The invention relates to a device and to a method for synchronising a light wave with an electronic signal comprising images that are made of interleaved frames, characterised in that said method comprises the following steps: the reception (20) of the electronic signal by a box; the extraction (13) of first information by the identification of even and odd frames restored by the signal; the processing (14) said first information from the detection of even and odd images restored by the electronic signal; the calculation (15) from a logical operation carried out on the basis of the odd frames and odd images thus obtained; and the transmission (21) of a command to a light source supply module based on the results of said calculation.