In the previous four decades, the two-coil mutual inductance (MI) technique has been widely employed in characterizing magnetic penetration depth, , of superconducting films. However, the conventional methods used to obtain are not applicable to small-sized films with common shapes, which limits the application of the MI technique in superconductivity research. Here, we first employed the fast wavelet collocation (FWC) method to a two-coil system and then proposed the possibility of directly obtaining the absolute of polygonal superconducting films with arbitrary sizes. To verify its accuracy and advantages, we extracted the values of square NbN films with different sizes using the FWC and conventional flux leakage subtraction (FLS) methods. Notably, the FLS method fails for a film, which is attributed to the significant current peak at the film edge. In contrast, the absolute extracted using the FWC method was independent of the film size. Finally, we established the applicability of the FWC method to large coil spacings, which may pave the way for integrating high-accuracy measurements with the ionic liquid gating technique.

在过去的四个十年中，双线圈互感 (MI) 技术已广泛用于表征超导薄膜的磁穿透深度。然而，传统的获得方法不适用于形状普通的小尺寸薄膜，这限制了MI技术在超导研究中的应用。在这里，我们首先将快速小波搭配（FWC）方法应用于双线圈系统，然后提出了直接获得任意尺寸的多边形超导薄膜绝对值的可能性。为了验证其准确性和优势，我们使用 FWC 和传统的漏磁减法 (FLS) 方法提取了不同尺寸的方形 NbN 薄膜的值。值得注意的是，FLS 方法失败了薄膜，这归因于薄膜边缘的显着电流峰值。相比之下，使用 FWC 方法提取的绝对值与胶片尺寸无关。最后，我们建立了 FWC 方法对大线圈间距的适用性，这可能为将高精度测量与离子液体门控技术相结合铺平道路。