Alain Miffre

• HDR
• Professor (Associate) at Claude Bernard University Lyon 1

Polarization optics, which characterize the orientation of the electromagnetic field through Stokes vectors formalism, have been effectively used in lidar remote sensing to detect particles that differ in shape, such as mineral dust or pollen. In this study, for the first time, we explore the capability of polarization optics to distinguish the lig...

In polarization lidar field experiments, the particles depolarization ratio (PDR) is key for accurate retrievals of particles backscattering vertical profiles specific to nonspherical particles, such as mineral dust. Precise values of the intrinsic depolarization of mineral dust are however difficult to obtain, due to the complexity of mineral dust...

In this paper, the dependence of the particles' depolarization ratio (PDR) of mineral dust on the complex refractive index and size is for the first time investigated through a laboratory π-polarimeter operating at 180.0∘ backscattering angle and at (355, 532) nm wavelengths for lidar purposes. The dust PDR is indeed an important input parameter in...

Atmospheric particles may somewhat counterbalance the global warming effect of the Earth’s atmosphere due to greenhouse gases by directly contributing to the Earth’s climate through light scattering and absorption processes. According to the IPCC report (IPCC in Climate change 2013: the physical science basis. New York: Cambridge Univ. Press, 2013)...

In this paper, the dependence of the particles depolarization ratio (PDR) of mineral dust on the complex refractive index and size is for the first time investigated through a laboratory π-polarimeter operating at 180.0° backscattering angle and at (355, 532) nm wavelengths for lidar purposes. The dust PDR is indeed an important input parameter in...

While pollen is expected to impact public human health and the Earth’s climate more and more in the coming decades, lidar remote sensing of pollen has become an important developing research field. To differentiate among the pollen taxa, a polarization lidar is an interesting tool since pollen exhibit non-spherical complex shapes. A key attribute i...

Pollen is nowadays recognized as one of the main atmospheric particles affecting public human health as well as the Earth's climate. In this context, an important issue concerns our ability to detect and differentiate among the existing pollen taxa. In this paper, the potential differences that may exist in light scattering by four of the most comm...

Pollens are nowadays recognized as one of the main atmospheric particles affecting public human health as well as the Earth's climate. In this context, an important issue concerns our ability to detect and differentiate among the existing pollen taxa. In this paper, the potential differences that may exist in light scattering by four of the most co...

Sulfate aerosol is responsible for a net cooling of the Earth’s atmosphere due to its ability to backscatter light. Through atmospheric multiphase chemistry, it reacts with isoprene epoxydiols leading to the formation of aerosol and organic compounds, including organosulfates and high-molecular weight compounds. In this study, we evaluate how sulfa...

TITLE Bioaerosols light scattering (polarization-resolved): case study of ragweed pollen. RESUME Ce travail présente les résultats d'une publication récente dans JQSRT (Cholleton et al., 2020). Les pollens sont des bioaérosols atmosphériques ayant un fort impact sanitaire via les réactions allergiques qui agissent également sur le climat terrestre...

In this paper, a controlled-laboratory experiment is carried out to evaluate the lidar depolarization ratio of freshly emitted soot aggregates in the exact backward scattering direction at 180.0°. The experiment is performed at two wavelengths simultaneously, namely 355 and 532 nm, often used in polarimetric lidar remote sensing. The soot aggregate...

While water and sulfuric acid droplets are the main component of stratospheric aerosols, measurements performed for about 30 years have shown that non-sulfate particles (NSPs) are also present. Such particles, released from the Earth mainly through volcanic eruptions, pollution or biomass burning, or coming from space, present a wide variety of com...

Ragweed or Ambrosia artemisiifolia pollen is an important atmospheric constituent affecting the Earth's climate and public health. The literature on light scattering by pollens embedded in ambient air is however rather sparse: polarization measurements are limited to the sole depolarization ratio and pollens are beyond the reach of numerically exac...

