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Dissertation
Master thesis and internship[BR]- Master's Thesis : Coupling of a single-mode fiber with a deformable mirror in a space-based nulling interferometer[BR]- Internship (linked to master's thesis)
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Year: 2020 Publisher: Liège Université de Liège (ULiège)

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Abstract

This master thesis is dedicated to the study of single mode fibers as spatial filter in a space-based nulling interferometer. They are used to decrease the requirements on the wavefront quality that an adaptive system needs to achieve.

In order to do so, a mathematical model of the coupling efficiency of a single mode fiber placed at the focus of a telescope was developed. The model is based on the Gaussian approximation of the fundamental mode LP_01 that is propagated in the single mode fiber. Also, the model is based on the theory of Fourier optics in order to determine the electric field at the input of the fiber. The model allows to compute the coupling efficiency for any static aberrations. Also, the point spread functions of a circular pupil subjected to different aberrations are simulated thanks to the fast fourier transform algorithm.

The study is performed in the waveband [3-7] µm in order to develop a nulling interferometer for exoplanets detections. The diffraction limited performances of the system are analysed. After that, the effect of static aberrations on the coupling efficiency is analysed. Then, the simulation of typical aberrations encountered in space is performed. They represent non common path aberrations (NCPA). 

The simulation of the model proves that the coupling efficiency drops from 81.45% (diffraction limited performance) to 30 % when 120 Zernike polynomials are used to represent NCPA. In order to get a RMS wavefront error below 0.1 rad a deformable mirror capable of reproducing the first 115 Zernike polynomials is needed.


Book
Optical Gas Sensing: Media, Mechanisms and Applications
Authors: ---
Year: 2022 Publisher: Basel MDPI - Multidisciplinary Digital Publishing Institute

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Abstract

Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band (QCL—Quantum Cascade Lasers, ICL—Interband Cascade Lasers, OPO—Optical Parametric Oscillator, DFG—Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques.

Keywords

Technology: general issues --- History of engineering & technology --- laser flow meter --- Pitot tube --- flow speed --- time of flight --- dilution method --- flow simulation --- flow turbulence --- gas sensing applications --- MEMS --- gas sensor --- photoacoustics --- cantilever --- capacitive detection --- analytic model --- infrared imaging --- multispectral and hyperspectral imaging --- air pollution monitoring --- remote sensing and sensors --- spectroscopy --- fourier transform --- image processing --- laser gas analyzer --- flux measurement --- eddy covariance method --- derivative absorption spectroscopy --- gas sensors --- antiresonant hollow core fibers --- laser spectroscopy --- wavelength modulation spectroscopy --- tunable diode laser absorption spectroscopy --- photothermal spectroscopy --- photoacoustic spectroscopy --- fiber gas sensors --- mid-infrared --- quantum cascade detector --- high-speed operation --- heterodyne detection --- high-resolution spectroscopy --- isotopic ratio --- frequency comb --- Vernier spectroscopy --- refractometry --- pressure --- short-term performance --- Fabry–Perot cavity --- gas modulation --- modulation techniques --- metrology --- integrated sensors --- waveguides --- absorption spectroscopy --- Raman spectroscopy --- gas sensing --- femtosecond laser micromachining --- microchannel fabrication --- microstructured fibers --- photoacoustic --- pressure transducer --- wafer-level --- CO2 --- combined NIR/MIR laser absorption --- laser multiplexing in a mid-IR single-mode fiber --- simultaneous multispecies (CO, CO2, H2O) in situ measurements


Book
Optical Gas Sensing: Media, Mechanisms and Applications
Authors: ---
Year: 2022 Publisher: Basel MDPI - Multidisciplinary Digital Publishing Institute

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Abstract

Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band (QCL—Quantum Cascade Lasers, ICL—Interband Cascade Lasers, OPO—Optical Parametric Oscillator, DFG—Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques.

