Active and adaptive optics are becoming more important in the field of beam shaping and wave front analysis. One of the main reasons for the progress and recent activities in active optics is the availability of new active elements like deformable mirrors, micro mirrors and liquid crystals. The application of spatial light modulators for wave front adaption, shaping and sensing will be discussed. An important application is a flexible testing procedure for testing aspheric surfaces using adaptive optics such as deformable mirrors liquid crystals and micro mirrors.

In history any field of activity shows periods that are characterized by evolutionary, revolutionary and stagnating moments, respectively. Especially in optics the 17th, 19th, and 20th century can be considered as revolutionary periods that changed our insight dramatically. However, the often observed opinion that a discipline is already completed was always revised by new facts that broadened our knowledge about the certain field. For instance, in modern optics the discovery of the wave front reconstruction principle (holography) and the implementation of the light amplification by stimulated emission in the laser pushed the further development of the field in an outstanding way. Nevertheless, a lot of questions are looking for an answer. Particularly, in order to justify its role as an enabling technology for most of the key technologies optics has to follow strictly the enormous requirements in spatial resolution, robustness, reliability and traceability. Since it is far beyond the claim of this contribution to address all these problems we concentrate our view on modern approaches of resolution enhancement only.

We will review recent developments in spectral interference microscopes for surface profilometry and tomography of discontinuous micro objects. To give specific examples, we will introduce some of the new devices and systems that have been developed in this group, among which are a tandem frequency-tunable liquid-crystal Fabry-Perot device with high spectral resolution and a wide tunable range, and a spectral interference microscope with a digital-holography-based numerical refocusing function to extend effective depth of focus.

We have investigated the application of a laser Doppler profile sensor for in-process shape and roundness measurements at turning machines. This sensor is an extension of a conventional laser Doppler velocimeter (LDV), where two interference fringe systems with contrary fringe spacing gradients are generated inside the same measuring volume using wavelength division multiplexing. Scattering objects passing the measuring volume generate scattered light signals with two different Doppler frequencies, from which the velocity as well as the position of the objects can be determined via a proper calibration function. Hence, the radius and the tangential velocity and, thus, the shape of rotating work pieces and components, e.g. turbine blades or turning parts, can be measured absolutely and with only one single sensor. Two-dimensional and three-dimensional measurements of shape, excentricity, and roundness on quickly rotating cylinders inside a turning machine are presented. The results are compared with tactile measurements conducted with a coordinate measuring machine.

CAD-driven metrology applications using laser guns, scanners or cameras require situating the instruments in CAD coordinates, both positionally and rotationally. The new Cartesia instrument setup technique overcomes the requirement for surveying skill. The CAD coordinate system is pinned to the site by emplacing point emitters or retroreflectors at 3 CAD-specified reference points. Then, instruments may be set out at unknown locations and orientations. No leveling is required. An instrument interacts directionally with each reference point, acquiring raw, instrument-based polar angles. The Cartesia algorithm processes these observations to solve for the instrument's 3D position and rotational attitude. These data enable the instrument to think and work in CAD coordinates for data acquisition and point shooting. Correlation of data from multiple instruments may be solved elegantly at the outset, by setting up on a common reference pointset. This work uses recent advances in algorithmic geometry. The Cartesia system shifts the role of surveying expertise toward one-time emplacement of optical reference points, and away from daily instrument operation. The major benefit is that future automated metrology instruments can be designed for less technically skilled workers, lowering daily operational costs, and serving a broader base of users and applications.

The explosive development of modern manufacturing technologies, particularly the laser beam manufacturing, has raised new challenges in the field of research. The laser beam welding process may be influenced by errors appearing from different causes. In this paper the authors present the influence of errors during the experiments regarding the laser beam welding of aluminium alloy. In the physical experiment, two major geometric welding characteristics (the welding surface and the welding width) of an aluminium alloy AlMgSi 1 were measured at different welding speeds, using a solid state laser Nd:YAG, HL 4006D. With the aim of obtaining the best results, a CCD-Camera was assembled on the device allowing to capture the most accurate photos from the experiments. The appearance of errors is more likely to be found in the domain of high rate welding speeds than in those of low welding speeds. The data analysis based on the dispersion criterion is useful to characterize the influence of thermal parameters of aluminium alloy upon the laser beam welding surface and width, which may be extended to other new materials with the same characteristics. The present researches started together with the University of Stuttgart will be continued at the Technical University of Cluj-Napoca with a new laser equipment.

The optimization of an automatic laser cutting system is reported. This CO2 laser system assisted by an O2 gas jet is used in the cutting of Constant Velocity (CV) joint for the automotive industry. The experimental parameters varied in order to obtain cuts with low roughness were the laser power, cutting speed and oxygen pressure. A mathematical model is presented which explains many of the features of the qualitative optimization realized.

A new method of white-light fringes analysis called multi-spectral phase-crossing detection is presented. The technique is based on analysis of phase distributions of at least two white-light interferograms recorded simultaneously by detectors with mutually different spectral sensitivities. The analysis of the phase crossing of multiple white-light interferograms with different spectral bands gives us the possibility to find the position of zero optical path difference without ambiguity. The theoretical background and measurement results are presented.

A common-path laser heterodyne interferometer capable of measuring the internal OPD with accuracy of the order of 10 pm was demonstrated at JPL. To achieve this accuracy, the relative power received by the detector that is contributed by the scattering of light at the optical surfaces should be less than -97 dB. A method has been developed to estimate the cyclic error caused by the scattering of the optical surfaces. The result of the analysis is presented.

We present the characterization of an optical fiber spool, of approximately 11 km length, to be used as reference standard for Optical Time Domain Reflectometers (OTDRs) distance scale calibration in the communications windows. The characterization method, based on the international standard IEC 60793-1-22, uses the phase shift change of a modulated optical signal traveling through the fiber. The method provides the optical length of the fiber as a function of the two dominant influence quantities, optical signal wavelength and temperature of the fiber.

Holographic interferometry was utilized for the first time to measure the electrical resistance of aluminium samples during the initial stage of anodization processes in aqueous solution without any physical contact. The anodization process (oxidation) of the aluminium samples was carried out chemically in different sulpheric acid concentrations (0.5 - 3.125% H₂SO₄) at room temperature. In the mean time, a method of holographic interferometric was used to measure the thickness of anodization (oxide film) of the aluminium samples in aqueous solutions. A long with the holographic measurement, a mathematical model was derived in order to correlate the electrical resistance of the aluminium samples in solutions to the thickness of the oxide film of the aluminium samples which forms due to the chemical oxidation. In addition, a comparison was made between the electrical resistance values obtained from the holographic interferometry measurements and from measurements of electrochemical impedance spectroscopy. The comparison indicates that there is good agreement between the data from both techniques, especially when an electromagnetic coefficient was introduced to make the values of the electrical resistance from both techniques are nearly the same.

As a numerical aperture of objective in interferometric microscope increases, the interference fringe spacing, in order word, the basic scale of the measurement becomes greater than half a wavelength of light source due to the obliquity effect of converging illumination. The effect is the most serious uncertainty source when the step height of the standard specimen is calibrated by the interferometric microscope. Therefore, we have developed a novel phase-shifting interferometric microscope whose interference fringe spacing is absolutely calibrated. The scheme and the instrument that realize the absolute fringe spacing calibration and 3D profile measurement by the phase-shifting interferometry (PSI) at the same time, are described. The PSI measurement is carried out under the condition in which two interference fringes are made in the field ofview. The phase calculation error by the PSI is also estimated under the condition. If the sample with 100 nm step height is measured, the typical expanded uncertainty is 0.6 nm.

One of the Airbus designed systems for Structural Health Monitoring utilizes small piezo-electric sensors to detect the vibration or stress wave that emanates from a growing crack in metallic structures. The signal must be detected amongst a plethora of other structural vibrations or noises and phenomenological filters are used isolate the crack generated signal. For the application to Civil Aircraft monitoring it is vital to know the sensitivity and consistency of all the PZT sensors used. The amplitude of vibration from a growing crack has been measured by a special laser based interferometer in order to form the basis of a National Standard to regulate quality of the sensors and the subsequent data.

A powerful and achromatic interferometric technique based on recent advances in the technology of non-diffracting arrays is used to evaluate wave-front distortions with a high transverse resolution and an easily tunable dynamic range. The device presented here belongs to the family of Multiple Wave Lateral Shearing Interferometers (MWLSI) and has the natural capability to measure simultaneously four wave-front derivatives. In this communication, we propose to exploit all the information de facto included in the interferogram; in this perspective we suggest a new method of reconstruction of the wave-front knowing its derivatives. We will show that our device is already successful in the field of laser metrology in the near infrared domain and that it is promising for the far infrared domain with the presentation of a prototype dedicated to measurements at 10.6µm.

