A method for determining a vibration amplitude of a tool, includes the steps of: generating a light beam of a light barrier with a transmitter for generating the light beam and a receiver for detecting a light intensity of the light beam; generating a receiver signal on the basis of a light intensity of the light beam that is detected by the receiver of the light barrier; positioning a tool tip of the tool in the light beam; causing the tool to vibrate; determining the vibration amplitude of the tool from a modulation of the receiver signal brought about by the vibration of the tool.