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Publication Number
US-11287494-B2
Publication Date
2022-03-29
Expiration Date
Abstract
Time-multiplexed atomic magnetometry uses first and second atomic vapor cells located adjacent to a sample to be measured. Each vapor cell operates according to a sequence of alternating pumping and probing stages. However, the sequences are temporally offset from each other such that the second vapor cell is pumped while the first vapor cell is probed, and the first vapor cell is pumped while the second vapor cell is probed. With this time-multiplexed operation, the magnetic field generated by the sample can be measured without any time gaps. The Hilbert transform of the signals may be taken to obtain their instantaneous phases, which may then be interleaved to form a single gapless time sequence that represents the magnetic field of the sample over a time window that lasts for several continuous pumping/probing stages.
Core Innovation
A time-multiplexed dual atomic magnetometer is described with first and second vapor cells located adjacent to a sample cell. A magnetic field generated by a sample within the sample cell induces Larmor precession of atoms within the first and second vapor cells. First and second probe beams propagate through the first and second vapor cells, respectively, and are measured as first and second polarization signals by corresponding polarimeters.
The magnetometer includes a signal processor that processes alternating data blocks of the first and second polarization signals to generate a single gapless temporal sequence representing the magnetic field generated by the sample. The time multiplexing uses alternating data blocks so the output is formed as one continuous temporal magnetic-field representation without gaps.
Instantaneous-phase retrieval is applied on each data block to obtain reconstructed magnetic-field sequences, and the reconstructed sequences are interleaved or concatenated into the single gapless temporal sequence. The description also includes timing relationships that select dead time such that measurement blocks abut, and magnetic bias-field directionality effects associated with instantaneous Larmor frequency modeling are addressed, including residual inversion for opposite bias-relative conditions.
Claims Coverage
The provided independent claims cover a time-multiplexed dual atomic magnetometer apparatus and a corresponding method for time-multiplexed dual atomic magnetometry. Across these independent claims, the core coverage centers on alternating polarization data blocks from two adjacent vapor cells and generating a single gapless temporal sequence representing the sample-induced magnetic field, with additional dependent refinements regarding multiplexed stages and gapless reconstruction.
Time-multiplexed dual atomic magnetometer with adjacent vapor cells
First and second vapor cells located adjacent to a sample cell such that a magnetic field generated by a sample within the sample cell induces Larmor precession of atoms within the first and second vapor cells.
Polarimetry of probe beams through respective vapor cells
A first polarimeter that measures a first polarization of a first probe beam after the first probe beam propagates through the first vapor cell, and a second polarimeter that measures a second polarization of a second probe beam after the second probe beam propagates through the second vapor cell, outputting first and second polarization signals indicative of the respective polarizations.
Processing alternating data blocks into a single gapless temporal sequence
A signal processor that processes alternating data blocks of the first and second polarization signals to generate a single gapless temporal sequence that represents the magnetic field generated by the sample.
Method of time-multiplexed dual atomic magnetometry with adjacent vapor cells
Generating, by a sample within a sample cell, a magnetic field that induces Larmor precession of atoms within first and second vapor cells located adjacent to the sample cell.
Polarimeter-based polarization measurement of first and second probe beams
Measuring with a first polarimeter a first polarization of a first probe beam after the first probe beam propagates through the first vapor cell, and measuring with a second polarimeter a second polarization of a second probe beam after the second probe beam propagates through the second vapor cell, producing first and second polarization signals indicative of the respective polarizations.
Processing alternating polarization blocks into a single gapless temporal sequence
Processing alternating data blocks of the first and second polarization signals to generate a single gapless temporal sequence that represents the magnetic field generated by the sample.
The independent claims require two adjacent vapor cells whose atoms undergo Larmor precession from a sample-induced magnetic field, polarimeter measurement of probe-beam polarizations through each vapor cell, and signal processing that combines alternating polarization data blocks into a single gapless temporal magnetic-field sequence.
Stated Advantages
Generates a single gapless temporal sequence representing the magnetic field generated by the sample.
Documented Applications
Geosciences.
Generating time-varying magnetic fields for cell-based therapy screening, including siRNA/mRNA.
Magnetic communication.
Threat detection.
Magnetoencephalography.
NMR.
MRI.
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