Fresnel and Fourier holograms recorded by CCD/CMOS cameras can be numerically or optoelectronically reconstructed in order to provide visualization of 3D objects or to enable further manipulation of their phases and amplitudes. In the paper we propose to introduce into digital holographic (DH) setup Liquid Crystal on Silicon (LCOS) spatial light modulator as an active 2D optoelectronic element which facilitates performing a variety of operations at the recording and reconstruction stages. This includes introducing phase shifting digital holography, additional phase manipulation for object contouring and displacement measurements as well as for optoelectronic reconstruction of all types of digital holograms. The results of initial experiments performed with LCOS are presented and discussed. Also the future directions of development of active DH and DHI system are outlined.

Two methods are described to measure diffusion coefficients by optical interferometry. One of the methods was tested in an experiment consisting of ethanol diffusing into an agarose gel. Results agree with the value of the diffusion coefficient reported in the literature.

We proposed a method for the 3D position estimation in particle image velocimetry. The method uses the pattern-matching between theoretical and experimental images by exploiting the scattered energy field and uses genetic algorithm. The simulations and experimental verification of this problem are discussed.

We present an all-optical approach to detecting magnetization reversal events in submicron ferromagnetic structures that is non-perturbative and compatible with ultrafast optical techniques. We demonstrate experimentally that structures much smaller than the wavelength of light can be probed using both near-field and far-field laser techniques combined with a cavity Kerr enhancement technique and two different polarimetry methods. Controlled magnetization reversal events are detected in nickel magnets approaching the 100nm scale. This leads to a promising way to measure sub-picosecond dynamics of nanomagnets for fast device applications.

This paper discusses some experimental results obtained by a force sensor utilizing the elasto-optical effect within a Nd:YAG crystal. The optical set-up, the force application system and the signal pick-up with a very high speed InGaAs photodetector is detailed. Some calibration results for forces in the mN up to N range are given.

We have recently developed a scatterometer for bi-dimensional rough surfaces which uses an elliptical mirror to direct the light toward the rough surface and to collect the scattered light and direct it to a CCD camera. This device has advantages over similar previous devices such as the time needed for measurement and operation range. We have calculated and measured the Mueller matrix of the elliptical mirror and we have compared them to test the validity of our method. Preliminary results show differences between theory and experiment that must be explained.

The transmission matrices are associated with the paraxial theory, usually assumed as rough approximation useful in non critical applications. The generalized Kosterbauder matrices of transmission are helping to develop a framework to analyze and to design optical systems, particularly systems where the phase description is important as in femtosecond and shorter pulses propagation. Here the primitive generalized matrices for each interface is presented and applied to analyze simple optical systems to describe its behavior, particularly the group velocity dispersion.

In the present work, the thermo-mechanical behavior, temperature versus thermal deformation with respect to time, of different coating films were studied by a non-destructive technique (NDT) known as shearography. Organic coatings, i.e., Epoxy, on metallic alloys, i.e., carbon steels, were investigated at a temperature range simulating the severe weather temperatures in Kuwait especially between the daylight and the night time temperatures. The investigation focused on determining the in-plane displacement of the coatings, which amounts to the thermal deformation and stress with respect to temperature and time. Along with the experimental data, a mathematical relationship was derived describing the thermal deformation and stress of a coating film as a function of temperature. Furthermore, results of shearography indicate that the technique is very useful NDT method not only for determining the thermo-mechanical behavior of different coatings, but also the technique can be used as a 2D-microscope for monitoring the deformation of the coatings in real-time at a microscopic scale.

A corner cube model is developed to calculate the SIM internal metrology optical delay bias (with the accuracy of picometer) due to the component imperfections, such as vertex offset, coating index error, dihedral error, and gimbal offset. This physics-based and Matlab-implemented ray-trace model provides useful guidance on the flight system design, integration, and characterization. In this paper, the details of the corner cube model will be described first. Then the sub-nanometer level model validation through the MAM testbed will be presented. Finally several examples of the model application, such as the metrology delay bias minimization, design parameter error budget (or tolerance) allocation, and the metrology beam prints visualization, will be shown.

This paper is a result of a review of several papers which are proposing methodologies to reduce the error measurement’s impact on coordinate measuring machines (CMM). The standard used in this paper is the ASME Y14.5M:1994 Dimensioning and Tolerancing which is created for "hard gages" (meaning those that control the full surface of a part) and not for the CMM that only inspect "partially" the surfaces of a part. As a consequence the errors begin since the standard interpretation.

The generalized ray tracing for the extraordinary ray through uniaxial crystals developed by M. Avendanyo-Alejo and O. Stavroudis, is applied to investigate the optical path difference between the ordinary and the extraordinary rays in a plane parallel uniaxial plate. When a ray of light from a monochromatic source S is incident on the surface of a plane parallel uniaxial plate, two rays: an ordinary ray and an extraordinary ray will propagate inside the plate until they are refracted at the second interface of the plate. These two rays are orthogonally polarized so they do not interfere unless a polarizer is placed after the plate to make the parallel components of their respective electric fields interfere. In the present work we analyze the optical path difference traversed by the ordinary ray and the extraordinary ray.

In the work, we present the absolute distance interferometer with a narrow-linewidth tunable VCSEL laser (Vertical-Cavity Surface-Emitting Laser) working at &lambda; ≈760 nm. As a detection technique, we use a fast wavelength-scanning interferometry improved by an amplitude division of the interference fringe with using two signals in quadrature. Used VCSEL laser is wide tunable with the mod-hop free tuning range more than 1.2 nm by means of the amplitude modulation of the injection current. We control the stabilization and tuning process of the laser wavelength with using the frequency lock to a Fabry-Perot resonator. We build that resonator as a glass plan-parallel etalon with high-fines. Except the frequency lock, the etalon helps us to measure a wavelength-tuning interval of VCSEL laser during the scanning process. We have stabilized an operating temperature of the VCSEL laser by means of a fast digital temperature controller. The optical set-up of the interferometer begins with a polarizing beam-splitter. It splits the laser beam into the measuring and reference arm of the Michelson interferometer. Two cubic corner cubes reflect beams back to this beam-splitter. It collects reflected beams to the same axis of propagation. Then a detection unit produces the combination of two perpendicularly polarized laser beams with production of two electronic signals that are in the quadrature. A fast analog-to-digital card equipped with the digital signal processor (DSP) samples these signals. DSP also controls the course of the scanning process. After Δλ ≈ 1 nm scan of the wavelength of VCSEL laser we obtain a record of passed interference fringes and passed Fabry-Perot resonance modes at the same time. On basis of these measured quantities we are able to calculate with high precision the instantaneous value of the optical path length difference between the measuring and reference arm of the Michelson interferometer. We experimentally compared the developed absolute interferometer with a conventional - incremental Michelson interferometer based on a single frequency He-Ne laser that has the resolution 1.2 nm. We achieved the relative uncertainty and scale linearity below 8 x 10^-5 for range of tested distances L ε < 78; 118 > mm. The interferometer is able to work as the conventional interferometer too in case the wavelength of the VCSEL laser is locked into the selected resonance mode of the Fabry-Perot resonator.

We present design and experimental setup for direct transformation of the relative change of distances in measuring arm of the Michelson interferometer to relative changes of the resonant optical-frequency of Fabry-Perot (F.-P.) resonator. The method consists of a mechanical coupled moving system of the corner cube mirror of the interferometer measuring arm with one of the mirrors of F.-P. resonator. A piezoelectric transducer (PZT) with elongation 10 microns approximately drives that moving system. An external tunable laser source at 633 nm wavelength provides identification of one of the resonant optical frequency of F.-P. resonator by the frequency locking mechanism with synchronous detection technique in the servo loop feedback. Because the definition of the meter unit is based on iodine stabilized He-Ne laser, then the optical frequency of the locked tunable laser is frequency compared with He-Ne-I₂ laser by the heterodyne optical mixing. A fast high-resolution counter counts the resultant radio-frequency signal as a product of the optical mixing. Measured frequency values and values of interference phase acquired by the interferometer are simultaneously sampled step by step for each elongation position of PZT element. We used that experimental setup for the testing process where a verification of scale-linearity of Michelson interferometer with total resolution 0,3 nm is investigated. The experimental data achieved by F.-P. resonator during such a way shows the absolute uncertainty better than 0,08 nm for the relative distance change 1.5 microns. We verified the scale-linearity of Michelson interferometer to ±1,0 nm limit.

An external cavity laser is assembled by using an antireflection coated laser diode together with the surface of a measurement object. The automatic evaluation of the longitudinal modespacing yields the distance between the laser diode and the measurement object. The measurement resolution is increased by utilizing the resonance effect due to synchronous pumping of the laser diode current. Thus, a distance sensor with interesting properties for industrial applications is set up. Nevertheless, a systematic measurement deviation arises as a result of the nonlinear properties of the laser diode. A fundamental understanding of the processes inside the laser diode is necessary for achieving a measurement uncertainty in the micrometer range. Seen applications are in-situ measurements at grinding processes or the focus control at laser material processing.

The physical limits of optical lithography are mainly determined by the aperture of the mask projection system and the wavelength of the light. In addition to the wavelength shift to the deep UV the application of special techniques to improve the processing window are required. This has furthered the application of the phase shift mask as a lithography tool. The generation of the exact intensity distribution needed in the plane of the wafer strongly depends on the accuracy of the phase shift introduced by the phase shift mask. However, one difficult issue is the reliable measurement of the phase shift introduced by the phase mask at the working wavelength. This is of course mainly due to the lack of suitable and simple interferometric devices for the deep-UV-region -- here 193 nm. We propose the use of a diffractive shearing interferometer as a way out. By combining two Ronchi-phase gratings in series it is possible to produce shear and phase shifts for the evaluation of the fringe patterns simply by axial and lateral shifts of the phase gratings relative to each other. Since the excimer laser emits spatially partial coherent light only, the coherence issue is one of the physical problems dealt with. The state of the art of our experiments will be presented.

A new phase-shifting technique is developed for a Jamin interferometer used in refractive index measurement. Only one wave plate is added to the original interferometer. Theoretical analysis is performed to derive the phase shifting algorithm. This technique overcomes the difficulty of limited space for installing a phase shifter in the interferometer. The test result demonstrates the effectiveness of this method.

Photorefractive two-wave mixing and energy transfer in BaTiO₃ are studied at three wavelengths using He-Cd, He-Ne and diode laser. The Photorefractive signal beam gain is measured as a function of the pump beam intensity, beam ratio intensity, spatial frequency of the grating, and angle between the grating vector and c axis of the crystal. The exponential gain coefficient is calculated from signal beam gain, and its dependence on the same parameters is studied. The dependence of the signal beam gain and exponential gain coefficient on spatial frequency are also evaluated theoretically and found to be in good agreement with the experimental data. Also, the signal beam gain is studied as a function of wavelength, and a very high value is obtained at 441.6nm. Diffraction efficiency of photorefractive gratings recorded in two-beam coupling configuration in crystal of BaTiO₃ at multiple wavelengths is reported. We study the distortive effects in a thick PR hologram due to the angle between the two interfering beams and present our results on effect of spatial frequency on the diffraction efficiency. The behavior of crystal is compared at 441.6 nm, 632.8 nm and 780 nm using He-Cd, He-Ne and semiconductor diode lasers respectively. Value of diffraction efficiency of the crystal is higher at 441.6 nm as compared to other wavelengths. Figure-of-merit parameters such as the maximum change in the refractive index, the space charge field at saturation, the trap density of the charge carriers, and the photorefractive sensitivity of the crystals are calculated from the experimental data. Since the absorption in BaTiO₃ varies strongly with wavelength, its influence has been included in the calculation of the figure-of-merit parameters.

The combination of flow velocimetry techniques and Temperature Sensitive Paints, (TSP), requires working with different laser beam intensities. Because velocity flow measurements (i.e. Particle Image Velocimetry, PIV) needs high level laser power compared with temperature surface measurement, where lower levels of laser power is required, is necessary to adjust the system to avoid the damage of the paint due to the high intensities in laser velocimetry measurements. The use of a paint of different grey levels, from white to black, as backgrounds above the TSP film deposition allows to make both, velocity and temperature measurements with the same laser power without damaging the TSP. This work is centered in the characterization, testing and calibration improvements of the temperature surface measurements using Temperature Sensitive Paints as a part of the 3D tunneling velocimetry system.

In this work, we present results on the characterization of ultrashort laser pulses in the range of tens of femtoseconds by three techniques: autocorrelation, spectral analysis and optical interference. Pulses are generated by a Ti-Sapphire (Ti:Sa) laser pumped by a solid state laser. The temporal width of the pulse (FWHM) was measured at different wavelengths from 730 to 820 nm. At the same wavelength, we obtained different values depending on the characterization technique used. We discuss those results and the theoretical models used in each case. For autocorrelation and spectral analysis, we assume an almost-Gaussian pulse to calculate the pulse width. The mathematical model employed allowed us to estimate deviations from this approximation. The experimental results obtained by interferometry allowed us to control the spatial and temporal distance between pulses. The spectral properties of almost-Gaussian functions are considered and applied to characterize to a second-order approximation in the expansion of the coefficients the pulses. Specifically, adding small amounts of odd-order Hermite-Gauss to a Gaussian induces a second-order increase in the time-bandwidth product, while the increase in the time-bandwidth product from adding even-order Hermite-Gaussian is higher-order and hence smaller. We compare the almost-Gaussian functions with femtosecond temporal width pulses data obtained for the Ti:Sa laser.

In unstable objects, such as biological specimens, vibrational patterns can change quickly with time. To determine phase relationships between several vibrating points in such an object, it is therefore necessary to measure those points simultaneously. We describe a dual channel heterodyne interferometer capable to acquire vibrational data at two arbitrary spatial points simultaneouly over the entire acoustic frequency range. The design allows extension to four or even eight independent channels. Channel cross-talk is measured to be about -30 dB, below the S/N ratio within the signal channel. Velocity resolution is estimated to be 10 μm/s, corresponding to an amplitude resolution of 1.5 nm at 1 kHz.

In the first part of our paper, a method based on digital holographic interferometry and its application to measurements of the elastic properties of the bone is presented. Samples of bone were loaded and deformed and a large number of interferograms (digital holograms) were recorded over a short period of time. The phase of the wave front was calculated from the recorded holograms by using the two dimensional digital Fourier-transform method. Consecutive phase measurements allowed the calculation of deformation of wet objects during loading and fracture. The system allows the measurement of out and in-plane deformations simultaneously. In the second part of the paper, we present endoscopic systems, which are adapted for perfroming measurements of biological tissues in hidden cavities.

The advances in 3D data modelling methods are becoming increasingly popular in the areas of biology, chemistry and medical applications. The Nuclear Magnetic Resonance Imaging (NMRI) technique has progressed at a spectacular rate over the past few years, its uses have been spread over many applications throughout the body in both anatomical and functional investigations. In this paper we present the application of Zernike polynomials for 3D mesh model of the head using the contour acquired of cross-sectional slices by active contour model extraction and we propose the visualization with OpenGL 3D Graphics of the 2D-3D (slice-surface) information for the diagnostic aid in medical applications.

In this work we implemented a hybrid joint Fourier transform correlator (JTC optical/electronic) helpful in the pattern recognition when the scene is in movement. We have been use the standard architecture JTC, but in our case, the first step of the correlation process is carried out optically, using coherent illumination to obtain the joint power spectrum (JPS) of each frame display on a spatial light modulator, we used a liquid crystal display CRL XGA4 with 1024 x 768 pixels of resolution in gray scale. It display a video sequence where is include a mobile scene and the reference, then, the JPS of each frame will be obtain in real time with the quadratic sensor (camera CCD) that is located in the back focal plane of the lens. For the second step was use the tools of the Imaging Developer Kit TMS3206711 DSP (IDK) of Texas Instruments, in order to take advantage of the high speed arithmetic offers by the Digital Signal Proccessor (DSP) and the electronics versatility offers to take decisions. The IDK is a tool of hardware and software that allows capture, process and display images in real time. The DSP microprocessor makes a Fourier transform of the image captured by the CCD, in this way, we obtain the correlation of the scene in movement in quasi real time. Using an efficient computation of the digital Fourier transform of a 2N-point real sequence, the hybrid correlator achieve 15 correlations per second, if the final result is display on the monitor the rate fall to 13 frames per second, the correlation peak was use to determine in real time the target position in the mobile scene.

An optical system was developed using a low-cost semiconductor laser and commercial optical and electronic components, to monitor food processes by measuring changes in optical rotation (OR) of chiral compounds. The OR signal as a function of processing time and sample temperature were collected and recorded using a computer data acquisition system. System has been tested during two different processes: sugar-protein interaction and, beer fermentation process. To study sugar-protein interaction, the following sugars were used: sorbitol, trehalose and sucrose, and in the place of Protein, Serum Albumin Bovine (BSA, A-7906 Sigma-Aldrich). In some food processes, different sugars are added to protect damage of proteins during their processing, storage and/or distribution. Different sugar/protein solutions were prepared and heated above critical temperature of protein denaturation. OR measurements were performed during heating process and effect of different sugars in protein denaturation was measured. Higher sensitivity of these measurements was found compared with Differential Scanning Calorimetry, which needs higher protein concentration to study these interactions. The brewing fermentation process was monitored in-situ using this OR system and validated by correlation with specific density measurements and gas chromatography. This instrument can be implemented to monitor fermentation on-line, thereby determining end of process and optimizing process conditions in an industrial setting. The high sensitivity of developed OR system has no mobile parts and is more flexible than commercial polarimeters providing the capability of implementation in harsh environments, signifying the potential of this method as an in-line technique for quality control in food processing and for experimentation with optically active solutions.

It is presented the results of experimental studies through the implementation of a Fizeau-based Fiber Tip Interferometer (FTI), as the realization of the open optics Fizeau Interferometer into Fiber-optics. The FTI was constructed with off-the shelf fiber optic components and can be compacted in a way of a “sensor head” for various purposes. The FTI can be used as a single probe device or as a multiple probes device for several simultaneous measurement points. The single probe FTI is integrated by a HeNe laser, a Fiber bi-conical tapered coupler and a fiber-coupled GRIN lens. A range of applications of such homodyne interferometer device for non-contact measurements, going from ultrasound detection to temperature measurements are presented.

We report about a laser Doppler velocity profile sensor for precision measurements of microfluidic flows. The sensor measures the velocity and position of a tracer particle in the measurement volume, which consists of two superposed interference fringe systems of different wavelength, one with convergent, one with divergent interference fringes. This arrangement was achieved with a special combination of a diffractive and achromatic lenses. Due to fiber-optic beam delivery the sensor can be build compact and offers potential for miniaturization. A spatial resolution in the sub-micrometer range and an uncertainty of the velocity of about 10^-4 could be achieved. The sensor offers potential for a variety of applications, like the investigation of shear flows or precise flow rate measurments.

In the paper details of analysis measurement uncertainties of the polarization parameters in the in-line fiber optic devices were presented. For measurement of polarization parameters two fiber optic devices were used. The first one Fiber-Optic Polarization Analyzer (FOPA) and the second one Fiber-Optic Interferometric Polarization Analyzer (FOIPA). The main idea of both devices operation is comparable and consists in measurement of appropriate electric signals by using polarization sensitive detectors and basing on its calculate polarization parameters. Uncertainties of measurement these parameters were considered from standard low of propagation uncertainties point of view. The experimental results obtained from testing of laboratory analyzers allow estimating standard deviations (uncertainties) and covariances measured electric quantities. Based on these information the theoretical model of uncertainties of the polarization parameters on its ranges were proposed. Results of these analyses showed that inteferometric device allows more accurate and in shorter measurement time. The polarimetric devices gives worst accuracy what was caused mainly by temperature instabilities. However measurement uncertainties of polarization parameters of both systems are better than in bulk-optic analyzers.

In the paper new results connected with application of the fiber-optic Sagnac interferometer in the area of investigation of special seismic events are discussed. The device presented in the paper is designed for investigation of rotational component existing in the earthquakes called seismic rotation waves. Generally it is a fiber-optic rotational seismometer (FORS) based on its resolution in the range of 10xE-8 rad/s which can detect the seismic rotation waves in a direct way. The paper describes the first results obtained on the base of data recorded in Ojcow standard seismic observatory. The presented discussion in paper shows a new aspect connected with physical fundamentals of the seismic rotation waves.

Duration of cutting tools has become a very wide field of study as of the beginning of tool machines for series production, since the life of a cutting tool is a very important economic factor in the cut of metals. In all production processes with chip outburst, it is very common that the wear and the fracture or breakages of the cutting tool are present. These factors for minimum that could seem modify the quality of the product. For such a reason one has the necessity of supervising the process and the cutting tool continually; this with the purpose of locating on time changes in the tools, so avoiding the generation of bad surfaces different of these schemed. In this work a method is presented for determining the wear and fractures of a cutting tool in a direct way by means of a fiber optic sensor with high resolution and large bandwidth, used during the manufacturing process. The sensor has been configured with two groups of fibers, distributed in a random fashion. One of the groups works as a light emitter that illuminates the tool, while the other captures the light reflected by the tool surface itself. The light is generated by a photodiode, which does not represent any risk to the health. This technique will allow observing the wear and breakage of the tool in real time while rotating with a high degree of accuracy.

Large-mode-area photonic crystal fibers with a limited number of air channels in the cladding are investigated theoretically and experimentally. An impact of the relative hole diameter on single-mode operation, the fiber transmission, and bending loss is addressed in detail.

The state of the art in the area of optical-fiber refractometric sensors includes a large number of different proposals about sensor designs and applications. However, there are few works that compare the transducer response to the refractive index of refractometric sensors with different geometrical shape. This makes it difficult to design the refractometric sensors optimized for particular applications. In addition, the existing knowledge relates mainly to the refractometric sensors with perfectly clean surfaces, while the surface of real sensors is frequently contaminated. In this work, we analyzed the response of optical-fiber refractometric sensors of ellipsoidal shape and the effect of the residual film of liquid (water, oil, etc.) on the transducer's surface on the transducer's response. Also, we determined the sensibility of the response to small variations of the geometrical parameters, in turn, allowed us to determine the tolerance margin in sensor fabrication. We obtained data on the effect of the liquid film of different thickness on the response of the optical detection element as well. These data allow one to make an optimal choice between different possible shapes of detection elements.

Wavelength tuning of fiber Bragg gratings (FBGs) by virtue of a lateral or transverse load is attractive for a variety of applications in the field of optical sensing. The wavelength response characteristic of the FBG upon application of a transverse load is highly dependent on the pressurizing media and the contact conditions. In this paper, we evaluate the effect of contact friction and contact angle of the pressurizing media on the lateral pressure tuning of FBGs. Our results showed that pressurizing media with a lower value of stiffness is favorable for greater contact areas and for distributing the lateral load. Thus, the sensing load becomes more hydrostatic in nature, which enhances the lateral pressure sensitivity and tuning range while reducing birefringence. Also, a higher contact friction is favorable for effective transfer of the load through the contact area and improved sensitivities accordingly. The present study is thus useful in better utilization of lateral pressure tuning of FBGs for sensing applications.

In this work, we present a new mathematical model of signal formation in the optical-fiber heterodyne-type LDA. This model accounts for different noise sources in the LDA including those associated with the optical-fiber guides used in the LDA. This model allows one to access the signal-to-noise ratio (SNR) of the optical-fiber LDA as a function of the optical fiber parameters and characteristcs of the laser source and photo-detector. We obtained the SNR under some typical combinations of LDA parameters. These included the laser power, photo-detector response, fiber attenuation, etc. Our analyses revealed the relative importance of different optical fiber parameters (optical absorption, Rayleigh and Brillouin scattering, etc) that together with the laser and photo-detector characteristics contribute to the SNR of the optical-fiber heterodyne-type LDA.

We studied changes over a polarized state of a light beam into an optical fiber, and under the influence of a magnetic field. Those results can be used as a current or magnetic optical fiber sensor. Here, the measurements are based only in intensity changes, and the experimental setup contains the minimum of optical components. We show a mathematical model to describe our setup including controllable parameters such as, the birefringence in fiber, the incident angle of the light, the current applied to a coil (the magnetic field involving the fiber), and length of the coil. The theory, simulations and experimental verification of this problem are discussed.

In this work the implementation of a sensor of optical fiber current is reported by means of a magnetic structure. The sensing element (magnetic structure) consists of a magnet placed in the center of a plastic membrane. The variation in the intensity of the light caused by a mirror adapted to the membrane allowed to detect the changes in the presence of a magnetic field produced by an alternating current. Its changes were detected optically. We design a circuit to convert the light to equivalent in data to be process by a PC. The data are read and by means of a program in software Labview, is the equivalent of current according to the intensity of detected magnetic field.

Chemical oxidation doping effect produced by 3000 ppm of NO₂ with N₂ balance on spin coated regioregular head-to-tail poly(3-octylthiophene) (P3OT) thin films is reported. Undoped and doped states mechanisms are discussed based on changes in optical absorptiometry, surface analysis and refractive index. The two midgaps created for few minutes in the P3OT under NO₂ doping effect by the polarons and bipolarons for mobility capabilities and its final doped state has been optically monitored and discussed. A significant change on the surface of undoped and doped P3OT thin films was inspected by atomic force microscopy (AFM). A P3OT refractive index transition from 1.69 (undoped) to 1.55 (doped) has been observed and discussed. Finally, the electrostatic attraction between the polaron and its counter ion (NO₂^-) has been analyzed for the possibility to diffuse the counter ion from the P3OT thin films and make possible its backward state (reversibility). The theoretical and experimental data results presented are part of a fiber optic chemical sensor (FOCS) project for NO₂ particles detection.

The analytical solution for the one-dimensional heat diffusion problem, involving three layers and assuming surface absorption only, is shown to be useful to provide of a simple photoacoustic methodology for the direct measurement of the thermal-wavelength for thermal waves generated across liquid samples. A simple methodology for measuring thermal diffusivity for liquids, taking advantage of the relationship between this thermal property and the thermal wavelength, is developed. The thermal diffusivity of two pure liquids (distilled water and ethylene-glycol) was measured and excellent agreement was obtained with the corresponding thermal-diffusivity values reported in the literature. A photoacoustic epxerimental setup, using diode laser as light source, is also showed to be very suitable to carry out this kind of experiments.

Photothermal techniques have been applied successfully in the study of the charge transport process in inorganic semiconductors in crystalline and polycrystalline form. Photothermal radiometry is a non-contact technique that could provide not only the thermal properties but also parameters related with recombination of charge. In this work the potential of photothermal radiometry in the study of charge recombination in organic polymeric semiconductors is explored. It has been shown that conjugated polymers are especially interesting for its charge transport properties. In this work, polyaniline samples grown on stainless steel by electrochemical methods are studied. Photothermal radiometry profiles were obtained by illuminating the sample with modulated light of an ion Argon laser and detecting the changes of temperature with an IR detector. The profiles show marked differences depending on the conditions of preparation. In order to determine the effects of charge recombination, and at the same time to eliminate the influence of the roughness of the different samples, a normalization procedure was devised. This procedure consisted in dividing the signal of the sample with charge recombination effects by the signal of the sample that would not present charge recombination. Our results are discussed and compared with an inorganic semiconductor.

