3 Target Shape

Because the eddy currents flow on the target in closed loops, any discontinuities in the current paths can result in higher measurement noise. If the target has any gaps or voids, the eddy currents on the target surface will need to flow around the void, as seen in Figure 3-1.

Figure 3-1 Current Flow for a Uniform Surface Target vs a Target With a Gap

This mismatch in image current path compared to sensor current path reduces the coupling between the target and the sensor, and results in a smaller shift in sensor inductance and reduced measurement resolution.