Device and method for focusing a light beam

Abstract

A device for focusing a light beam comprises a optical assembly comprising at least one focusing lens and/or mirror, a support structure which supports the optical assembly, a magnetic actuator configured to move the optical assembly with respect to the support structure along a moving direction substantially parallel to an optical axis (X) of the optical assembly and at least one position sensor configured to provide an indication of the position of the optical assembly with respect to the support structure. The magnetic actuator comprises at least one permanent magnet integrally associated with the optical assembly and at least one first electrical winding integrally associated with the support structure and configured to cause flowing of an electric current within it, wherein the electrical current interacts with said at least one permanent magnet and causes the movement of the optical assembly along said moving direction until the optical assembly is brought to a desired focusing position. The focusing device comprises at least one second electrical winding integrally associated with the support structure and configured to be short-circuited so as to generate, due to the electromagnetic induction generated by the relative motion between said at least one permanent magnet and said at least one second electrical winding, a braking force that opposes the movement of the optical assembly along said moving direction.