This PDF file contains the front matter associated with SPIE Proceedings Volume 7499, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

Raman spectroscopy is in the scientific community an accepted and applied noninvasive technique, which can be used to identify many classes of potentially explosive materials, based on vibrational molecular information. This technique has demonstrated to be a useful tool for the identification and characterization of explosives that are of interest for forensic services and security, and is used due to the necessity for a fast identification of potentially explosive materials of homemade manufacture, which can be made using chemical agents available in the market. This technique allows the identification of precursory substances, without direct handling, nor exposure to any potentially harmful environment, providing high personal security in the process. In this work, the analysis of some commonly used precursors for explosives' production was done, by means of a portable Raman spectrometer, in a fast way and using transparent sample-containers.

In the present work, automation of a dynamic system to measure response of gas sensors based on quartz crystal microbalance (QCM) is presented. Automation was used to study transient response, which is necessary for sensor characterization. A valves system, which controls the gas flow towards the sensor, was implemented to generate the step function. The system was fully automated by using a PIC16F877 microcontroller. Results of sensor response measurements are presented.

The industrial processes need to control many variables such as temperature, flow, pressure, position, etc. For this reason, one sensor is required for each signal to be controlled. Therefore, multipoint sensors that can measure different signals in the same system have been proposed. In this work a multipoint sensor, which consists of a fiber laser with two Fabry-Perot cavities based on fiber Bragg gratings was studied. The sensor operation principle is based on the overlapping of the gratings reflection spectra, which produce a laser emission with a wavelength of 1536 nm. For this kind of sensors, various detection methods to identify and quantify the signals from its intermodal frequencies, have been used which employ some circuits like PLL (Phase Loop Lock), lock-in amplifiers and electrical spectrum analyzers. However these equipments are quite expensive. Therefore in the present work signal analysis with Fourier discrete transform to identify and quantify the sensor signals based on the laser intermodal frequencies is proposed. Such frequencies were 200 and 800 kHz corresponding to cavities of 500 and 130 m length, respectively.

We present an application of coherent homodyne detection to the problem of low photon number communications and cryptography. As the coherent demodulation of an optical field requires the measurement of its (non commutating) inphase and quadrature components, we present the structure and operation of an 8-port optical hybrid comprising 2 balanced homodyne detection structures, for the simultaneous measurement of the 2 quadratures. We analyze this receiver operating with a strong local oscillator field, when the received field is in weak coherent states, with digital phase modulation: we obtain the homodyne statistics and the uncertainty product in the presence of vacuum noises from the input signal port and unused ports and discuss the increase in uncertainty due to the simultaneous measurements of the quadratures. We obtain the signal to noise ratio as well of the bit error rate performance for binary phase shift keying and discuss the departure from the standard quantum limit.

The optical wireless communications systems are an important alternative for providing high bandwidth over short or medium range links. Although, most of such links are currently, based in no-coherent schemes, there exist the optical coherent techniques offering a greater sensitivity and selectivity at the receiver stage and the possibility of impairments compensation using high-speed post-detection DSP algorithms. We present the a scheme to demonstrate the use of the optical coherent technique in wireless communications for a last-mile application under turbulence, in the laboratory scope.

It is present a unique compact optical circular-polarization-splitting common-path interferometer, described based on a zero-twist liquid crystal display (LCD) [1]. A blazed diffraction grating is encoded onto the LCD. The optical train produces two beams, a reference beam with a sense of circular polarized light and a diffracted one with the opposite sense of circular polarized light. Using a linear polarizer, these two beams form an interferogram that can be used to analyze optically active media. The detail of the light behaviour through the optical train is present using Jones matrix's.

In this paper is presented construction and implementation of a mechatronic robot to obtain porosity in parts mechanics of centrifugal pumps using ultrasonic wave. Considerations about the methods applied and their use in the field of metrology for the metal mechanic industry are taken into consideration. This project is inserted in ITT Goulds Pumps industries, with a headquarter in Tizayuca Hidalgo State, Mexico. A mechatronic robot with 5 free grades (XYZUV) of 170 X 104 X 120 cm controlled by a PC is built. The robot let us scan metal mechanic pieces of 120 X 90 X 170 cm. It is incorporated a sensor ultrasonic in miniature in the Z axis. Such arrangement allows applying the techniques of ultrasonic wave to obtain maps of porosity in parts mechanics in manufacturing pumps to test mechanic deformation. The scan is done by the Z axis when traveling around the piece under test with the objective of finding fragility zones when applying cutting efforts to the pieces.

