This PDF file contains the front matter associated with SPIE Proceedings Volume 8287, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

Contemporary optical effects and photonic component necessary for the realization of nanoscale integrated photonic circuit for developing lab-on-a-chipincluding light sources, detectors and filters is summarized. We present the concept of a lab-on-a-chip for the next generation optoelectronics and biophotonic industry including novel nanoscale material systems for lasers and detectors. Using principles such as plasmonics and near-field optics highly efficient nano-photonic lasers or modulators can be realized. The light source can be tuned from the UV to the visible range using ion implantation of noble metal such as Ag or Au in Silicon or silica. The presence of Ag or Ag nanoparticles can result in a significant enhancement of the light emission in the UV, green or red wavelength regime. Novel molecular electronics materials has been used to design olegonucleotide based photodetectors on transparent substrates for the detection of analytes in an all-optical system. Either a transparent GaN semiconductor or glass can be used as an substrate. Hybrid photonic crystal based microfluidic channels synthesized using hydrogel material can be optimized to control the flow of fluid using light. In this paper, the device components developed at the University of North Texas will be presented for the realization of a lab-on-a-chip.

The optics industry in Spain pooled together to create the Southern European Cluster in Photonics and Optics - SECPhO, founded in April 2009, with the mission to help the sector increase competitiveness, specially through collaboration. From 10 founding members, SECPhO no incorporates over 40 members, which is nearly 40% of the optics industry in the region. From the beginning of operations the cluster has focused on three strategic challenges: R&D+i and Productivity, Visibility and Internationalization, and Betterment and Retention of Talent. A brief summary of the clusters activities is given. In this article, the focus will be on R&D and innovation, through industry driven collaborative initiatives and the tools and actions that lead to successful partnerships. Topics discussed in this work are will be a cluster's role in promoting strategic change, the value chain approach to partnerships, international collaboration in projects and specific cluster activities. Some practical examples of initiatives relating to effective collaboration are described, focusing on one of the mayor challenges of our time: the greening of the planet. Examples will be addressed in smart cities, efficient LASER applications and lightweight optical sensors for civil security. In all cases the collaboration between the public and private sectors is shown.

In this work, we present an experimental investigation for welding Nylon: Bi-Oriented Polyamide (BOPA) thin films using a CO2 waveguide laser in a pulsed configuration. The material used in this study is Nylon 6, all set in square sheet thin films samples of 100 cm² with 15 μm thickness. Our optical setup is based on deliver the laser beam all the way through the work piece using X-Y scanning mirrors mounted on galvo-like motors and an f-theta lens with 15 cm focal length and 50 μm focal spot sizes. The fluence (laser energy) is controlled by a pulse signal generator having the possibility to change the pulse repetition rate (PRR) and the pulse width (PW) of the laser beam. Our results show the best weld seam for scanning speeds of 20mm/s and the pulsed laser beam with 2 KHz PRR and 80 μs for the PW time. The scanning speed and trajectory for the welding process are all controlled by a computer in which one can modify the weld parameters. The irradiance at the focal point is set to 1.146 MW/cm² while the average optical power was set to 22.5W. Our experimental parameters are previously modeled by using COMSOL Multiphysics software were the laser heat source is modeled on the selected material. This model is based on the heat transfer partial differential equation and solved by finite elements procedure. Model results show a perfect agreement with the experiments. Finally, the quality of the welded seam is studied by means of sealed tight and share force critical mechanical test.

Keratoconus is a corneal disease in which the cornea assumes a conical shape due to an irregular alteration of the internal structure of the corneal tissue and sometimes is progressive, especially in young people. Anatomically, the main signs of keratoconus are thinning of the cornea in its central or paracentral region, usually accompanied by an increase in this part of a high irregular astigmatism, with a consequent loss of vision. Its diagnosis requires a thorough study including the family history, a complete ophthalmologic examination and imaging studies. This diagnosis allows classifying the type of keratoconus, which allow determining options of management, with what it is possible to establish a visual prognosis of each eye. One of the indicators that help in the diagnosis of keratoconus is an inherited familiar propensity. The literature reports an incidence of keratoconus of 11%¹ in first-degree relatives of patients with keratoconus. Results suggest an ethnic dependence, which implies that the knowledge of the tendency of keratoconus in the Mexican population is important. In this work, we present the preliminary results of the study realized to a group of relatives of patients who underwent corneal transplant by advanced keratoconus using Orbscan II topographic diagnosis, to determine the predisposition to Keratoconus in this group.e<a

Here we show a method to make compound optofluidic lenses with sizes of some millimeters. These lenses could have several chambers which combined could help to decrease aberrations. Liquids used in the lenses are ionic liquids. We present an optical characterization study of some of these liquids. A two cell compound lens is show.

