Revista elektron

7-11

Authors: Carlos Carreño Romano, German Perez Fogwill, Guillermo D. Santiago, Martin G. Gonzalez

We present a new photoacoustic gas-trace measurement setup, based on a chirped optical chopper. This method combines features of the resonant and pulsed techniques. To show the advantages of this setup, we carried out a comparison with the resonant method in samples of NO2 contained in a one-dimensional acoustic resonator. The results show the chirped technique allows carrying out short-term acquisitions with good signal-to-noise ratio.

16-25

Authors: Liliana Inés Perez, Francisco Ezequiel Veiras

One of the most used tools in optics is ray tracing, due to the fact that is a fundamental tool for optic instruments design. In this work we analyze the successive deformations that both cylindrical and conical beams suffer when they impinge normal to a uniaxial crystal plane-parallel plate and go through the different interfaces. This is accomplished by following the path of each incident ray on the first interface. The ray tracing for the ordinary beam is the same as in isotropic media, but the extraordinary beam ray tracing is more difficult, for these rays are no longer contained in the incidence plane and their directions are different from those of the corresponding normals to the wavefront. We also analyze the loss of revolution symmetry of the beams and the image formation.

30-38

Authors: Inga Leonie Rittner, Walter Gustavo Fano

This article presents an implementation of the transmission/reflection line method to determine the intrinsic electromagnetic properties of unknown materials with relative magentic permeability not equal to one. With a vector network analyser (VNA) the forwardand back-scattered energy are measured to simultaneously extract the electric permittivity and magenetic permeability. The classic Nicolson-Ross-Weir extraction technique in frequency domain is explained in detail and presented such that the equations can be easily implemented by open-source post-processing with GNU Octave. The shift in phase reference planes and connector calibration measurements are performed such that a very low-cost VNA without de-embedding function can be used. A coaxial transmission line with N type female connectors is used providing a low-cost, easy to manufacture solution of a sample holder. The measurement procedure is valid from 2 MHz to 6 GHz, whereas the preliminary results are shown in the GHz range from 1 to 6 GHz. The article also comments on the sample preparation especially the thickness of the material slab.