Search results for " Sensor."

Experiments with a fiber-based optical dipole trap for cold Cs-Atoms

2011

Pulling a standard optical fiber to a diameter of less than the wavelength of the guided light causes the light field to project slightly over the fiber boundaries in form of an evanescent wave. The latter can be used for light-matter-interactions in the vicinity of the surface of the fiber and therefore allows to perform quantum optic experiments.

Raman based distributed fiber optic temperature sensors for structural health monitoring in radiation environment

2015

Raman distributed temperature sensor (RDTS) measurements were performed during γ-radiation on three different classes of standard multimode fibers (pure, Ge-doped and F-doped). The sensor response is affected by the radiation induced attenuation phenomena leading to errors in the temperature measurements. The amplitude of this error strongly depends on the fiber type and the irradiation conditions. These results are promising in view of the integration of these RDTS into the deep geological repository for radioactive waste.

<title>Optical fiber loop sensors</title>

2003

Article presents prepared and tested constructions of loop hybrid fiber optical sensors with light amplitude modulation used for measuring loads and temperature.

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…

Steady state γ-ray radiation effects on Brillouin fiber sensors

2015

International audience; Brillouin optical time-domain analysis (BOTDA) sensors offer remarkable advantages for the surveillance of the planned French deep geological radioactive wastes repository, called Cigéo1,2. In this work we study the performances of Brillouin distributed sensors in harsh environment. We evaluate the radiation tolerance of different sensor classes and their responses evolution during γ-ray exposition with 1kGy/h dose rate (to reach ~0.2MGy) and after 1, 3, 6 and 10 MGy accumulated doses. Measurements on strained Ge-doped SMF are reported to highlight the variation on Brillouin scattering proprieties, both intrinsic frequency position of Brillouin shift and its dependen…

High-speed and high-resolution interrogation of FBG sensors using wavelength-to-time mapping and Gaussian filters

2019

In this work we report a novel intensity-based technique for simultaneous high-speed and high-resolution interrogation of fiber Bragg grating (FBG) sensors. The method uses a couple of intensity Gaussian filters and the dispersion-induced wavelength-to-time mapping effect. The Bragg wavelength is retrieved by means of the amplitude comparison between the two filtered grating spectrums, which are mapped into a time-domain waveform. In this way, measurement distortions arising from residual power due to the grating sidelobes are completely avoided, and the wavelength measurement range is considerably extended with respect to the previously proposed schemes. We present the mathematical backgro…

Optical sensors for ethanol vapor based on polystyrene opals infiltrated with hydrogel

2013

This paper deals with a novel class of optical sensors for ethanol vapor, based on polystyrene opals infiltrated with a hydrogel sensitive to ethanol. Optical characterization of such opals has been performed, proving their effectiveness as sensors

Ethanol vapor optical sensors based on polystyrene opals infiltrated with hydrogel

2013

Single-shot digital holography
by use of the fractional Talbot effect

2009

We present a method for recording in-line single-shot digital holograms based on the fractional Talbot effect. In our system, an image sensor records the interference between the light field scattered by the object and a properly codified parallel reference beam. A simple binary two-dimensional periodic grating is used to codify the reference beam generating a periodic three-step phase distribution over the sensor plane by fractional Talbot effect. This provides a method to perform single-shot phase-shifting interferometry at frame rates only limited by the sensor capabilities. Our technique is well adapted for dynamic wavefront sensing applications. Images of the object are digitally recon…

Glowing optical fiber designs and parameters

1997

Side-emitting optical fiber designs and main parameters have been studied. A simplified model to describe emission of the 'glowing' fiber is developed. Basic expressions for the emission parameters as functions of the input radiation intensity, distance along the fiber axis and scattering efficiency longitudinal distribution are given for several design modifications. The model assumptions have been checked experimentally by testing silica core side-glowing optical fiber samples.