## 1 Introduction  
Carbon fiber-reinforced polymer (CFRP) has found widespread applications in aerospace, defense, transportation, and other fields due to its exceptional specific strength, specific stiffness, and corrosion resistance, making it an ideal lightweight structural material [1]. However, during its manufacturing and usage, various types of damages are inevitable, with delamination being one of the major forms [2]. Delamination presents as local separation, insufficient bonding, and cracking between layers. The presence of delamination compromises the integrity of CFRP, impacting its outstanding performance. Moreover, delamination can propagate during service, leading to premature failure of laminates and even causing production accidents [3]. Therefore, delamination is one of the most significant and impactful defects, making non-destructive testing for it crucially important. The current five major non-destructive testing methods are ultrasonic testing, radiographic testing, magnetic particle testing, penetrant testing, and eddy current testing. They are widely used in various fields due to their respective unique advantages. However,magnetic particle testing and penetrant testing are inherently difficult to implement in CFRP non-destructive testing due to their characteristics. Magnetic particle testing is a non-destructive testing method that utilizes magnetic changes to detect surface and near-surface defects in ferromagnetic materials. It has advantages such as displaying defects intuitively, high sensitivity, and fast detection speed [4]. However, it has certain limitations since it is only applicable for inspecting ferromagnetic materials (such as steel). Penetrant testing is primarily used to detect surface-opening defects in non-porous metallic and non-metallic components, making it suitable for non-destructive testing of materials such as ceramics and plastics [5]. However, this method is only applicable for detecting defects indicated on the material's surface, and it cannot achieve non-destructive testing for deep-seated or internal defects. Ultrasonic testing, radiographic testing, and eddy current testing are commonly used for non-destructive testing of CFRP [6]. Ultrasonic testing takes advantage of the low density and high elastic modulus of CFRP, allowing ultrasonic waves to penetrate and propagate inside, thereby detecting defects such as delamination and cracks in CFRP [7; 8; 9]. However, ultrasonic testing requires a certain level of surface cleanliness on the sample being tested, and the use of a coupling agent is essential during testing. This means that subsequent drying processes for the CFRP sample may have an impact on the testing results. X-rays have strong penetration capabilities and can penetrate CFRP samples. When defects are present in the CFRP, the X-rays are reflected, absorbed, or scattered by the internal defects [10]. However, the expensive equipment and the need for specialized operators limit the widespread application of this technology in CFRP non-destructive testing. Compared with the aforementioned methods, eddy current testing has the advantages of low cost, high efficiency, and no need for a coupling agent, etc. CFRP exhibits orthotropic conductivity, making eddy current testing suitable for detecting delamination. Currently, many scholars have conducted in-depth research on eddy current testing for delamination in CFRP. [PERSON] et al. [11] designed high-frequency eddy-current sensors that can be used to detect delamination. By observing the polar plot of voltage amplitude when the probe rotates to scan CFRP, significant changes in voltage amplitude can be observed at the location of the delamination. [PERSON] et al. [12] utilized 32 pancake coils to simultaneously detect delamination and conducted imaging studies based on the varying eddy current density at the delamination sites. [PERSON] et al. [13] utilized a CP probe with a rectangular exciting coil to detect multidirectional artificial delamination in CFRP, and this probe had a high signal-to-noise ratio.