The invention concerns, in one aspect, an actuator for generating a bidirectional force intended for being integrated into a deformable mirror comprising a deformable reflective substrate. Said actuator comprises a stationary body (10); a drive device; a drive rod (20) able to be driven in a translatory movement with respect to the stationary body (10), along an axis of translation (xx′), by means of the drive device; a floating head (30) designed to be attached to the deformable reflective substrate, and mounted in floating manner with respect to the drive rod via first and second elastic means (33, 35). The first and second elastic means (33, 35) are each mounted between the drive rod (20) and the floating head (30) and are designed to apply forces to the floating head, whose projections on the translation axis (xx′) are of opposite directions.