LIDAR-type device for a remote spectroscopy of a matter and detection method thereof

Abstract

A LIDAR-type device (1) for a remote spectroscopy of a matter includes an optical emission channel (2) that includes a laser source (3) and an optical waves frequency generator (4) to generate a firstcomb (P1), a second comb (P2), and a local comb (POL). Each comb includes at least one stripe. A transmit telescope (5) emits an emission signal. A reception channel (7) includes a receive telescope(8) that receives a signal (9) reflected by the matter traversed by the emission signal (6) and a detection system (10) that detects a first beat signal (11) of the at least one stripe of the local comb with the corresponding first stripe of the first reflected comb, a second beat signal (12) of the at least one stripe of the local comb with the corresponding second stripe of the second reflectedcomb, and a third beat signal (13) of the at least one first beat signal with the at least one second beat signal.

Description

Technical field [0001] The present invention relates to the field of detection and measurement lasers, or lidars, which are used to detect the atmosphere by spectroscopy. Background technique [0002] It is known to use a laser source configured to emit light from a first narrowband frequency band centered on a first frequency to generate a first light wave including a first plurality of spectral components, each component covering a segment or strip, which is A narrow band or strip centered on a frequency different from other components, so that in the frequency space, the spectral composition of the light wave has a first spectral comb shape, and the height of each strip of the comb corresponds to the The energy of the spectrum bar emitted by the first light distributed on each bar. [0003] It is also known that not only the first light wave is generated from the first light emission, but also the second light wave is simultaneously generated, which is coherent with the first l...

AI Technical Summary

Problems solved by technology

This arrangement, known as "heterodyne detection" or "coherent detection," can be limited to the optical frequency through the correlation length of the laser source, which results in a random phase shift between the feedback light wave and the local oscillator.

This phase drift randomly simulates a radio frequency signal, which requires averaging of several random strength measurements, and has an unfavorable statistical standard deviation, and thus a reduced final signal-to-noise ratio

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