Michelson interferometer vibrometer using self-correcting synthetic-heterodyne demodulation

Synthetic-heterodyne demodulation is a useful technique for dynamic displacement and velocity detection in interferometric sensors, as it can provide an output signal that is immune to interferometric drift. With the advent of cost-effective, high-speed real-time signal-processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. In synthetic heterodyne, to obtain the actual dynamic displacement or vibration of the object under test requires knowledge of the interferometer visibility and also the argument of two Bessel functions. In this paper, a method is described for determining the former and setting the Bessel function argument to a set value, which ensures maximum sensitivity. Conventional synthetic-heterodyne demodulation requires the use of two in-phase local oscillators; however, the relative phase of these oscillators relative to the interferometric signal is unknown. It is shown that, by using two additional quadrature local oscillators, a demodulated signal can be obtained that is independent of this phase difference. The experimental interferometer is aMichelson configuration using a visible single-mode laser, whose current is sinusoidally modulated at a frequency of 20 kHz. The detected interferometer output is acquired using a 250 kHz analog-to-digital converter and processed in real time. The system is used to measure the displacement sensitivity frequency response and linearity of a piezoelectric mirror shifter over a range of 500 Hz to 10 kHz. The experimental results show good agreement with two data-obtained independent techniques: the signal coincidence and denominated n-commuted Pernick method.

Diffusive random laser modes under a spatiotemporal scope

At present the prediction and characterization of the emission output of a diffusive random laser remains a challenge, despite the variety of investigated materials and theoretical interpretations given up to now. Here, a new mode selection method, based on spatial filtering and ultrafast detection, which allows to separate individual lasing modes and follow their temporal evolution is presented. In particular, the work explores the random laser behavior of a ground powder of an organic-inorganic hybrid compound based on Rhodamine B incorporated into a di-ureasil host. The experimental approach gives direct access to the mode structure and dynamics, shows clear modal relaxation oscillations, and illustrates the lasing modes stochastic behavior of this diffusive scattering system. The effect of the excitation energy on its modal density is also investigated. Finally, imaging measurements reveal the dominant role of diffusion over amplification processes in this kind of unconventional lasers. (C) 2015 Optical Society of America

Farmacocinética pré-clínica e avaliação toxicológica do novo composto α2-adrenérgico 3-(2-cloro-6-fluorobenzil)-imidazolidina-2,4-diona - PT-31 GIRSUPAN

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Epidemiological profile of hepatitis C virus infection in patients from west region of Minas Gerais State, Brazill

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Importância da avaliação hematológica e sorológica (dot-blot ELISA) no diagnóstico de erliquiose em cães

This study compared the hematological and serological analysis of diagnosis of canine ehrlichiosis. The survey of Ehrlichia canis was performed through the evaluation of blood smears from 150 dogs. The serological test was performed on 12 samples selected by the platelet count (less than 170,000 platelets / uL). Serologic testing was performed with the Imunocomb kit - Dot-blot-ELISA. No cytoplasmatic inclusion characteristic of morula of E. canis was found in blood smears. In serologic testing, eight samples were positive for Ehrlichia canis, concluding that thrombocytopenia is an important hematological finding of ehrlichiosis diagnosis and the detection of Ehrlichia canis morulae is uncommon. The serological evaluation Dot-blot ELISA is an accurate and brief diagnosis method of canine ehrlichiosis, been the most appropriate to be used in veterinary practice routine.

Validation of a HPLC method for determination of glutamine in food additives using post-column derivatization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Aplicação de técnicas de processamento e análise de imagens para detecção de edificações e vegetação a partir de dados LiDAR

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Detecção do peptídeo p17 (HIV) baseado em SERS (Surface-enhanced Raman Spectrosocpy)

Pós-graduação em Química - IQ

Caracterização clínica epidemiológica e geográfica da hanseníase em município hiperendêmico do Brasil

Pós-graduação em Saúde Coletiva - FMB