Laser anemometry system and method

Laser anemometry method comprising the following steps:

• a step of transmission of an incident beam by at least one coherent laser source, said beam being backscattered by a set of particles passing through said incident beam;
• a mixing step, respectively associated with a laser source, for mixing said backscattered beam and a reference beam, said reference beam being the duplication of said incident beam, creating an interferometry wave;
• a conversion step, respectively associated with a laser source, converting said wave into an electrical signal, the instantaneous intensity of which is proportional to the instantaneous power of said wave;
• a first determination step, respectively associated with a laser source, for determining a time-frequency diagram of said electrical signal;
• characterized in that it also comprises:
• a second determination step, respectively associated with a laser source, for determining spots of said diagram, each spot being a set of connected points of said diagram, that have exceeded a detection threshold;
• a computation step, respectively associated with a laser source, for computing an average of the frequency, a duration and a slope characterizing the trend of the frequency as a function of time in the time-frequency diagram, respectively associated with a spot;
• a third determination step for determining the air speed from all or part of said averages of the frequency, of said durations and of said slopes, said third determination step also being suitable for computing a Doppler frequency, said Doppler frequency being the average of all or part of said averages of the frequency respectively associated with spots for which one of the following conditions is met:
• said slope is less than a first slope threshold;
• the multiplication of said duration by said slope is less than a second threshold;
• or
• said multiplication of said slope by the square of said duration is less than a third threshold.