Method for determining a change in a rotational orientation in the space of an NMR gyroscope, and NMR gyroscope

Patent metadata

Field	Value
Publication number	US-12061085-B2
Application number	US-202017756891-A
Country	US
Kind code	B2
Filing date	Oct 21, 2020
Priority date	Dec 6, 2019
Publication date	Aug 13, 2024
Grant date	Aug 13, 2024

Abstract

A method for determining a rotational orientation change using an NMR gyroscope includes making use of a measure of determining, in a vapor cell, which is filled at least with a gaseous first element and a gaseous second element having non-vanishing nuclear spin, a nuclear spin component of the second element in the second direction and a nuclear spin component of the second element in a third direction. The second direction and the third direction are perpendicular to a first direction, which corresponds to the direction of the static magnetic field and to the polarization direction of the nuclear spin of the second element. Moreover, the second direction corresponds to the direction of an applied alternating magnetic field, the frequency of which corresponds to the Larmor frequency of the Larmor precession of the nuclear spin of the second element about the static magnetic field.

First claim

The invention claimed is:

1. A method for determining a change of a rotational orientation in a space of a nuclear magnetic resonance (NMR) gyroscope having a vapor cell, which contains a mixture including at least one gaseous first element and at least one gaseous second element having non-negligible nuclear spin, the method comprising:
polarizing electron spins of the first element in a first direction, so that due to a strong electron-nuclear spin interaction between the first element and the second element, nuclear spins of the second element are polarized in parallel to electron spins of the first element;
applying, with a static magnetic field generator, a static magnetic field in a polarization direction of the nuclear spins of the second element, so that the nuclear spins of the second element precess around the static magnetic field at a first Larmor frequency dependent on the static magnetic field;
applying, with a first alternating magnetic field generator, an alternating magnetic field in a second direction perpendicular to the polarization direction of the nuclear spins of the second element, wherein the alternating magnetic field has a frequency which corresponds to the first Larmor frequency of the Larmor precession of the nuclear spins of the second element around the static magnetic field, so that the Larmor precession of the nuclear spins of the second element is in phase inside the vapor cell;
measuring, with a measuring unit, a nuclear spin component of the second element in the second direction and a nuclear spin component of the second element in a third direction, which is perpendicular to the first direction and differs from the second direction; and
determining, with an evaluation unit, a rotational orientation change of the vapor cell having an axis of rotation parallel to the first direction, a rotational orientation change having an axis of rotation parallel to the second direction, and a rotational orientation change having an axis of rotation parallel to the third direction from the nuclear spin component of the second element in the second direction and the nuclear spin component of the second element in the third direction.

2. A nuclear magnetic resonance (NMR) gyroscope comprising:
a vapor cell configured to contain a mixture including at least one gaseous first element and at least one gaseous second element having non-negligible nuclear spin;
a pump laser configured to generate a pump laser beam in a first direction to polarize electron spins of the first element in the vapor cell in a direction of polarization;
a static magnetic field generator configured to generate a static magnetic field in the direction of polarization of the electron spins of the first element;
a first alternating magnetic field generator configured to generate a magnetic field in a second direction perpendicular to the first direction at a frequency which corresponds to a Larmor frequency of a Larmor precession of nuclear spins of the second element around the static magnetic field;
a measuring unit configured to measure a nuclear spin component of the second element in the second direction and a nuclear spin component of the second element in a third direction, which is perpendicular to the first direction and differs from the second direction; and
an evaluation unit configured to determine a rotational orientation change having an axis of rotation parallel to the first direction, a rotational orientation change having an axis of rotation parallel to the second direction, and a rotational orientation change having an axis of rotation parallel to a third direction from the nuclear spin component of the second element in the second direction and from the nuclear spin component of the second element in the third direction.

3. The method as claimed in claim 1 , wherein the first direction, the second direction, and the third direction each have an angle of 90° in relation to one another.

4. The method as claimed in claim 3 , wherein:
k 2 is the nuclear spin component of the second element in the second direction,
k 3 is the nuclear spin component of the second element in the third direction,
Ω 1 (t) corresponds to the determined rotational orientation change having an axis of rotation parallel to the first direction,
Ω 2 (t) corresponds to determined rotational orientation change having an axis of rotation parallel to the second direction,
Ω 3 (t) corresponds to determined rotational orientation change having an axis of rotation parallel to the third direction,
the determined rotational orientation having an axis of rotation parallel to the first direction, the determined rotational orientation change having an axis of rotation parallel to the second direction, and the determined rotational orientation change having an axis of rotation parallel to the third direction are obtained from:

∂

k
2

(
t
)

∂
t

=

k
3

(

γ
k

⁢

B
DC

+

2
⁢
π
⁢

Ω
1

(
t
)

)

-

k
1

(

0
+

2
⁢

πΩ
3

(
t
)

)

-

Γ
2

⁢

k
2

,

∂

k
3

∂
t

=

k
1

Assignees

• Bosch Gmbh Robert

Inventors

• Fuchs Tino
• Riedrich-Moeller Janine
• Brenneis Andreas
• Roelver Robert
• Curcic Michael
• Degenfeld-Schonburg Peter

Classifications

• G01R33/26

  using optical pumping · CPC title

• G01R33/0322

  using the Faraday or Voigt effect · CPC title

• G01C19/62 Primary

  with optical pumping · CPC title