I had an idea the other day facing a problem at work.. instead of using graphical methods, I imported data from the thermal simulation into excel and adjusted the time scale of the data to form next to a baseline, then using a 3rd order polynomial to describe a part of the graph, I calculated the time it took for the slope coefficients to come back together and thereby calculating the time it takes for the magnetic lens to respond to a sudden outside temperature spike of about 0.14 degree C.