A target finding system identifies a surgical target such as a kidney stone by disposing an emitter such as a magnetic source behind or adjacent the surgical target, and employing a circuit to identify an axis to the emitter, thus defining an axis or path to the surgical target. An array of sensors arranged in an equidistant, coplanar arrangement each senses a signal indicative of a distance to the emitter. A magneto resistor sensor generates a variable resistance is responsive to the distance to a magnetic coil emitting a magnetic field. An equal signal from each of the coplanar sensors indicates positioning on an axis passing through a point central to the sensors and orthogonal to the plane. In one embodiment, a pair of Wheatstone bridges enhances the accuracy of the system.