The CRD technique has been successfully applied in various environments since it directly provides the frequency-dependent absorption strengths of the medium under study. As mirrors with a sufficiently high reflectivity, detectors with a sufficiently fast time response, and tunable (pulsed) light sources are available, there is no intrinsic limitation to the spectral region in which CRD can be applied. In this work, cavity-ring down (CRD) technique was employed to stabilize the absorption of a cell filled with ammonia gas to 120μs pulses from a 904nm GaAlAsP semiconductor laser.

In this work a novel system for the study of thermal profiles and time dependent heat diffusion is presented. In this system the modulation of light is made directly using an electronic driver that turns on and off the laser diode. The data acquisition is made with a higher accuracy than in the conventional systems because the electronics that detects the signal is the one that generates the modulating signal. The system is very compact and as a consequence, shows a higher stability, and can be integrated in systems in which other measurements are performed or inside of chambers where the conditions of the surroundings are controlled. In order to show the potential of our system, applications using photoacoustic and photopyroelectric techniques are presented. In the case of photoacoustics, the specific case of the open photoacoustic cell for thermal diffusion characterization is shown. Using a conventional photoacoustic cell, it is shown that the dynamics of evaporation and crosslinking can be followed in polymers. In the case of photopyroelectric technique, thermal depth profiles are also performed and the study of dynamics a as function of time is discussed. The advantages of our system and the different modes of detection are discussed.

In this work, the Photopyroelectric (PPE) technique using a Thermal Wave Resonator Cavity (TWRC) is used to measure the thermal diffusivity of agar. We, determine the liquid to gel phase transition temperature as a function of agar concentration, detecting a shift in that temperature. As agar concentration decreases, the phase transition temperatures get lower. The thermal diffusivity of agar as a function of temperature was measure by means of a cavity length variation due to thermal expansion of the TWRC. It was compared against the typical mechanic length variation with a micrometer.

The radiative transfer equation (RTE) is an important theoretical tool in biomedical optics for describing light propagation in tissues. The solutions to its derived diffusion equation (DE) are used, for example, for dose calculation in photodynamic therapy and for optical tomography. The RTE is valid for constant refractive index and zero ray divergence. These conditions limit its applicability in biomedical optics. To eliminate these drawbacks three new RTEs have been proposed. In this paper we test the standard RTE and the new RTEs by solving them for the irradiance of rays propagating in an infinite medium with no scattering, no absorption and no amplification. The solutions to this problem must coincide with the irradiance laws of geometrical optics. We show that only one of those equations gives solutions, which are consistent with irradiance laws of geometrical optics due to its ability to model, the effect of spatially varying refractive index and non-negligible ray divergence. Consequently that equation gives a better description of light propagation in scattering media with spatially varying refractive index and near sources, a physical situation occurring frequently in biomedical optics.

We report experimental evidence of light-induced changes in the transmission spectrum of human venous blood under the action of low-intensity radiation from He-Ne laser. We have applied a sensitive registration technique and the transmission spectra of diluted and nondiluted heparinized human venous blood have been analyzed before, after and in the course of irradiation. When irradiating nondiluted blood, reproducible variations of the blood transmission spectrum in the range of 640 - 805 nm have been observed for the first time. We found these changes correlate with oxygen saturation. The changes in transmission spectra and oxygen saturation of venous blood after 1-3 procedures of irradiation can be used as a method to detect an individual sensitivity to intravenous laser irradiation.

The analysis of teeth is an interesting field, given the importance of these pieces for the individual or for humanity in the case of remains recovered from an archeologically site; therefore, the development of non-destructive techniques is important to study these materials. Photothermal techniques are ones of the most interesting possibilities; they are based in the generation of a train of thermal waves inside of a material due to the illumination with modulated light. Among these techniques photothermal radiometry has an outstanding role, since it is a non-contact technique, based in the detection of infrared emission of the samples heated with the laser. The experimental configuration consists of an Ar laser beam that impinges on the surface of the teeth and the infrared radiation generated is measured using a HgCdTe IR detector. Results for the analysis of cracks on teeth and the low frequency profiles are presented. A strong influence of the signal due to the microstructure of teeth is observed. Furthermore, surface effects are analyzed changing the color of teeth when whitening products are applied. The process of whitening is monitored in real time by optical spectroscopy in the visible and by photothermal radiometry.

To analyze the error obtained in the evaluation of the shape of the surface with the method that uses a linear array of sources, we performed a numerical simulation introducing Gaussian random errors in the coordinates of the centroids of the bright spots on the image plane, and in the coordinates of the sources (apertures of the mask). Here we found that to measure the quality of the surface with accuracy lower than 8 μm we have to place the sources with accuracy better than 0.5 mm, and measure the coordinates of the centroids with accuracy better than 0.5 pixels. Additionally, we performed an analysis of the aberrations effects on the evaluation due to a steep surface and the CCD camera lens. Here, we found that in the best image plane for all the image points the main aberration is astigmatism, which is symmetric and do not change the position of the centroid. Also, the analysis of the CCD camera lens was performed experimentally by the star test for different positions of the object in the visual field and for different apertures of the CCD diaphragm; here, in the worst case we observe changes in the positions of the centroid smaller than 0.46 pixels. In both cases, the aberrations are very small and have no influence on the determination of the centroids of the images. Finally, we analyzed the influence of the scattering at the surface have onto the evaluation. For this experiment, we observe that this effect can be considered as a very random error on the final evaluation of the surface.

We propose the design of tilted null screens in order to test the off-axis segments of conic surfaces. Furthermore we reduce the size of the screen in order to increase the performance of the test. The sensitivity is increased while the size of the screen is reduced in the saggital caustic region and vice versa in the tangential caustic region. Further analysis and experimental results are presented, for an off-axis concave parabolic mirror which has an elliptical aperture, with a distance offset Xc=25.4mm, the radius of curvature at the vertex R= 20.4mm, major axis of the mirror DM=49.4mm and minor axis Dm=29.5mm.

During the process of manufacture or measuring large components, position and orientation are needed thus; a method based in surveying the surface can be used to describe them. This method requires an ensemble of measurements of fixed points whose coordinates are unknown. Afterwards resulting observations are manipulated to determinate objects position in order to apply surface metrology. In this work, a methodology to reduce uncertainties in surface measuring is presented. When measuring large surfaces, numerical methods can reduce uncertainties in the measures, and this can be done with instruments as such as the Laser Tracker (LT). Calculations use range and angles measures, in order to determinate the coordinates of tridimensional unknown positions from differents surveying points. The purpose of this work, is to solve problems of surface metrology with given tolerances; with advantages in resources and results, instead of making time sacrifices. Here, a hybrid methodology is developed, combining Laser Tracker with GPS theories and analysis. Such a measuring position system can be used in applications where the use of others systems are unpractical, mainly because this kind of measuring instruments are portables and capable to track and report results in real-time, it can be used in virtually anyplace. Simulations to measure panels for the Large Millimetric Telescope (LMT/GTM) in Mexico were done. A first benefit from using this method is that instrument is not isolated from its measuring environment. Instead, the system is thought as a whole with operator, measuring environment and targets. This solution provides an effective way, and a more precise measurement, because it does optimize the use of the instrument and uses additional information to strength the solution.

The results of the R & D activity of TDI SIE SB RAS in the field of the 3D optical measuring technologies and systems for noncontact 3D optical dimensional inspection applied to atomic and railway industry safety problems are presented. This activity includes investigations of diffraction phenomena on some 3D objects, using the original constructive calculation method. The efficient algorithms for precise determining the transverse and longitudinal sizes of 3D objects of constant thickness by diffraction method, peculiarities on formation of the shadow and images of the typical elements of the extended objects were suggested. Ensuring the safety of nuclear reactors and running trains as well as their high exploitation reliability requires a 100% noncontact precise inspection of geometrical parameters of their components. To solve this problem we have developed methods and produced the technical vision measuring systems LMM, CONTROL, PROFIL, and technologies for noncontact 3D dimensional inspection of grid spacers and fuel elements for the nuclear reactor VVER-1000 and VVER-440, as well as automatic laser diagnostic COMPLEX for noncontact inspection of geometric parameters of running freight car wheel pairs. The performances of these systems and the results of industrial testing are presented and discussed. The created devices are in pilot operation at Atomic and Railway Companies.

