A new optically pumped tandem magnetometer: principles and experiences

Abstract

In this paper we describe a new design for an optically pumped tandem magnetometer situated at the GeoForschungsZentrum Potsdam. A tandem magnetometer combines the fast response of a self-oscillating vapour magnetometer with the accuracy of a narrow line M z -type magnetometer. A newly patented method of coupling the two sensors avoids any stray magnetic fields and so allows a compact design of the instrument itself, as well as facilitating its operation in close proximity to other magnetometers. A prototype Cs-K tandem magnetometer for use in magnetic observatories is described. We then show typical results of a long-term comparison with both a second type of optically pumped magnetometer and an Overhauser proton magnetometer. Finally, a resumé is given of four years of continuous operation of this new type of magnetometer with respect to the data quality produced and its operational reliability.

Modern radio-optical methods in quantum magnetometry

“…The choice of 87 Rb was far from optimal because the magnetic resonance spectrum of this isotope contains a group of lines, the distance between which in EMS at a minimal number of perturbations was only severalfold greater than their width. This disadvantage was overcome after many years by a group of researchers headed by E Pulz [142], who proposed a tandem in which Cs was used in the M x -scheme and K in the M z -scheme. The spectrum of K magnetic resonance, unlike that of Rb, is known to be well resolved over the entire EMF range, which excludes interference between the adjacent lines.…”

“…The CsÀK-tandem described in Ref. [142] combines CsÀM x and KÀM z magnetometers such that the signal from the slower but more accurate M z -device being used for gradual correction of the feedback loop characteristics of the faster M x -magnetometer. The system has the response time 1 ms, the resolving power 10 pT, and the absolute accuracy 0.1 nT.…”

How to build a magnetometer with thermal atomic vapor: a tutorial

“…It is important to emphasize that this list is not exhaustive and that there are no clear boundaries between different methods. Indeed, many researchers have successfully combined the characteristic features of two or more of these techniques: examples include the M z -M x tandem [120,121], RF atomic magnetometers sensitive to RF magnetic fields [62,122], magnetometers based on free spin precession [123], active self-oscillating magnetometers [93,124], and many others. A commercial example is the QuSpin zero-field magnetometer mentioned in table 1, which is essentially a Hanle/SERF device using a single-beam M z -type geometry to measure transverse magnetic fields [125].…”

How to build a magnetometer with thermal atomic vapors: A tutorial

“…It is important to emphasize that this list is not exhaustive and that there are no clear boundaries between different methods. Indeed, many researchers have successfully combined the characteristic features of two or more of these techniques: examples include the M z -M x tandem [112,113], RF atomic magnetometers [57,114], magnetometers based on free spin precession [115], active self-oscillating magnetometers [87,116], and many others. A commercial example is the QuSpin zero-field magnetometer mentioned in Table 1, which operates in the Hanle/SERF regime using a single-beam M z geometry to measure transverse magnetic fields [117].…”