Cavity cell for an optically-pumped atomic magnetometer and a magnetic gradiometer, and a system comprising the gradiometer and a microscopy system

Patent metadata

Field	Value
Publication number	US-12481008-B2
Application number	US-202217958850-A
Country	US
Kind code	B2
Filing date	Oct 3, 2022
Priority date	Oct 1, 2021
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

Provided is a cell for optically-pumped atomic magnetic gradiometry that includes a first confining chamber containing alkali atoms and configured to receive a co-propagating pump and probe light beam, including pump light polarized to spin polarize the alkali atoms, and at least a second confining chamber containing alkali atoms, distanced from the first confining chamber, and which is also configured to receive a co-propagating pump and probe light beam. Also provided are an optically-pumped atomic magnetic gradiometer including the presently disclosed and a system that includes the presently disclosed gradiometer and a microscopy system.

First claim

What is claimed is:

1 . A cell for an optically-pumped atomic magnetometer, comprising:
a first confining chamber containing alkali atoms, wherein said first confining chamber is configured to receive co-propagating pump and probe light beams, including pump light polarized to spin polarize the alkali atoms; at least a second confining chamber containing alkali atoms, distanced from said first confining chamber, and which is also configured to receive co-propagating pump and probe light beams, wherein at least the first and second confining chambers are configured either to receive:
respective first co-propagating pump and probe light beams and second co-propagating pump and probe light beams, from a same side of the cell and striking at the first and second confining chambers at a same time; or
same co-propagating pump and probe beams, from a same side of the cell but striking at the first and second confining chambers at different times; and
top and bottom walls arranged at and covering opposite ends of at least the first and second confining chambers, wherein each of said top and bottom walls comprises an optical coating on an external face, wherein said optical coatings provide a partial reflectivity for the pump and probe lights of the co-propagating pump and probe light beams, thus making the cell become an optical cavity cell.

2 . The cell of claim 1 , wherein at least the first and second confining chambers are coplanar and comprise at least two physics chambers at distance from each other from 100 μm to 10 mm, the cell comprising further confining chambers including a reservoir and channels fluidically connecting said at least two physics chambers with said reservoir.

3 . The cell of claim 1 , wherein the at least first and second confining chambers have a confinement height below 1 mm.

4 . The cell of claim 1 , wherein said at least first and second confining chambers further contain a buffer gas at a pressure above 3 bar and up to 20 bar, to prevent atomic depolarizing collisions.

5 . The cell of claim 2 , wherein said at least two physics chambers have a width or diameter ranging from 100 μm to 10 mm.

6 . An optically-pumped atomic magnetic gradiometer, comprising:
a first cell comprising a confining chamber containing alkali atoms, wherein said first confining chamber is configured to receive a co-propagating pump and probe light beams, including pump light polarized to spin polarize the alkali atoms; a second confining chamber containing alkali atoms, distanced from said first confining chamber, and which is also configured to receive a co-propagating pump and probe light beams, wherein at least said first and second confining chambers are configured either to receive: respective first co-propagating pump and probe light beams and second co-propagating pump and probe light beams, from a same side of the cell and striking at the first and second confining chambers at a same time, or same co-propagating pump and probe beams, from a same side of the cell but striking at the first and second confining chambers at different times;
top and bottom walls arranged at and covering opposite ends of at least the first and second confining chambers, wherein each of said top and bottom walls comprises an optical coating on an external face, wherein said optical coatings provide a partial reflectivity for the pump and probe lights of the co-propagating pump and probe light beams, thus making the cell become an optical cavity cell;
an illumination mechanism configured to generate:
first co-propagating pump and probe light beams and a second co-propagating pump and probe light beams, and to direct the first and second co-propagating pump and probe light beams to different sensing chambers of a same side of the cell, namely a front side, such that the first co-propagating pump and probe light beams enter the first confining chamber, and the second co-propagating pump and probe light beams enter the second confining chamber; or
same co-propagating pump and probe light beams, and to direct the same co-propagating pump and probe light beams to different sensing chambers of a same side of the cell, a front side, to enter; and

a measuring unit configured and arranged to receive at least part of the probe lights of the first and second co-propagating pump and probe light beams, once coming out of the cell as first and second probe light beams, and perform a differential measurement between them, on at least one parameter of those probe light beams, to obtain a magnetic gradiometry measurement.

7 . The optically-pumped atomic magnetic gradiometer of claim 6 , wherein it operates according to a transmission detection mode, wherein the magnetic gradiometer further comprises:
a polarizing mechanism configured and arranged for linearly polarizing the probe light and circularly polarizing the pump light, of the first and second co-propagating pump and probe light beams, before they strike the front side of the cell; and first and second optical components configured and arranged to respectively receive the first and second co-propagating pump and probe light beams, once coming out of the cell through a back side of the cell opposite to said front side, and transmit only the probe light contained in those beams, in the form of said first and second probe light beams;
wherein said measuring unit comprises first and second polarimeters configured and arranged to respectively receive said first and second probe light beams, and to detect Faraday rotation, and wherein said at least one parameter on which the measuring unit is configured to perform said differential measurement is Faraday rotation.

8 . The optically-pumped atomic magnetic gradiometer of claim 7 , wherein at least the first and second confining chambers of the cell are coplanar and comprise at least two physics chambers at distance from each other from 100 μm to 10 mm, the cell comprising further confining chambers including a reservoir and channels fluidically connecting said at least two physics chambers with said reservoir, the cell further comprising top and bottom walls arranged at and covering opposite ends of at least the first and second confining chambers and further confining chambers, wherein said first, second and further confining chambers are laterally demarcated and gas-tight sealed from the environment by intermediate partition and contour walls arranged between and bonded to said top and bottom walls, and wherein the bottom wall defines said front side of the cell and has a reflectivity for the probe light ranging between 90% and 99% and for the pump light below 50%, and the top wall has a reflectivity for the probe light ranging between 98% and 99.9%.

9 . The optically-pumped atomic magnetic gradiometer of claim 6 , wherein it operates according to a reflection detection mode, further comprising:
a polarizing mechanism configured and arranged for circularly polarizing both the probe light and the pump light, of the first and second co-propagating pump and probe light beams, before they strike the front side of the cell; and wherein:
said measuring unit is configured to receive the first and second probe light beams of the first and second co-propagating pump and probe light beams, once coming out of the cell, by reflection, through the front side of the cell, and
said at least one parameter on which the measuring unit is configured to perform said differential measurement is:
light intensity of the first and second probe beams; or
PDH error signals provided by a Pound-Drever-Hall detection arrangement.

10 . The optically-pumped atomic magnetic gradiometer of claim 9 , wherein the cell further comprises

Assignees

• Inst Catalana Recerca Estudis Avancats
• Fundacio Inst De Ciencies Fotòniques
• Fundacio Inst De Ciencies Fotoniques

Inventors

• Mitchell Morgan
• Lucivero Vito Giovanni
• Reichel Jakob

Classifications

• G01R33/022

  Measuring gradient · CPC title

• G01R33/26 Primary

  using optical pumping · CPC title

• G01R33/032 Primary

  using magneto-optic devices, e.g. Faraday {or Cotton-Mouton effect} · CPC title