I am trying to find a way to accurately detect the distance from a stretched wire for alignment purposes (within 10um). I am not concerned with the absolute value of the distance, rather the repeatable indication that the apparatus is centered on the wire.
I came across the following question Arduino robot wire follower + how to position on wire, where @Marko Buršič wrote:
If wire is located in the middle, signals from both coils are in phase. You could measure the phase difference with phase comparator.
The above implies that if the wire is not located exactly between the coils there will be a phase difference which could be used to detect the offset from the wire. The problem is that I do not understand this statement. Shouldn't the flux generated by the current in the wire affect all coils in equally, i.e. the induced current in both coils have the same phase?
I could use just the amplitude of the induced current to center the apparatus but I am not sure I could get the required accuracy.