Identifying subsurface metal microstructure and its materials via quantum wide-field microscope

Targeted detection of subsurface metal microstructure is crucial for evaluating the performance of engineering structures. This paper presents a nondestructive inspection method for characterizing subsurface metal microstructure by integrating quantum sensing, electromagnetic transmission theory, and optical field imaging. In a field of view of 1000×1000 µm², the induced microwave fields of six different metallic materials were characterized by NV centers, and the relationship between the induced microwave fields and the conductivity of the metallic materials was analyzed theoretically. Meanwhile, the induced microwave fields generated by different metallic defect structures were characterized, and the reasons for the differences in microwave fields were analyzed based on the microstrip transmission theory. This phenomenon verifies the feasibility of utilizing quantum, combined with optical field imaging, to characterize subsurface metallic materials and structures. The method is expected to be applied in materials evaluation and engineering maintenance, thus effectively enhancing quantum testing technology applications.