Search the digital library catalog

Abstract: This article presents an all-fiber, miniature Fabry-Perot gas sensor based on photothermal absorption spectroscopy with a custom-made and cost-efficient interrogation system. The sensing gas microcell has a diameter of 125 μ m and a length of 1 mm, and allows for free gas exchange within the optical resonator through micromachined slits. High light intensity and confinement are ensured by delivering the excitation light directly into the gas microcell through a lead-in single-mode fiber. This enhances the photothermal effect and provides a short system response time. The interrogation system utilizes the modulation of an excitation laser diode with a fixed frequency while locking the probe laser onto the gas microcell’s quadrature point (QP) and observing the variations of the reflected optical power. To show the potential of the proposed system, nitrogen dioxide (NO2 was measured in dry air. Thereby, a limit of detection of 20 ppm could be achieved for 10 s integration time. Furthermore, the small dimensions of the sensor allow for improved dynamic performance with photothermal modulation frequencies as high as 7 kHz.
Keywords: Fabry–Perot interferometer, FPI, fiber gas cell, fiber gas sensor, nitrogen dioxide, NO2, photothermal effect
Published in DKUM: 29.08.2024; Views: 96; Downloads: 11
Full text (15,77 MB)

Abstract: This paper presents a fiber optic sensor for the detection of corrosion processes that occur on metal surfaces. In the proposed sensor design, a sensing fiber with an inscribed high-order Bragg grating is attached to the observed metal surface. A broadening of high-order Bragg grating spectral characteristics is observed and used to detect small and highly localized longitudinal strain variations that occur along the fiber as a result of corrosive rust flakes' formations beneath the sensing fiber. The proposed approach provides a straightforward fabrication method, the possibility for unobtrusive mounting, including mounting of the sensor beneath the corrosion-protective layers, and consistent corrosion detection yields.
Keywords: optical fiber sensors, corrosion, impact of corrosion, optic sensors
Published in DKUM: 09.02.2024; Views: 320; Downloads: 21
Full text (1,58 MB)
This document has many files! More...

Abstract: This paper presents a miniature, all-silica, flow-injection sensor. The sensor consists of an optical fiber-coupled microcell for spectral absorption measurements and a microfluidic reagent injection system. The proposed sensor operates in back reflection mode and, with its compact dimensions, (no more than 200 µm in diameter) enables operation in small spaces and at very low flow rates of analyte and reagent, thus allowing for on-line or in-line colorimetric chemical sensing.
Keywords: optical fiber sensor, spectral absorption microcell, colorimetry
Published in DKUM: 31.07.2023; Views: 457; Downloads: 22
Full text (4,40 MB)
This document has many files! More...

Abstract: This Letter describes a miniature Fabry–Perot, contactless, magneto-optic sensor for angular position measurement. The sensor utilizes a magneto-optic fluid comprising barium hexaferrite nanoplatelets that become birefringent in the presence of an external magnetic field and a compact fiber-optic sensor system for tracking the liquid’s optical axis direction. An efficient temperature compensation system is provided which allows the use of otherwise highly temperature-sensitive magneto-optic liquids. An unambiguous measurement range of 90° and a resolution of better than 0.05° are demonstrated experimentally.
Keywords: Fiber optic sensor, magneto-optic sensor, angular position measurement
Published in DKUM: 12.05.2023; Views: 623; Downloads: 86
Full text (3,76 MB)
This document has many files! More...

Abstract: Diplomsko delo opisuje realizacijo linearnega polja fotodetektorjev, ki se bo uporabljalo za spektralno razločanje optičnih vlakenskih senzorjev. Sistem temelji na uklonski mrežici, ki projicira posamezne spektralne komponente vpadne svetlobe na linearno polje fotodetektorjev. Projekcija z uporabo ustreznih algoritmov omogoča rekonstrukcijo spektra vpadne svetlobe, prav tako pa sistem omogoča nadaljnjo obdelavo signalov z namenom izluščevanja merjene veličine iz zajetega spektra. Realiziran optični spektrometer ne vsebuje gibljivih delov in predstavlja cenovno učinkovito rešitev za spektralno razločanje optičnih vlakenskih senzorjev, kot je npr. Fabry-Perotov interferometer.
Keywords: linearno polje, optični spektrometer, optični vlakenski senzorji
Published in DKUM: 25.10.2022; Views: 544; Downloads: 77
Full text (3,95 MB)