The present invention provides a process for suppressing abnormal grain growth in friction stir welded aluminum alloys by inserting an intermediate annealing treatment after the welding step on the article. The locking members are entirely contained within the box when the box is closed, and they can be disengaged only with the use of a special tool. The cutting body or each cutting body is inclined in relation to the disk-shaped base body or the plate-shaped base body. By applying a series of known voltages while the probe is vibrating, the skin’s local surface potential can be measured and the lateral electric field can be calculated from the spatial distribution of surface potential measurements. According to the first radiation signal, a first controlling module of the receiving unit is for driving a light-emitting device to emit a control light signal to the optical fiber.