In this work a surface roughness measurement performed by Hurst exponent determination, calculated at the same time from data processing of an optical reflected signal is presented. An industrial plate roller rod covered with a polymeric coating is illuminated using a laser source. A lens is used for casting the scattered light reflected from several sectors of the plate roller, and also to focus it into a power meter connected to a computer where corresponding data series are stored. Information related to specific points of the considered object is contained into the optical reflected signal and post-processing of related data signal series allows calculation of the Hurst exponent, also known as roughness exponent. A wear analysis on considered surface sectors of the roller is performed and as a result a relation between Hurst exponent and the coating thickness for each surface sector is clearly established. The simplicity of the opto-mechanical setup among other evident advantages may suggest the application of this non-destructive technique on surface metrology.

We present the development of a semi-automated photometric bench implemented at the Laboratorio de Fotometria of the Centro Nacional de Metrologia of Mexico, in order to reduce the illuminance meters calibration time. This photometric bench reproduces the minimum values established in the Mexican regulation NOM-025-STPS-2008 and allows the fast calibration of the luxmeters required for illuminance levels checks. The photometric bench design uses neutral optical density filters in order to realize different illuminances at the same distance. Here we also present the uncertainty estimated for the reference illuminance values realized by the implemented photometric bench.

For a successful phase demodulation it is important to have a good quality fringe pattern image. For this reason preprocessing fringe patterns is, many times, an unavoidable task. Often, noise removal is the main problem to be solved, however, the use of ordinary linear filters is not always a proper procedure specially in the presence of high density fringes because the signal and noise are mixed in the Fourier space. Also, as fringe pattern images are two-dimensional functions, frequencies are two-component vectors which requires consider the filtering direction. We present a new denoising technique for preprocessing fringe pattern images which requires to previously estimate the fringe orientation. For cases of high noise levels we modify the proposed technique by means of a regularized local cost function in order to get a better noise response. We present a noise response analysis of the proposed technique, some experimental results and its application to wrapped phase maps denoising.

The aim of this work is to propose the use of printed acetate sheets as quasi-sinusoidal 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 printers. A study of the discretization effects 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 semi-sinusoidal 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 roughness average of the impressions as to observe the behavior of the ink on the acetate.

In this work we quantified the effective UV radiation dose in orange and colorless polyethylene samples exposed to weather in the city of Aguascalientes, Ags. Mexico. The spectral distribution of solar radiation was calculated using SMART 2.9.5.; the samples absorption properties were measured using UV-Vis spectroscopy and the quantum yield was calculated using samples reflectance properties. The determining factor in the effective UV dose is the spectral distribution of solar radiation, although the chemical structure of materials is also important.

We describe a fast method for measuring the refractive-index dispersion of transparent and absorbing liquid solutions. The method is based on measuring the reflectance spectra of an optical beam of white light in an internal reflection configuration near the critical angle defined by the refractive indices of the incident medium (a glass prism) and that of the solvent, which is assumed to be transparent. From a few reflectance spectra taken near the critical angle with the pure solvent and the solution, the dispersion of the contribution to the refractive index of the solute (the sample) can be obtained. We present results with solutions of Rodamine 6G dissolved in distilled water and in methanol showing the feasibility of the proposed method.

Scanning laser ophthalmoscopes (SLOs) and optical coherence tomographs are the state-of-the-art retinal imaging instruments, and are essential for early and reliable diagnosis of eye disease. Recently, with the incorporation of adaptive optics (AO), these instruments have started to deliver near diffraction-limited performance in both humans and animal models, enabling the resolution of the retinal ganglion cell bodies, their processes, the cone photoreceptor and the retinal pigment epithelial cells mosaics. Unfortunately, these novel instruments have not delivered consistent performance across human subjects and animal models. One of the limitations of current instruments is the astigmatism in the pupil and imaging planes, which degrades image quality, by preventing the wavefront sensor from measuring aberrations with high spatial content. This astigmatism is introduced by the sequence of off-axis reflective elements, typically spherical mirrors, used for relaying pupil and imaging planes. Expressions for minimal astigmatism on the image and pupil planes in off-axis reflective afocal telescopes formed by pairs of spherical mirrors are presented. The formulas, derived from the marginal ray fans equation, are valid for small angles of incidence (≤15°), and can be used to design laser cavities, spectrographs and vision adaptive optics systems. An example related to this last application is discussed.

An automatic technique for gear reconstruction is presented. In this technique, the gear modeling is performed by means of an approximation network. To carry it out, a vision system is implemented based on laser metrology. The approximation network is performed based on the gear pattern. To perform the contouring, the gear is scanned by a laser line. This process involves image processing of a laser line pattern. The network performs the gear modeling without measurements on the optical setup. In this manner, errors of the measurement are not added to the computational model. Thus, the setup performance and accuracy are improved. To describe the accuracy a mean square of error is calculated using data provided by the network and data given by a contact method. This technique is tested with real gears and its experimental results are presented.

The fringes projection technique allows evaluating 3D profiles from testing objects without contact. To obtain those profiles it is necessary to get a photograph of the projected fringes. This image contains the information of the profile testing object as a deformation of the projected fringes. In order to evaluate the profile it is necessary to extract the phase from image fringes, usually this process requires an arctan()function. As is well known this function is limited by ±π and as a result the called wrapped phase is obtain. Therefore in order to get the real phase an unwrapping technique must be employed. In this work experimental and theoretical results of implementation of Itoh algorithm to unwrap phase are shown. This algorithm was written in MatLab and results show that this technique is suitable to measure profiles using fringes projection if images obtained are free of shadows or if the sampling satisfies Nyquist theorem.

This paper presents a sensor of liquids using Raman spectroscopy. Results are displayed using 96 degrees alcohol mixed with collagen, moreover we used samples of acetone with alcohol, acetone with collagen. Raman spectrum noise is decreased using a matlab ® algorithm that works with wavelets symmlets. The results show main spectral lines for each of the samples used.

In this paper we propose a new method of analysis to obtain the spherical power in ophthalmic lenses based on ray traces of geometric optics techniques, formation, capture and image processing. We determine the spherical power in ophthalmic lenses considering the total magnification of the optical system and the Gauss's formula. A simple, practical and easy to implement experimental setup is presented for the measurement of positives and negative lenses. The setup consists in a circular object displayed in a LCD monitor, the ophthalmic lens to be measured and a digital camera in order to send information to a PC containing the software algorithm which calculates and displays the spherical power.

Several techniques have been used to determine the radius of curvature of the cornea. In this article, we describe the use of a method obtained trough ray analysis, based in geometrical analysis and lateral magnification equation. A pattern of an increasing point was displayed in a flat screen monitor; images of this point were captured for a test sphere with a CCD camera. The obtained data was then processed for the calculation of the sphere curvature. The experimental setup is presented.

Motivated by the growing number of applications the light emitting diodes, LEDs, are having in solid-state lighting systems, we summarize the new internationally standardized measurement methods for photometric and colorimetric quantities in LEDs; since they are commonly used to quantify some of the key performance parameters of several products used in automotive industry, traffic signaling, etc. Finally, special emphasis is given to the mismatch corrections factors calculation, and its use when measuring LEDs photometric and colorimetric quantities.

This paper presents the development of an automatic alignment system for specialty optical fibers. Based on a XY coordinates system, the alignment is achieved by the control of stepping motors through displacement algorithms. A hexagonal shape arrangement of SMF´s fibers generates a map location of the spot light. This photo-detection system enables to analyze the launching of the beam into the fiber. Through an USB based PC interface and software to automate the alignment process the device's performance has been improved in time and in optical coupling efficiency. The results obtained are 2 or 3 seconds in the alignment process and roughly 80% coupling efficiency.

We present the results of the optical characterization of the mirrors of the telescope of 62cm observatory "SEVERO DIAZ GALINDO" property of the University of Guadalajara. We use the Ronchi test and a spherometer to measure by first time, the radius of curvature for the primary and secondary mirror, the parameters of the telescope system were obtained by using the commercial software ZEMAX. We confirm that both mirrors are adequate to work in the telescope configuration and to do optical astronomy.

