Search

CN-122029445-A - Magnetic field sensor

CN122029445ACN 122029445 ACN122029445 ACN 122029445ACN-122029445-A

Abstract

The invention relates to a magnetic field sensor (1) having an NV diamond (3), an excitation light source (4) which is designed to emit excitation radiation (5) for exciting an electronic state of the NV diamond (3), a microwave structure (6) which is designed to generate a microwave field for manipulating spin states of the NV diamond (3), a detector (11) which is designed to detect fluorescent radiation, the NV diamond (3) being able to emit fluorescent radiation as a result of irradiation with the excitation radiation (5), and a magnetic field generating device (8) which is arranged and designed to generate a permanent magnetic field in the region of the NV diamond (3), wherein the excitation light source (4), the microwave structure (6) and the magnetic field generating device (8) are arranged on a sensor circuit board (2).

Inventors

  • M. Trier Weiler
  • HASSELBACH JOHN
  • S.D. Bindel
  • S. Nechayev
  • VOELK MARKUS
  • M. SCHWEITZER
  • N Hargreaves
  • K. warms
  • K. SCHMIDT
  • F. Dold
  • M. Booker
  • J. Cassell
  • A. Brennes
  • F mach
  • B.CHEN

Assignees

  • 罗伯特·博世有限公司

Dates

Publication Date
20260512
Application Date
20240923
Priority Date
20231009

Claims (10)

  1. 1. A magnetic field sensor (1) having: -NV diamond (3); -an excitation light source (4) configured for emitting excitation radiation (5) to excite an electronic state of the NV diamond (3); -a microwave structure (6) configured for generating a microwave field for manipulating the spin state of the NV diamond (3); -a detector (11) configured for detecting fluorescent radiation from which the NV diamond (3) is able to emit due to irradiation with the excitation radiation (5); A magnetic field generating means (8) arranged and constructed for generating a permanent magnetic field in the region of the NV diamond (3), Wherein the excitation light source (4), the microwave structure (6) and the magnetic field generating means (8) are arranged on a sensor circuit board (2).
  2. 2. The magnetic field sensor (1) according to claim 1, wherein the magnetic field sensor (1) comprises a reference detector (10).
  3. 3. The magnetic field sensor (1) according to claim 1 or 2, wherein the detector (11) and/or the reference detector (10) are arranged on a carrier plate (9) opposite the sensor circuit board (2).
  4. 4. A magnetic field sensor (1) according to claim 2 or 3, wherein a reflecting prism (12) or an optical scattering element (13), in particular a volume scattering element, is arranged in the optical path of the excitation radiation (5) between the reference detector (10) and the NV diamond (3).
  5. 5. The magnetic field sensor (1) according to any one of the preceding claims, wherein the excitation light source (4) is arranged such that excitation radiation (5) emitted by the excitation light source impinges on one of the sides of the NV diamond (3) with an angle of incidence between 55 ° and 75 °.
  6. 6. The magnetic field sensor (1) according to any one of the preceding claims, wherein within the NV diamond (3) the excitation radiation (5), the microwave field and the permanent magnetic field are at an angle of between 80 ° and 100 °, in particular 90 °, relative to each other.
  7. 7. The magnetic field sensor (1) according to any one of claims 3 to 5, wherein the NV diamond (3), the excitation light source (4), the microwave structure (6), the detector (11) and/or the reference detector (10) are arranged in an enclosed space (21).
  8. 8. The magnetic field sensor (1) according to claim 6, wherein the carrier plate (9) is configured as a ceiling of the enclosed space (21), and the sensor circuit board (2) is configured in particular as a floor of the enclosed space (21).
  9. 9. The magnetic field sensor (1) according to claim 6 or 7, wherein at least one side of the closed space (21) is configured as a scattering element (15).
  10. 10. The magnetic field sensor (1) according to any of the preceding claims, wherein the magnetic field generating means (8) comprises a permanent magnet or an array of permanent magnets.

Description

Magnetic field sensor Technical Field The invention relates to a magnetic field sensor based on NV diamond. Background For detecting the magnetic field, a so-called NV magnetic field sensor is used. They include diamond whose crystal lattice has defects in the form of NV colour centers. In the NV color center, a nitrogen atom occupies a lattice position of a carbon atom, wherein a vacancy is arranged immediately adjacent to the nitrogen atom, in turn, on the lattice position of the carbon atom. If such a lattice is irradiated with excitation radiation having a wavelength between 490 nm and 575 nm, an electron transition from the ground state 3A2 to the excited state 3 E is induced in the lattice. The NV colour centre relaxes again from the excited state 3 E to the ground state 3A2 in the case of fluorescent radiation with an emission wavelength in the range 600nm to 850 nm. The ground state 3A2 has three magnetic sub-states with m s=0、ms = ±1. The states with m s =0 and m s = ±1 differ by an energy difference of 2.87 GHz (zero field splitting). The excited state 3 E also has three magnetic sub-states, m s=0、ms = ±1, respectively. If the NV color center in the ground state 3A2 is now exposed to microwave radiation at a frequency of 2.87 GHz, the NV color center oscillates between the m s=0、3A2 ground state and the m s=±1、3A2 ground state. Upon irradiation with excitation radiation, the NV colour centre now partially shifts from the m s=±1、3A2 ground state to the excited m s=±1、3 E state. From there, it relaxes again to the ground state mainly without radiation. If the amplitude of the fluorescent radiation is measured in terms of the frequency of the microwave radiation, a sudden drop in the amplitude of the fluorescent radiation (the so-called "Dip") occurs at a frequency of 2.87 GHz. The decrease in the amplitude of the fluorescent radiation may be interpreted as a smaller probability of occupying the m s=0、3A2 ground state when the microwave radiation is injected at a frequency of 2.87 GHz. In an external magnetic field, the m s=±1、3A2 ground state splits into two states (zeeman effect) with spin quantum numbers m s =1 and m s = -1. If the amplitude of the fluorescent radiation is now measured with the frequency of the microwave radiation changed, two valleys are obtained. The frequency at which these valleys occur depends on the magnitude of the ground state splitting of m s=±1、3A2 and thus on the field strength of the external magnetic field. In this way, the field strength of the external magnetic field can be determined. Such a magnetic field sensor is known, for example, from Xue Zhang (2021) paper "Battery Characterization via Eddy-Current Imaging with Nitrogen-Vacancy Centers in Diamond"（Appl. Sci., 11(7), 3069）. Wherein linearly polarized light of the green laser is coupled into the NV diamond. Microwave radiation is generated by means of an RF coil, wherein the NV diamond is arranged within the windings of the RF coil. The fluorescent radiation emitted by the NV diamond is directed by means of a beam splitter onto two photodiodes, one of which acts as a reference detector, while the other one of the two photodiodes is connected upstream to a filter, which blocks the radiation of the green laser. Here, NV diamond was stuck to the uppermost layer of the parabolic concentrator. Such magnetic field sensors require space and require high outlay for adjustment. In the magnetic field sensors commonly used in the prior art, the dimensions of the field generating means, in particular the microwave source and the magnetic field generating device, are chosen such that the range of the fields generated by them is so large that they have a sufficiently large homogeneous area. Furthermore, in the prior art, the NV diamond is surrounded in a three-dimensional structure by a microwave source, a magnetic field generating device and an excitation light source, which results in an arrangement that is difficult to adjust and a manufacturing process that cannot be automated. The object of the present invention is to provide a magnetic field sensor which does not have the disadvantages of the prior art. Disclosure of Invention The invention relates to a magnetic field sensor for detecting a magnetic field according to claim 1. Advantageous configurations of the invention are the subject matter of the dependent claims and the description. In particular, the magnetic field sensor has a NV diamond, an excitation light source configured for emitting excitation radiation for exciting an electronic state of the NV diamond, a microwave structure configured for generating a microwave field for manipulating a spin state of the NV diamond, a detector configured for detecting fluorescent radiation from which the NV diamond is able to emit as a result of irradiation with the excitation radiation, and a magnetic field generating device arranged and configured for generating a permanent magnetic field in the region of the N