Abstract: Apparatus for treating a material having a miniaturized photoionic head including at least one optical fiber (2), a pulsed light source permitting the treatment of the material (10), a light injector for injecting light into one end of the fiber and a miniaturized photoionic head (8) having a ring (16). One side of the ring is fixed to the other end of the fiber, and the other side of the ring is against the material. This ring confines a plasma forming, due to the pulsed light, in the space defined by the ring, from a material or a substance (20) placed in the space, for the treatment of the material such as surface treatment of metals.