In this work, the measurements done, by way of digital holography, of auto-induced mechanical oscillations assumed by signals of frequency near to the first natural modal of resonance, are reported. Using a high speed digital camera, the study of a rectangular membrane under external excitation of a very low mechanical amplitude level, is done. The optical technique of high temporal and spatial resolution allows the acquisition and processing of data coming from thousands of acquired images with a relation of 5000 frames per second.

In a previous work the monitoring of the fringes pattern shift produced by the interaction of a polymeric film with volatile organic compounds (VOC), by a Pohl interferometric arrangement has been reported. Such fringes shift was measured by a conventional photodetector. In the present work the optimization of an optoelectronic system for detection and quantification of VOC is presented. In this new arrangement a charge coupled device (camera CCD) was used to monitor such fringes shift. The CCD takes advantage of the fact that each pixel can be used as a single photodetector. A program was realized in matlab for the acquisition and processing of the data, which allows to evaluate faster the obtained results. Up to the moment results of the system performance by the measurement of the steady state response of dimethylpolysiloxane (DMPS) to ethanol vapour are reported.

Productive activities require measuring systems as a key tool for manufacturing quality goods. Metal mechanical industries develop their processes based on the control of a high precision fit between two pieces of a pressureassembled product. Therefore, engineering materials are constantly subjected to resistance tests. Balance test equipment and mechanical vibrations work under the principle of force measurements. The most precise stress measurement methods are done with electromechanical devices known as load cells. They basically consist of a tiny electric resistor that is adhered to a mechanical element that may be under stress. Cyclic stresses also directly affect the performance of the measuring element including the resistance itself, which changes as the cyclic fatigue progresses (the measuring element is a very thin coil with limited strength). In this research, we developed an optomechatronic load cell¹ whose operating principle is based on measuring the stress load applied to a mechanical element. The deformation causes a reduction in the distance between the emitter and the receptor producing an electrical signal. It must be established that the distribution of the light intensity varies between the emitter and the receptor due to the generated displacement. An infrared emitter was adapted to the load cell whose signal was received by the receptor at the other end. The second stage included a demonstration that the optoelectronic system is capable of measuring external stresses on a mechanical element by using an indirect method of measuring stresses. Here we present the results from those experiments, which include some adaptations on the mechanical element. We implemented a prototype sensitive to the deformation produced by the mechanical element (load cell). As a result of the two stages, we plan to test the system in academic and industrial applications. The third step in the research is to validate the optomechatronic load cell under the E74-065 ASTM Standard² showing the results based on the resolution, sensitivity, and repeatability required by the standard.

We present experimental results of monitoring pressure over samples painted with paint called Pressure Sensitive Paint (PSP), employing optical spectroscopy and imaging analysis. An electronic system to control pressure is implemented to restricted low pressure monitoring of the samples with PSP. The surface under analysis is excited with 370 nm wavelength (UV). The signal of fluorescence generated at 580 nm is correlated to variation of pressure over the interval of 4 to 200 kPa. As a complement, a set of images is acquired in the same interval of pressure. The images are processed and then lead to a set of histograms obtained from the samples images. We assess the transfer function of the system analyzing the histograms and the spectral response curves.

Oxidation in polymeric materials and special polyurethane is manifested by a yellow color, highly visible in white soles for footwear, besides presenting changes in its properties. Its importance varies according to the application of the material for which it was created. The most common way to detect this process is through a visual color change on the surface. In the present proposal we present a technique using digital photography for quantifying the color change in the polymer. The analysis of the photography is realized by means of projective geometry, since, relates the plane of the object and the one of the image of the object. This allows determining the area of the studied object, and by means of a histogram, which is determined each time for to record the progress of oxidation on the surface of the material. We present results of visual analysis and its behavior through a mathematical model.