In macroscopic production processes several measuring methods are used to assure the quality of 3D parts. Definitely, one of the most widespread techniques is the fringe projection. It’s a fast and accurate method to receive the topography of a part as a computer file which can be processed in further steps, e.g. to compare the measured part to a given CAD file. In this article it will be shown how the fringe projection method is applied to a fiber-optic system. The fringes generated by a miniaturized fringe projector (MiniRot) are first projected onto the front-end of an image guide using special optics. The image guide serves as a transmitter for the fringes in order to get them onto the surface of a micro part. A second image guide is used to observe the micro part. It’s mounted under an angle relating to the illuminating image guide so that the triangulation condition is fulfilled. With a CCD camera connected to the second image guide the projected fringes are recorded and those data is analyzed by an image processing system.

Microinterferometric tomography allows for determination of three-dimensional refractive index distributions in phase isotropic microelements. In this paper we present the measurement of the refractive index profile of the optical fibers exposed to the gamma radiation. Nuclear radiation is known to affect the guiding properties of optical fibers and it is therefore essential to characterize these effects to assess the applicability of fiber-optic technology for communication and sensing in nuclear industry. It is already well known that radiation affects the absorption of the fiber. Here, we investigated whether we could quantify the effect of radiation on the refractive index of core and cladding of an optical fiber.

This article presents improvements on a methodology for the estimation of the 3D structure of retinal blood vessels from a sequence of fundus images taken from the same subject. The following problems are addressed: the use of a self-calibration method in order to find the intrinsic and extrinsic camera parameters based on correspondences between images, the extraction of blood vessels skeletons from fundus images, the matching of corresponding points of two labelled skeleton trees, the triangulation of matched points in and generation of surface model for visualisation. An image mapping was defined in order to correct optic distortions of the fundus camera, and a new set of fundus images was used.

An experimental setup for tomographic inspection of phase objects is presented. The system is based on an interferometer which uses two windows in the input plane and a translating grating as its pupil. In the output, interference of the fields associated with replicated windows can be achieved by a proper choice of the spacing between windows with respect to the grating period. Placing a rotating object in one window and with a reference crossing through the second one, the phase of projections results encoded in a composite interference pattern over the plane of the traditional sinogram. Phase stepping of such composite interferograms can be achieved by lateral translation of the grating to obtain the unwrapped phase distribution as the corresponding sinogram of the object slide under inspection. The sinogram allows tomographic reconstruction of slices by standard procedures. Composite interferograms and preliminary reconstructions for some transparent samples are shown.

This paper presents an instrument for 3D metrology of smooth free form work pieces. In our scheme, the integration of structured laser light and coordinate measuring systems provides high levels of accuracy, sample rate and automation of the measurement process. In order to get 3D information, a computer vision system uses the 2D projection of a non-coherent structured laser light diode on the scene. The object under inspection is placed over an indexed rotary table in order to perform multiple acquisitions in the whole measurement volume. The measurement vision system and the rotary table are calibrated by means of integrating a coordinate measuring machine into the measurement system. Experimental results are developed in order to estimate the accuracy in the 3D reconstruction.

A simple technique for object shape detection is presented. In this technique, the object is moved along of an axis and scanned by a light line. The object shape is reconstructed by processing a set of images of a light line, which are captured in the scanned step. The profile of the object is obtained applying a Bezier Neural Network. This network is built using data from images of a light line projected onto the known objects. The data from the images are extracted by applying Gaussian approximation. This approximation corresponds to the model of a light line, whose intensity distribution is Gaussian. By using the neural networks in this technique, the object shape is determined without the geometry parameters of the set-up. In this way, the accuracy is improved, because the errors of the set-up parameters are not introduced in the system. To determine the accuracy, a root mean square is calculated using as reference a contact method. This technique is tested with simulation and its experimental results are presented.

Modern forming technology allows the production of highly sophisticated free form sheet material components, affording great flexibility to the design and manufacturing processes across a wide range of industries. This increased design and manufacturing potential places an ever growing demand on the accompanying inspection metrology. As a consequence of their surface shape, these parts underlie a reversible geometrical deformation caused by variations of the material and the manufacturing process, as well as by gravity. This distortion is removed during the assembly process, usually performed in automated robotic processes. For this reason, the part's tolerated parameters have to be inspected in a defined state, simulating the assembly process' boundary conditions. Thus, the inspection process chain consists of six steps: picking the workpiece up, manual fixation of the workpiece, tactile measurement of the surface's coordinates using a defined measurement strategy, manual removal of the fixation and removal of the workpiece from the inspection area. These steps are both laborious and time consuming (for example, the inspection of a car door can take up to a working day to complete). Using optical measuring systems and virtual distortion compensation, this process chain can be dramatically shortened. Optical measuring systems provide as a measurement result a point cloud representing a sample of all nearest surfaces in the measuring range containing the measurand. From this data, a surface model of the measurand can be determined, independent of its position in the measuring range. For thin sheet material parts an approximating finite element model can be deduced from such a surface model. By means of pattern recognition, assembly relevant features of the measurand can be identified and located on this model. Together with the boundary conditions given by the assembly process, the shape of the surface in its assembled state can be calculated using the finite elements method. In application these methods culminate in a shortened inspection process chain (which can now also be automated): picking the workpiece up, placing it in the measuring range, optical measurement, virtual distortion compensation and removal of the workpiece from the inspection area. This work discusses the methodology of our approach in detail and also provides and analyses experimental results. The underlying research was greatfully funded by the German Research Foundation (DFG).

In present article the foundations base of the prototype called TRI_IDENT are exposed, as well as the elements that at the moment compose it, so much to level hardware as software and it will be spoken of the applications that it offers with purpose biometrics, that are guided for identification and people recognition go, as a system of security and a tool for facial surgeons, which use it to improve the precision and easiness in the it diagnose prescribe. In this article it showed the advantages that the TRI_IDENT offers, regarding two-dimensional systems, which lose quality and detail when they have been captured with an inappropriate illumination, produce shades that hide features and characteristic essential for the description of an individual or when the images are compressed digitally, in format to diminish space and to be able to keep them in database. The system TRI_IDENT also offers the understanding of this technology that this arriving to the world society.

This work presents the results of implementing the first stages of the process of registration in FPGA's. The main motivation is to initialize the pose of objects in movement as quickly as possible. We present the summary of the algorithm and its performance on a PC running Linux. Later we give details for such the implementation on FPGA's of edge detection and features extraction.

Analysis of fringe patterns with partial-field and/or closed fringes is still a challenging problem that requires the development of robust methods. This paper presents a method for fringe pattern analysis with those characteristics. The method is initially introduced as a phase refinement process for computed coarse phases, as those obtained from partial-field patterns with a full-field method for open fringes analysis. Based on the phase refinement method, it is proposed a propagative scheme for phase retrieval from closed-fringe interferograms.

In this work a hybrid algorithm genetic (GA) is proposed in order to obtain the wavefront OPD of experimental interferograms. The method takes as input an experimental interferograms, and it is by solving of an optimization problem in an accurate form that the evolutionary algorithm (GA) performs an automatic polynomial fitting under experimental data. In this way the method gives as output the vector of Zernike aberration coefficients to 5^th order that best matches to the analyzed interferograms. It is important to point out that the experimental interferograms analysis was applied to confirm the quality of a manufactured optical surface.

A fringe normalization procedure is presented in this paper. The main idea of the computer algorithm is to normalize the fringe pattern using spline interpolation functions. To achieve this, two splines are fitted using the maximum and minimum irradiance peaks detected over each fringe image line. Then, each pixel in the fringe image is interpolated and normalized by using of the values of the max and min splines. The fringe contrast is enhanced with an error around 1%. Preliminary results are presented.

One of the powerful approaches to demodulate a single fringe-pattern is the regularized phase tracking (RPT) technique. We present here some modifications in the algorithm, which consist in the addition of the modulation estimation and the modification of the minimization algorithm. With these changes, the RPT technique can be used in the demodulation of non-normalized fringe patterns with significative improvement in the processing time.

Forming Limit Diagrams (FLD’s) can be defined by the criteria of either diffuse or localized necks. We used Electronic Speckle Pattern Interferometry (ESPI) in commercial 1100 aluminum sheet metals annealed at 400°C to determine the strains at which both types of neck started in uniaxial tension (U) and in quasi plane strain tension (PS) tests. In biaxial (B) loading we observed only the localized neck, but we were also able to detect a small defective spot at which fracture was incubated. The strains that produced the diffuse neck and the defective spot were approximately comparable to those predicted by Swift’s criterion for plastic instability. The difference between the FLD defined by a diffuse neck or by a defective spot leading to fracture and the one defined by a localized neck was found to be very noticeable in the U tests and less important, but still significant, in the PS and B tests. We found also that maximum load occurred at some point within the diffuse neck region and that afterwards the load carrying capacity was still substantial. We thus conclude that the decision on the criterion to use should be based on parts quality, safety and costs.

This paper presents an application of a radial in-plane digital speckle pattern interferometer and a local heating combined system to measure residual stresses in ductile materials. The system allows the local heating of a small spot and the measurement of the radial in-plane displacement field generated around it. In order to quantify the residual stresses from the measured displacement field, the thermomechancial problem is simulated using the finite element method and a modified hole-drilling model is applied. The performance of the system is evaluated by measuring the stress generated by a preloaded specimen. It is shown that the combined system can measure residual stresses with a typical error of approximately 5%.

