To improve laser anti-UAV technology and UAV laser protection capabilities, research on continuous laser damage to a UAV flight control system has been carried out. Combining waveform and function monitoring, the performance of the flight control system under laser irradiation was observed in real time, and the temperature and ablation process were recorded, which were used to analyze its damage characteristics and thresholds. Our experimental results show that the flight control system had two damage modes: temporary failure and permanent damage. Temporary failure had a temperature threshold, which was on average $450.85$ K. All temporarily failed flight control system functions could be restored after cooling and a manual restart, but permanently damaged flight control systems could not be manually restarted. This experiment showed that, within K. All temporarily failed flight control system functions could be restored after cooling and a manual restart, but permanently damaged flight control systems could not be manually restarted. This experiment showed that, within $10 \mathrm{s}$, the power density required for temporary failure and permanent damage to the flight control system was ${28.4 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$ and ${42.6 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$, respectively. The power density required for permanent damage was ${82.0 \mathrm{W}/\mathrm{c}\mathrm{m}}^2$ within $16 \mathrm{s}$ if the flight control system was encapsulated with aluminum alloy. Based on the circuit fault diagnosis of the flight control system samples that has been permanently damaged, the laser’s thermal effects damaged the diodes and linear regulators, ultimately rendering the flight control system unable to be manually restarted.

With the development of optoelectronic countermeasures and ultrashort pulse laser technology, the study of the interaction between ultrashort pulse laser and monocrystalline silicon has a very important theoretical and practical significance. In order to further clarify the damage mechanism of 532 nm picosecond pulsed laser on monocrystalline silicon, we have conducted an experimental study to measure the damage threshold, clarify the damage mechanism, and discuss the pulse accumulation effect at low flux. Firstly, using a laser with a wavelength of 532 nm, a pulse width of 30 ps and a metallurgical microscope based on the 1-on-1 laser damage test method, the zero damage probability threshold is determined to be 0.52 J/cm(2). Secondly, the damage effect of a picosecond laser irradiated on monocrystalline silicon was studied under different laser fluxes, and it was found that the damage of 532 nm picosecond laser to monocrystalline silicon is manifested as heated-effect damage and plasma impact damage. The increase in energy density can be divided into three stages according to the main damage mechanism: thermal effect (0.52 similar to 3 J/cm(2)), thermal ablation (3 similar to 50 J/cm(2)) and plasma effect (>50 J/cm(2)), and the damaged areas are corresponded to different growth laws with the laser energy density, respectively. Finally, an experiment for the multi-pulse cumulative effect was carried out at a low laser flux and it was found that at a laser energy density of 0.52 J/cm(2), the surface was irradiated continuously for 16 shots. The formation of a heat-affected zone confirms that the cumulative effect of multiple pulses can lower the laser damage threshold on monocrystalline silicon.

An aluminum-coated grating (ACG) is a core component of laser systems and spectrometers. Understanding damage to the ACG induced by nanosecond lasers is critical for future high-power laser applications. In this study, we applied finite element simulation and practical experimentation to investigate the characteristics of ACG damage. Based on a coupling model using fluid heat transfer with the level-set method, we simulated the damage caused to an ACG by a 1064 nm nanosecond single pulse laser. The theoretical modeling showed that the ridge and bottom corners of the grid will be preferentially damaged, and the simulated damage threshold will range from 0.63 J/cm² to 0.95 J/cm². We performed a one-on-one damage test according to the ISO21254 standard to investigate the failure condition of 1800 l/mm ACGs; the laser-induced damage threshold (LIDT) was 0.63 J/cm² (1064 nm, 6.5 ns). Microscopy images showed that the damaged area decreased with decreasing laser fluence, and scanning electron microscopy measurements showed that the main damage mechanism was thermodynamic damage, and that damage to the grid occurred first. The results of the experiments and simulations were in good agreement.