In this Letter, we exploit the polarization property of light to investigate the Ångström exponent describing the wavelength dependence of optical backscatter between two wavelengths. Where previous interpretation of Ångström exponent was that of a particle size indicator, the use of light polarization makes it possible to investigate the Ångström...

In this letter, we exploit the polarization property of light to investigate the Angstroem exponent describing the wavelength dependence of optical backscatter between two wavelengths. Where previous interpretation of Angstroem exponent was that of a particles size indicator, the use of light polarization makes it possible to investigate the Angstr...

Abstract. While droplets with pure mixtures of water and sulfuric acid are the main component of stratospheric aerosols, field measurements performed for more than 30 years have shown that non-sulfate materials, thereafter referred to by us as NSP (for Non-pure Sulfate Particles , not considering frozen material) are also present. Such materials, w...

Observations of new particle formation events in free troposphere are rather seldom and limited in time and space, mainly due to the complexity and the cost of the required on-board instrumentation for airplane field campaigns. In this paper, a calibrated (UV, VIS) polarization elastic lidar (2β + 2δ) is used to remotely sense new particle formatio...

In this paper, the scattering matrix elements of an ensemble of mineral dust particles are for the first time evaluated in laboratory for scattering angles ranging from 176.0° to the π-backscattering angle of 180.0° with a high angular resolution of 0.4° and compared with the outputs of T-matrix numerical code. Elastic light scattering is addressed...

Optical sensors based on absorption spectroscopy play a central role in the detection and monitoring of atmospheric trace gases. We here present for the first time the experimental demonstration of OSAS-Lidar on the remote sensing of CH4 in the atmosphere. This new methodology, the OSAS-Lidar, couples the Optical Similitude Absorption Spectroscopy...

Monitoring the emission of gases is difficult to achieve in industrial sites and in environments presenting poor infrastructures. Hence, robust methodologies should be developed and coupled to Lidar technology to allow remote sensing of gas emission. OSAS is a new methodology to evaluate gas concentration emission from spectrally integrated differe...

Our understanding of the contribution of mineral dust to the Earth's radiative budget is limited by the complexity of these particles, which present a wide range of sizes, are highly-irregularly shaped, and are present in the atmosphere in the form of particle mixtures. To address the spatial distribution of mineral dust and atmospheric dust mass c...

In this contribution, we present recent work on the ability to achieve range-resolved greenhouse gases concentration measurements in the Earth’s atmosphere (CH4, H2O) by combining broadband optical correlation spectroscopy (OCS) with lidar. We show that OCS-Lidar is a robust methodology, allowing trace gases remote sensing with a low dependence on...

In this contribution, we present the results of two recent papers [1,2] published in Optics Express, dedicated to the development of two new lidar methodologies. In [1], while the carbon aerosol (for example, soot particles) is recognized as a major uncertainty on climate and public health, we couple lidar remote sensing with Laser-Induced-Incandes...

We propose a new methodology to measure gas concentration by light-absorption spectroscopy when the light source spectrum is larger than the spectral width of one or several molecular gas absorption lines. We named it optical similitude absorption spectroscopy (OSAS), as the gas concentration is derived from a similitude between the light source an...

In this paper, a controlled laboratory experiment is performed to accurately evaluate the depolarization from mineral dust particles in the exact backward scattering direction (=180.0±0.2°). The experiment is carried out at two wavelengths simultaneously (λ=355. nm, λ=532. nm), on a determined size and shape distribution of Arizona Test Dust (ATD)...

Carbon aerosol is now recognized as a major uncertainty on climate change and public health, and specific instruments are required to address the time and space evolution of this aerosol, which efficiently absorbs light. In this paper, we report an experiment, based on coupling lidar remote sensing with Laser-Induced-Incandescence (LII), which allo...

Understanding new particles formation in the free troposphere is key for air quality and climate change, but requires accurate observation tools. Here, we discuss on the optical requirements ensuring a backscattering device, such as a lidar, to remotely observe nucleation events promoted by nonspherical desert dust or volcanic ash particles. By app...

