## 1 Introduction
Health monitoring systems are not commonly used for checking the condition of glass curtain walls due to their high cost and difficult installation [42]. Moreover, not all damage conditions result in large areas of peeling and stripping of the structural adhesive. In many cases, the structural adhesive may appear to be intact from the outside but is already failing or delaminating from the inside. This issue hinders identification using traditional vision-based methods. Conventional methods often rely on periodic inspections, and the time between inspections can lead to prolonged damage and delayed repairs. Therefore, the detection method of debonding damage on glass curtain walls should be efficient, immediate, safe, and cost-effective. These problems can be avoided by identifying damage using the vibration characteristics of the curtain walls [13]. Laser technology provides benefits of range, accuracy and efficiency. However, the power of a laser is limited, which makes ground-based damage assessment an impossible task. The combination of UAV and laser vibration measurement technology effectively addresses the challenge of detecting debonding damage on glass curtain walls. Remote, non-contact, and low-error vibration measurements can be achieved by attaching the Laser Doppler Vibrometer (LDV) to a UAV. Some researchers have identified hidden vehicles in the forest by using LDVs placed at high altitudes to detect the vibrations of leaves [43]. Although the effect of wind turbulence on leaf vibration was considered, the interference with the LDV signals was not. Previous research also proposed the concept that LDVs could be transported in aerial platforms for testing, but their experiment still used a lift vehicle, which is no different from a stationary LDV. Other scholars claimed that they have built a UAV-LDV system to achieve aerial testing. However, the utilization of the UAVs in these systems is limited to the placement of reflective targets [44], for the enhancement of the reflected laser intensity or the carriage of acoustic exciters [45], for the replacement of manual tapping, or carrying mirrors to reflect the laser light from stationary LDVs [46; 47]. Their actual tests still rely on stationary LDVs, and the purported UAV-LDV systems have not been fully realized. The UAV-LDV system is susceptible to factors that can cause interference, which in turn compromises the accuracy of the measurements. It is only used for vibration monitoring in situations with a significant degree of displacement, such as dynamic lateral displacements in railways [48]. While some studies have optimized UAV-LDV systems based on the assumption that the target remains in a steady state of vibration [49] and that the main source of error is induced by vibrations from the UAV [50], it is crucial to recognize that the UAV-LDV system is notably prone to inaccuracies resulting from the UAV's aerial instability, and more damage detection methods are based on transient vibration. Specifically, the vibration monitoring of LDVs relies on detecting differences in the optical path, which is significantly affected by the deflection of the UAV-LDV system during flight. Consequently, the most substantial errors in these systems typically stem from strong winds and difficulties in the attitude adjustment of UAVs during operation. The dynamic response of the curtain wall can be obtained by the subsequent analysis of the filtered vibration signals, which can ultimately reveal the debonding damage of glass curtain walls. This study investigates multiple sets of test conditions that differed in the location and extent of damage to the structural adhesive on curtain walls. The obtained signals were analyzed using the first-order of natural frequency, frequency response function, and the Sum of Squared Differences (SSD) of wavelet packet band energy as indicators. The reliability of the vibration signals obtained from the UAV-LDV system is verified by comparing them with those obtained from the fixed LDV.