Keywords

Technology: general issues --- History of engineering & technology --- laser flow meter --- Pitot tube --- flow speed --- time of flight --- dilution method --- flow simulation --- flow turbulence --- gas sensing applications --- MEMS --- gas sensor --- photoacoustics --- cantilever --- capacitive detection --- analytic model --- infrared imaging --- multispectral and hyperspectral imaging --- air pollution monitoring --- remote sensing and sensors --- spectroscopy --- fourier transform --- image processing --- laser gas analyzer --- flux measurement --- eddy covariance method --- derivative absorption spectroscopy --- gas sensors --- antiresonant hollow core fibers --- laser spectroscopy --- wavelength modulation spectroscopy --- tunable diode laser absorption spectroscopy --- photothermal spectroscopy --- photoacoustic spectroscopy --- fiber gas sensors --- mid-infrared --- quantum cascade detector --- high-speed operation --- heterodyne detection --- high-resolution spectroscopy --- isotopic ratio --- frequency comb --- Vernier spectroscopy --- refractometry --- pressure --- short-term performance --- Fabry–Perot cavity --- gas modulation --- modulation techniques --- metrology --- integrated sensors --- waveguides --- absorption spectroscopy --- Raman spectroscopy --- gas sensing --- femtosecond laser micromachining --- microchannel fabrication --- microstructured fibers --- photoacoustic --- pressure transducer --- wafer-level --- CO2 --- combined NIR/MIR laser absorption --- laser multiplexing in a mid-IR single-mode fiber --- simultaneous multispecies (CO, CO2, H2O) in situ measurements


Book
Optical Gas Sensing: Media, Mechanisms and Applications
Authors: ---
Year: 2022 Publisher: Basel MDPI - Multidisciplinary Digital Publishing Institute

Loading...
Export citation

Choose an application

Bookmark

Abstract

Optical gas sensing is one of the fastest developing research areas in laser spectroscopy. Continuous development of new coherent light sources operating especially in the Mid-IR spectral band (QCL—Quantum Cascade Lasers, ICL—Interband Cascade Lasers, OPO—Optical Parametric Oscillator, DFG—Difference Frequency Generation, optical frequency combs, etc.) stimulates new, sophisticated methods and technological solutions in this area. The development of clever techniques in gas detection based on new mechanisms of sensing (photoacoustic, photothermal, dispersion, etc.) supported by advanced applied electronics and huge progress in signal processing allows us to introduce more sensitive, broader-band and miniaturized optical sensors. Additionally, the substantial development of fast and sensitive photodetectors in MIR and FIR is of great support to progress in gas sensing. Recent material and technological progress in the development of hollow-core optical fibers allowing low-loss transmission of light in both Near- and Mid-IR has opened a new route for obtaining the low-volume, long optical paths that are so strongly required in laser-based gas sensors, leading to the development of a novel branch of laser-based gas detectors. This Special Issue summarizes the most recent progress in the development of optical sensors utilizing novel materials and laser-based gas sensing techniques.

Keywords

laser flow meter --- Pitot tube --- flow speed --- time of flight --- dilution method --- flow simulation --- flow turbulence --- gas sensing applications --- MEMS --- gas sensor --- photoacoustics --- cantilever --- capacitive detection --- analytic model --- infrared imaging --- multispectral and hyperspectral imaging --- air pollution monitoring --- remote sensing and sensors --- spectroscopy --- fourier transform --- image processing --- laser gas analyzer --- flux measurement --- eddy covariance method --- derivative absorption spectroscopy --- gas sensors --- antiresonant hollow core fibers --- laser spectroscopy --- wavelength modulation spectroscopy --- tunable diode laser absorption spectroscopy --- photothermal spectroscopy --- photoacoustic spectroscopy --- fiber gas sensors --- mid-infrared --- quantum cascade detector --- high-speed operation --- heterodyne detection --- high-resolution spectroscopy --- isotopic ratio --- frequency comb --- Vernier spectroscopy --- refractometry --- pressure --- short-term performance --- Fabry–Perot cavity --- gas modulation --- modulation techniques --- metrology --- integrated sensors --- waveguides --- absorption spectroscopy --- Raman spectroscopy --- gas sensing --- femtosecond laser micromachining --- microchannel fabrication --- microstructured fibers --- photoacoustic --- pressure transducer --- wafer-level --- CO2 --- combined NIR/MIR laser absorption --- laser multiplexing in a mid-IR single-mode fiber --- simultaneous multispecies (CO, CO2, H2O) in situ measurements

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