An optical system for real-time measurements on a turning surface was designed and implemented in the optical metrology laboratory at CICATA-IPN. Different profiles of machined parts can be determined using a single detector or a photo-diode array. The basis of the measurement is the scattering of a laser beam which is reflected by the turning surface. Two different configurations were tested, the first one uses a single photodetector and a commercial lock-in amplifier, and the second uses a photodetector array and a proprietary platform. The samples under test were mounted on two different lathes for each configuration. The samples were rotating while the measurements were taken by the electronic system. Under these conditions it was possible to detect the intensity changes of the scattered light in the single detector case, and changes of the spread in the intensity distribution in the multidetector case. With the acquired data, qualitative profiles of the samples were obtained, with promising results. Potential applications in industry are straightforward when surface inspection is necessary to asses product's quality.

Development of experimental setup to study strain/stress state in materials emerges from a need to evaluate by a nondestructive and non-invasive technique the performance in new materials like semiconductor heterostructures, composite materials and alloys. The system was designed and built to be used as a multi-functional experimental setup. The main purpose is to characterize materials in elastic and plastic regime by reflectance difference laser measurements and strain gages. This system allows the generalization of results obtained from a theoretical model based in Finite Element Model and experimental measurements taken in finite specific points with strain gages. A NI™ platform is used for signal conditioning and processing. System built is described which includes an optical setup to measure reflectance difference laser (RDL), and a flexor which applies deformation in a link, with a micrometer. A correlation bigger than 0.95 was found between optical signal, strain gage signal, and finite element modeling.

This work propose an array using a plate λ/4 as a way to get a phase difference equal to zero between the interferometers. Experimental results show that adjusting the orientation angles of the axis of the plate inside the loop, is possible to get the phase shift. Although exist a decreasing in the maxim transmission peak, is possible to reduce the time and difficulty of adjusting and achieve by mean of the temperature the need conditions to the filter tuning.

The Laser Interferometer Gravitational-Wave Observatory (LIGO) has designed to detect Gravitational Waves (GW); its system of detection is based on the Michelson interferometer configuration. When a GW hit on it, the optical elements are disturbed inducing a change in the optical path difference (OPD). The arms length in the detector should be of hundreds of kilometers, due to the small value of the expected GW intensity (h ≈10^-21). This length values are not so easy to achieve because many factors, such as source noise and the profile of the earth. In order to increase the optical path of the beam, LIGO team has implemented a Fabry-Perot cavity in each arm, improving the interferometer response, such as laser amplification and noise reduction. We has build of a prototype of Michelson interferometer for show of a simple way the operation mechanism of the GW detectors and open new researches in this area. Now, we will implement a Fabry-Perot cavity in each arm of our prototype. In this work, we are showed the theoretical features and the simulation of the Fabry-Perot cavity response.

Optical applications of TiO₂ nanoparticles depend directly on their size and phase. The sol gel process is widely used to obtain TiO₂ nanoparticles. We obtained TiO₂ nanoparticles with different sizes by varying the water molar ratio during the sol-gel process. From the asymmetrical shape of the Raman spectrum it is possible to obtain the structural characteristics of the materials. Fitting a Space Correlation Model (SCM) in the LO mode is an alternative way to determinate the crystal size, plus by adding a Crystal Size Distribution (CSD) function in this model, average size fluctuations could be determinate. In this work we present the results obtained by applying the SCM with different phonon dispersion relations and a CSD function in Raman spectra of TiO₂ nanoparticles.

Using a 4f optical system, the Hilbert transform [1] of the projections of the object slice is implemented to reconstruct its edge enhancement using the parallel projection tomography. The projection going out of the object is considered as the entrance to the 4f optical system, the filter employed in the Fourier plane consisting of a phase step of π radians, in the image plane, as it is well known, the output function is given by the convolution of the impulse response and the input function, then in the image plane the Hilbert transform of the projection is obtained. We show that the reconstruction in this case is the Hilbert transform in vertical direction of the slice function, which is a special case. Also study in detail the synthesis of the filter in order to obtain the reconstruction the edge enhanced in an arbitrary direction, which is general case.

In this work, fast and reliable spectroscopic methods in combination with chemometric tools were developed for simultaneous determination of Acetylsalicylic Acid, Acetaminophen and Caffeine in commercial formulations. For the first-order multivariate calibration method (PLS-1), calibration and validation sets were constructed with 23 and 10 samples respectively according to a central composite design. The Micro-Raman, FTIR-HATR and UV absorption spectra in the region of 100-2000 cm^-1, 400-4400 cm^-1 and 200-350 nm, respectively, were recorded. The % REP's (Percentage of relative error of prediction) was less than 18 for all used spectroscopic techniques. Subsequently, commercial pharmaceutical samples were analyzed with percentage of recovery between 90 and 117% for the three compounds.

