Search results for "Optical path"
showing 10 items of 22 documents
Infrared monitoring of underground CO2 storage using chalcogenide glass fibers
2009
International audience; An optical-fiber-based system suitable for monitoring the presence of carbon dioxide, so-called "greenhouse gas", is investigated. Since each pollutant gas shows a characteristic optical absorption spectrum in the mid-infrared (mid-IR), it is possible to detect selectively and quantitatively the presence of gases in a given environment by analysing mid-IR spectra. The main infrared signature of carbon dioxide gas is a double absorption peak located at 4.2 μm. Chalcogenide optical fibers, which can transmit light in the 1-6 μm range, are well-adapted for CO2 analysis. In this wavelength range, they show attenuation losses that compare favourably with other types of fi…
First analysis of the ν3+ν5 combination band of SF6 observed at Doppler-limited resolution and effective model for the ν3+ν5-ν5 hot band
2018
Abstract Sulfur hexafluoride is a greenhouse gas with a long lifetime in the atmosphere and an important tracer for air mass circulation atmospheric models. The IR spectrum of this heavy species, however, features many hot bands at room temperature (at which only 30% of the molecules lie in the ground vibrational state), especially those originating from the lowest, v 6 and v 5 = 1 vibrational states. Using a cryogenic long path cell with variable optical path length and temperatures regulated between 168 and 163 K, coupled to Synchrotron Radiation and a high resolution interferometer, Doppler-limited spectra of the very weak ν 3 + ν 5 band near 1450 cm−1 have been recorded. Low temperature…
Observation and analysis of the SF6 ν2+ν4−ν5 band: Improved parameters for the v5= 1 state
2016
Abstract In this paper, we present the high resolution analysis of the weak ν 2 + ν 4 - ν 5 band of SF6 around 735 cm−1. The spectra were recorded on the AILES Beamline at the SOLEIL Synchrotron facility using a cryogenic multipass cell coupled to a Bruker 125HR spectrometer with a maximum resolution of 0.00102 cm−1. For this band, we worked with 4 mbar of SF6 at a temperature of 223 ± 2 K. The optical path length was fixed to 141 m and the spectrum recorded with 0.001 cm−1 of resolution. A new, cold spectrum of the ν 2 + ν 4 band was also collected at 153 K, 15-m path length, and 0.0015 cm−1 resolution. The analysis was performed by using the Dijon group XTDS and SPVIEW software, based on…
Study of the Fundamental Bands of 70GeD4 by High-Resolution Raman and Infrared Spectroscopy: First Experimental Determination of the Equilibrium Bond…
2002
Abstract The four fundamental bands of 70 GeD 4 have been analyzed using the STDS software developed in Dijon (http://www.u-bourgogne.fr/LPUB/sTDS.html). Both infrared and Raman spectra were used to observe all fundamental bands. Infrared spectra of monoisotopic 70 GeD 4 were recorded in the regions 600 and 1500 cm −1 using the Bruker 120HR interferometer at Wuppertal. The resolution (1/maximum optical path difference) was between 2.3 and 3.3×10 −3 cm −1 for the ν 3 and ν 4 infrared-active fundamental bands as well as for the interacting ν 2 band. A high-resolution stimulated Raman spectrum of the ν 1 band has been recorded in Madrid. The instrumental resolution of the Raman spectrum was 3.…
THE UFFO SLEWING MIRROR TELESCOPE FOR EARLY OPTICAL OBSERVATION FROM GAMMA RAY BURSTS
2013
While some space born observatories, such as SWIFT and FERMI, have been operating, early observation of optical after grow of GRBs is still remained as an unexplored region. The Ultra-Fast Flash Observatory (UFFO) project is a space observatory for optical follow-ups of GRBs, aiming to explore the first 60 seconds of GRBs optical emission. Using fast moving mirrors to redirect our optical path rather than slewing the entire spacecraft, UFFO is utilized to catch early optical emissions from GRB within 1 sec. We have developed the UFFO Pathfinder Telescope which is going to be on board of the Lomonosov satellite and launched in middle of 2012. We will discuss about scientific potentials of t…
Non-Markovianity of a quantum emitter in front of a mirror
2014
We consider a quantum emitter ("atom") radiating in a one-dimensional (1D) photonic waveguide in the presence of a single mirror, resulting in a delay differential equation for the atomic amplitude. We carry out a systematic analysis of the non-Markovian (NM) character of the atomic dynamics in terms of refined, recently developed notions of quantum non-Markovianity such as indivisibility and information back-flow. NM effects are quantified as a function of the round-trip time and phase shift associated with the atom-mirror optical path. We find, in particular, that unless an atom-photon bound state is formed a finite time delay is always required in order for NM effects to be exhibited. Th…
Ultra-Fast Flash Observatory for observation of early photons from gamma ray bursts
2012
We describe the space project of Ultra-Fast Flash Observatory (UFFO) which will observe early optical photons from gamma-ray bursts (GRBs) with a sub-second optical response, for the first time. The UFFO will probe the early optical rise of GRBs, opening a completely new frontier in GRB and transient studies, using a fast response Slewing Mirror Telescope (SMT) that redirects optical path to telescope instead of slewing of telescopes or spacecraft. In our small UFFO-Pathfinder experiment, scheduled to launch aboard the Lomonosov satellite in 2012, we use a motorized mirror in our Slewing Mirror Telescope instrument to achieve less than one second optical response after X-ray trigger. We des…
Moderate-to-Strong Turbulence Generation in a Laboratory Indoor Free Space Optics Link and Error Mitigation via RaptorQ Codes
2016
Free Space Optics (FSO) is rapidly gaining interest as a line-of sight communication technology that offers capabilities similar - in terms of bandwidth and transfer rates - to optical fibre, also possessing several advantages compared with traditional radio frequency links. However, FSO link quality can be strongly affected by unfavourable weather conditions and also by the phenomenon of optical turbulence, even in clear sky. In this work, we have implemented an indoor FSO link and generated moderate-to-strong turbulence conditions along the optical path by using heaters and a mechanical ventilation system. In this way, we have been able to investigate the effects of the generated turbulen…
Development of Motorized Slewing Mirror Stage for the UFFO Project
2013
The Ultra-Fast Flash Observatory (UFFO) is a space observatory for optical follow-ups of gamma ray bursts (GRBs), aiming to explore the first 60 seconds of GRBs optical emission. UFFO is utilized to catch early optical emissions from GRBs within few sec after trigger using a Gimbal mirror which redirects the optical path rather than slewing entire spacecraft. We have developed a 15 cm two-axis Gimbal mirror stage for the UFFO-Pathfinder which is going to be on board the Lomonosov satellite which is to be launched in 2013. The stage is designed for fast and accurate motion with given budgets of 3 kg of mass and 3 Watt of power. By employing stepping motors, the slewing mirror can rotate fast…
Drifts in real-time partial wavefront correction and how to avoid them
2017
In visual experiments that require real-time partial correction of wavefront aberrations, small errors occur that accumulate over time and lead to drifts in Zernike coefficients of the uncorrected aberrations. A simple algorithm that does not require the inclusion of an additional optical path to obtain independent measurements of the eye's aberrations is described here, and its effectiveness in preventing these drifts is demonstrated.