Optically pumped alkali magnetometers for biomedical applications
نویسنده
چکیده
20 Optically pumped atomic magnetometers measure the Larmor frequency νL at which the bulk magnetization of a spin-polarized alkali metal vapour in a glass cell precesses around the field of interest B0. !e precession frequency is related to the modulus of the magnetic field by νL=(γ/2π)|B0|, where γ/2π≈3.5Hz/nT for 133Cs, so that the magnetic field measurement consists in a frequency measurement. In so-called ODMR magnetometers, νL is determined by Optically Detected Magnetic Resonance using laser radiation. !e general principle of an ODMR magnetometer can be understood as follows: A bulk spin polarization is created in the atomic medium through optical pumping, a process introduced in the 1950s, by which angular momentum of polarized light, resonant with an atomic ! Partial view of sensor array in the 19-channel Fribourg magnetocardiography (MCG) device and (inset) subject positioned for MCG measurements (Details in the text). Optically pumped alkali magnetometers for biomedical applications
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