Here we report on the first CENAM realization of the phase-shift method for chromatic dispersion measurements in mono-mode phase-shifted optical fibers used for the telecommunications C-band (1 550 nm). This chromatic dispersion measurement and calibration capability development at CENAM will provide the Mexican telecommunications industry with a formally established SI units traceability source, thus promoting this rapidly growing and high impact economic sector competitiveness in Mexico. We also identified a 40 MHz modulation frequency, a 2.5 nm wavelength step and the 1 535 nm to 1 570 nm wavelength scanning range, as the optimum experimental parameters that have to be set in order to obtain experimental data which numerical Sellmeier polynomials fittings produce representative determinations for the group delay and the chromatic dispersion. We also obtained 1 549.388 nm ± 0.098 nm, (k=1), for the zero dispersion wavelength, and 0.719 7 ps-nm^-2 ± 0.005 5 ps·nm^-2, (k=1), for the zero dispersion slope of the tested optical fiber.

Here we report on the estimation of the effective plane location uncertainty component in commercially available luxmeters calibration as performed at the Laboratorio de Fotometría of the Centro Nacional de Metrología of Mexico. The study was carried out by using a twelve luxmeters sample, comprising three of the most common detection heads shapes, and as a result we found 0.17 % as the highest uncertainty component value, which once combined to the typical luxmeters calibrations uncertainty budget, fully agree with the 1 % (k=2) illuminance Calibration and Measurement Capability declared by Mexico to the Bureau International des Poids et Mesures.âA

The main spectroscopic properties of a new B-Te-Na-Si-Al:Er³⁺ glass are investigated. The Judd-Ofelt (JO) intensity parameters (Ωt), the spontaneous emission probabilities, the branching ratios and the radiative lifetimes for each observed Er3⁺-ion levels were determined. The stimulated emission cross section, the fluorescence full width at half maximum (FWHM), Δλ_eff, the Δλ_eff x σe factor, and the gain spectra of the main Er³⁺-ion lasing emission (⁴I_13/2→⁴I15/2) are obtained after exciting the glass sample at 532 nm (⁴I_15/2 →⁴S_3/2 ). The absorption cross section of the ⁴I_15/2→4I13/2 transition of the Er³⁺-ions was also obtained from absorption spectrum of the new glass. The results are compared with those reported for other Er³⁺-doped oxide glasses pumped at various excitation wavelengths, indicating the new Er³⁺- doped boro-tellurite glass has potential properties as an optical amplifier in the C-telecommunication window (1.53 μm) and a IR tunable laser. Additionally a radiative energy transfer from the glass host to the Er3+-ions was observed at 520 nm by exciting the glass sample at 466 nm into the Er³⁺-ion dark region.

Holographic interferometry-based methods represent an interesting innovation for monitoring electrochemical corrosion processes. One of these techniques based on a Michelson interferometric configuration allows quantitative and qualitative obtaining of information related to corrosion, being based on simple inspection of intensity patterns with no direct physical contact with sample during reaction time, and physical preservation practically guaranteed. In this work the performance of Michelson interferometry for investigation of such phenomena on uncovered, partial and totally covered copper metallic samples is presented and experimental results suggest important information gathered about the type and mechanism of corrosion taking place.

Diabetes is a disease with no cure, but can be controlled to improve the quality of life of sufferers. Currently there are means to control, but this means they have the disadvantage that in order to measure the amount of glucose is necessary to take blood samples that are painful. This paper presents a system for measuring glucose using non-invasive optical techniques: using absorption spectroscopy and polarimetry technique. It shows the results obtained from experiments done on samples containing distilled water and different amounts of glucose to study the absorption coefficient of glucose with both techniques. Water is used because it is one of the main elements in the blood and interferes with glucose measurement. This experiment will develop a prototype to measure glucose through a non-invasive technique.

