The disks coated at Montreal are hold with three small clips. Therefore there are three small regions close to the edge that are not coated. See the picture below to see one of the samples with the clips.
To check the effect of the clip fingerprints on the dilution factor, I set up a COMSOL simulation. For simplicity, I started with only two small clips as shown below:
The result is that they have a very small effect. The first plot below compares the dilution factor (energy in the coating over total energy) with and without the fingerprints:
Another way to look at it is given below: the plot shows the percentage difference in the computed dilution factor. It's always smaller than 1%, so completely neglegible. In conclusion: we don't need to model the clips.