In this work we present experimental results of the twist-induced birefringence changes for a single-mode erbium-doped fiber with uniform residual birefringence. Two polarimetric methods were used in this study. Both discern evolution of the azimuth and ellipticity angles of the output polarization state. According to these results when the initial residual birefringence is elliptical, the modified optical anisotropy does not enhance its optical activity.

In this work an investigation into the viability of a dual gas sensor based on correlation spectroscopy using a single Fabry-Perot Interferometer (FPI) is presented. Here, based on sensor response simulations, it is demonstrated that the commonly considered undesirable effect due to multiple internal reflections of the FPI's mirror substrate can be used to increase the sensing capability of the system. Usually designers tend to minimize these reflections to improve the FPI transmission spectrum. However we let them to occur in order to used them as a part of the modulation system of the sensor which allows us to detect two gases simultaneously using a single FPI.

Nowadays, the implementation of an accurate non-destructive technique for the measurement of mechanical properties in small samples has become a main subject of interest due to the recent development of MEMS and intelligent materials, which need a safe procedure for their characterization.In this work we study a non-destructive method for determining the Young's modulus of an aluminium circular plate. Our technique is based on Electronic Speckle Pattern Interferometry (ESPI), a mechanical loading setup, and digital processing, which allows to obtain accurate values of Young's modulus for the sample agreeing those values from the literature.

In this study, the opto-mechanical design and functional characterization of a Variable Focal Liquid Length Lens (VFLLL) are presented. This VFLLL is formed by a hydro-pneumatic system, a mount with two elastic membranes and the liquid medium between them. The hydropneumatic system allows the entrance and exit of the liquid at any moment to change the shape of the surfaces as well as the axial thickness of the lens. The functional characterization consists in measure the spherical aberrations present in VFLLL when changes on the amount of liquid medium are made. We used the Zygo interferometer to measure the spherical aberration. The changes of aberration as function of the focal length are shown. Finally the experimental results are presented.

The use of small satellites has opened up new areas of opportunity enabling the use of this technology to solve problems with a high level of confidence at low cost for many areas including the remote sensing area. This paper presents the technical considerations for the design of a multispectral optical imaging system suitable for medium-resolution image acquisition working under the limitations of a small satellite, specifically a nano-satellite (satellite of less than 10Kg). The specifications of this kind of satellite platforms and how this affects the design considerations are discussed. The document describes a proposed design for the system and the applicability and potential use of such development.

Here it is presented a comparison of two calibration techniques applied to a thermistor element used in a surface microcalorimeter which operates under Isoperibol conditions. Usually surface microcalorimeters employ a thermistor as a temperature sensing element, whose heat capacity requires to be evaluated before they can be used. One alternative method to estimate its heat capacity is by supplying a known amount of energy and detecting its temperature changes. Thus, surface heating can be achieved by different techniques; one of them is by supplying energy to the thermistor by passing current through a Ni-Cr coil wined around the glass bulb thermistor. A rather different and more convenient technique consists of directly illuminating a small well-defined thermistor area with an infrared 1550 nm wavelength laser beam, while detecting the thermistor temperature changes. Both procedures are thoroughly compared and the heat capacities obtained by both methods are presented.

Complex concatenated channel waveguides and multimode interference devices have been fabricated by laser ablation of silica-on-silicon substrates for the first time to our knowledge. The technique is based on a tightly focused carbon dioxide laser beam that modifies the refractive index of the area sorrounding the optical waveguide; the process is fast (a few seconds) without any subsequent mechanical or chemical treatment, and the writing speed is about 500 times faster than with UV or femtosecond writing. The results are encouraging for prototyping for the development of an optical sixport device, the equivalent of the widely known microwave technique for amplitude and phase measurements.

