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Author: search.filters.author.Duchowicz, RicardoHas files: Yes

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    Improved spectral resolution in time-varying interferometry
    (2018-11) Antonacci, Julian; Morel, Eneas Nicolás; Torga, Jorge Román; Duchowicz, Ricardo; Arenas, Gustavo
    In this work, we present a procedure that allows increasing the resolution of dynamic length measurements made by spectral interferometry. The proposed scheme leads to obtaining a compact photonic instrument with the ability to measure distances, variations on positions and vibrations with a very high resolution. This measurement system includes a superluminescent source (SLED), a digital spectrometer and a Fizeau interferometer. Spectral data is processed by applying Fourier domain techniques previously applied in optical coherence tomography. The resolution of the spectral measurement system is determined by the spectrometer bandwidth and the light source employed. A signal is obtained by analysing the time evolution of a single pixel from the spectrometer CCD sensor, which is later analysed using time domain interferometry (TDI) techniques. This procedure works by detecting changes in the optical path below those that can be detected by spectral analysis. The original resolution obtained with the solely spectral techniques was 2.2 µm but was improved to 40 nm by complementary analysis of temporal signals.
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    Interferometric system based on swept source-optical coherence tomography scheme applied to the measurement of distances of industrial interest
    (2015-12-11) Morel, Eneas Nicolás; Russo, Nélida A.; Torga, Jorge Román; Duchowicz, Ricardo
    We used an interferometric technique based on typical optical coherence tomography (OCT) schemes for measuring distances of industrial interest. The system employed as a light source a tunable erbium-doped fiber laser of ∼20-pm bandwidth with a tuning range between 1520 and 1570 nm. It has a sufficiently long coherence length to enable long depth range imaging. A set of fiber Bragg gratings was used as a self-calibration method, which has the advantage of being a passive system that requires no additional electronic devices. The proposed configuration and the coherence length of the laser enlarge the range of máximum distances that can be measured with the common OCT configuration, maintaining a good axial resolution. A measuring range slightly >17 cm was d0.etermined. The system performance was evaluated by studying the repeatability and axial resolution of the results when the same optical path difference was measured. Additionally, the thickness of a semitransparent medium was also measured.
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    Spectral sensor resolution measurement improvements by temporal analysis
    (IEEE Xplore, 2017-12-18) Antonacci, Julian; Morel, Eneas Nicolás; Torga, Jorge Román; Duchowicz, Ricardo; Arenas, Gustavo F.
    In this work we present time domain interferometry (TDI) and spectral domain interferometry (SDI) techniques applied to a fiber optic Fizeau interferometer sensor. This class of sensor is capable of measuring parameters such as position, length and vibrations, in the spectral domain with improved resolution by a temporal analysis. In particular, Fourier domain SDI (FD-SDI), is able of measuring absolute cavity lengths with a resolution of 10 μm typically, depending on the bandwidth of the optic source and the spectrometer. Alternatively, TDI allows making displacement measurements within a resolution of λ/10, depending on the laser light wavelength (λ) used.
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    Dimensional characterization of large opaque samples and microdeformations by low coherence interferometry
    (2020-01-25) Torga, Jorge Román; Morel, Eneas Nicolás; Russo, Nélida A.; Duchowicz, Ricardo
    We report on the application of an interferometric system based on the low-coherence interferometry technique to the dimensional characterization of large opaque mechanical parts as well as microdeformations experienced by them. The implemented scheme is capable of simultaneously measuring very small deformations and relatively large dimensions or thicknesses (several centimeters) of the sample. By applying the chirp Fourier transform algorithm, it was possible to measure changes in thickness with an uncertainty of 0.35  μm when a 7-cm-thick sample was measured. The measurement scheme was implemented in optical fiber, which makes it highly adaptable to industrial conditions. It employs a tunable light source and a Sagnac–Michelson configuration of the interferometric system that allows the thickness of the opaque sample and the topography of both faces to be obtained simultaneously. The developed system can be used to perform profilometry of opaque samples and to analyze the dimensional behavior of mechanical pieces in production lines or under mechanical efforts capable of introducing some deformations on them. This feature enables the system to perform quality control in manufacturing processes.