Fig. 13

Registration of a magnetic image with an optical image using two point sources. Sensor-to-sample distance was 216 µm when the magnetic field was measured. a Optical scanner image of a basalt thin section sample with two point sources on the corners. b Magnetic image of the same sample with NRM after 20-mT AFD. c Magnetic image overlaid on the gray-scaled optical image. d The image is an enlargement of the magnetic field produced by point source A placed in the lower-left corner of b outside of a thin section. The contours represent the magnetic field estimated for an optimized magnetic dipole after a nonlinear least-squares fit. The red cross in the center indicates the estimated position of the dipole on the XY plane. e Optical microscopic image of a 75-µm φ point source made of FeCo on a Si square substrate. f The image is an enlargement of the magnetic field produced by point source B in the upper-right corner of b. Explanations on contours and the red cross are the same as d