We report the fabrication of glass multilayer doped with semiconductor nanoparticles. The glass matrix was fabricated by Plasma Enhanced Chemical Deposition (PECVD using tetramethoxysilane (TMOS) as precursor. The RF power was supplied by a RF-150 TOKYO HI-Power operating at 13.56 MHz and coupled to the RF electrodes through a matching box. The nanoparticles were grown by pulsed laser deposition (PLD) of a PbTe target using the second harmonic of a Q-Switched Quantel Nd:YAG laser in high purity inert gas atmosphere. The influence of gas and background pressure and in the nanoparticle size and size distribution is studied. The morphological properties of the nanostructured material were studied by means of High Resolution Transmission Electron Microscopy(HRTEM), grazing-incidence smallangleX-ray scattering (GISAXS).

An experimental measurement by using Laser Induced Breakdown Spectroscopy (LIBS) and Photoacoustic Induced by Laser Ablation (PILA), in order to monitoring the microcraks formation inside the glass induced by laser pulses is presented in this work. The laser was operated in both single pulse and multi-pulse Q:Switched regime using a passive Cr:YAG crystal as switching element. The LIBS spectra captured inside the glass avoid identifying the sample composition without influence of surrounding atmosphere like occurs if the spectra are obtained on the surface. On the other hand, the PILA signal permits to monitor the process and its dependence from the number and intensity of micro-pulses.

In this work we present the modal study of a dispersion shifted fiber (4 layers) and also in a fabricated long period grating in the same fiber type using the RSoft Software ®. For the grating analysis, the refraction index and the diameters were varied to simulate the changes due to the diameter increment provided by the electrical arc discharges effect. The structural optical fiber change, due to the periodic fattening induced by the electric arc, is added to the grating analysis as a sinusoidal type variation in each optical fiber layer. Several wavelengths are considered for the analysis and some of them are the ones commonly used by operational lasers and diodes launched in optical fibers. Results depicted the existence of many excited light modes when working with a wide spectrum white light source. When these modes satisfy the phase matching condition, they will couple in the LPFG providing it of particular filtering characteristics because of the fiber type and technique (fattening) of fabrication.

Recently [Proc. SPIE 6422, 64220P (2007)] we proposed the construction of electromagnetic and electronic multicavity resonators using chaotic two-dimensional waveguides. In this paper we go one step further and design multidirectional tunable wave resonators. We use waveguides formed by a linear array of coupled cavities whose geometrical parameters are chosen to produce mixed phase space. The islands of stability in the phase space induce the formation of quasi-bound states whose structure in real space determines the directionality of the resonator. To form the waveguide we choose cavities with different geometrical parameters (different phase space), so that different quasi-bound states can be excited in the same waveguide resonator by properly tuning the excitation frequency/energy.

The potential of Nd:YAG pulsed laser to processing PVC sheets minimizing HCl gases emission is investigated. We studied the gas emission when the PVC is cut by either CO2 or Nd:YAG pulsed laser by using FTIR Spectroscopy. Optical microscopy of laser treated PVC samples was performed in order to demonstrate the carbonization. On the other hand, LIBS spectroscopy for two different ranges of pulse duration was employed in order to investigate the plume composition during the Nd:YAG pulsed laser ablation process. The experiments shows that Cl atoms are emitted during the Nd:YAG pulsed laser ablation although the HCl gases are produced at low levels. In order to explain the sub-surface irregularities detected for Nd:YAG laser irradiation, a one-dimensional model is developed to study the temperature evolution inside the sample. We demonstrate that the ablation mechanisms prevail on thermally drive emission until 70 μm, afterwards the thermal expansion process is already observed.

A method is proposed for the design of fundamental mode high power resonators, with joined stability zones. A parameter is created which gives the minimum length a laser resonator should have while having at the same time the broadest stabilities zones. For multimode and large mode volume resonators, a configuration is introduced for maximizing the laser overall efficiency due to the compensation of the astigmatism induced by the flash lamp pumping heating. The later configuration proposes a dual-active medium resonator, with 90 degree rotation around the optical axis between the astigmatic thermal lenses of the mediums. The reliability of this configuration is corroborated experimentally using a Nd:YAG dual-active medium resonator. It is found that in the pumping power range where the astigmatism compensation is possible, the overall efficiency is constant, even when increasing the excitation power with the consequent increase of the thermal lens dioptric power.

