Abstract: A drive device for rotating a main mobile assembly relative to a support about a rotation axis includes an intermediate mobile assembly rotated about the same rotation axis. A small travel linear electromagnetic drive device operates tangentially between the intermediate mobile assembly and the mobile assembly, being controlled in accordance with the position of the main mobile assembly relative to the support. A large travel drive device rotates the intermediate mobile assembly relative to the support in accordance with the relative position of the intermediate mobile assembly and the main mobile assembly. End stops delimit predetermined movement of the main mobile assembly relative to the intermediate mobile assembly.

Abstract: An interferometer delay line includes an optical payload displaced along a guide track under the control of a control device including at least one sensing device which senses the position of the payload along the guide track and a drive device acting on the payload. The sensing device includes a linear succession of fixed optical read heads parallel to the guide track and a graduated rule carried by the optical payload in any position on the latter facing at least one of the optical read heads. The sensing device also includes a synchronizing/switching unit causing a counter to count pulses from the heads in succession, the pulses representing distance increments.