Influence of laser output parameters on film damage threshold

Abstract

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.