A method for verifying a deflection speed of an energy beam spot, the method comprising the steps of: providing a predetermined pattern on a work table with the energy beam spot while deflecting the energy beam spot with a first deflection speed, detecting first positions of the energy beam spot on the work table created with the first deflection speed, providing the predetermined pattern on a work table with the energy beam spot while deflecting the energy beam spot with a second deflection speed, detecting second positions of the energy beam spot on the work table created with the second deflection speed, comparing the first and second positions, wherein the deflection speed is verified if each one of the first positions are deviating less than a predetermined distance from corresponding second positions.