文献类型：期刊文献

中文题名：光路优化提高金刚石氮-空位色心磁成像质量

英文题名：Optical Path Optimization for Improving Magnetic Imaging Quality of Diamond Nitrogen?Vacancy Centers

作者：唐雨桐[1];叶安[1];李晓林[1];钮月萍[1];龚尚庆[1]

机构：[1]华东理工大学物理学院,上海200237

年份：2026

卷号：53

期号：2

起止页码：94

中文期刊名：中国激光

外文期刊名：Chinese Journal of Lasers

收录：;EI(收录号：20260520001423);WOS:【ESCI(收录号:WOS:001697325000003)】；北大核心:【北大核心2023】；

基金：上海市教委科研创新重大项目(2023ZKZD39)。

语种：中文

中文关键词：金刚石氮-空位色心;光学探测磁共振;磁场测量;场平均效应;光路优化

外文关键词：nitrogen-vacancy centers in diamond;optically detected magnetic resonance;magnetic field measurement;field averaging effect;optical path optimization

摘要：磁成像技术在生物医学、地质勘测以及新能源等领域被广泛应用。金刚石系综氮-空位(NV)色心磁力计以其卓越的空间分辨率和灵敏度,被广泛应用于磁成像。在现有磁成像光路方案中,激发光斜入射方案形成的椭圆形光斑会引入场平均效应,导致成像质量降低;而垂直入射方案虽然能形成圆形光斑,但荧光收集效率较低。为此,本团队提出了一种基于楔形棱镜组的光路优化方案,旨在提升金刚石系综NV色心磁力计的磁成像质量。该方案不仅显著缩小了NV色心表面的光斑尺寸,x向和y向均方根半径分别从斜入射方案下的23.17μm和0.73μm降至0.35μm和0.35μm,还实现了更高的辐照度,并且光斑内的辐照度分布更加均匀。实验结果表明,采用优化方案获得的磁场强度均方偏差为0.14,优于斜入射方案的0.30,有效减轻了场平均效应对磁场测量的影响。
Objective Magnetic imaging technology has extensive applications in biomedicine,geological exploration,and new energy fields.Diamond ensemble nitrogen-vacancy(NV)center magnetometers,with their high spatial resolution,high sensitivity,and full-vectormagnetic field measurement capabilities,have become representative of magnetic measurement instruments.In the magnetic field imaging process using diamond ensemble NV center magnetometers,the size of the excitation light spot directly determines the number of excited NV centers,and excessive excitation of NV centers can degrade the quality of magnetic field imaging due to field averaging effects.In existing optical path schemes,the oblique incidence scheme has two main deficiencies:On one hand,the oblique incidence of excitation light forms an elliptical spot on the NV center surface,while scattering caused by uniplanar inner surfaces of the optical waveguide affects spot focusing.On the other hand,the optical waveguide simultaneously transmits both excitation light and fluorescence,causing the excitation light to interfere with the fluorescence signal,thereby reducing the signal-to-noise ratio.Although the vertical incidence scheme can form a uniformly distributed circular spot,the fluorescence collection efficiency is relatively low due to not using an optical waveguide.Methods In order to improve the quality of the light spot and enhance the signal-to-noise ratio while maintaining the fluorescence collection efficiency,we develop a novel scheme.First,it is essential to ensure that the excitation light reaches the NV center surface vertically without passing through an optical waveguide,thus forming a circular spot.Second,fluorescence must be guided through an optical waveguide to the photodetector to keep collection efficiency while effectively separating the excitation light from the fluorescence.We propose an optimized scheme based on a wedge prism group(Fig.3).To form a circular spot,we employ a wedge prism group,which allows the excitation light to be vertically illuminated on the surface of the NV centers.To enhance focusing performance,we replace the standard plano convex lens with an achromatic lens.For effective separation of excitation light from fluorescence,we integrate a dichroic mirror with the wedge prism group,while transmitting the fluorescence to the photodetector through an optical waveguide.Results and Discussions To demonstrate the effectiveness of our optimized optical path scheme based on a wedge prism group,we conduct analyses through both light spot simulation and magnetic field imaging experiments.Firstly,we simulate the light spots on the NV center surface by both the oblique incidence scheme and our optimized scheme.The light spot formed by the oblique incidence scheme exhibits an elliptical shape,with root mean square(RMS)radii of 23.17μm and 0.73μm in the x and y directions,respectively(Fig.4(a)).Regarding irradiance distribution,the spot shows non-uniformity along the x-direction at y=0(Fig.4(b)).In contrast,the light spot formed by our optimized scheme displays a basically circular geometry with identical RMS radii of 0.35μm in both x and y directions,achieving excellent focusing(Fig.4(c)).Moreover,the irradiance within the spot is higher and more uniformly distributed(Fig.4(d)).Subsequently,we perform magnetic field imaging of a circuit board using both schemes.The magnetic field image obtained using our optimized scheme clearly reveals the contour features of three current loops,with magnetic field strengths in the same order of magnitude as theoretical values(Fig.5(d)).In contrast,the spatial distribution of the magnetic field in the oblique incidence scheme is significantly expanded,with more blurred current loop boundaries and magnetic field strengths an order of magnitude lower than theoretical values(Fig.5(c)).Quantitative analysis of imaging quality using mean squared deviation(MSD)shows that the MSD of magnetic field for our optimized scheme is 0.14,and the oblique incidence scheme’s is 0.30.These experimental results confirm that our optimized scheme substantially improves magnetic imaging quality.Conclusions An optimized optical path scheme with a wedge prism group is designed to enhance the imaging quality of diamond ensemble NV center magnetometers.Theoretical simulations demonstrate that this scheme achieves a smaller,circular focused light spot on the NV center surface while providing higher irradiance with superior spatial uniformity in its distribution.Experimental results show that the MSD of magnetic field obtained using our optimized scheme is 0.14,significantly outperforming the 0.30 of the oblique incidence scheme.These findings confirm that our optimization effectively reduces the influence of field averaging effects and improves magnetic field imaging quality.