Method for calibrating a thickness gauge

A method for calibration of a thickness gauge, in which the thickness gauge measures the thickness of a measured object in a stipulated measurement direction with at least one displacement sensor, operating contactless or by scanning, said method comprising:

• bringing a reference object with known thickness and shape into at least a partial area of a measurement field of at least one displacement sensor;
• recording at least two independent measured values by the at least one displacement sensor at at least two stipulated locations on a first surface of reference object at stipulated times tj or as a function of stipulated positions pj of reference object in the measurement field, in which j=1, 2, . . . ;
• determining tilting or a spatial position of the reference object in the measurement field from the recorded measured values of times tj or as a function of positions pj of the reference object;
• recording an additional measured value with the at least one displacement sensor on another location situated in the measurement direction on a second surface opposite the first surface or on a surface area of reference object opposite the first surface, in order to determine a thickness value of the reference object in measurement direction;
• calculating the thickness value of the reference object from the measured values of at least one displacement sensor at times tj or in positions pj in measurement direction;
• and
• calculating the difference between the calculated thickness value and the known thickness of the reference object to obtain position- and tilting- or location-dependent correction values in the partial area or measurement field, in order to be able to compensate for geometric errors and/or non-linearities of at least one displacement sensor in the partial area or measurement field during a thickness measurement.