The aim of this work is to propose the use of printed acetate sheets as quasi-sinusoidal and quasi-triangular diffraction gratings, as low-cost alternative gratings for application in non-invasive optical tests. Gratings were generated with Matlab® software and made with various models of laser and inkjet printers. A study of the profile gratings that depend on the symmetry in the sample was included, gratings were placed in the entrance pupil of a positive lens (illuminated by a collimated plane wave) to observe their Fourier transforms. It was found that diffraction patterns of various types of quasi-sinusoidal and quasi-triangular profiles were very close to that of sinusoidal gratings. Gradual change in the size of printed ink spots was observed in more detail through a magnification of 40x. Additionally, an atomic force microscope was used to measure the average superficial roughness of the impressions as to observe the behavior of the ink on the acetate.

A radial displacement cyclic interferometer parallel beams is used to generate phase shifts. Simultaneously engages an architecture that generates the same moment two interferograms with a phase shift of pi / 2 between them. This phase shift is obtained using optical components. Unlike the arrangements that use a grid in the Fourier plane, where the distance between interference patterns obtained are not adjustable, but is determined by the length of the grid, in the configuration presented, is sufficient to shift one of the reflecting mirrors in order to control the separation between interferograms.. A phase object is used. Interferometric arrangement is presented, and the results obtained experimentally.

The development of this work is important in the morphological study of plant parts, specifically in the study of the cuticle of fruits or leaves. The implemented optical technique for fringe projection can identify potential fracture zones which damage the presentation of the fruits impacting business as well as producing them. Specifically, we obtained information on the thickness of a cuticle corresponding to the abaxial surface of a leaf of apple (Malus domestica) of the variety Golden Delicious.

A polarimetric characterization, consisting of the Mueller matrix determination and the measurement of the refractive index, is employed to study bee honey and corn syrup differences. Two samples of commercial marks of bee honey and one sample of commercial mark corn syrup are studied. Results show the corn syrup and one of the bee honey samples have a similar polarimetric behavior, which differs from the second bee honey sample. This behavior can be employed as a simple, qualitative test, to discriminate true bee honey from corn syrup or from adulterated bee honey.s-powe

Electronic speckle pattern interferometry is a useful technique in the measurement of displacement fields and topography. Traditionally, arrangement with dual collimated illumination to topography measurement is used. In this case, the object analysis is limited to the size of optical collimating lens. In the case of large objects, an optical system with divergent illumination can be used. It is known that displacement fields and the phase are related by the sensitivity vector. At once, to compute the sensitivity vector, illumination sources position and superficial shape need to be considered. The last condition becomes an impediment to surface contouring. In a published work¹, a simple iterative algorithm based on the Gauss-Seidel technique is presented to compute contouring measurement. In the present work, the uncertainty associated to the measurement of the topography is calculated by using the Monte Carlo method.

Polyethylene (PE), is a polymer formed by carbon-carbon single bonds, is a very stable material with a very slow degradation rate. In this paper, polyethylene films bag type were exposed to UV-B radiation (320-280 nm) at different exposure times (2 to 12 days). The UV radiation effects on PE samples were characterized using infrared spectroscopy with attenuated total reflectance (ATR). The vinyl group formation indicates the PE degradation. These chemical groups have IR absorption in 900-1300 cm-1; additionally the degree of crystallinity increase with the increasing of the exposure time. The experiment showed significant changes in PE molecular structure.

A numerical study of the effects of tapering a hollow-core photonic bandgap fiber (HC-PBGF) on the spatial parameters: effective area, nonlinear parameter and dispersion parameter is presented. The taper on the fiber is modeled by scaling the cross section of the original fiber geometry. Both the air and the silica contribution to the effective area and the nonlinear parameter are shown. The obtained results show a blueshift of the transmission band and of the zero-dispersion wavelength. By tapering the fiber 30%, the transmission band and the zerodispersion wavelength blueshift around 300 nm and 320 nm, respectively. HC-PBGFs have made possible the study of nonlinear optical effects and by tapering the fiber, such nonlinear phenomena can be made stronger.

Laser provides a high controllable and localized spot for soldering joint formation and this is a valuable tool in Sn/Pb Soldering process on electronic industry, in recent years, laser beam welding has become an emerging welding technique, the use of laser in welding area is a high efficiency method. A 60 Watts CO2 continuous laser was used on this study, during welding experimental results indicated the laser could significantly improve speed and weld quality. In this work, the welding interactions of CO2 laser with Sn/Pb wire have been investigated in details through varying the energy ratios of laser. And at the same time, the effect of distance from laser spot to material.

Nowadays the measurement of the contact area of the foot has become an objective way of classifying feet and to describe the form of the longitudinal arch of the foot. In this work, the implementation of a digital podoscope that enables remote sensing for evaluation of the foot is described. The podogram includes an outline of the plantar pressure, and the contour of the arch. This method of evaluation is relatively simple and inexpensive while maintaining precision. The recognition system compares the image of the actual foot with that of a reference image. Information from the comparison can be sent by internet to obtain a remote diagnosis from an expert.

The optical Differential Optical Absorption Spectroscopy (DOAS) is a technique to measure pollutant emissions like SO₂, from point sources and total fluxes in the atmosphere. Passive DOAS systems use sunlight like source. Measurements with such systems can be made in situ and in real time. The goal of this work is to report the implementation of hardware and software of a portable system to evaluate the pollutants emitted in the atmosphere by industrial chimneys. We show SO₂ measurements obtained around PEMEX refinerys in Tula Hidalgo that enables the identification of their pollution degree with the knowledge of speed wind.

In this work we present an optical system for the supervision of the operation of an induction motor. We used a Cyclic interferometer for the measurement of the vibrations produced by the motor motion and obtain a frequency spectrum via a Fourier transform of the signal. According to the spectrum, we can know the operation conditions of the induction motor. The optical system consists of a Cyclic Interferometer, a data acquisition board and virtual instrument.

This paper describes a computer vision system designed to perform an inventory of traffic signals. The system consists of five Ethernet synchronized cameras; the acquisition strategy allows us to take one image per camera every other second. We then use those five images to generate a panoramic image each second. Signal detection and recognition is carried out offline. Detection of traffic signal is done in the panoramic image using the Hough transform and enhancement of HSV color space. Traffic signal recognition is made by a combination of Haar wavelet and violates Jones classifier. Finally, we present experimental results using a database of one hundred images.

The aim of this work was to develop an active material for optical memory phase change that allows multilevel record. We measure the reflectance of Ge₁Sb₂Te₄ films doped with oxygen with a Static Meter of Reflectivity by laser SMRL, which was built specially for this application. Experimental reflectance results shown that the nucleation time tnucl (minimum duration of the laser pulse to start the laser induced crystallization) and the crystallization time tcrys (time it takes to crystallize the material) depend on the concentration of oxygen. X ray diffraction showed that films with high percentage oxygen concentration (10- 18 %) have a phase segregation of Sb2Te3. This phase segregation in films containing more than 10% oxygen gives, as a result, an increase in nucleation times and in laser-induced crystallization times, allowing multilevel recording.

We present the evaluation of wireless optical communication systems through laboratory recreation of atmospheric turbulence, and analyze the scope of this form of experimental validation in various optical communication systems.

Diffraction of an obliquely incident 􀜶􀜧-polarized Gaussian beams by 􀜰 equally spaced slits (finite lamellar grating) with conducting substrate is treated. The substrate can be either vacuum or conductor. The diffracted (transmitted) patterns, the transmission coefficient, and the normally diffracted energy are analyzed as a function of several optogeometrical parameters. Particularly, the coupling between slits and the influence of the substrate is considered. We have found that, when the substrate is a conductor the grating equation in transmission predicts with good precision the positions of the orders of diffraction of a finite grating; the angular positions of these orders are independents of the beam width, the spot position on the finite grating, and the conductivity of the substrate.

A rigorous numerical analysis of the diffraction of finite-size Hermite-Gaussian beams by two slits is presented. The case of TM (Transversal Magnetic) polarization and oblique incidence is considered. We assume the double slit is ruled onto a metallic screen of non-zero thickness h, width ℓ and separation d. Far-field spectra and transmission coefficients are analyzed as a function of several opto-geometrical parameters, i.e. the wavelength λ, slit width ℓ and separation d. Particular emphasis is put on the description of the energy diffracted along the incident direction Ei because of its applications on optical-metrology. Finally, the validity of a well known scalar property Ei=2τ/λis studied within the vectorial regime.

Diffraction of an obliquely incident TE-polarized Gaussian beams by 􀜰 equally spaced slits (finite lamellar grating) with conducting substrate is treated. The substrate can be either vacuum or conductor. The diffracted and scattered patterns, the transmission and reflection coefficients, and the normally diffracted energy are analyzed as a function of several optogeometrical parameters. Particularly, the coupling between slits and the influence of the substrate is considered. We have found that, when the substrate is a conductor the grating equation in reflection predicts with good precision the angular positions of the orders of a finite grating; the angular positions of these orders are independents of the beam width, the spot position on the finite grating, and the conductivity of the substrate. Besides, the envelope of the reflected energy is conserved constant when the position of the spot is changed.

We present FDTD calculations for transmission of electromagnetic waves through periodic arrays of slits in a metallic screen. The results show resonant, frequency dependent, transmittance peaks for subwavelength widths of the slits which can be up to a factor of ten with respect to those out of resonance. Although our conclusions agree with previous work by Lezec and Thio as regards both the magnitude of the enhancement and the lack of contribution of surface plasmon polaritons of the metal surface to this effect, we derive an interpretation from a theory that deals with emerging beam-Rayleigh anomalies of the grating, and with Fabry- Perot resonances of the perforated screen considered as an effective medium.

Stereo Vision is a powerful tool used to make a 360° scan of an object in order to obtain topography details or getting the spatial position of interest points, but the process could be slow due to the computing time. In this work we present the alternative of using high reflective markers, which are used as reference points to track an object movement. The advantage of these markers is that their detection is faster than a full scene correlation and it is done by comparing the position of the centroids of each marker without using pixel-pixel analysis.

We present a method to fully reconstruct real objects acquired by any means of digitalization and where many scans from different views of point have been made. The current problem is modeled as an optimization problem and solved with a Genetic Algorithm (GA) using a custom fitness function based in regular squared distance minimization (SDM). We present examples to show the applicability of our method to reconstruct full objects as well as a possible application in reverse engineering.

In this paper, it is presented a device to measure the whole Mueller matrix of a sample using one wavelength. It is also described some industrial applications where the instrument can be useful. The instrument comprises one set of liquid crystal variable retarders and other of photoelastic modulators. In the particular view of the author, this technique can still evolve in order to satisfy new challenges in the industrial environment.

We have divided this project in stages the first being the construction of an optomechatronics load cell1, the operating principle is based on the fact that the application on a mechanical load produces a deformation on that element. This deformation causes a reduction in the distance between the transmitter and receiver, resulting in a change in the electrical signal. It should be noted that the distribution of light intensity varies between sender and receiver due to the displacement generated. In a load cell, it was adapted an infrared emitter whose signal is received by the detector at the other end. The second stage was the demonstration that our system is able to measure external loads on a mechanical device through an indirect method for measuring stresses, which we present results generated from the experimental trials with adequate mechanical equipment in the cited work. We have implemented a strain sensitive prototype. As a result of the first and second stages to implement the system is to test it on academic applications and then adapt it to industrial environment. Note that the third stage there was a validation of the optomecatronic load cell with ASTM E74-061-2 shows the result with the basic metrological characteristics of resolution, sensitivity, repeatability, which requires it. We are currently analyzing other mechanical design proposals to improve their elastic behavior and the efficiency of this measurement system, because they increase the range of load values at which the expected response should be linear.

A novel phase shifting interferometry method based on the variation of the electric field under the scheme of a three beams interferometer is proposed. One beam contains the object under study, that makes this beam the probe beam; the other two will be consider as the reference beams with a phase difference of π 2 . Due to this, one of the three resulting interference terms will be cancelled and the two remaining will be in quadrature. Applying some trigonometric identities, we show that the resulting interference pattern could become modeled by the interfering of two beams with an additional phase term; we obtain that the tangent function of the additional phase depends on the division of the amplitude of the third field divided by the amplitude of the first, and it is possible to group the sum of the squares of these fields in a square amplitude. To recover the phase by using the phase shifting interferometry techniques it is necessary to keep constant the visibility of the interference pattern, at first sight we can think that this is not possible because the variations of the field amplitude affect the visibility of the patterns. However this problem is solved if the values of the amplitude corresponding to the fields one and three are seen as an ordered pair contained over an arc segment at the first quadrant. We justify the viability of this method by a theoretical analysis and a numerical simulation of the interference of three beams under the conditions mentioned above.

