Abstract: Most of the whole-field optical methods for vibration measurement have low sensitivity when the points of the studied surface vibrate with the same amplitude. Those techniques also usually require complex and/or expensive solutions which are difficult to implement in engineering processes when the vibration amplitudes are relatively high. In order to overcome those limitations we propose a method for out-of-plane vibration measurement which uses structured light projection. The vibrating surface is obliquely illuminated by straight and parallel interference fringes produced by a Twyman-Green interferometer with a 532-nm laser as light source. In order to enable fringe visualization two techniques were employed, namely, the phase modulation of the fringe pattern by using a vibrating mirror in the interferometer, and a stroboscopic illumination by using a Fabry-Perot etalon amplitude modulator. We demonstrated the technique by measuring the vibration amplitudes of small objects in the millimeter and submillimeter range.

Resumo Uma atividade didática para o estudo teórico e experimental do princípio de funcionamento do telescópio refrator é proposta para cursos de graduação em física, tecnologia e engenharia. Utilizou-se o formalismo matricial para determinar as propriedades do telescópio, como a distância entre as lentes e a magnificação, em função dos comprimentos focais das lentes objetiva e ocular e da distância objeto-telescópio. Na parte experimental, foi montado um arranjo com o telescópio em si e um olho artificial, composto de uma lente positiva como cristalino e um anteparo plano como retina. A magnificação foi medida diretamente da retina do olho artificial e comparada, à luz dos cálculos de propagação de incertezas, com medidas obtidas com o auxílio de expressões extraídas do método matricial.

Abstract A didactical activity aiming the theoretical and experimental study of the refractive telescope is proposed for undergraduate physics, technology and engineering courses. The matrix method was used for determining the telescope properties like distance between the lenses and magnification, as a function of the lenses focal lengths and the distance between the object and the telescope. In the experiments the optical setup was comprised by the telescope itself and an artificial eye, which in turn is comprised by a positive lens as the eye lens and a planar screen as the retina. The magnification was directly measured from the retina and compared with the measurements obtained with the help of the equations retrieved from the matrix method, concerning the uncertainty propagation.

The filtering hydrocyclone is a solid-liquid separation device patented by the Chemical Engineering Department at the Federal University of Uberlândia, which consists of a hydrocyclone whose conical section was replaced by a conical filtering wall. The objective of this work is to compare the performances of the filtering hydrocyclones designed by Bradley and by Rietema. The experimental results obtained with the filtering hydrocyclones under the same operational conditions as those used with the conventional device allow the conclusion that performance of the Bradley and Rietema types is significantly influenced by the filtering medium. Rietema's filtering hydrocyclones had a lower volumetric feed flowrate than the conventional device and Bradley's filtering hydrocyclones showed increases in this same variable. In both designs, overall efficiency was influenced by the underflow-to-throughput ratio.