No description available.

Banca: Amílcar Careli César / Banca: Josemir Coelho Santos / Banca: Marco Isaías Alayo Chávez / Banca: Aparecido Augusto de Carvalho / Banca: Ricardo Tokio Higuti / Resumo: Neste Texto Sistematizado, o candidato a Livre Docente expõe os principais resultados alcançados em sua trajetória após o doutorado, em termos de atividades de ensino, extensão, administrativas e de pesquisa. Ênfase especial é destinada à análise crítica das atividades de pesquisa e orientação de dissertações e teses junto ao Programa de Pós-Graduação em Engenharia Elétrica - PPGEE, da FE-IS UNESP. O enfoque principal da pesquisa refere-se à proposição teórica e experimental de novas técnicas de detecção de fase óptica empregando-se interferometria laser, e suas aplicações na medição de deslocamentos microscópicos, na caracterização de atuadores piezoelétricos flextensionais e em medições de tensões elétricas elevadas. A motivação para a realização da pesquisa, a exposição dos desafios e as soluções propostas são discutidas. Inserções em outras áreas, que envolvam sensores e sistemas ópticos, bem como, a cooperação com grupos de pesquisas afins, internos e externos à FE-IS UNESP, são apresentadas. No final, discutem-se as pesquisas atuais e as perspectivas futuras

Synthetic aperture radar interferometry (InSAR) is a technique that enables generation of Digital Elevation Models (DEMs) and detection of surface motion at the centimetre level using radar signals transmitted from a satellite or an aeroplane. Deformation observations can be performed due to the fact that surface motion, caused by natural and human activities, generates a local phase shift in the resultant interferogram. The magnitude of surface deformation can be estimated directly as a fraction of the wavelength of the transmitted signal. Moreover, differential InSAR (DInSAR) eliminates the phase signal caused by relief to yield a differential interferogram in which the signature of surface deformation can be seen. Although InSAR applications are well established, the improvement of the interferometry technique and the quality of its products is highly desirable to further enhance its capabilities. The application of InSAR encounters problems due to noise in the interferometric phase measurement, caused by a number of decorrelation factors. In addition, the interferogram contains biases owing to satellite orbit errors and atmospheric heterogeneity These factors dramatically reduce the stlectiveness of radar interferometry in many applications, and, in particular, compromise detection and analysis of small-scale spatial deformations. The research presented in this thesis aim to apply radar interferometry processing to detect small-scale surface deformations, improve the quality of the interferometry products, determine the minimum and maximum detectable deformation gradient and enhance the analysis of the interferometric phase image. The quality of DEM and displacement maps can be improved by various methods at different processing levels. One of the methods is filtering of the interferometric phase. / However, while filtering reduces noise in the interferogram, it does not necessarily enhance or recover the signal. Furthermore, the impact of the filter can significantly change the structure of the interferogram. A new adaptive radar interferogram filter has been developed and is presented herein. The filter is based on a modification to the Goldstein radar interferogram filter making the filter parameter dependent on coherence so that incoherent areas are filtered more than coherent areas. This modification minimises the loss of signal while still reducing the level of noise. A methodology leading to the creation of a functional model for determining minimum and maximum detectable deformation gradient, in terms of the coherence value, has been developed. The sets of representative deformation models have been simulated and the associated phase from these models has been introduced to real SAR data acquired by ERS-1/2 satellites. A number of cases of surface motion with varying magnitudes and spatial extent have been simulated. In each case, the resultant surface deformation has been compared with the 'true' surface deformation as defined by the deformation model. Based on those observations, the functional model has been developed. Finally, the extended analysis of the interferometric phase image using a wavelet approach is presented. The ability of a continuous wavelet transform to reveal the content of the wrapped phase interferogram, such as (i) discontinuities, (ii) extent of the deformation signal, and (iii) the magnitude of the deformation signal is examined. The results presented represent a preliminary study revealing the wavelet method as a promising technique for interferometric phase image analysis.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains v, 81 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 80-81).

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 85-88).

No description available.

This work examines a novel method of dynamic single frame interferometry. In this dynamic approach to phase shifting measurements, steps are taken to combat performance degradation due to environmental factors such as air turbulence and vibration. We explore the system functionality and performance, and examine some of the limiting factors using this technique such as effects due to imperfect system components, irradiance variations and sensitivity of the instrument accuracy based on calculation methodology. We present the errors associated with these various aspects of the system and show the majority cause phase calculation errors less than 0.005λ P-V to the calculated wavefront. This new approach involves the placement of a micropolarizer phase-shifting array directly onto a CCD camera which allows the construction of a dynamic single frame interferometric system. Hardware and manufacturing preparations such as inspection, positioning and alignment are discussed. Experimental results of system performance are combined with mathematical simulations to provide a performance baseline. We present experimental results showing the effects of averaging on measurement data, which results in a reduction of fringe print-through errors associated with a combination of many of the system error sources.

No description available.

The use of dichromated gelatin (DCG) for the formation of holographic optical elements is investigated. In particular, a study is made of the possible sources of spurious recording and replay in such diffracting media. The formation of spurious gratings due to boundary mismatch, when recording a transmission grating in air, is investigated. Experimental results are treated using a simple linear theory which is capable of predicting the relative modulation strengths of each of six recorded gratings. The efficiencies of each of these gratings is related to Fresnel's Laws of reflection and therefore the beam ratio. A brief experimental study of the beam ratio is made. It is found that linear theories do not explain replay of gratings recorded at high exposure energies. This is because DCG exhibits a saturating recording characteristic. A theoretical model is developed to verify experimental results of modulation versus exposure energy for the recording of single and double exposure transmission gratings and their subsequent harmonics. This gives good agreement for most cases, however, it does not explain fully the replay of a difference grating formed due to nonlinearities in the double exposure hologram. A coupled wave theory is therefore developed to take account of both multiple grating interactions between the two primary recordings and the recording of a third grating with a spatial frequency equal to the difference of the two fundamental frequencies. The model gives good agreement with experimental results for varying replay angles and wavelengths. DCG is finally used as a tool to investigate the formation of noise gratings in silver halide emulsions. In particular, results are presented for experiments which were performed to study the effect of high angular scatter upon the selectivity of the noise grating and the recording of reflection noise gratings.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: MEMS characterization; stroboscopic illumination; interferometry; phase modulation. Includes bibliographical references (leaves 97-104).