Patent ID: 9383419
Filing Date: 2016-07-05
CPC Classification: G01R

Claim Text:
1. A gradiometer using an optically pumped magnetometer, the gradiometer using the optically pumped magnetometer comprising: one or more cells each containing a group of atoms in a gaseous state, including an alkali metal, encapsulated therein; a pump beam source that applies a first pump beam and a second pump beam to each of the one or more cells to spin-polarize the group of atoms, the first pump beam and the second pump beam being parallel to each other; a probe beam source that applies a probe beam to the one or more cells to which the pump beams have been applied; a detector for detecting a rotation of a polarization plane of the probe beam that has passed through the one or more cells in a state in which the group of atoms is spin-polarized, wherein the first pump beam and the probe beam cross each other at a first measurement position, the second pump beam and the probe beam crosses each other at a second measurement position, the first measurement position and the second measurement position are arranged along a first direction that is linear with respect to a signal source, and the probe beam sequentially passes through the first measurement region and the second measurement region; wherein an alkali metal density, a measurement position length, a pump beam intensity and a spin polarization ratio for the first measurement position are the same as those of the second measurement position; and wherein each of a direction of a magnetic field measured at the first measurement position and a direction of a magnetic field measured at the second measurement position is the same as the first direction, a sign of spin polarization caused by optical pumping is different between the first measurement region and the second measurement region; and an angle of rotation of the polarization plane of the probe beam that has sequentially passed through each of the first measurement position and the second measurement position is obtained, thereby obtaining a difference in magnetic flux density between the first measurement position and the second measurement position.