We present the fabrication and characterization of a micro-displacement sensor using Mach-Zehnder interferometer in conventional optical fiber SMF28-e. The Mach-Zehnder interferometer uses a configuration of two long-period gratings (LPG) in series mechanically induced. The Mach-Zehnder interferometers were made to operate in the region of 1300 nm. As a result the interferometers were obtained with transmission bands with a bandwidth of 2 nm, extinction ratio of 12 dB and insertion loss of 2 to 3 dB. The characterization of the interferometer was found to be measured displacements up to 500 μm with a resolution of 7 microns, which envisions potential applications of micro-displacement sensor in the measurement of micro-deformations.

An automatic re-calibration for mobile vision is presented. In this technique, the vision parameters are determined by means of a Bezier network. This procedure is carried out by image processing of a laser line. From the network structure, the initial calibration and the online re-calibration are performed. The proposed technique avoids calibrated references and physical measurements, which are used in traditional calibration. Thus, the proposed re-calibration improves the accuracy and performance of the mobile vision. This procedure represents a contribution in the re-calibration. To elucidate this contribution, an evaluation is performed based on the re-calibration methods. Also, the time processing is described.

Three-dimensional object topography is obtained by using the fringe projection technique. In fringe projection technique, digitalization is done when black and white lines are projected over the sample object and the image is captured by the CCD. It is applied the phase shifting method to evaluate the phase of the projected fringes. In this paper it is proposed a method in which red, green and blue fringes are projected sequentially. It is obtained the topography to each color (RGB) and finally the three obtained shapes are averaged. By using this method, we obtain information about color, texture and topography details of the object.

The measurement of phase is important in multiple applications, such as in interferometry, radar applications, tomography, among others. As a particular application, phase extraction can be used to evaluate the chromatic dispersion coefficient in optical fibers. There are multiple setups that employ the phase of an interferometric signal to evaluate this coefficient. Usually in those systems the phase shift evaluation of the sine-like interferometric signal is performed measuring the shift of a single maximum. This means that only a few points in the interferogram are used and many other are wasted. In this work a Fourier Transform method to obtain interferogram phase shift to evaluate chromatic dispersion of an optical fiber is presented. Results of the dispersion coefficient of fiber with a length of hundreds of meters evaluated by using a Sagnac interferometer are shown.

In this work we propose the simulation of a fringe pattern in analogy with a oscilating pendulum with adaptive parameters. This technique will be used in future to recovery the phase of interferograms by mean a dynamical model. We reproduce a reference fringe pattern solving the dynamical model of a pendulum with adaptive length parameter, by computer simulation. We obtained good preliminary results with this dynamical system. The differential equation (DE) was simulated with Simulink Toolbox of MATLAB. We show our results.

We present experimental results obtained by using phase-shifting interferometry by polarization to measure the radial slope of transparent samples, by implementing a Radial-Shear interferometer and using a grating to replicate the interference patterns modulated by polarization; the interferometer is capable to process the optical phase data by obtaining four interferograms in one-shot. The experimental results for transparent samples are presented in this research.

In optical tomography of parallel projections, the light rays that cross the slice of the object are experimentally approached to suffer minimal refraction, i.e. take refractional limits. Generally, a media is used for immersion whose refractive index rate tied the environment to study, but the geometry of the containment vessels also affects refraction and may be the case that the approach is not subject performed. In this work we make a numerical study of the refraction of a ray of light that enters a typical experimental system for studying the thermodynamic behaviour of a paraffinic wax around their cloud point. Since it has special properties in the heat capacity and refractive index near the phase transition, these results will be used to characterize the transition and is intended to give tomographic information to the study of thermal properties obtained using the T-History calorimetric technique. In this study, we simulate the behaviour of the refraction of parallel rays crossing the T-History test system to find the optimal values of the dimensions of the containment vessels and the index of refraction of the medium for immersion, considering that the optical properties of the sample under study vary with temperature. Thus, we obtain the optimum conditions of minimum refraction technique for which reconstruction of a tomographic slice parallel projection can be applied. The distribution of the linear attenuation coefficient on the slice of the object, typically, is obtained by applying the filtered backprojection algorithm to the set of projections (sinogram) obtained experimentally, which constitutes a way to detect mobile interfacial boundaries in real time. The projections are sequentially measuring the intensity of the wave emerging from the slice of the object at different angles.