System for the rigorous positioning of an object along an axis

System for the rigorous positioning, along an axis OX of an object 1 such as a semiconductor material wafer during an integrated circuit manufacturing process. According to the invention, this system comprises: - control means 15 of the motor 5 to perform the carriage 3, a displacement acquisition whose amplitude is at least equal to the pitch of the second optical network 10; - a generator 18 generating during said displacement acquisition, a periodic reference signal of period equal to the pitch of said second network; - multiplying means 19 to form the product of said periodic reference signal and the actual signal delivered by the photoelectric sensor 14; - means 19 for summing the signal formed by the succession of said products; - calculating means 20 to determine any offset between said optical network; and - means 16 for controlling the motor 5 to bring said optical networks in rigorous alignment .