In this paper the mechanical stresses taking place in diamond like thin films prepared by the plasma enhanced chemical vapor deposition onto silicon single crystal substrates are studied. For determination of the stress values the Stoney's formula is used. The values of the film thicknesses are determined using the combined method of variable angle spectroscopic ellipsometry and near-normal spectroscopic reflectometry. The values of the curvature radii of the deformed silicon substrates in consequence of the film stresses are evaluated using interferometric method based on two-beam interferometry and chromatic aberration method. The dependence of the mechanical stress inside these films on their thickness values is determined. It is found that this dependence can be approximate by the straight-line. The results achieved for the mechanical stresses obtained by both the optical methods, i.e. by the interferometric and chromatic aberration method, are compared. It is shown that within the experimental accuracy the stress values determined using both these method are identical. Thus, it is shown that the chromatic aberration method is suitable for measuring the mechanical stresses inside the thin solid films and it is the competitive method for the other optical methods utilized for this purpose so far.

Digital holographic interferometry in combination with a flexible fiber endoscope allows high precision measurements of deformations on hidden objects surfaces, inside cavities and objects with small access apertures. A digital holographic endoscopy system is described with a frequency-doubled, twin oscillator Q-switched pulsed Nd:YAG laser as light source. A sequence of digital hologram pairs are recorded with a maximum repetition rate of 260 ms. Each digital hologram is captured at separate video frames of a CCD-camera. The time separation between the laser pulses from each cavity can be set in the range from 50 to 500 μs. The digital holograms are transferred to a PC via a frame grabber and evaluated quantitatively by the Fourier transform method. The resulting phase fringe pattern has the information needed to evaluate quantitatively the amount of the deformation. Experimental results of vibration measurements of hidden mechanical and biological object surfaces are presented. The quality of the results obtained by mechanical object surfaces is usually higher than for biological surfaces. This can be explained easily by the fact that a biological surface is much more complex than a mechanical surface in the sense that some parts of the surface may reflect the light well whereas other parts may absorb the light. Also, biological surfaces are translucent, which means that part of the light may enter inside the sample where it may be absorbed or reflected.

A radial in-plane electronic speckle pattern interferometer (ESPI) has been developed by the authors’ group. This interferometer is used in this paper to measure residual stresses in combination with the indentation method. A semi-empirical mathematical model is developed to quantify the residual stresses. Several tests were made in a specimen with different levels of residual stresses imposed by a mechanical loading. Empirical constants were computed from those tests and are used in combination with the developed model to predict the residual stresses levels. The radial displacement field around a controlled indentation print is measured, processed and fitted to a mathematical model to predict residual stresses. Series of tests were designed and executed. Different indentation tip geometry and different loading conditions were involved. This paper presents the measurement principle, implementation details and results of the performance evaluation. The tests presented here are not complete since they are restricted to only one material, one-axis stress state, two indentation tip geometry and only one indentation force, but they are sufficient to encourage further development.

Twin-pulsed digital holography in its 3D set up is used to recover exclusively the micro-mechanical deformation of an object. The test object is allowed to have rigid body movements such as rotation and translation, with the result that the fringe patterns contain information of the latter and the object deformation, a feature that may significantly modify the interpretation of the results. Experimental results from a flat metal plate subject to micro stress and a displacement in the x-z plane are presented to demonstrate that using this optical method it is possible to recover exclusively the contribution of the micro stress.

A novel measurement technique, based on a laser beam, is proposed to measure the amplitude of vibration by using fractal analysis of speckle patterns. Experimental measurements of nodes and antinodes, and its respective speckle pattern structures in the two sates, are presented in terms of fractal dimensions. It is shown that a correlation with the fractal dimension of the speckle pattern and each amplitude of vibration can lead to a new method for amplitude of vibration analysis.

In this work we propose a new technique to measure micro displacements using high frequency holographic gratings. In this technique the grating is placed on an object with micro displacement and these displacements are measured counting the displaced fringes of an amplified grating image as the object is moving.

The Proper Orthogonal Decomposition (POD) method is applied to the vibrations analysis of a metal plate. The data obtained from the metal plate under vibrations were measured with a laser vibrometer. The metal plate was subject to vibrations with an electrodynamical shaker in a range of frequencies from 100 to 5000 Hz. The deformation measurements were taken on a quarter of the plate in a rectangular grid of 7 x 8 points. The plate deformation measurements were used to calculate the eigenfunctions and the eigenvalues. It was found that a large fraction of the total energy of the deformation is contained within the first six POD modes. The essential features of the deformation are thus described by only the six first eigenfunctions. A reduced order model for the dynamical behavior is then constructed using Galerkin projection of the equation of motion for the vertical displacement of a plate.

Nowadays many techniques exist to determine the different physical properties of a material. The elastomers, or called rubbers too, are materials that can be deformed by the external loads application, their use and application depends of the material physical properties. A physical property that should be kept on mind to study the diverse associated applications to a material is the Young’s module. In this work, we use the electronic speckle patterns interferometry (ESPI) technique to measure the natural rubber latex Young’s module. A dual illumination interferometer of equal angles to both surface normal sides was implemented, the shifting phase technique and a four frames algorithm were used to find the phase maps. Besides, to apply the external loads to the rubber latex sample an electromechanical traction system was build. We verify that ESPI technique can be used like optical extensometer to determinate mechanical properties of materials and components in the industry. The Young’s module is compared with a reference Young's module.

In this work, a system to perform the measurement of small changes of temperature in solids and liquids using a laser beam deflection is presented. It consists in a tungsten lamp that illuminates a solid material enclosed in a glass container filled with distilled water; generating heating of the sample. The monitoring of the temperature was made using a probe He-Ne laser whose path is altered by the local change in the index of refraction of the water close to the surface of the sample. A four quadrants position sensor monitors the movement of the spot of the laser using a lock-in amplifier. The lamp is modulated using a power circuit driven by the same lock-in amplifier. This configuration allows the study of very small changes in temperature due to the fact that the lock-in detects at the same frequency that drives the circuit of the lamp. In order to show the potential of our system, applications in pulsed and modulated form and for the measurement of thermal diffusivity are presented. The advantages and limitations as well as the possible improvements of our system are discussed.

Displacement measurements by optical interferometry are affected by errors in the determination of the phase-difference and in interferometer sensitivity. In this paper, we perform an uncertainty analysis of displacements measured by in-plane ESPI with spherical wavefronts. The displacements were induced by applying uniaxial tensile load on a nominally flat elastic sample. Our attention was focused on the quantification of the effect of eventual errors in the sensitivity vector determination. We found that the displacement uncertainty depends on the geometry of the optical arrangement, and on the dimensions of the illuminated field. Moreover, the displacement uncertainty increases with the deformation.

A feasibility study for amplitude and frequency vibration measurement in aerial electricity transmission cable has been made. This study was carried out incorporating a fringe projection method for the experimental part and horizontal taut string model for theoretical one. However, this kind of model ignores some inherent properties such as cable sag and cable inclination. Then, this work reports advances on aeolic vibration considering real cables. Catenary and sag are considered in our theoretical model in such a way that an optical theodolite for measuring has been used. Preliminary measurements of the catenary as well as numerical simulation of a sagged cable vibration are given.

A shearing system for crack inspection on tanks is reported. A compact device comprised of a Michelson type shearing interferometer, a diode laser, a phase shifting element, a pzt to deform the object under test and a car with magnetic wheels to move the full system. It is proved that a light car with magnetic wheels can support vertically a shearing system and obtain in real-time wrapped deformation phase without decorrelating the fields. This phase deformation system would enable us to analyze big tanks with confidence and security.

A simple fiber optic Michelson interferometer for vibration measurement and analysis is presented in this paper. It has been conceived and realized with the purpose of using it as the basic measuring element of a complete system for multiple point vibration measurements. One of its main features is that it is operated in the homodyne mode allowing the detection of the direction of motion without using Bragg cells or other optical or mechanical frequency shifting devices, which usually present some inconveniences (alignment problems, dimensions, complexity of the signal processing electronic and costs). The capability of the fiber interferometer in detecting periodic signals and a comparison with a commercial laser Doppler vibrometer is reported.

In this paper we describe a speckle speedometer based on the use of the wavelet transform for signal processing. The optical set-up is composed of the moving object, a He-Ne laser, a converging lens, a pinhole and a linear photodetector. The pinhole permits irradiance measurements within a single speckle. The random signal from the photodetector was digitized by a commercially available data acquisition card and saved in a personal computer, where it is processed with wavelet transform. The wavelet transform allows discomposing the signal in several coefficients that represent low-pass and high-pass filters applied to the signal at different frequencies. From processed data the base frequency of the signal can be obtained. That frequency is related to the speed of the moving object, which can be determined after calibration. To test the method we carried out a digital simulation of the system and experiments. In the experiment we measure the speed of points of a rotating disc of glass and compare it with the values obtained from simulations. A good correspondence between measurements and simulated speed values were obtained. Advantages and disadvantages of the method are discussed.

