A machining device comprising - a light source for producing an incoming light beam, the machining device being characterised by the following: - an optical system for obtaining from the incoming light beam produced by the light source an outgoing light beam for machining a target, the optical system comprising ▪ a movable mirror, for obtaining a first reflected light beam by reflection of a first incident light beam obtained from the incoming light beam; ▪ a retro reflection system for directing first reflected light beam such that it comes back to the mirror as a second incident light beam, said first reflected light beam and said second incident light beam being parallel for all possible incidence of said first reflected light beam with respect to the retro reflection system, for producing the outgoing light beam obtained from the reflection of the second incident light beam on the mirror, - driving means for moving said movable mirror; - focusing means for focusing said outgoing light beam on a target, said outgoing light beam remaining parallel to a given direction upstream the focusing means whatever the position and orientation of the mirror the optical system being configured such that ▪ the outgoing light beam is spatially offset from incoming light beam ▪ a change in position between the mirror and the retro reflection system is able to induce a variation of the spatial offset between incoming and outgoing light beams, and ▪ depending on the position of the mirror, the outgoing light beam follows a different trajectory serving to drive the precession of the outgoing light beam downstream the focusing means. - a light source for producing an incoming light beam, the machining device being characterised by the following: - an optical system for obtaining from the incoming light beam produced by the light source an outgoing light beam for machining a target, the optical system comprising ▪ a movable mirror, for obtaining a first reflected light beam by reflection of a first incident light beam obtained from the incoming light beam; ▪ a retro reflection system for directing first reflected light beam such that it comes back to the mirror as a second incident light beam, said first reflected light beam and said second incident light beam being parallel for all possible incidence of said first reflected light beam with respect to the retro reflection system, for producing the outgoing light beam obtained from the reflection of the second incident light beam on the mirror, ▪ a movable mirror, for obtaining a first reflected light beam by reflection of a first incident light beam obtained from the incoming light beam; ▪ a retro reflection system for directing first reflected light beam such that it comes back to the mirror as a second incident light beam, said first reflected light beam and said second incident light beam being parallel for all possible incidence of said first reflected light beam with respect to the retro reflection system, for producing the outgoing light beam obtained from the reflection of the second incident light beam on the mirror, - driving means for moving said movable mirror; - focusing means for focusing said outgoing light beam on a target, said outgoing light beam remaining parallel to a given direction upstream the focusing means whatever the position and orientation of the mirror the optical system being configured such that ▪ the outgoing light beam is spatially offset from incoming light beam ▪ a change in position between the mirror and the retro reflection system is able to induce a variation of the spatial offset between incoming and outgoing light beams, and ▪ depending on the position of the mirror, the outgoing light beam follows a different trajectory serving to drive the precession of the outgoing light beam downstream the focusing means. ▪ the outgoing light beam is spatially offset from incoming light beam ▪ a change in position between the mirror and the retro reflection system is able to induce a variation of the spatial offset between incoming and outgoing light beams, and ▪ depending on the position of the mirror, the outgoing light beam follows a different trajectory serving to drive the precession of the outgoing light beam downstream the focusing means.