Abstract: Device and method for determining mechanical stresses in a substrate coating has a substrate holder and actuating element configured as a piezoelectric actuator moveable at least partially in relation to the holed. The actuating element mechanically prestresses the substrate by applying an electric starting voltage to the piezoelectric actuator to cause the actuating element to be partially displacement by a predetermined and/or determinable starting displacement relative to the holed. A coating is applied to a deposition area of the substrates and a change in displacement of the actuating element is determined.