We report the changes occurring in cement pastes irradiated by 10.6μm CO₂ laser at different stages of hydration. Raman spectroscopy, X-rays and Scanning Electronic Microscopy (SEM) techniques had been used to observe molecular structural changes. Intensity of cement paste Raman peaks after laser irradiation was monitored in samples irradiated 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11 days after their preparation. Applied laser power changed Raman peaks intensity at 187.5cm^-1, 563cm^-1, 695cm^-1, 750cm^-1, 897cm^-1, 1042cm^-1 and 1159cm^-1 that corresponds to compounds already presents in cement pastes. X ray diffraction and SEM images confirm the recrystalization of cement paste compounds into new phases (alite and belite) after irradiation. The produced changes show a clear dependence on the applied laser power density and age of samples.

This paper proposes the application of a monochromatic wavelength dispersive X-ray fluorescence (MWDXRF) technique developed in the X-ray Optical Systems laboratory Inc. The technique measures low-level sulfur (uls) in fuel. Data for ultra low sulfur in diesel were collected and analyzed using the combination of the mentioned technique and the usage of engineering tools as a fastloop array and a measurement technique. This provides a qualitative method for Diesel sulfur analysis of the Refinery Ing. Antonio M Amor (RIAMA) in Salamanca, Guanajuato. The pooled limit of quantification (PLOQ) for ultra-low-sulfur diesel was found to be less than 1.5 ppm in this study. The reproducibility of 15-ppm sulfur diesel fuel was determined to be better than 3 ppm (95 % confident level). This work shows the performance of the production of Diesel with less than 15-ppm in sulfur lines in the Hydrodesulfurizer Unit of Diesel (HDD) of the refinery. Results and conclusions discusses the better and cheaper method for the production of ultra low sulfur Diesel in the refinery.

An optical set-up was developed to measure transmitted and scattered light in real time using a photodiode array as a detector and tested during starch heating. Statistical parameters calculated were Partial Integrated Scattering (PIS) and variance. Understanding behavior of starch under heat treatment in the presence of water is very important in food industry. The structure of heated starch granule changes depending on different factors like pH, solvent type and amount, enzime presence, amylose/amylopectin relation, etc., such changes has been attempted by using several techniques. In this work, solutions in distilled water of amylopectin, were evaluated. Calcium hydroxide solution was also tested and mixed with previous amylopectin samples to evaluate any interaction in a two-phase system. A close relationship was found between the observed optical signals with literature reported structure changes in starch, demonstrating that the system developed has potential to be used in a real industrial process for monitoring and control.

The search of clean, inexpensive and renewable energy sources is one of the most important challenges that the mankind is currently confronting. Recently there has been a notable interest of the scientific community to develop organic photovoltaic (OPV) technology as a mean of renewable energy source since it combines low-cost and easy fabrication. We have fabricated and tested plastic solar devices (OPVs) by using the bulk heterojunction approach. OPVs were prepared by blending 6-Nitro-3-(E)-3-(4-dimethylaminophenyl)allylidene)-2,3 dihydrobenzo[d][1,3,2]-oxazaborole (M1) and (E)-3-(4-Dimethylaminophenyl)allylidene)-2,3-dihydrobenzo[d]-[1,3,2]oxazaborole (M2), which are conjugated and non-linear low molecular weight molecules prepared in our laboratories, and the well known photoconductor polymer MEH-PPV; fullerene PC₆₁BM was the sensitizer. The morphology of thin polymer films prepared by using the spin coating technique was analyzed by Atomic Force Microscopy (AFM). For the electric contact, commercial and transparent indium tin oxide (ITO) deposited on glass slides was used, and a metal alloy of Pb/Bi/Cd/Sn as cathode, was easily deposited on the polymer film by melting the alloy at 75 °C. Open circuit voltages (Voc) of ~ 700 mV and short circuit currents (J_sc) of ~ 0.75 mA/cm² under solar (AM1.5) illumination were measured for MEH-PPV and M1 based samples. For OPVs cells based on mixtures of either M1 and MEH-PPV or M2 and MEH-PPV there was a large electrical enhancement showing V_oc ~ 700 mV and J_sc ~ 2.0 mA/cm². OPVs cells were also tested under Xe-lamp illumination. Measurements from the I-V curves gave electrical efficiencies close to 1%.