An array of 21 first-order gradiometers based on zero-field optically-pumped magnetometers is demonstrated for use in magnetoencephalography. Sensors are oriented radially with respect to the head and housed in a helmet with moveable holders which conform to the shape of a scalp. Our axial gradiometers have a baseline of 2 cm and reject laser and vibrational noise as well as common-mode environmental magnetic noise. The median sensitivity of the array is 15.4 fT/Hz1/2, measured in a human-sized magnetic shield. All magnetometers are operated independently with negative feedback to maintain atoms at zero magnetic field. This yields higher signal linearity and operating range than open-loop operation and a measurement system that is less sensitive to systematic and ambient magnetic fields. All of the system electronics and lasers are compacted into one equipment rack which offers a favorable outlook for use in clinical settings.

中文翻译：

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用于脑磁图的微加工光学泵浦一阶梯度仪的保形阵列

演示了基于零场光泵磁力计的21个一阶梯度计的阵列，用于脑磁图。传感器相对于头部呈放射状定向，并容纳在带有可移动支架的头盔中，该支架符合头皮的形状。我们的轴向梯度仪的基线为2厘米，可以消除激光和振动噪声以及共模环境磁噪声。阵列的中值灵敏度为15.4 fT / Hz1 / 2，在人大小的磁屏蔽罩中测得。所有磁力计在负反馈下独立运行，以将原子保持在零磁场下。与开环操作和对系统磁场和环境磁场不太敏感的测量系统相比，这产生了更高的信号线性度和工作范围。