Mikiya Muramatsu

Single-exposure, photorefractive holographic surface contouring with multiwavelength diode lasers.

We studied the use of multiwavelength diode lasers for surface profilometry through holographic recording in sillenite Bi12TiO20 crystals. When such lasers are used, the holographic image from single-exposure recordings appears covered with interference fringes providing information on the surface relief of the object. By taking advantage of the narrow interference fringes due to the multiwavelength emission of the laser, we obtained interferograms by holographic recording with two reference beams, which improves the surface analysis by visual inspection and enhances the profilometry sensitivity.

Mastication effort study using photorefractive holographic interferometry technique

The purpose of this work was the force-displacement response analysis of the masticatory process in a dried human skull by Double-Exposure Photorefractive Holographic Interferometry Technique (2E-PRHI). The load concentration and dissipation of the forces from dried human skull were analysed at applied loading stands as a Simulation of Isolated Contraction (SIC) of some mastication muscles. The 2EHI and Fringe Analysis Method were used to obtain the quantitative results of this force-displacement response. These results document quantitatively the real biomechanical response from dried human skull under applied loading and it can be used for complementary study by finite element model and others analysis type.

Phase-shifting real-time holographic interferometry applied to load transmission evaluation in dried human skull

Phase-shifting real-time holography with photorefractive Bi(12)SiO(20) crystal as holographic recording medium applied to load transmission evaluation and tension dissipation on a dried human skull under loading is presented. The applied loading stands as a simulation of isolated contraction (SIC) of some masticatories muscles. The four-frames phase-shifting technique and the unwrapping branch-cut technique were used to obtain the phase map. The quantitative results show the feasibility of the employed system in the study of microdisplacements in the skull structure provided by SIC.

Enhanced multiwavelength holographic profilometry by laser mode selection

A method for improving the accuracy of surface shape measurement by multiwavelength holography is presented. In our holographic setup, a Bi 12 TiO 20 photorefractive crystal was the holographic recording medium, and a multimode diode laser emitting in the red region was the light source in a two-wave mixing scheme. On employing such lasers the resulting holographic image appears covered with interference fringes corresponding to the object relief, and the interferogram spatial frequency is proportional to the diode lasers free spectral range (FSR). Our method consists in increasing the effective free spectral range of the laser by positioning a Fabry-Perot etalon at the laser output for mode selection. As larger effective values of the laser FSR were achieved, higher-spatial-frequency interferograms were obtained and therefore more sensitive and accurate measurements were performed. The quantitative evaluation of the interferograms was made through the phase-stepping technique, and the phase map unwrapping was carried out through the cellular-automata method. For a given surface, shape measurements with different interferogram spatial frequencies were performed and compared with respect to measurement noise and visual inspection.

Mapping of vibration amplitudes by time average holography in Bi12SiO20 crystals

Abstract We report the performance of a holographic set-up with a Bi12SiO20 (BSO) photorefractive crystal for measuring vibration amplitudes in a time average holography system. The volume hologram is recorded with the 514.5 nm wavelength of an Ar+ laser. In this set-up the reference beam is sinusoidally phase-modulated with the same frequency of the vibrating object. By increasing the value of the phase modulation, the fringes of the time average pattern run along the object surface, so that the vibration amplitude mapping is carried out. This technique allows the improvement of the measurement sensitivity compared with conventional time average holography, even for interferograms with poor visibility.

Holographic interferometry method for assessment of static load stress distribution in dog mandible

This study compared the transmission of tensions in fresh, fixed and macerated dog mandibles in order to clarify the diversity of behavior of bone tissues under dry and moist conditions. Double-exposure holographic interferometry was applied and holograms were obtained from 12 fresh hemi-mandibles under static load (control group), which were randomly assigned to 2 groups: 6 were fixed in 10% formalin and 6 were macerated. The specimens were submitted to the same initial force and their respective holograms were obtained. Analysis of the holograms showed that the fresh specimens transmitted significantly less tension than the fixed and macerated ones (p<0.05), and the tension direction was different. An average two-fold tension increment was observed in the experimental conditions. The holographic interferometry method was efficient in quantifying and qualifying tension transmission. However, depending on the type of analysis, the anatomical specimens must be fresh because macerated specimens will produce different results.

O fenômeno do speckle como introdução à metrologia óptica no laboratório didático

In this work we present the measurement of the linear coefficient of thermal dilatation of aluminium, using the obtained interferogram from Fourier transform over the sum of two displaced speckle images. The achieved result is in good agreement with tabled value and the required components have an accessible cost, turning the experiment an interesting alternative for introduction of optical metrology in teaching laboratory or a project to be developed in experimental subjects.

Haciendo hologramas en la escuela y en la casa

La comunidad cientifica que se ocupa de los problemas relacionados con el proceso de ensenanza-aprendizaje de la fisicas, ha dedicado muchos esfuerzos en los ultimos anos al perfeccionamiento del mismo, motivado en primera instancia, por las demandas de renovacion que el impetuoso desarrollo cientifico-tecnico le impone en la actualidad a la ensenanza de las ciencias. En los ultimos anos se ha producido un desarrollo vertiginoso en la fabricacion de diodos laser que emiten en el espectro visible, esto ha permitido su utilizacion creciente en multiples aplicaciones y hace factible su utilizacion en la ensenanza aprendizaje de la fisica universitaria y en particular de la holografia, por sus grandes ventajas frente a los laseres convencionales de gran costo y dificil manipulacion. En el trabajo se describen la instalacion experimental portatil disenada para la obtencion de hologramas en la escuela y en la casa con la utilizacion de diodos laser, la metodologia de trabajo a seguir, los metodos de procesamiento utilizados para diferentes tipos de emulsiones holograficas y un analisis de los defectos que pueden presentar los hologramas producidos y la forma de detectarlos y erradicarlosDepartamento de Fisica, Instituto Superior Politecnico Jose Antonio Echeverŕia, Ciudad de la Habana, Cuba Instituto de Fisica, Universidade Estadual de Campinas, Campinas SP, Brasil Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, SP, Brasil Departamento de Ciencias Basicas, Facultad de Ingenieŕia, Universidad Libre de Colombia, Bogota, Colombia Recebido em 28/10/2009; Aceito em 11/12/2009; Publicado em 17/2/2011

Stress analysis of fresh, fixed and macerated dog mandibles. Holographic interferometric double exposition method

In this work we studied some of the main effects of the bone tissue behaves in different ways according to dry or humid conditions, this research intended to evaluate stress transmission in dog mandibles, through holographic interferometric, in such conditions: fresh, formalin fixed and macerated. The experimental set up was made to get holograms at same place, to view a distribution of fringe at the jaw of dog. The deformation was find less on the presence of periodontal ligament in the fresh samples made the tooth and bone behave as distinct structures, while the fixed and macerated samples, bone and teeth behave as a rigid body. The macerated and fixed hemi-mandibles suffered more torsion during displacement than the fresh ones.

Digital speckle correlation for nondestructive testing of corrosion

This paper describes the use of optical correlation speckle patterns to detect and analyze the metallic corrosion phenomena, and shows the experimental set-up used. We present some new results in the characterization of the corrosion process using a model based in electroerosion phenomena. We also provide valuable information about surface microrelief changes, which is also useful in numerous engineering applications. The results obtained are good enough for showing that our technique is very useful for giving new possibilities to the analysis of the corrosion and oxidation process, particularly in real time.