Detector with deflecting elements for coherent imaging

A coherent lidar imaging system comprising:

• a detector (Det) comprising a matrix array of pixels (P), each pixel (P) comprising a photodetector component (PD) having a photosensitive surface (Sph), the detector being designed to be illuminated by a coherent beam, called the image beam (Lo,rim) consisting of grains of light called speckle grains (SG),
• a matrix array of transmissive deflecting elements (DE) arranged on the side of the illumination by the coherent beam, a deflecting element being associated with a group of one or more pixels comprising at least one pixel, and configured to be individually orientable by means of an electrical signal, so as to deflect a fraction of the image beam incident on said group, and thus modify the spatial distribution of the speckle grains in the plane of the photosensitive surface,
• each group of one or more pixels further comprising a feedback loop (SL) associated with the deflecting element and configured to actuate the deflecting element so as to optimize the signal or the signal-to-noise ratio from the light detected by the one or more photodetector components of said group of pixels, the feedback loop comprising a feedback circuit (SLC),
• a laser source (SL) configured to emit a laser radiation (L) with a temporally modulated optical frequency (FL),
• a splitting/recombining optical system (SSR) comprising at least:
• a splitter optical system (LS) designed to spatially split the laser radiation (L) into a beam called the reference beam (Lref) and into a beam called the object beam (Lo) that is directed towards the scene to be observed (Obj);
• a recombining optical system (SR) designed to spatially superpose the reference beam (Lref) onto the beam reflected by said scene (Lo,r), so as to form a recombined beam (Lrec),
• an optical imaging system (Im) having an optical axis (AO) and producing an image of the scene by focusing a beam reflected by the scene (Lo,r) on the detector, forming the image beam (Lo,rim),
• the splitting/recombining optical system (SSR) and the optical imaging system (Im) being configured such that each pixel of the detector receives a portion of the image beam (Lo,rim) and a portion of the reference beam (Lref), and that said portions are spatially superposed coherently onto each pixel,
• the coherent lidar imaging system further comprising at least one electronic processing circuit (PC) configured to calculate, for each pixel, a frequency (F(i,j)) of a beat of the portion of the image beam with the portion of the reference beam illuminating said pixel,
• a processing unit (UT) connected to the laser source and to the detection device and configured to determine a distance of points of the scene that are imaged on said pixels, on the basis of the calculated beat frequency associated with each pixel and on the basis of the modulated optical frequency of the laser radiation, said electronic processing circuit being located in the detector and/or in the processing unit.