US 12,422,355 B2
LIDAR system for differential absorption and background distance measurements
Laurent Lombard, Palaiseau (FR); Anne Durecu, Palaiseau (FR); Nicolas Cezard, Palaiseau (FR); François Gustave, Palaiseau (FR); and Guillaume Canat, Palaiseau (FR)
Assigned to OFFICE NATIONAL D'ETUDES ET DE RECHERCHES AÉROSPATIALES, Palaiseau (FR)
Filed by OFFICE NATIONAL D'ETUDES ET DE RECHERCHES AÉROSPATIALES, Palaiseau (FR)
Filed on Nov. 5, 2021, as Appl. No. 17/519,978.
Claims priority of application No. 20 11430 (FR), filed on Nov. 6, 2020.
Prior Publication US 2022/0146411 A1, May 12, 2022
Int. Cl. G01N 21/31 (2006.01); G01S 7/481 (2006.01); G01S 17/10 (2020.01)
CPC G01N 21/31 (2013.01) [G01S 7/4814 (2013.01); G01S 17/10 (2013.01); G01N 2201/06113 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A LIDAR (Light Detection and Ranging) system, adapted for performing differential absorption measurements between two distinct optical frequencies, and measurements of a separation distance from an obstacle which is present in a background of a measurement zone where the absorption occurs, the LIDAR system comprising:
a laser source assembly, suitable for producing radiations at either of the two optical frequencies;
intensity modulation means, adapted for applying a pulse envelope shape to each radiation, including a pulse duration and a pulse optical power value; and
an emission controller, adapted for controlling the intensity modulation means, the LIDAR system being adapted so that, during an operation of the LIDAR system, said LIDAR system emits, in a target direction in which a measurement of differential absorption and a measurement of the separation distance from the background obstacle are to be performed, a radiation emission sequence which comprises:
first time intervals during which the radiation emission is spectrally located at a first of the two optical frequencies, with a first spectral width, a first pulse duration, and a first pulse optical power value; and
second time intervals during which the radiation emission is spectrally located at a second of the two optical frequencies, with a second spectral width, a second pulse duration, and a second pulse optical power value,
the first and second spectral widths being such that the radiation emission during the first time intervals and during the second time intervals corresponds to spectral intervals which are disjoint, the first spectral width being greater than the second spectral width,
the first pulse optical power value being greater than the second pulse optical power value, and
the first pulse duration being shorter than the second pulse duration,
the LIDAR system further comprising a detection path which is adapted for independently detecting, processing, and analyzing backscattered radiations which correspond to the first optical frequency and to the second optical frequency, and which respectively correspond to emissions during the first and second time intervals.