Unfortunately it is necessary in some cases to test completely irregularly shaped test regions. May it because the optics simply is of this shape and needs to be tested in this state or because the used area is irregular and it is undesired to extend the test region to a larger, but regular shape.
We present a simple method that not only provides a possibility to evaluate any arbitrary shaped test region but also to have a tolerance model that gives reasonable and uses worldwide accepted specification standards.
Certain interferometer software may be suited for an appropriate data analysis. An overview over some commercially available interferometer software is given with respect to the requirement of the presented method.