Analysis of misaligned optics effects on beam pointing stability in dual-pass optical system

Abstract

The high-power laser device utilizes a multi-pass amplification system to achieve elevated power laser output. Laser beam is transmitted several times through the amplifier, and the pointing stability is a critical factor affecting the efficiency of the system. Any perturbation of the optics during laser transmission can cause misalignment and further lead to beam pointing errors. Laser beam propagation simulation was conducted using the ray tracing method. Equivalent experiment was performed using a laser with a wavelength of 532 nm, and the centroid position data of the laser beam were collected to characterize the effect of the optics misalignment on laser pointing. A model evaluating the sensitivity of the optics was constructed, and the analysis of how various optics impact pointing accuracy was conducted. Results indicate that, a linear relationship exists between the misalignment of the optic and the pointing shift and angular deviation of the beam when a single optic is misaligned. If multiple optics are misaligned, the shift in centroid position of the laser beam can be calculated by adding up the shifts caused by each misaligned optic. Furthermore, the shift in the centroid position of the laser beam is the linear superposition of the misalignment of each optic.