The wide-field (2.42 mm × 1.36 mm, resolution: 5.04 µm) tomography imaging of double circuits is performed using nitrogen-vacancy (NV) center ensembles in a diamond. The magnetic-field distribution on the surface of the circuit produced by the lower layer is obtained. Vector magnetic superposition is used to separate the magnetic-field distribution produced by the lower layer from the magnetic-field distribution produced by two layers. An inversion model is used to perform the tomography imaging of the magnetic-field distribution on the lower layer surface. Compared with the measurements of the upper layer, the difference in the maximum magnetic-field intensity of inversion is approximately 0.4%, and the difference in the magnetic-field distribution of inversion is approximately 8%, where the depth of the lower layer is 0.32 mm. Simulations are conducted to prove the reliability of the imaging. These results provide a simple and highly accurate reference for the detection and fault diagnosis of multilayer and integrated circuits.

In this paper, we implement integrated magnetic flux concentrators (MFCs) combined with a multi-frequency modulation method to achieve high-magnetic-detection sensitivity using a nuclear spin on the solid nuclear spin in diamonds. First, we excited the nuclear spin in diamonds using a continuous-wave technique, and a linewidth of 1.37 MHz and frequency resolution of 79 Hz were successfully obtained, which is reduced by one order of the linewidth, and increased by 56 times in frequency resolution compared to that excited by an electron spin. The integrated high-permeability MFC was designed to magnify the magnetic field near the diamond, with a magnification of 9.63 times. Then, the multi-frequency modulation technique was used to fully excite the hyperfine energy level of Nitrogen Vacancy (NV) centers along the four axes on the diamond with MFC, and magnetic detection sensitivity of 250pT/Hz1/2 was realized. These techniques should allow designing an integrated NV magnetometer with high sensitivity in a small volume.

We propose a method for microwave target source localization based on the diamond nitrogen vacancy color center. We use coherent population oscillation effect and modulation and demodulation techniques to achieve the detection of microwave intensity of microwave target sources, with a minimum detection intensity of 0.59 µW. Positioning of the microwave source was achieved within 50×100cm2 distance from the system 1 m away using the cubic spline interpolation algorithm and minimum mean squared error. The maximum positioning error was 3.5 cm. This method provides a new, to the best of our knowledge, idea for the passive localization of microwave targets.