Tomografia ótica computadorizada VIS/IR

Abstract

The present work studies the application of optical techniques to obtain tomographic images in opaque media in the visible spectrum region, but translucent in some regions of the infrared IR spectrum. The objective is to verify the feasibility of generating digital volumetric models of real objects immersed in opaque media, using infrared radiation at MIR (Mid-Infrared) and FIR (Far Infrared) regions. This work applied concepts of geometric and wave optics, concepts about IR radiation, principles of the interaction of IR radiation with matter and IR spectroscopy. In addition to optics, studies on computer networks, embedded systems, circuits amplifiers and, mainly, on computed tomography were necessary for the development of this research. The applied tomographic technique was based on the reconstruction algorithm Backprojection and reconstructs three-dimensional surfaces from multiple cross-sections. A mechanical assembly was constructed to provide rotational movement to the sample during tomographic scanning. With the system constructed, three regions of the electromagnetic spectrum were tested, one in visible light, and the other two regions in the infrared, first in the range of 8 to 12mm and the other centered in 4mm. When the proportions were saved, the results found in the three regions were promising, with three-dimensional reconstructions in the first two and detectability of the signal using a point sensor in 4mm. The study showed that by applying the technologies dimensioned to the problem, it is perfectly possible to make tomographic reconstructions in strongly absorbent and scattering media, such as petroleum, by appropriating low absorption characteristics in specific spectral windows.