Optical film damage threshold is an important basis for measuring the ability of film to resist laser damage, and laser parameters are the key factors affecting its accurate measurement. The single-factor control variable method was used to establish the the numerical model of laser energy error, the focused spot size error and the damage threshold error, and the M 2 factor and the damage threshold. The theoretical analysis and computer simulation of the energy error, the focused spot size error and the beam quality on the film damage threshold influences. A method based on the Shack-Hartman wave-front detection method is proposed to measure the pulsed laser beam parameters. The working principle is described in detail, and the Shack-Hartman beam shape parameter measurement system is designed. The actual output energy of the laser and the size of the focused spot were measured experimentally, and the uncertainty of the film damage threshold was evaluated according to the statistical principle. The results shows that the energy error and the focused spot error are directly proportional to the damage threshold error, and M 2 is inversely related to the damage threshold. From the thin film sample analysis, the relative uncertainty of the damage threshold measurement is 18.78%. Therefore, studying the influence of laser parameters on the damage threshold provides a direction for obtaining accurate film damage threshold test results.
In order to improve the shielding effectiveness of graphene films, graphene films were prepared by chemical vapor deposition. The effects of hydrogen flow rate, methane flow rate, reaction temperature and reaction time on the electromagnetic shielding properties of the films were investigated. The shielding effectiveness of the film was tested and the preparation process of the film was optimized based on the test results. The results show that when the hydrogen flow rate is 8sccm, the methane flow rate is 15sccm, the reaction temperature is 1030°C, and the reaction time is 30minutes, the shielding effectiveness of the film is 1.2dB (0.3-3000MHz) and the average transmittance is 96%. (400-800nm), the photoelectric comprehensive performance is better.