Sigmoid was chosen because historically we didn’t calibrate ODs past ~.8 with 1 photodiode. If the cut off is there, the sigmoidal fit works pretty well (OD measurements with two photodiodes? - #5 by bgwong). But after adding an additional photodiode at 90 degrees, we found the range is much higher. You can feel free to add more types of fit. Just make sure to modify the code appropriately.
The easiest way is to change the evolver.py transform_data function and have it transform the incoming data with your own custom fit: