Elf France

Societe Nationale Elf Aquitaine

Gerard Fortunato

Dominique Laurent

Bernard Damin

Marcel Napoleon

Andre Galais

Dominque Laurent

An interferometric unit consisting of a birefringent plate combined with an isotropic plate. This unit makes it possible to work with materials whose birefringence is slight and/or to reduce the necessary thickness of the birefringent plate. The unit is suited for integration into an interferometric device whose particular application is the detection of gases with quasi-periodic absorption structure absorbing in the infra-red.

Interferometric device for detecting and measuring the concentration of

Process and interferometric device for detecting and measuring the concentration, in a single operation, of all gases, having almost periodic absorption structures, contained in a gaseous mixture, each of the gases being associated with a characteristic path difference. Luminous flux is analyzed after passage through a cell containing the mixture, using to a multiple-wave interferometer, for example, a Fabry-Perrot interferometer, in which the inside faces of plates therein are highly reflective, and one of which plates is displaceable at a constant speed, it thus being possible to sweep a very wide range of path difference. Analysis of the output signal is performed frequency band by frequency band, by seeking the maximum.

Process for the simultaneous detection of several gases in a gaseous

The present invention concerns a process and a device for determining the cloud point of a diesel oil, comprising a light source and, aligned on a single axis, a diaphragm comprising a central hole on the said axis, an objective forming the image of the hole on a light trap, and behind the screen, a wide-diameter photoelectric detector intended to deliver an electric current when it receives a light flux, and, disposed between the objective and the screen, a cell containing a diesel oil sample to be analyzed, means for controlling the temperature of this sample being associated to the said cell.

Process and device for determining the cloud point of a diesel oil

Interferometric device for the detection and/or analysis of gas, of the type comprising an optical assembly forming the image of a light source on the sensitive element of the detector, comprising a photoelastic modulator comprising a silica or fluorine plate associated to a piezoelectric ceramic to vibrate in order to give the plate a birefringency variable by compression, having an axis parallel to that of a birefringent plate and an interferential filter constituted by a grating multiplexer device; and having application to the interferometric detection of gas through high-sensitivity.

Interferometric device for detecting gas

Selective modulation interferometric detector, intended for specifically detecting and/or identifying at least one gas in a gaseous mixture, especially with the aim of carrying out analysis and/or proportioning operations, the assembly E consists of a first strip L.sub.1 of interferometric quality having plane and parallel faces, of thickness e and index n introducing a displacement .DELTA.=2ne adapted to the gas to be analyzed, this strip L.sub.1 supplying on the detector a brilliant fringe, and a second strip L.sub.2 made of the same material as the first strip L.sub.1 which is slightly prismatic and supplying on the detector average illumination.

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Lyons, France

Gerard Fortunato