Magnetic field measurement apparatus, magnetic field measurement method, and storage medium with magnetic field measurement program stored thereon

A magnetic field measurement method for measuring a magnetic field with a magnetic field measurement apparatus, the magnetic field measurement method comprising:

• converting, with the magnetic field measurement apparatus, analog detection signals output respectively by a plurality of magnetic sensors, in a magnetic sensor array having a plurality of magnetic sensor cells capable of detecting magnetic fields in three axial directions arranged in three dimensions, with each magnetic sensor cell including a plurality of the magnetic sensors that each have a magnetoresistive element and a magnetic flux concentrator arranged at least at one of one end and another end of the magnetoresistive element, into digital measurement data;
• acquiring the digital measurement data;
• calibrating the digital measurement data using at least one of a main-axis sensitivity, cross-axis sensitivities, and an offset;
• and
• calculating a gradient magnetic field using magnetic field measurement data resulting from the calibration of the digital measurement data, wherein
• the calculating the gradient magnetic field includes calculating the gradient magnetic field in three dimensions for magnetic fields in all three axial directions, by calculating a difference in magnetic fields between adjacent magnetic sensor cells among the plurality of magnetic sensor cells, using the magnetic field measurement data measured between the adjacent magnetic sensor cells.

A storage medium storing thereon a magnetic field measurement program that, when executed by a computer, causes the computer to function as:

• a plurality of AD converters that respectively convert analog detection signals output by a plurality of magnetic sensors into digital measurement data, the plurality of magnetic sensors being in a magnetic sensor array having a plurality of magnetic sensor cells capable of detecting magnetic fields in three axial directions arranged in three dimensions, each magnetic sensor cell including a plurality of the magnetic sensors that each have a magnetoresistive element and a magnetic flux concentrator arranged at least at one of one end and another end of the magnetoresistive element;
• a magnetic field acquiring section that acquires the digital measurement data;
• a calibration computing section that calibrates the digital measurement data from the magnetic field acquiring section, using at least one of a main-axis sensitivity, cross-axis sensitivities, and an offset;
• and
• a gradient magnetic field computing section that calculates a gradient magnetic field using magnetic field measurement data resulting from the calibration of the digital measurement data, and also calculates the gradient magnetic field in three dimensions for magnetic fields in all three axial directions, by calculating a difference in magnetic fields between adjacent magnetic sensor cells among the plurality of magnetic sensor cells, using the magnetic field measurement data measured between the adjacent magnetic sensor cells.