Lidar imaging system with fmcw type heterodyne detection comprising a device for correcting the phase of the reference signal

A LIDAR imaging system of the FMCW type, comprising:

• a coherent light source configured to emit a continuous frequency modulated primary signal;
• an optical device for projecting part of the primary signal, called object signal, onto a scene to be instantaneously illuminated;
• an optical device for transmitting part of the primary signal, called reference signal, to an optical imaging device;
• the optical imaging device configured to receive part of the object signal backscattered by the scene, called backscattered object signal, having a speckle pattern;
• a matrix photodetector comprising a matrix of detection pixels, each intended to receive, in a reception plane conjugated with the scene by the optical imaging system, the backscattered object signal and the reference signal that form a heterodyne signal having a frequency, called beat frequency, representing a distance between the matrix photodetector and the illuminated scene;
• a phase correction device, comprising:
• a spatial phase modulator, arranged on the path of the reference signal upstream of the optical imaging device, configured to apply a spatial phase distribution, called corrected spatial phase distribution, to the reference signal;
• a computation unit connected to the matrix photodetector and to the spatial phase modulator and configured to:
• determine an optimal corrected spatial phase distribution to be applied to the reference signal by the spatial phase modulator,
• as a function of a first spatial distribution representing a spatial intensity distribution of the backscattered object signal in the reception plane, detected by the matrix photodetector,
• so that the reference signal has a spatial intensity distribution, called corrected spatial intensity distribution, in the reception plane optimizing a spatial distribution of a parameter of interest representing the heterodyne signal, selected from among the intensity of the heterodyne signal, an intensity of an alternating component of the heterodyne signal, or a signal-to-noise ratio.