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We present the first experimental observation of exact backscattering of light by an ensemble of particles in ambient air. Our experimental set-up operates in the far-field single scattering approximation, covers the exact backscattering direction with accuracy (θ = π ± ε with ε = 3.5 × 10⁻³ rad) and efficiently collects the particles backscatterin...

During transport by advection, atmospheric non-spherical particles, such as volcanic ash, desert dust or sea-salt particles experience several chemical and physical pro-cesses, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this paper, a new methodology is proposed to analyse this complex ver-t...

In this paper, the first experimental demonstration of the optical correlation spectroscopy lidar (OCS-lidar) is proposed. It is a new active remote sensing methodology to measure range-resolved atmospheric gas concentrations, based on broadband laser spectroscopy and light amplitude modulation. As a first step, a numerical study is performed for O...

During transport by advection, atmospheric nonspherical particles, such as volcanic, desert dust or sea-salt particles experience several chemical and physical processes, leading to a complex vertical atmospheric layering at remote sites where intrusion episodes occur. In this contribution, a new methodology is proposed to analyze this complex vert...

Large quantities of mineral dust particles are frequently ejected into the atmosphere through the action of wind. The surface of dust particles acts as a sink for many gases, such as sulfur dioxide. It is well known that under most conditions, sulfur dioxide reacts on dust particle surfaces, leading to the production of sulfate ions. In this report...

In this paper, we propose a new active remote sensing methodology, based on laser spectroscopy, to evaluate the content of atmospheric trace gases. Its principle consists in coupling a lidar with optical correlation spectroscopy (OCS-lidar). Our theoretical and numerical studies show that OCS-lidar is a robust measurement methodology allowing trace...

In this paper, accurate UV polarization measurements are performed on a volcanic ash cloud after long-range transport at Lyon, France (45.76 degrees N, 4.83 degrees E). The volcanic particles are released from the mid-April 2010 eruption of the Eyjafjallajokull Icelandic volcano (63.63 degrees N, 19.62 degrees W). The aerosol UV depolarization, whi...

An UV-VIS polarization Lidar has been designed and specified for aerosols monitoring in the troposphere, showing the ability to precisely address low particle depolarization ratios, in the range of a few percents. Non-spherical particle backscattering coefficients as low as 5 {\times} 10-8 m-1.sr-1 have been measured and the particle depolarization...

In this paper, an UV-polarization Lidar is used to study the optical properties of volcanic aerosol in the troposphere. The particles were released by the mid-April 2010 eruption of the Eyjafjallajökull volcano (63.63°N, 19.62°W, Iceland) and passed in the troposphere above Lyon (45.76°N, 4.83°E, France) after advection over 2600 km. The FLEXPART p...

Polarization and spectrally resolved light scattering of laser light into the atmosphere allows remote evaluation of atmospheric particulate matter and trace gases by applying the lidar technique.

In this contribution, we present a new method to remotely evaluate Methane greenhouse gas concentration in the atmosphere. It is based on combining the Optical Correlation Spectroscopy (OCS) method with laser remote sensing (see fig. 1). The novelty of this work is that an Acoustic Optical Programmable Dispersive Filter (AOPDF) is used and is coupl...

In this paper, an optical remote sensing method is proposed to retrieve the number concentration of non spherical volcanic ash particles. An UV-polarization sensitive remote sensing experiment is interpreted in the frame of the scattering matrix formalism. It follows that UV-optical scattering and depolarization, when they are used together and in...

In this contribution, the optical backscattering properties of atmospheric non-spherical particles are analyzed after long-range transport with a highly sensitive and accurate UV-polarization lidar. Far from the source region, the aerosol cloud is considered as a mixture of spherical (s) and non-spherical (ns) particles. Aerosols UV-depolarization...

