The position detector of an object includes a body defining an input receiving an optical fibre delivering a light signal, and an output delivering a signal representative of the position of the object. A mirror is mounted to move between first and second positions in the body with respect to the input. The first position or the second position ensures transmission of the light signal from the input to the output. The other of the first position and the second position prevents transmission of the light signal to the output. A spring is mounted in the body in order to place the mirror in the first position. A tip is movable relative to the body between a first position and a second position along a direction of movement and is intended to cooperate with the object to be monitored.