Miniature quad-channel spin-exchange relaxation-free magnetometer for magnetoencephalography

Li Jian-Jun^{1, 2}, Du Peng-Cheng^{1, 2}, Fu Ji-Qing³, Wang Xu-Tong^{1, 4}, Zhou Qing⁴, Wang Ru-Quan^{1, 2, ‡}

Photo of the magnetometer sensor head. 1: Five sets of Helmholtz coils; 2: optical section; 3: low noise preamplifier; 4: heaters covered by Kapton tape; 5: optical fiber; 6: Farrow cables.