A LIDAR system, adapted for performing differential absorption measurements between two distinct optical frequencies (v 1, v 2), 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 (v 1, v 2); characterized in that: - intensity modulation means, adapted for applying a pulse envelope shape to each radiation, including a pulse duration and a pulse optical power value (P 1, P 2); 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 (v 1) of the two optical frequencies, with a first spectral width (Δv 1), a first pulse duration (Δt 1), and a first pulse optical power value (P 1); and - second time intervals during which the radiation emission is spectrally located at a second (v 2) of the two optical frequencies, with a second spectral width (Δv 2), a second pulse duration (Δt 2), and a second pulse optical power value (P 2), the first (Δv 1) and second (Δv 2) 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 (P 1) being greater than the second pulse optical power value (P 2), and the first pulse duration (Δt 1) being shorter than the second pulse duration (Δt 2), 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 (v 1) and to the second optical frequency (v 2), and which respectively correspond to emissions during the first and second time intervals. - a laser source assembly, suitable for producing radiations at either of the two optical frequencies (v 1, v 2); - intensity modulation means, adapted for applying a pulse envelope shape to each radiation, including a pulse duration and a pulse optical power value (P 1, P 2); 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 (v 1) of the two optical frequencies, with a first spectral width (Δv 1), a first pulse duration (Δt 1), and a first pulse optical power value (P 1); and - second time intervals during which the radiation emission is spectrally located at a second (v 2) of the two optical frequencies, with a second spectral width (Δv 2), a second pulse duration (Δt 2), and a second pulse optical power value (P 2), - first time intervals during which the radiation emission is spectrally located at a first (v 1) of the two optical frequencies, with a first spectral width (Δv 1), a first pulse duration (Δt 1), and a first pulse optical power value (P 1); and - second time intervals during which the radiation emission is spectrally located at a second (v 2) of the two optical frequencies, with a second spectral width (Δv 2), a second pulse duration (Δt 2), and a second pulse optical power value (P 2), the first (Δv 1) and second (Δv 2) 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 (P 1) being greater than the second pulse optical power value (P 2), and the first pulse duration (Δt 1) being shorter than the second pulse duration (Δt 2), 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 (v 1) and to the second optical frequency (v 2), and which respectively correspond to emissions during the first and second time intervals.