A bolt fastening system for a turbomolecular pump wherein a first member is fastened in an axial direction with respect to a second member by multiple bolts arranged concentrically with respect to a rotor shaft center. The device acts as identification of the user. The dental implant also includes a jig body accurately fixed on a positioning member integral with the dental implant, and an elongated part or socket which slides in the jig body to be urged in contact with the bone. The arm member is held rotatably by the body at an opposite end, and is held rotatably by the lid at a remaining opposite end. A chromophore substance is applied to the location of the energy input before or at the same time as the energy input, such that a physical, chemical or biological visible change in the solid body or the workpiece is achieved at the location of the energy input.