In this paper, a ground-based UV-polarization Lidar is used to characterize the optical properties of volcanic particles that originated from the Eyjafjöll volcano (63.63°N, 19.62°W, Iceland) and advected over Lyon (45.76°N, 4.83°E, France), a distance 2,600 kilometers away. The volcanic origin of the observed particles has been confirmed with 7-da...

Vertical profiles of particle mass concentration in the urban canopy above the city of Lyon have been obtained from Lidar measurements of atmospheric backscattering, over a period of three days. The concentrations measured at 50 m above the ground have been compared with the mass concentration of PM10 measured by a ground-based sampler located near...

We reanalyzed our atom interferometer measurement of the electric polarizability of lithium now accounting for the Sagnac effect due to Earth rotation. The resulting correction to the polarizability is very small but the visibility as a function of the applied phase shift is now better explained. The fact that the Sagnac and polarizability phase sh...

A magnetic field gradient applied to an atom interferometer induces a $M$-dependent phase shift which results in a series of decays and revivals of the fringe visibility. Using our lithium atom interferometer based on Bragg laser diffraction, we have measured the fringe visibility as a function of the applied gradient. We have thus tested the isoto...

We have built an atom interferometer of the Mach Zehnder type. The atomic wave (lambdadB=54 pm) is a supersonic beam of lithium seeded in argon. The realization of mirrors and beams splitters for the atomic wave relies on elastic Bragg diffraction on laser standing waves at lambda= 671 nm. We first present our experimental setup and signals with at...

The high inertial sensitivity of atom interferometers has been used to build accelerometers and gyrometers but this sensitivity makes these interferometers very sensitive to the laboratory seismic noise. This seismic noise induces a phase noise which is large enough to reduce the fringe visibility in many cases. We develop here a model calculation...

Atom interferometers are very sensitive to accelerations and rotations. This property, which has some very interesting applications, induces a deleterious phase noise due to the seismic noise of the laboratory and this phase noise is sufficiently large to reduce the fringe visibility in many experiments. We develop a model calculation of this phase...

In this paper, we present a brief overview of atom interferometry. This field of research has developed very rapidly since 1991. Atom and light wave interferometers present some similarities but there are very important differences in the tools used to manipulate these two types of waves. Moreover, the sensitivity of atomic waves and light waves to...

In this paper, we present a brief overview of atom interferometry. This field of research has developed very rapidly since 1991. Atom and light wave interferometers present some similarities but there are very important differences in the tools used to manipulate these two types of waves. Moreover, the sensitivity of atomic waves and light waves to...

Using an atom interferometer, we have measured the static electric polarizability of 7Li α=(24.33 ±0.16)×10-30 m3 = 164.2±1.1 atomic units with a 0.66% uncertainty. Our experiment, which is similar to an experiment done on sodium in 1995 by Pritchard and co-workers, consists in applying an electric field on one of the two interfering beams and meas...

Atom interferometers are very sensitive to accelerations and rotations. This property, which has some very interesting applications, induces a deleterious phase noise due to the seismic noise of the laboratory and this phase noise is sufficiently large to reduce the fringe visibility in many experiments. We develop a model calculation of this phase...

Using an atom interferometer, we have measured the static electric polarizability of $^7$Li $\alpha =(24.33 \pm 0.16)\times10^{-30} $ m$^3$ $= 164.19\pm 1.08 $ atomic units with a 0.66% uncertainty. Our experiment, which is similar to an experiment done on sodium in 1995 by D. Pritchard and co-workers, consists in applying an electric field on one...

Président du Jury : M. J.A. BESWICK, Professeur de l'Université Rapporteur : M. C. SALOMON, Directeur de Recherches, L.K.B., Paris Rapporteur : M. R. KAISER, Directeur de Recherches, I.N.L.N., Nice Examinateur : M. P. VERKERK, Directeur de Recherches, Ph.L.A.M., Lille Examinateur : M. M. BÜCHNER, Chargé de Recherches, L.C.A.R., Toulouse Directeur d...

