitivity compared to the interferometry measurement but without the expense of its complex arrangement.