Eddy-current imaging with nitrogen-vacancy centers in diamond

TL;DR

This paper introduces a microwave-free eddy-current imaging technique using nitrogen-vacancy centers in diamond, enabling material discrimination and defect detection with high spatial resolution and broad bandwidth.

Contribution

The authors demonstrate a novel diamond-based eddy-current imaging method that operates without microwaves, offering improved bandwidth and spatial resolution over existing technologies.

Findings

Sensitivity of 8×10^5 S/m√Hz at 3.5 MHz

Spatial resolution of 348 μm

Flat frequency response from DC to 3.5 MHz

Abstract

We demonstrate microwave-free eddy-current imaging using nitrogen-vacancy centers in diamond. By detecting the eddy-current induced magnetic field of conductive samples, we can distinguish between different materials and shapes and identify structural defects. Our technique allows for the discrimination of different materials according to their conductivity. The sensitivity of the measurements is calculated as 8$\times 10 ^{5}$\,S/m\,$\sqrt[]{\textrm{Hz}}$ at 3.5\,MHz, for a cylindrical sample with radius $r_0$\,=\,1\,mm and height $h$\,=\,0.1\,mm (volume $\sim$\,0.3\,mm$^3$), at a distance of 0.5\,mm. In comparison with existing technologies, the diamond-based device exhibits a superior bandwidth and spatial resolution. In particular, we demonstrate a flat frequency response from DC to 3.5 MHz and a spatial resolution of 348\,$\pm$\,2\,$\mu$m.