We have built an atom interferometer and, by applying an electric field on one of the two interfering beams, we have measured the static electric polarizability of lithium with a 0.66 % uncertainty. Our experiment is similar to an experiment done on sodium in 1995 by D. Pritchard and co-workers, with several improvements: the electric field can be...

We have built and operated an atom interferometer of the Mach-Zehnder type. The atomic wave is a supersonic beam of lithium seeded in argon and the mirrors and beam-splitters for the atomic wave are based on elastic Bragg diffraction on laser standing waves at =671nm. We give here a detailed description of our experimental set-up and of the procedu...

Supersonic expansion is a very powerful tool to produce an atomic beam with a well defined velocity and, by seeding a test gas in such an expansion, the energy of the test gas can be transferred, at least partially, to the very-low-temperature carrier gas. The case usually studied is the one of a heavy gas seeded in a light carrier gas and, in this...

We have built an atom interferometer of the Mach-Zehnder type, operating with thermal lithium atoms [1]. Its design is largely inspired by previous works done by the groups of D. Pritchard [2], A. Zeilinger [3] and S.A. Lee [4]. In our apparatus, the atomic wave is diffracted in the Bragg regime by three laser sanding waves to achieve a Mach-Zehnde...

Using Bloch states to describe atomic motion, we show how to calculate the phase shifts associated to atomic diffraction by a laser standing wave and we illustrate our calculation by the evaluation of the phase shifts in the contrast interferometer developed by D. Pritchard and co-workers [Phys. Rev. Lett. 89, 140401 (2002)].

We have built and operated an atom interferometer of the Mach-Zehnder type. The atomic wave is a supersonic beam of lithium seeded in argon and the mirrors and beam-splitters for the atomic wave are based on elastic Bragg diffraction on laser standing waves at 671 nm. We give here a detailed description of our experimental setup and of the procedur...

The measurement of parallel velocity distribution of a lithium supersonic beam produced by seeding lithium in argon, was described. The parallel temperature for lithium was found to be lower than the calculated parallel temperature of argon carrier gas. The theory of velocity distribution in supersonic beams was extended to a mixture of monoatomic...

Diffraction of atoms by laser is a very important tool for matter wave optics. Although this process is well understood, the phase shifts induced by this diffraction process are not well known. In this paper, we make analytic calculations of these phase shifts in some simple cases and we use these results to model the contrast interferometer recent...

In this paper, we present a tutorial set-up based on an optical three-grating Mach–Zehnder interferometer. As this apparatus is very similar in its principle to the Mach–Zehnder interferometers used with matter waves (neutrons, atoms and molecules), it can be used to familiarize students with particle optics, and in our explanations, we use the com...

In the present paper, we analyze several factors which limit the fringe contrast in atom interferometers of the Mach--Zehnder type. We consider only the case of interferometers operating with thermal atoms, as there are very specific problems in this case. All the effects considered here are already known to reduce the fringe contrast but the quant...

Nous venons d'observer les premiers signaux d'interférence atomique grâce à un interféromètre atomique de Mach-Zehnder à trois réseaux, fonctionnant avec un jet supersonique de lithium. La diffraction utilise des ondes lasers quasi résonnantes à 671 nm et fonctionne dans le régime de Bragg et les atomes de lithium sont détectés par un détecteur de...

This paper describes the construction and optimization of a Langmuir-Taylor detector for lithium, using a rhenium ribbon. The absolute detection probability of this very sensitive detector is measured and the dependence of this probability with oxygen pressure and surface temperature is studied. Sources of background signal and their minimization a...

In this contribution, we present some recent theoretical results concerning the fringe contrast in Mach–Zehnder atom interferometers and the use of Bloch states to describe atomic diffraction. We also describe the observation of diffraction of lithium at thermal energy by a quasi-resonant laser standing wave.

In this contribution, we present some recent theoretical results concerning the fringe contrast in Mach-Zehnder atom interferometers and the use of Bloch states to describe atomic diffraction. We also describe the observation of diffraction of lithium at thermal energy by a quasi-resonant laser standing wave.