scholarly journals Cepstral analysis for baseline-insensitive absorption spectroscopy using light sources with pronounced intensity variations

2020 ◽  
Vol 59 (26) ◽  
pp. 7865
Author(s):  
Christopher S. Goldenstein ◽  
Garrett C. Mathews ◽  
Ryan K. Cole ◽  
Amanda S. Makowiecki ◽  
Gregory B. Rieker
Keyword(s):  
Absorption Spectroscopy ◽  
Light Sources ◽  
Cepstral Analysis

scholarly journals Broadband Cavity Enhanced Differential Optical Absorption Spectroscopy (CE-DOAS) – applicability and corrections

2008 ◽  
Vol 1 (1) ◽  
pp. 481-507 ◽  
Author(s):  
U. Platt ◽  
J. Meinen ◽  
D. Pöhler ◽  
T. Leisner
Keyword(s):  
Absorption Spectroscopy ◽  
Broad Band ◽  
Gas Absorption ◽  
Trace Gas ◽  
Optical Absorption Spectroscopy ◽  
Light Sources ◽  
Light Path ◽  
Gas Concentration ◽  
Mirror Reflectivity ◽  
Gas Measurements

Abstract. Atmospheric trace gas measurements by cavity assisted long-path absorption spectroscopy are an emerging technology. An interesting approach is the combination of CEAS with broad band light sources, the broad-band CEAS (BB-CEAS). BB-CEAS lends itself to the application of the DOAS technique to analyse the derived absorption spectra. While the DOAS approach has enormous advantages in terms of sensitivity and specificity of the measurement, an important implication is the reduction of the light path by the trace gas absorption, since cavity losses due to absorption by gases reduce the quality (Q) of the cavity. In fact, at wavelength, where the quality of the BB-CEAS cavity is dominated by the trace gas absorption (esp. at very high mirror reflectivity), the light path will vary inversely with the trace gas concentration and the strength of the band will become nearly independent of the trace gas concentration c in the cavity, rendering the CEAS Method useless for trace gas measurements. Only in the limiting case where the mirror reflectivity determines Q at all wavelength, the strength of the band as seen by the BB-CEAS instrument becomes proportional to the concentration c. We investigate these relationships in detail and present methods to correct for the cases between the two above extremes, which are of course the important ones in practice.

scholarly journals Baseline-free quantitative absorption spectroscopy based on cepstral analysis

2019 ◽  
Vol 27 (26) ◽  
pp. 37920 ◽  
Author(s):  
Ryan K. Cole ◽  
Amanda S. Makowiecki ◽  
Nazanin Hoghooghi ◽  
Gregory B. Rieker
Keyword(s):  
Absorption Spectroscopy ◽  
Cepstral Analysis ◽  
Quantitative Absorption

scholarly journals Silicon Multi-Pass Gas Cell for Chip-Scale Gas Analysis by Absorption Spectroscopy

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 463
Author(s):  
Alaa Fathy ◽  
Yasser M. Sabry ◽  
Martine Gnambodoe-Capochichi ◽  
Frederic Marty ◽  
Diaa Khalil ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Strong Solutions ◽  
Design Guidelines ◽  
Gas Analysis ◽  
Optical Absorption Spectroscopy ◽  
Spectral Signature ◽  
Light Sources ◽  
Gas Cell ◽  
Mems Technology ◽  
Analysis System

Semiconductor and micro-electromechanical system (MEMS) technologies have been already proved as strong solutions for producing miniaturized optical spectrometers, light sources and photodetectors. However, the implementation of optical absorption spectroscopy for in-situ gas analysis requires further integration of a gas cell using the same technologies towards full integration of a complete gas analysis system-on-chip. Here, we propose design guidelines and experimental validation of a gas cell fabricated using MEMS technology. The architecture is based on a circular multi-pass gas cell in a miniaturized form. Simulation results based on the proposed modeling scheme helps in determining the optimum dimensions of the gas cell, given the constraints of micro-fabrication. The carbon dioxide spectral signature is successfully measured using the proposed integrated multi-pass gas cell coupled with a MEMS-based spectrometer.

Swept-Cavity Ringdown Absorption Spectroscopy: Put Your Laser Light In and Shake It All About

2003 ◽  
Vol 56 (3) ◽  
pp. 219 ◽  
Author(s):  
Richard A. Shorten ◽  
Yabai He ◽  
Brian J. Orr
Keyword(s):  
Absorption Spectroscopy ◽  
High Performance ◽  
Continuous Wave ◽  
Low Cost ◽  
Optical Cavity ◽  
Wavelength Region ◽  
Tunable Diode Laser ◽  
Light Sources ◽  
Coherent Light ◽  
Cavity Ringdown

Cavity ringdown (CRD) absorption spectroscopy with continuous-wave (cw) tunable coherent light sources provides a convenient, sensitive, and precise way to measure very weak optical absorption spectra and to analyze trace gas concentrations. Several recently introduced innovations in cw-CRD spectroscopy are described. Our approach involves one or more single-mode tunable diode laser sources, a rapidly swept ringdown cavity, and a simple optical heterodyne detected approach (based on the dynamics of coherent light reflected from such an active optical cavity). This offers high performance in a relatively simple, low-cost, compact instrument that is facilitated by fibre optic and other standard photonics or telecommunications components. New experimental results are reported, comprising CRD spectra of water vapour in the 0.815 µm wavelength region and of mixtures of CO2 and CO in the range of 1.56–1.59 µm. Promising applications of such techniques include chemical analysis of trace gases in medicine, agriculture, industry, and the environment.

scholarly journals Integrated Nanophotonic Waveguide-Based Devices for IR and Raman Gas Spectroscopy

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7224
Author(s):  
Sebastián Alberti ◽  
Anurup Datta ◽  
Jana Jágerská
Keyword(s):  
Raman Spectroscopy ◽  
Absorption Spectroscopy ◽  
Gas Sensing ◽  
Light Sources ◽  
Low Loss ◽  
Figures Of Merit ◽  
Sensing Applications ◽  
Sensitivity And Selectivity ◽  
On Chip ◽  
Ir And Raman

On-chip devices for absorption spectroscopy and Raman spectroscopy have been developing rapidly in the last few years, triggered by the growing availability of compact and affordable tunable lasers, detectors, and on-chip spectrometers. Material processing that is compatible with mass production has been proven to be capable of long low-loss waveguides of sophisticated designs, which are indispensable for high-light–analyte interactions. Sensitivity and selectivity have been further improved by the development of sorbent cladding. In this review, we discuss the latest advances and challenges in the field of waveguide-enhanced Raman spectroscopy (WERS) and waveguide infrared absorption spectroscopy (WIRAS). The development of integrated light sources and detectors toward miniaturization will be presented, together with the recent advances on waveguides and cladding to improve sensitivity. The latest reports on gas-sensing applications and main configurations for WERS and WIRAS will be described, and the most relevant figures of merit and limitations of different sensor realizations summarized.

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