Iskanje po katalogu digitalne knjižnice

Opis: 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.
Ključne besede: Fabry–Perot interferometer, FPI, fiber gas cell, fiber gas sensor, nitrogen dioxide, NO2, photothermal effect
Objavljeno v DKUM: 29.08.2024; Ogledov: 96; Prenosov: 10
Celotno besedilo (15,77 MB)

Opis: Magistrsko delo obsega dva dela, teoretični in praktični del. Opisana je izdelava senzorja za zaznavanje raztezkov na osnovi Michelsonovega interferometra z dvema laserskima diodama. Nadalje so v delu predstavljene tudi simulacije, izbira komponent, uporabljene naprave, rezultati in smernice za razvoj nadaljnjih senzorskih sistemov, baziranih na Michelsonovem interferometru.
Ključne besede: Optično vlakno, Michelsonov interferometer, laserska dioda, mikrokrmilnik, Goertzelov algoritem, valovna dolžina, procesiranje signalov, LabView, merilni sistem, temperaturna kompenzacija, fotodioda, senzor raztezka
Objavljeno v DKUM: 16.12.2021; Ogledov: 943; Prenosov: 158
Celotno besedilo (4,02 MB)

Opis: In the master thesis, we have created an interrogation system for measuring the change of the optical path in the Fabry-Perot interferometer caused by the strain of the surface at which it was attached to. The change of strain can be calculated via a change in optical path length which is visible as a shift in phase angle. The system will be used as a system for measuring strain, although it can be used for measuring various physical parameters that can cause a change in optical path length, such as pressure, force, temperature, etc. Initially, the theoretical background of the system and project components are represented and explained, following the building process of the electronic and optical part of the project. Lastly, the working principle and programming algorithms of a system are presented and explained. Measurement results are shown at the end, as well as the conclusion that is drawn from the thesis.
Ključne besede: optical fibers, sensors, interferometer, signal processing
Objavljeno v DKUM: 04.11.2020; Ogledov: 1244; Prenosov: 115
Celotno besedilo (5,11 MB)

Opis: V magistrskem delu se bomo ukvarjali z uporabo detektorja RGB za procesiranje vlakenskih Fabry-Perotovih senzorjev s kratko režo. Detektor RGB deluje v širokem valovnem področju in zaradi tega potrebujemo širokopasovni vir. V prvem delu raziskave bomo poskusili izdelati poceni izvor svetlobe, ki bo povezan z optičnim vlaknom. V nadaljevanju bomo s pomočjo RGB senzorja razločili lastnosti valovnih dolžin, s katerih bomo poskusili določiti dolžino Fabry-Perotovega interferometra. Obdelali bomo teoretično ozadje Fabry-Perotovega interferometra, gradnjo optičnega in elektronskega sistema ter izvedli zgodnji prototip merilnega sistema.
Ključne besede: optični senzor, Fabry-Perotov interferometer, detektor RGB
Objavljeno v DKUM: 25.09.2015; Ogledov: 1594; Prenosov: 217
Celotno besedilo (7,16 MB)

Opis: Diplomska naloga opisuje princip merjenja vibracij preko optičnega senzorja s Fabry-Perotovim interferometrom. Najprej je opisan razvoj visoko občutljivega optičnega vlakenskega senzorja za zaznavanje vibracij. Senzor je zgrajen iz segmenta optičnega vlakna, občutljivega na raztezek. Sprememba dolžine senzorskega dela optičnega vlakna ob prisotnosti vibracij povzroči spremembo optičnega signala. Procesiranje signala je bilo izvedeno z mikrokrmilnikom.
Ključne besede: Optično vlakno, signalni procesor, Fabry-Perotov vlakenski interferometer, merjenje vibracij
Objavljeno v DKUM: 16.12.2014; Ogledov: 2165; Prenosov: 140
Celotno besedilo (2,49 MB)