Moire interferometry provides contour maps of in-plane displacement fields with high sensitivity and high spatial resolution. It has matured rapidly as an invaluable tool for engineering analyses, proved by many industrial and scientific applications. With the typical reference grating frequency of 2400 lines/mm, the contour interval is 0.417 &mu;m displacement per fringe order. For microscopic moire interferometry, sensitivity corresponding to 17 nm per contour has been achieved. Reliable normal strains and shear strains are extracted from the displacement data for bodies under mechanical, thermal and hydrostatic loading. The characteristics and basic concepts of moire interferometry are reviewed. Significant examples from the fields of composite materials, fracture mechanics, electronic packaging and biomechanics are presented.

Based on a heterodyne interferometric measurement, an original system to measure the linear thermal expansion coefficient (LTEC) of parallel gauge blocks (GB) has been developed. The automatic instrument measures the displacement of the parallel reference faces of the GB, which is mounted in horizontal way. The dilatometer has to measure the change of temperature and displacement of the GB simultaneously. The measurement displacement is carried out by a laser interferometer using the reference surface of a GB as part of the flat mirror optical interferometer. Termistor sensors in the body of the block measure the temperature. The GB changes its temperature by thermal conduction from electrical heaters. The optical system consists of two plane mirror high stability interferometers and an optical fiber to receive the measurement signal from interferometers. Two laser beams reflect the surface of the GB face in order to provide an optical resolution of λ/4. The total resolution of the commercial interferometric system is λ/128. For the measurement of GB of steel and tungsten carbide, a reproducibility of 0,03 x 10^-6 K^-1 has been achieved. The estimated uncertainty in the measurement of LTEC is less than 3 x 10^-7 K^-1 for GB of 100 mm. The results for short GBs, the uncertainty analysis and uncertainty budget, the measurement time optimization and the capability to measure objects of different shape of GB are discussed.

Metal components subjected to cyclic stress develop surface-evident defects (microcracks, slip bands, etc). Monitoring the formation and evolution of these fatigue damage precursors (FDPs) with increasing numbers of cycles can be an effective tool for determining the fatigue state of the component, which can be used in remaining fatigue life prognostics. In this paper a laser scanning technique (LST) for FDP detection is described and experimental results from examination of specimens made of nickel-based superalloy and aluminum are presented. The proposed detection technique is based on scanning a focused laser beam over the specimen surface and detecting variations in spatial characteristics of the scattered light signal. These variations indicate the presence of surface abnormalities and therefore can be associated with incremental fatigue damage formation. The studies performed show that the proposed LST can serve as a basis for design of a portable non-contact instrument for in situ structural health monitoring.

In this work we use an experimental set-up implemented in the Optical Physics Laboratory of PUCP, in order to study and to measure the roughness of different surfaces. The surfaces have different finishing obtained in different mechanic process (milling, turning, etc). The measurement method is based on a two-dimensional scan of scattered light from a rough metal surface illuminated by laser light. The light is scattered as speckle pattern and it is captured by the CCD of a digital camera in two different configurations, with and without an imaging lens and under different angles of illumination. Using two-dimensional Fast Fourier Transform it has been possible to compute the angular correlation between speckle pattern images and find out the relationship between surface roughness and speckle patterns decorrelation for different metal surface finishing.

The design of the present laser optical torquemeter arose from the need to measure the mechanical power furnished by a prototype of chirale turbine, which exploits the lift force produced in the rotor, due to the "Magnus effect." The particular optical reading system allows the device to determine both the torque and the mechanical power. The torque value is obtained through the reading of the torsional angle. From this value, together with that of the transmission shaft angular speed measured by the same torquemeter, the mechanical power of the turbine is calculated. The optical system output signals are acquired, processed and elaborated by a virtual logic circuit, simulated by means of a suitable home-made software in LabVIEW environment. The torquemeter has been tested operating with the prototype of turbine in a wind tunnel.

The Laser Diode intensity noise as a function of laser current and temperature has been studied in this paper. It is shown that the intensity noise in the current-temperature coordinates forms "islands" of noise amid larger areas of relatively low-noise operation. Although these "islands" of noise exhibit some drift over time, it is generally possible to find operational points characterized by long-term stability and low noise. We show also that the laser noise severely deteriorates the signal-to-noise ratio (SNR) at the receiver --photodiode circuit-- causing random fluctuations of SNR, impairing the performance of interferometric applications. The comparison of noise distributions for isolated laser modules and laser modules incorporated into laser Doppler velocimeters allowed us to reveal design faults contributing to unwanted back reflections deteriorating the overall SNR and operationl stability of the system.

The paper describes the design of a high-precision three-dimensional nanopositioning and nanomeasuring machine (NPM-Machine). The NPM-Machine has been developed by the Institute of Process Measurement and Sensor Technology of the Technische Universität Ilmenau and manufactured by the SIOS Meßtechnik GmbH Ilmenau. The machine was successfully tested and continually improved in the last few years. The NPM-Machine has a resolution of less than 0,1 nm over the entire positioning and measuring range of 25 mm x 25 mm x 5 mm. An Abbe offset-free design and the application of a new concept for compensating systematic errors resulting from mechanical bearings provide extraordinary accuracy. An important part of the NPM-Machine is constituted by a mirror corner. The integration of several probe systems and Nanotools makes the NPM-Machine suitable for various tasks, such as large-area scanning probe microscopy, mask and wafer inspection, nanostructuring, biotechnology as well as measuring mechanical precision workpieces a.s.o. Various probe systems have been integrated into the NPM-Machines. The machines are operating successfully in several German and foreign institutes including the Physikalisch-Technische Bundesanstalt (PTB). The article gives basic information on the NPM-Machine and describes the mode of operation and the measurements by means of probe systems.

The classical method for wavefront retrieval from Hartmann test data by integration of the transverse aberrations using a linear approximation between the sampled points: In this work we report a method using splines that produces a more precise wavefront shape.

In this paper we extend previous studies to further diffraction properties of Ronchi rulings. Our considerations are based on the physical theory of gratings with different strip-widths geometry. Under scope are absorptive gratings, phase gratings and mixed gratings. The case of gratings with diverse structures is also considered. In particular, gratings of phase with absorption (mixed gratings) are considered by means of the observed diffraction properties for absorption rulings as it is described in the work. Ronchigrams resulting for different grating parameters and different values from primary aberrations are shown. Some experimental results of Ronchi rulings for diverse structures are including. This study can be used not only for optical testing, but also for gratings of light for diffraction of atoms or to describe diffraction effects of micro-gratings.

It is described a technique where different views of an object are connected to recover its three-dimensional form in a field of vision of 360°. The object is placed on a rotary motorized platform and projected a linear fringe pattern. In each angular object displacement, the projected fringe pattern is captured by a camera CCD. Each pattern is digitally demodulated providing information of depth. The format of the digital matrix, this is, the image type, is changed for one of triads (x, y, z). This way, a cloud of independent points of their position in the matrix is constructed. As a reference, one point in each cloud (known it a priori), is taken. All the clouds are rotated and displaced until the reference point taking its corresponding position. Different mixed clouds of points (views) are ordered in a single triad matrix that describes the complete surface of the object surface target. Finally a mesh of quadrilaterals is built up that makes possible to generate a solid surface.

At the present time, some astronomical telescopes exist with segmented primary mirrors, as those located in Mauna Kea, Hawai. The Keck telescopes are a classical example. With the purpose of collecting light of weak stellar objects, it is necessary to control the segments of the primary mirror of the telescope, so that whole mirror works as a monolithic mirror. In this paper, it is proposed the subapertures method for the alignment of the segments of the primary mirror. The subapertures method finds tilt, tip, and pistons effects or longitudinal displacements as the defocus error; all of them are necessary to achieve the fitting of a series of measurements. It is shown the experimental results for a parabolic mirror divided in two segments using the proposed method; for this case, the particular equations were developed as well as the necessary software for the alignment of the two parts. The experimental results were obtained in a controlled situation in the laboratory. The alignment process is achieved in a short time, and furthermore is an interactive process.

In this work, we present a method for the asynchronous direct demodulation of spatiotemporal fringe patterns by the estimation of the quadrature sign (sign of the fringe pattern quadrature signal) from one of the irradiance gradient components. The technique is based in the normalization of one plane of a spatio-temporal fringe pattern, an arcos demodulation and a final sign correction by means of the estimated quadrature sign. We present two experimental applications of the direct demodulation method presented. The first application is the measurement of surface topography by RGB Shadow-Moire. The second application is isochromatics retardation measurement by load stepping photoelasticity. In both cases good results are obtained confirming the suitability of the presented technique.

An optical fiber deformed as a micropipette is employed to force the evanescent wave to interact with its environment. The multimode fiber is removed of its cladding and with a combination of heat and tension a reduction in the diameter is achieved to force the evanescent wave to increase its power. A dispersive analysis of the radiation transmitted between 400 nm and 2000 nm is measured and compared with simulation on a similar geometry.