The AOS FFT (fast Fourier transform) method for solving the TIE (transport of intensity equation) fails in the "offAxis" mode when x != y, where (x,y) is the centroid of the donuts. This is a problem both on wave front sensors and on the science chips. It includes cases where x = -y.

For a demonstration of these failures, see this notebook: https://gist.github.com/jfcrenshaw/6e85d8f83e3301ec569f896c93590b2e