A matrix-array optical sensor including individual detection cells each including at least one photodiode operating in photovoltaic mode, a first amplifier stage connected directly or indirectly to the photodiode and a capacitance connected directly or indirectly to the output of the first amplifier stage and the voltage of which varies with the illuminance on the photodiode, the sensor being arranged to a ensure a one-way flow of current to or from said capacitance in order to bring the latter to a voltage corresponding to an extremum of the illuminance during an operating cycle of the photodiode.