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| Author(s): |
Marcus Paulo Raele
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Pesquisas Energéticas e Nucleares (IPEN/BT) |
| Defense date: | 2013-11-18 |
| Examining board members: |
Anderson Zanardi de Freitas;
Adriano Mesquita Alencar;
Anderson Stevens Leonidas Gomes;
Gessé Eduardo Calvo Nogueira;
Nicolau Andre Silveira Rodrigues
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| Advisor: | Anderson Zanardi de Freitas |
| Abstract | |
Optical Coherence Tomography also largely known as the acronym OCT, is a technique developed to generate transversal sections images of light scattering media. Based on optical interferometry, it provides images correlated to histological images with the advantages of being not invasive, painless besides and does not use ionizing radiation. This study was divided into two separate goals; one refers to the application of interferometric autocorrelation signals for forming images of samples with complex structures. The second objective was the study of structures called harmonics and its application in increasing the axial resolution of an OCT system. Regarding the first part, it was found that the interferometric autocorrelation signal is often ignored or discarded by traditional OCT. Further analysis of the theory of interferometry, along with some previous studies have pointed to the possibility of generating images of greater morphological complexity using the signal autocorrelation, with the advantage of using a simplest optical arrangement and also allow static images of samples in axial movement. To test the benefits and limitations of the autocorrelation technique (Au-OCT) a setup was assembled in and images of samples were performed at rest and in motion and compared with images generated in conventional OCT system. The system Au-OCT was able to generate images of several structures (teeth, plastic films etc.), and despite having a lower image quality to the OCT, it presented advantages when the sample undergoes axial motion. Regarding the harmonic characteristics that are present in samples of high optical reflectivity as false structures in OCT images, a whole study to the understanding of the phenomenon was developed. Also demonstrated the possibility of using these structures to enhance the differential axial resolution (structures between the sample itself) using a numerical and experimental study. Dimensional standards step height like were measured and results handled according to metrological procedures, showing that the harmonics can be used to promote the increase of axial resolution by a factor of about two. Finally a critical analysis of the results and a discussion of perspectives of the topics discussed were performed. (AU) | |
| FAPESP's process: | 09/13764-3 - Development of autocorrelation optical coherence tomography technique for biomedical applications |
| Grantee: | Marcus Paulo Raele |
| Support Opportunities: | Scholarships in Brazil - Doctorate |