Optically pumped atomic magnetometers operating in the spin exchange relaxation free (SERF) regime play increasingly important roles in magnetoencephalography measurements. In this application, a multichannel arrangement is necessary. A method to construct the multichannel system is to arrange multiple individual sensor modules, where each sensor module is designed in the one-beam configuration with the necessary magnetic modulation. However, such an arrangement restricts the spatial resolution, affects the uniformity of the sensor characteristics, and increases the system complexity. To address these issues, we developed a compact multichannel pump-probe configuration magnetometer based on a single vapor cell. Each channel of the multichannel system shares the same vapor cell. As a result, the influence of different cells is eliminated. Further, a two-beam configuration with an independent pump and probe beam is introduced. Compared with the one-beam configuration, the two-beam magnetometer achieves a higher sensitivity and does not require extra magnetic modulation. And then the magnetic field crosstalk between adjacent channels can be avoided. A sensitivity of 10 fT/Hz1/2 at 2 Hz is achieved for all channels. Using the compact multichannel magnetometer, an auditory evoked response is clearly observed. If more channels are required, the arrangement based on the single vapor cell configuration can be easily expanded by applying the photodiode with more than four quadrants.
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机译：在无自旋交换弛豫（SERF）模式下运行的光泵原子磁力计在脑磁图测量中起着越来越重要的作用。在该应用中，多通道布置是必要的。构造多通道系统的一种方法是布置多个单独的传感器模块，其中每个传感器模块以具有必要磁调制的单光束配置设计。然而，这种布置限制了空间分辨率，影响了传感器特性的均匀性，并且增加了系统复杂性。为了解决这些问题，我们开发了基于单个蒸汽电池的紧凑型多通道泵浦探针配置磁力计。多通道系统的每个通道共享一个相同的蒸气室。结果，消除了不同单元的影响。此外，引入了具有独立泵浦和探测光束的两光束配置。与单束配置相比，两束磁力计具有更高的灵敏度，并且不需要额外的磁调制。然后可以避免相邻通道之间的磁场串扰。所有通道在2 Hz时的灵敏度均为10 fT / Hz1 / 2。使用紧凑的多通道磁力计，可以清晰地观察到听觉诱发的反应。如果需要更多通道，则可以通过应用具有四个以上象限的光电二极管来轻松扩展基于单蒸气电池配置的布置。
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