原子磁力仪低功耗控制系统设计研究

Study on Design of Low Power Control System for Atomic Magnetometer

对原子光泵磁力仪控制系统的低功耗设计进行了研究。介绍了光泵原子磁力仪的物理原理,给出了研制的原子磁力仪控制电路系统的组成。针对铯光泵磁力仪中的低功耗光源,对垂直腔面发射激光器(VCSEL)的温控和恒流驱动进行了研究。用低功耗直接数字合成器(DDS)产生精确的低噪声射频信号,并将Freescale公司的ARM Cortex-M0+微控制器作为主控单元,用数字算法替代锁定放大器硬件电路,实现了激光波长锁定和磁共振频率跟踪的数字化环路,有效降低了电路功耗。实际系统测试表明:控制部分的功耗小于185mW,地磁场强度下原子磁力仪噪声小于10pT/Hz^(0.5)(1Hz时)。

The design of low power control system for atomic optical pumped magnetometer was studied in this paper. The physical principle of the atomic optical pumped magnetometer was introduced. The composition of the control circuit system for the atomic optical pumped magnetometer was presented. For the low power light source in cesium optical pumped magnetometer, the temperature control and constant current driving of vertical cavity surface emitting laser （VCSEL） were designed. The low power direct digital synthesis （DDS） chip was used for low noise accurate RF signal generation. An ARM Cortex-M〇 ＋ based microcontroller of Freescale Semiconductor Company was used as master control chip, replacing the hardware circuit of lock-in amplifier with digital algorithm. The locking of the laser wavelength and tracking the magnetic field dependent resonances frequency were implemented in digital closed loops. The circuit power consumption was effectively reduced. The results of the ground tests showed that power consumption of the control system was less than 185 mW, and the noise floor of atomic magnetometer was less than 10 pT/Hz0,5 at 1 Hz under geomagnetic field.