The influence of temperature and modulated magnetic field on the transmission intensity of atomic magnetometer

Abstract

The single-beam miniaturized atomic magnetometer with modulated magnetic field is one of the most capable approaches to biomagnetic measurements. The transmission intensity of the pumping beam is critical to the sensitivity of the magnetometer, which is affected by the density of alkali metal and the polarization of atomic spin. In this study, we investigated into the influence of three variables: the temperature of atomic vapour; the amplitude of the modulated magnetic field; the frequency of modulated magnetic field on the transmission intensity of pumping beam. We have defined their relationship into a function, and the calculated values through theoretical analysis have a high degree of fit with the measured values of numerous experiments. It is discovered that the transmission intensity decreases with the increase in temperature, and this effect is modified by the modulation index. A compact magnetometer is developed as a proof of concept based on single-beam scheme. The volume of this magnetometer is 10 cm 3 , and its dual axis sensitivity are both 30 fT/Hz 1/2 . Based on this relationship we find that two major improvements are achieved by separating the DC and AC components of transmission intensity: 1. Realizing closed-loop temperature control for atomic vapour which improved the stability of the magnetometer. 2. Achieving closed-loop dual axis magnetic measurements under a single-beam scheme, which extends the magnetometer's scope of application.

High-precision alkali-atom density measurement and control methods using light absorption for dual-beam SERF magnetometers

“…In previous studies, this method has been successfully used. Yin et al analyzed the influence of modulated magnetic fields on the transmitted intensity and achieved temperature control in SERF magnetometers by detecting the transmitted pump light intensity [14] . Liu et al measured and controlled atomic number density over a wide temperature range based on light absorption [15] .…”

In-situ measurement and close-loop control of atomic number density in an optically pumped magnetometer based on light absorption

“…Ito et al measured the densities of K and Rb in a glass cell, which contains K and Rb, based on light absorption [27]. Yin et al analyzed the influence of the modulated magnetic field on the transmitted light intensity in the temperature range of 110 • C-150 • C [28]. Jimenez-Martinez et al used the optical depth to detect the atomic number density of Cs in an Mx magnetometer and a Bell-Bloom magnetometer [29].…”

Analytical model for calculation of the magnetic field of triaxial uniform coils in magnetically shielded cylinder

“…The external stray field can be attenuated to a few nT using a passive magnetically shielded cylinder (MSC) with high permeability, and the triaxial uniform magnetic field coils are then used to generate magnetic fields with equal amplitudes in opposite directions to compensate accurately for the remanence [8][9][10]. Additionally, triaxial coils are constructed to generate uniform magnetic fields with the specific intensities and frequencies required to perform particular experiments [11][12][13]. For example, in the SERF atomic magnetometer, the magnetic field determines the signal-to-noise ratio, the calibration, and the bandwidth of the magnetometer [14,15].…”