An acousto-optic imaging method for imaging a region of observation of a medium, the method comprising: - a measurement step during which a plurality of measurement signals S mj (t) associated with unfocused acoustic waves respectively propagating in various directions of propagation m, are acquired by optical means, said unfocused acoustic waves being respectively emitted in the region of observation by an array of ultrasonic transducers (T k) regularly spatially distributed, said unfocused acoustic waves being emitted, in each direction of propagation m, successively J times with respectively J periodic spatial amplitude modulations j in order to form spatially-modulated unfocused acoustic waves, the periodic spatial amplitude modulations j having an identical spatial period in at least one direction of spatial periodicity, and corresponding to a given number P of transducers, the periodic spatial amplitude modulations j being mutually spatially phase-shifted, the measurement step comprising, for each periodic spatial amplitude modulation j, a plurality of successive measurement operations comprising the following sub-steps: o an acoustic emission sub-step in which a spatially-modulated unfocused acoustic wave is emitted with said periodic spatial amplitude modulation j and propagates in a direction of propagation m, o a light emission sub-step in which, at the same time as the spatially-modulated unfocused acoustic wave, an incident light wave is emitted in the region of observation in order to generate a spatially-modulated tagged light wave, comprising at least one acousto-optic component respectively shifted in frequency by the spatially-modulated unfocused acoustic wave, o an acquisition sub-step in which the spatially-modulated tagged light wave is captured and a measurement signal S mj (t) is thus acquired corresponding to the periodic spatial amplitude modulation j and to the unfocused acoustic wave propagating in the direction m, - a spatial demodulation step, during which the various measurement signals S mj (t) corresponding to the J periodic spatial amplitude modulations are combined for a same direction of propagation m, in order to obtain a demodulated signal S m (t) specific to the direction of propagation m, - a processing step during which an image of at least a part of the region of observation is determined using the demodulated signals S m (t). - a measurement step during which a plurality of measurement signals S mj (t) associated with unfocused acoustic waves respectively propagating in various directions of propagation m, are acquired by optical means, said unfocused acoustic waves being respectively emitted in the region of observation by an array of ultrasonic transducers (T k) regularly spatially distributed, said unfocused acoustic waves being emitted, in each direction of propagation m, successively J times with respectively J periodic spatial amplitude modulations j in order to form spatially-modulated unfocused acoustic waves, the periodic spatial amplitude modulations j having an identical spatial period in at least one direction of spatial periodicity, and corresponding to a given number P of transducers, the periodic spatial amplitude modulations j being mutually spatially phase-shifted, the measurement step comprising, for each periodic spatial amplitude modulation j, a plurality of successive measurement operations comprising the following sub-steps: o an acoustic emission sub-step in which a spatially-modulated unfocused acoustic wave is emitted with said periodic spatial amplitude modulation j and propagates in a direction of propagation m, o a light emission sub-step in which, at the same time as the spatially-modulated unfocused acoustic wave, an incident light wave is emitted in the region of observation in order to generate a spatially-modulated tagged light wave, comprising at least one acousto-optic component respectively shifted in frequency by the spatially-modulated unfocused acoustic wave, o an acquisition sub-step in which the spatially-modulated tagged light wave is captured and a measurement signal S mj (t) is thus acquired corresponding to the periodic spatial amplitude modulation j and to the unfocused acoustic wave propagating in the direction m, o an acoustic emission sub-step in which a spatially-modulated unfocused acoustic wave is emitted with said periodic spatial amplitude modulation j and propagates in a direction of propagation m, o a light emission sub-step in which, at the same time as the spatially-modulated unfocused acoustic wave, an incident light wave is emitted in the region of observation in order to generate a spatially-modulated tagged light wave, comprising at least one acousto-optic component respectively shifted in frequency by the spatially-modulated unfocused acoustic wave, o an acquisition sub-step in which the spatially-modulated tagged light wave is captured and a measurement signal S mj (t) is thus acquired corresponding to the periodic spatial amplitude modulation j and to the unfocused acoustic wave propagating in the direction m, - a spatial demodulation step, during which the various measurement signals S mj (t) corresponding to the J periodic spatial amplitude modulations are combined for a same direction of propagation m, in order to obtain a demodulated signal S m (t) specific to the direction of propagation m, - a processing step during which an image of at least a part of the region of observation is determined using the demodulated signals S m (t).