Abstract: A method for qualifying a mask for a lithography system, the mask having measurement points for detecting critical dimensions of the mask, comprising: first detection of critical dimensions of the mask at the measurement points, the first detection taking place sequentially and the duration of the first detection defining a measurement time period; determining reference measurement points from the measurement points, the number of reference measurement points being less than the number of measurement points; second detection of the at least one critical dimension of the mask at the reference measurement points; determining a deviation between the first and the second detected critical dimension at each of the reference measurement points; and applying a determined temporal profile of the correction factor to the at least one critical dimension to obtain a corrected critical dimension of the mask, and also a corresponding device for qualifying a mask for a lithography system.