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.

Maturidade pulmonar e fetal de bezerros da raça holandesa preta e branca tecém-nascidos, a termo e hígidos: análise do líquido amniótico

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Correção da deficiência transversa da maxila por meio da expansão rápida da maxila cirurgicamente assistida

Fundamentation: The correction of maxillary transverse deficiencies involves orthodontic and surgical procedures that can be performed before or after skeletal maturity. The surgically assisted rapid maxillary expansion (SAR ME) is performed by osteotomies through the lateral walls of the maxilla, zygomatic and canines buttresses, palatal and pterygomaxillary sutures, causing the maxillary disjunction. Followed by activation of the expander to the desired over-expansion in order to correct intercuspal later. Objective: The purpose of this study was to discuss the issues involved in the diagnosis of maxillary atresia, SAR ME indications, as well as surgical technique, through a case study. Methods: The male patient, 19 years old, had severe transverse maxillary deficiency with facial pattern III , Class III , with great lip incompetence. The patient underwent general anesthesia in a hospital environment, the osteotomies was done according to the technique described by Epker and Wolford (1980). Postoperatively, the patient underwent activations daily for 15 days and after 6 months, the orthodontist installed fixed orthodontic appliance to prepare the patient to orthognathic surgery later. Conclusion: The diagnosis by clinical evaluation and models study is essential for the indication of SAR ME and this procedure provides good predictability in the correction of transverse deficiency, with minimal morbidity.

Marino Del Favero, escultor e entalhador (1864-1943)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

La Casa Nel Vicolo: um romance de Maria Messina à moda do “feuilleton”

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)