The Method for Measuring the Non-Orthogonal Angle of the Magnetic Field Coils of a K-Rb-21 Ne Co-Magnetometer

The sensitivity of a dual-axis K-Rb-(21) Ne co-magnetometer is subject to the accuracy of the magnetic field compensation and the calibration coefficient, which are determined by the orthogonality of the coil system. In this paper, an ingenious method of measuring the non-orthogonal angles between the x- and z-axes coils and that between the y- and z-axes coils is demonstrated. This in situ measurement method is based on the magnetic field responses of the dual-axis co-magnetometer. The non-orthogonal angle can be obtained by solving the relevant trigonometric function of the geometric relationship. Finally, the non-orthogonal angles of about 7.93 degrees between the z- and y-axes coils and 7.39 degrees between the z- and x-axes coils are obtained by fitting the response formulas. Besides, the influence of the applied transverse magnetic field on the accuracy of the non-orthogonal angle calibration is analyzed. This method is also verified to be valid at different working temperatures.