You can either build a system where the field lands on the detector in a known way, or build one where it lands in an unknown way and try to figure out what the

You can either build a system where the field lands on the detector in a known way, or build one where it lands in an unknown way and try to figure out what the heck happened. In light of many functional designs (for example, Phasics, Zygo) I don't see why your group introduces the unknown factor. Could this have been done by a camera from Phasics?