Surface defects (SDs) and subsurface defects (SSDs) are the key factors decreasing the laser damage threshold of optics. Due to the spatially stacked structure, accurately detecting and distinguishing them has become a major challenge. Herein a detection method for SDs and SSDs with multisensor image fusion is proposed. The optics is illuminated by a laser under dark field condition, and the defects are excited to generate scattering and fluorescence lights, which are received by two image sensors in a wide-field microscope. With the modified algorithms of image registration and feature-level fusion, different types of defects are identified and extracted from the scattering and fluorescence images. Experiments show that two imaging modes can be realized simultaneously by multisensor image fusion, and HF etching verifies that SDs and SSDs of polished optics can be accurately distinguished. This method provides a more targeted reference for the evaluation and control of the defects of optics, and exhibits potential in the application of material surface research.

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Prosocial behavior has played an irreplaceable role during the COVID-19 pandemic, not only in infection prevention and control, but also in improving individual mental health. The current study was conducted after COVID-19 control was under the stage of Ongoing Prevention and Control in China. Using the Interpersonal Response Scale, Prosocial Tendencies Measure and Big Five Personality Questionnaire. In total, 898 college students participated in the current study (Mage = 19.50, SDage = 1.05, Age range = 16–24). The result showed that against the background of the COVID-19 pandemic, college students' social responsibility partially mediated the relationship between empathy and prosocial behavior. This study provides new insights and inspiration for improving college students' mental health in the context of the pandemic.

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In this paper, a disturbance-observer-based composite anti-disturbance control method is proposed for landing control of the carrier-based UAV subject to both external and internal disturbances. By the virtue of the composite control scheme, two nested loops are simultaneously designed. In the inner loop, disturbance observers are employed to estimate the effect of disturbances. On the other hand, in the outer loop, the sliding mode control (SMC) is designed to attenuate both the disturbance estimation error and guarantee the control performance. Then, with the disturbance estimation provided by the disturbance observer, the composite anti-disturbance controller is designed to achieve disturbance compensation and attenuation using both the feed-forward and feed-back channels. Besides, the stability of overall closed-loop is analyzed via Lyapunov theory. Finally, simulation results are presented to demonstrate the effectiveness of the proposed method.