Method for emissivity-corrected pyrometry

A method for coating a substrate (7) with a layer, the method comprising:

• depositing the layer on the substrate (7);
• during the deposition of the layer, determining measurement value pairs ({UE,n, UR,n}) multiple times in succession with at least one optical measuring device on the layer, each of which contains an emissivity value (UE,n) that corresponds to a thermal radiation output measured at a first wavelength, and a reflectance value (UR,n) measured at a second wavelength that differs from the first wavelength;
• calculating temperature values (Ti) of the substrate (7) from the measurement value pairs ({UE,n, UR,n}), wherein the emissivity values (UE,n) lie on a first curve that oscillates with a first angular frequency (ωE) over time (t), and the reflectance values (UR,n) lie on a second curve that oscillates with second angular frequency (ωR) over time (t), and a quotient of the first angular frequency (ωE) and the second angular frequency (ωR) differs from 1;
• and
• through a numerical time transformation, in which at least two measurement values each of the emissivity value (UE,i) or the reflectance value (UR,i) calculated at different times are used, forming transformed values (U*i) from the emissivity values (UE,i) and/or the reflectance values (UR,i), wherein the temperature values (Ti) are calculated using the transformed values (U*i) instead of the emissivity values (UE,i) or the reflectance values (UR,i),
• wherein one of the emissivity values (UE,i) or the reflectance values (UR,i) is a current measurement value,
• wherein one of (i) a first gradient value of the first curve of the emissivity values (UE,i) is calculated from the emissivity values (UE,i), or (ii) a second gradient value of the second curve of the reflectance values (UR,i) is calculated from the reflectance values (UR,i), and
• wherein the transformed values (U*i) are calculated with the first gradient value or the second gradient value.