Novel nested saddle coils used in miniature atomic sensors

Abstract

A novel uniform magnetic field coil structure with two pairs of saddle coils nested is proposed in order to minish the aspect ratio without losing much field uniformity, which is significant in innovative miniature atomic instruments and sensors. Optimal configuration parameters are obtained from the Taylor expansion of the magnetic field. The remainder terms are used to estimate the field uniformity and optimize the configuration while minishing computation time. Compared with traditional saddle coils, the nested saddle coils have unique advantages in miniature applications where the aspect ratios are strictly limited. The optimized nested saddle coils were manufactured by Flexible Printed Circuit (FPC) technology and the magnetic field uniformities were verified experimentally using a flux-gate magnetometer. Furthermore, the example application of a miniature nuclear magnetic resonance (NMR) gyro demonstrates the practical use of the nested coils.

Mode locking suppression in a magneto-optical gyro

“…Thus, the correction to the medium parameters depends on interference between counter-propagating waves, leading to gain modulation and mode interaction. However, the wave coupling after the propagation through entire resonator circumference is absent due to the suppression of waves interference [see (4) and (5)].…”

“…The development and production of the miniature gyroscope with a resolution less than 1 • / h are important technological tasks that stimulate research efforts 1 . There are three well-known technological approaches to the problem 1 : the improvement of micro-electro-mechanical gyroscopes (MEMS gyros) 2 , the development of compact nuclear magnetic resonance gyroscopes (NMR gyros) [3][4][5] , and the miniaturization of optical gyroscopes by means of integrated optics technology (on-chip optical gyros) [6][7][8] . The MEMS gyroscopes have almost reached their performance limits, and the miniature NMR gyroscopes are still being developed.…”

Design of Highly Uniform Magnetic Field Coils Based on a Particle Swarm Optimization Algorithm

“…However, with this coil structure it is difficult to produce a very uniform magnetic field especially for coils with small length to diameter ratios. In [7], we proposed saddle coil nesting schemes with two nested pairs of coils to improve the uniformity of saddle coils with small length to diameter ratios. In this paper, we extend this approach by nesting N pairs of saddle coils to obtain a more uniform cylindrical radial magnetic field.…”

“…Cylindrical coil structure is simple and convenient fabricate for creating triaxial magnetic fields. It is widely used in industrial equipment and medical instruments, and is also the first choice for miniature atomic sensors [5]- [7]. In a triaxial cylindrical uniform field coil configuration, Helmholtz coils and saddle coils are typically used to generate axial and radial magnetic fields, respectively.…”

“…However, even with these improvements it is still difficult to reach the magnetic field uniformity of an ideal saddle coil. To address the contradiction between the volume and the field uniformity of the saddle coil, we proposed a novel coil structure nested by two pairs of saddle coils in [7]. This design allows us to obtain better magnetic field uniformity for small length to diameter ratios, but its parameter optimization needs further study.…”