Examinando por Autor "Uribe-Patarroyo, Nestor"

Mostrando 1 - 2 de 2
  • No hay miniatura disponible
    Ítem
    Lab-made accessible full-field optical coherence tomography imaging system
    (Sociedad Espanola de Optica, 2019-09-01) Cuartas-Velez, Carlos; Ruiz-Lopera, Sebastian; Uribe-Patarroyo, Nestor; Restrepo, Rene; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    In this work, an easy to understand optical system was developed for the study of the medical imaging technique optical coherence tomography (OCT). This technique allows volumetric reconstruction of inhomogeneous, non-transparent and scattering samples such as biological tissues. The implementation was based on using non-specialized components for OCT under the scheme of a Michelson interferometer with a CCD camera to capture the interference patterns in a configuration known as full field OCT (FFOCT). Our system, explained in detail, was designed using components commonly found in most optical labs because our focus is to provide an accessible experimental setup for understanding the basics of OCT. The developed system possesses an axial resolution of 1.74 mu m and a lateral resolution of 4.5 mu m. With the described system, tomograms of two samples were obtained: a metal coin and an ex-vivo insect wing of the blattodea family.
  • No hay miniatura disponible
    Ítem
    Noise and bias in optical coherence tomography intensity signal decorrelation
    (OPTICAL SOC AMER, 2020-04-15) Uribe-Patarroyo, Nestor; Post, Anouk L.; Ruiz-Lopera, Sebastian; Faber, Dirk J.; Bouma, Brett E.; Universidad EAFIT. Departamento de Ciencias Básicas; Óptica Aplicada
    Functional optical coherence tomography (OCT) imaging based on the decorrelation of the intensity signal has been used extensively in angiography and is finding use in flowmetry and therapy monitoring. In this work, we present a rigorous analysis of the autocorrelation function, introduce the concepts of contrast bias, statistical bias and variability, and identify the optimal definition of the second-order autocorrelation function (ACF) g((2)) to improve its estimation from limited data. We benchmark different averaging strategies in reducing statistical bias and variability. We also developed an analytical correction for the noise contributions to the decorrelation of the ACF in OCT that extends the signal-to-noise ratio range in which ACF analysis can be used. We demonstrate the use of all the tools developed in the experimental determination of the lateral speckle size depth dependence in a rotational endoscopic probe with low NA, and we show the ability to more accurately determine the rotational speed of an endoscopic probe to implement NURD detection. We finally present g((2))-based angiography of the finger nailbed, demonstrating the improved results from noise correction and the optimal bias mitigation strategies. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement