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The chemical space perceived by a consumer of champagne or other sparkling wines is progressively modified all along tasting. Real-time monitoring of gas-phase CO2 concentration was performed, through a CO2-diode laser sensor, along a two-dimensional array of nine points in the headspace of three types of glasses poured with champagne. Two original glasses with distinct headspace volumes were compared with the standard INAO tasting glass. For each of the three glass types, a kind of temperature-dependent CO2 fingerprint was revealed and discussed as a function of the glass geometry and headspace volume. Moreover, a simple model was developed, which considers the rate of decrease of the concentration of gas-phase CO2 in the headspace of a glass after the pouring process as being mainly ruled by natural air convection in ambient air. The timescale which controls the rate of decrease of gas-phase CO2 was found to highly depend on the ratio of the headspace volume to the open aperture of the glass.

Key upgrades to a previously developed CO2-Diode Laser Sensor (CO2-DLS) were done to monitor as accurately as possible the level of gas-phase CO2 in champagne glasses. The upgraded CO2-DLS allows to access a wide range of CO2 concentrations (10-100%). An additional set of mirrors with two pairs of galvanometer scanners was developed in order to provide simultaneous measurements of gas-phase CO2 concentrations in the whole glass headspace. During the five minutes after pouring, the CO2-DLS unambiguously unveiled horizontal homogeneity in the glass headspace in terms of gas-phase CO2 concentrations. Nevertheless, a strong vertical gradient of gas-phase CO2 was highlighted, with ever increasing CO2 concentrations ranging from approximately 15% to 50% while moving away from the glass edge to the champagne interface. This strong vertical gradient was found to persist during the five next minutes following the pouring process, but with ever decreasing CO2 concentrations as time elapses.

We report on the simulation of the non-linearity of photoacoustic signals for gas detection using laser sources. These phenomena occur mainly in the near-infrared and/or in the presence of water vapor in the gas mixure.

We report on the latest developments and applications of a near-infrared diode laser spectrometer for the monitoring and the mapping of gaseous carbon dioxide in the headspace of Champagne and sparkling wine glasses.

During Champagne or sparkling wine tasting, gas-phase CO2 and volatile organic compounds invade the headspace above glasses, thus progressively modifying the chemical space perceived by the consumer. Gas-phase CO2 in excess can even cause a very unpleasant tingling sensation perturbing both ortho- and retronasal olfactory perception. Monitoring as accurately as possible the level of gas-phase CO2 above glasses is therefore a challenge of importance aimed at better understanding the close relationship between the release of CO2 and a collection of various tasting parameters. Here, the concentration of CO2 found in the headspace of champagne glasses served under multivariate conditions was accurately monitored, all along the 10 min following pouring, through a new combined approach by a CO2-Diode Laser Sensor and micro-gas chromatography. Our results show the strong impact of various tasting conditions (volume dispensed, intensity of effervescence, and glass shape) on the release of gas-phase CO2 above the champagne surface.

Laser spectrometers based on Quantum Cascade Lasers (QCL) provide good results for gas sensing in terms of sensibility and selectivity thanks to the characteristics of these sources. Distributed feedback (DFB) configuration provides narrow linewidth that enhances selectivity and their emission in the mid-IR enables to reach the fundamental absorption bands of molecules. The main limitation of these sources is their narrow tuning range (∼ 10 cm−1) that prevents from monitoring complex species with broad absorption spectra or realizing multi-gas sensing. To obtain a broader tuning range, one solution consists of QCL DFB array with an arrayed waveguide grating to perform multi-species spectroscopy [1]. A more common technique is to implement the laser in an external cavity system. In GSMA, a commercial Extended-Cavity Quantum Cascade Laser emitting at 10.5 μm has been used to demonstrate photoacoustic gas sensing of heavy molecules such as butane [2] and a lab-made EC-QCL emitting at 7.5 μm was developed for detection of acetone and POCl3 in gas phase [3].

Portable and remote sensing solutions to detect the nature of gases in the air are highly demanded. In particular for instance, for the measurement of fire smoke or uncontrolled discharge on risk sites or on an accident including a vehicle transporting hazardous substances [1]. Spectroscopic-based solutions would need a widely-tunable and powerful mid-infrared compact laser source that could be used on field and scan a large number of species.

The laser group of the Groupe de Spectrometrie Moleculaire et Atmospherique (GSMA, Reims, France) has developed various laser spectrometers for the study of the atmospheres [1]. Based on this technology we developed the same type of instrument for enological studies conducted by the Effervescence team of GSMA. A diode laser detection system for the measurements of gas-phase carbon dioxide (CO 2 ) above a glass of bubbly drink such as champagne has been designed [2]. In champagne and sparkling beverages in general, the progressive desorption of CO 2 dissolved in the liquid phase is responsible for bubble formation. Moreover, dissolved CO 2 may also escape by diffusion at the air-champagne interface. A first step in the understanding of the role of CO 2 was to precisely measure its concentration above champagne glasses, under standard tasting conditions [3]. To address this purpose, many optimizations of the set-up have been realized. First the original 2.68 μm diode laser was coupled to an optical fibre to prevent from atmospheric CO 2 interferences. Then, a second laser emitting around 2 μm was adapted to realize measurements with large concentrations of CO 2 . Finally, the whole set-up, namely the CO 2 -DLS, was driven by a LabView ® program in order to automatically record the temporal evolution of gas-phase CO 2 concentration in one position of the headspace above liquid [4]. A set of data showing the impact of champagne temperature and volume as well as the intensity of effervescence on the release of gas phase CO 2 was realized [5].

We have developed a fast wavelength modulated mid-IR source, especially designed for gas spectroscopy. The whole laser source is composed of a picosecond fiber laser emitting a spectrally narrow signal which can be modulated between 1028.3 nm and 1029.3 nm at the kHz range. This fiber laser seeds a Synchronously Pumped Optical Parametric Oscillator. This latter converts the near-IR pump (1028.3 nm) to the mid-IR region (3000-3500 nm) with equivalent modulation parameters i.e. 10 cm-1 tuning range at the kilohertz modulation frequency. This laser was combined with a photo-acoustic cell for methane detection.

The spectrometry is an important tool for atmospheric studies. In particular, passive spectrometric analysis implies associating a spectrometer with a heliostat. Indeed the heliostat enables to compensate for the Earth rotation relative to the Sun. In this way the sunlight can be collected at any time in order to detect atmospheric gases. Unfortunately, the instruments described in the literature need to be placed close to the spectrometer ( 5 m ) that is insufficient for the layout of our laboratory. So a servo-controlled heliostat, which is able to track the Sun with a great stability for several hours and which can be placed at a big distance from the spectrometer ( > 10 m ), has been designed and built.

A rapidly tunable picosecond PM ytterbium fiber laser pumps an OPO for wavelength conversion to the mid-IR. This compact and transportable source permits fast sensing of methane, and hydrochloric acid with two different detection schemes.

Photoacoustic cells are a type of optical sensors than can be used to detect trace gases. The photoacoustic spectroscopic technique is based on the absorption of photons by the molecules of interest and the subsequent creation of acoustic waves. It is extremely sensitive but the sensors bulkiness and cost prevent its mass deployment in several applications, such as greenhouse gases survey or indoor air monitoring. A trend towards miniaturization is thus engaged. In this paper, two centimeter-sized photoacoustic cells are presented. After an initial design stage by the finite element method, the cells have been fabricated and characterized. The experimental limit of detection reached with a centimeter-size cell made by direct metal laser sintering and an interband cascade laser delivering an optical power of 2.2 mW at 3.36 μm wavelength, is estimated at 92 ppbv methane in nitrogen.

We report on the development of a coherent quantum cascade laser array that consists in the fabrication of multi-stripes array. The main characteristic of this kind of source is that an anti-symmetrical signature with two lobes is obtained in the far field. Taking advantage of this drawback, a grating is aligned with one lobe of the source. Thus a Littrow configuration is designed that permit to obtain a wide tunability of the source. First results are presented and a preliminary test of the source is realized by measurements on acetone.

Champagne and sparkling wines are multicomponent hydroalcoholic systems supersaturated with dissolved carbon dioxide (CO2). Under standard tasting conditions, CO2 progressively invades the headspace above glasses, thus progressively modifying the chemical headspace perceived by the consumer. Monitoring in situ, and as accurately as possible the level of gas-phase CO2 above liquid is therefore a challenge of importance aimed at better understanding the close relationship between the release of gas-phase CO2 and a collection of various parameters such as glass-shape, and champagne temperature, for example. The development and validation of an instrument which combines two infrared diode lasers coupled with an optical fiber and devoted to real-time monitoring of gas-phase CO2 above sparkling beverages are reported. A first set of data showing the impact of liquid phase temperature on the release of gas-phase CO2 found in the headspace of champagne glasses is presented.

We report the development, the validation and the application of an infrared laser spectrometer devoted to the measurement of gaseous carbon dioxide in the headspace of Champagne and sparkling wines glasses.

We report the development, the validation and the application of an infrared diode laser spectrometer devoted to the monitoring of gaseous carbon dioxide in the headspace of Champagne and sparkling wines glasses.

We report the development of an extended-cavity quantum cascade laser emitting in the mid-infrared region and its use to the detectorless intracavity detection of atmospheric molecules such as methane and water vapor.

We report the development of an external-cavity quantum cascade laser emitting in the mid-infrared region and its application to the detectorless intracavity detection of atmospheric molecules such as methane and water vapor.

We report the latest developments and the application of an infrared diode laser spectrometer devoted to the monitoring of gaseous carbon dioxide in the headspace of Champagne and sparkling wines glasses.

We report the latest results obtained with an intra-cavity quantum cascade laser emitting in the mid-infrared region and its application to the detectorless detection of atmospheric molecules such as methane and water vapor.

In the framework of research program called MIRIADE, GSMA reports simulations and developments of mm-size Helmholtz resonant photoacoustic cells for the optical sensing of the atmosphere when associated with mid-infrared sources such as QCLs.

In the framework of the INTERREG V research program SAFESIDE, we report the test and development of a mid-infrared laser source for fume and gases detection by infrared laser spectroscopy.

Photoacoustic spectroscopy is one of the most sensitive techniques used to monitor chemical emission or to detect gas traces. However the sensors bulkiness, cost and complexity prevent their use in applications where mass deployment is required. In this paper, the development and characterization of centimeter sized photoacoustic sensors is presented. With a 2.2 mW optical power interband cascade laser at 3.36 μm wavelength, a limit of detection of 320 ppbv is obtained for methane.

Wide tunable lasers sources are useful for spectroscopy of complex molecules that have broad absorption spectra and for multiple sensing of smaller molecules. A region of interest is the mid-infrared region, where many species have strong ro-vibrational modes. In this paper a novel broad tunable source composed of a QCL DFB array and an arrayed waveguide grating (also called multiplexer) was used to perform multi-species spectroscopy (CO, $$\mathrm{C}_{2}\mathrm{H}_{2}$$ , $$\mathrm{CO}_{2}$$ ). The array and the multiplexer are associated in a way to obtain a prototype that is non-sensitive to mechanical vibrations. A 2190–2220 cm $$^{-1}$$ spectral range is covered by the chip. The arrayed waveguide grating combines beams to have a single output. A multi-pass White cell was used to demonstrate the efficiency of the multiplexer.

We report the complete designing process and realization of a photoacoustic spectrometer. In a first step, the cell design is optimized in order to achieve maximum cell constant and working frequency using a finite element method. Technological and integration constraints are used to define dimensional constraints on the cell. In a second step, a dedicated optical bench is presented along with the photoacoustic cell. The resonator response is then measured using a quantum cascade laser for methane detection and condenser microphones as detectors. The system detection limit is also discussed as it depends not only on the cell response but is also a combination of parameters linked together: environmental noise, microphones characteristics and cell conception. The gas flow required in a dynamic operation of the sensor degrades the detection limit regardless of the microphones quality. Choices on cell conception to minimize gas flow noise are discussed.

We report the development of an external cavity quantum cascade laser spectrometer at 7.5 μm. The quantum cascade laser and its anti-reflection coating were specially developed for this application. We provide details of the external cavity design and data processing. A continuous wave emission is demonstrated from 1,293 up to 1,350 cm−1. A preliminary test of the spectrometer was realized by measurements on acetone and phosphoryl chloride.

We report the implementation of a commercial external cavity-quantum cascade laser emitting at 10.5 μm in a photoacoustic spectrometer. This spectrometer enables measurements on broad spectral range up to 60 cm −1 which means that spectra of complex molecules can be recorded as well as a whole absorption band of a small molecule. The wide tuning range of the source of this photoacoustic spectrometer demonstrates the possibility to detect small and complex molecules such as carbon dioxide and butane.

This paper aims to demonstrate the quantitative simulation of photoacoustic signals using finite element modelling software. The software Comsol Multiphysics is used to calculate the response of a differential Helmholtz resonator cell previously modeled using an electrical analogy. Quality factors and resonance frequencies are compared with experimental ones. Moreover, for the first time, the absorption coefficient of the gas sample and the laser intensity are also used to quantitatively predict photoacoustic signal that can be obtained in such a configuration.

We report on the use of a photoacoustic Helmholtz sensor for the detection of large concentrations of methane. In this case, methane is in concentration where the photoacoustic signal is no more linear with concentration. Moreover the resonance frequency of the Helmholtz resonant cell is modified, as the concentration of methane cannot be neglected. This situation is simulated using a finite element method with the software Comsol Multiphysics\(^{\circledR }\). Simulation is compared with experimental results from 0.1 % up to 8 % of methane concentration in air.

We report the development of a field-deployable infrared laser spectrometer using new quantum cascade laser technology at 4.5 μm. The instrument is designed to measure in situ N2O concentrations at ground level even in bad weather conditions. We provide details of the instrument design and data processing. The long-term stability of the instrument was evaluated using the Allan variance technique. A preliminary evaluation of the instrument performance was realized by in situ measurements of N2O concentration outside the laboratory.

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

Red and orange bands of laser-induced fluorescence in NiH have been recorded on a Fourier transform interferometer at Doppler resolution. The spectra show strong transitions to low-lying vibronic states which are not thermally populated in a laboratory source, and therefore do not appear in laser excitation spectra, but which would be expected to contribute significantly to any stellar spectrum. The strongest bands belong to the G[Ω′ 5/2]–X 2 2Δ3/2, I[Ω′ 3/2]–X 2, and 2Δ3/2 I[Ω′ 3/2]–W 1 2Π3/2 systems. Measurements are reported for 58NiH, 60NiH, and 62NiH.

We have recorded electronic spectra of some diatomic species (I 2 , K 2 , and NaK), to illustrate the potential power of the combination of two high resolution techniques: intra-cavity laser induced fluorescence (ICLIF) and Fourier transform (FT) spectroscopy. Active and passive optical cavities have been used, working with visible continuous wave (cw) laser sources. The active cavity is a modified commercial ring dye laser, allowing for a sample up to 25 cm in length. Dispersed fluorescence spectra recorded on a Bomem Fourier transform spectrometer showed a signal enhancement of about 10 when a molecular source was placed within the resonator. The system was tested with a heatpipe source, producing alkali metal vapour at about 300 °C. These experiments illustrate enhanced cascade excitation mechanisms in K 2 ; the highest vibrational levels of the electronic ground state of K 2 can be observed with surprising ease. The increase in available power within the cavity has also led to the observation of fluorescence in NaK excited by a two-photon transition ( Q (66) 6 1 Σ + ← X 1 Σ + transition). Spatial limitations have driven us to build a more versatile ring cavity able to accommodate larger sources. This broad-band (590–650 nm) build-up cavity is locked by a Hansch–Couillaud servo-loop to an input laser of (instantaneous) bandwidth ∼1 MHz. Power enhancement factors of around 30 have been obtained with a 2.6% input coupler. The performance of the build-up cavity has been tested by recording FT spectra of intra-cavity laser induced fluorescence of iodine. The technique clearly has useful applications for weakly absorbing species, or for those whose electronic states are inaccessible to single-photon absorption techniques. This paper describes the arrangement we have used, highlighting some of the advantages and describing some of the particular difficulties we have encountered.

In the framework of research program “COCASE”, GSMA and III-V lab report the development of a monolithic quantum cascade array emitting at 8.2 μm mounted in an external-cavity system in order to obtain wide tunability.

In the framework of the ANR project called COCASE, GSMA and III-V Lab develop a coherent quantum cascade laser array to obtain high power emission. This source will be combined to a photoacoustic spectrometer devoted to trace gas detection [1]. In such a spectrometer the sensitivity limit is directly proportional to the laser power.

A metal sputtering source suitable for laboratory production of metal hydrides is described. Sputtering from pure nickel or iron in an Ar/H2 discharge is analyzed at low resolution. High resolution laser excitation and dispersed fluorescence spectra of NiH have also been recorded. The source has been designed to operate with a ferromagnetic circuit for Zeeman spectroscopy. Signals from the source are strong enough to record dispersed fluorescence from NiH by Fourier transform interferometry in magnetic fields up to 1 T. We establish that FeH can also be formed in this source.

A metal sputtering source suitable for laboratory production of metal hydrides is described. Sputtering from pure nickel or iron in an Ar/H(2) discharge is analyzed at low resolution. High resolution laser excitation and dispersed fluorescence spectra of NiH have also been recorded. The source has been designed to operate with a ferromagnetic circuit for Zeeman spectroscopy. Signals from the source are strong enough to record dispersed fluorescence from NiH by Fourier transform interferometry in magnetic fields up to 1 T. We establish that FeH can also be formed in this source.

Active and passive optical cavities have been incorporated in laser induced fluorescence experiments, allowing resolved fluorescence spectra of weak systems to be recorded in the visible and near infrared on a Bomem DA3 FT spectrometer.

Nous avons enregistre des spectres moleculaires de K 2 et de I 2 en associant la fluorescence laser intracavite (ICLIF) et la spectrometrie de Fourier (FTS). Deux types de cavites ont ete testes: une cavite active (celle d'un laser a colorant Spectra Physics 380D modifie), et une cavite passive realisee au LASIM (finesse 150, operationnelle de 590 a 650 nm) asservie sur le laser d'injection. L'observation aisee des niveaux voisins de la limite de dissociation de K 2 illustre les possibilites de ce couplage de techniques pour observer des transitions faibles.

Le spectre d'excitation laser de NiH a ete enregistre vers 575 nm: il revele les 5 isotopes naturels du nickel. L'analyse de la fluorescence montre des mecanismes de transfert d'energie tres efficaces, et isotopiquement selectifs, dans la molecule electroniquement excitee. La fluorescence des deux isotopologues principaux ( 58 NiH, 60 NiH) est observee dans ces conditions, les autres requierent une source laser plus intense: une experience intracavite est en cours dans notre laboratoire.

GSMA laser team reports simulations and optimization of a differential Helmholtz resonant photoacoustic gas sensor using a finite element method. The sensor characteristics and gas detection limit are estimated and compared to the experimental ones.

In the framework of research program “MIRIADE”, GSMA and CEA-LETI report simulations and developments of Si-integrated resonant photoacoustic cells developed for the optical sensing of the atmosphere when associated with mid-infrared sources such as QCLs.

In the framework of research program called MIRIADE, GSMA reports simulations and developments of compact Helmholtz resonant photoacoustic cells developed for the optical sensing of the atmosphere when associated with mid-infrared sources such as QCLs.