The output energy of regenerative amplifiers and its stability are crucial performance indicators. With the rapid advancement of high-power laser technology, there is a growing demand for higher output energy and power in regenerative amplifiers. However, the peak pulse energy in these amplifiers is limited by the damage threshold of the optical elements in the resonator. When the pulse width and peak power are fixed, increasing the output energy requires expanding the beam diameter in the resonator. Consequently, regenerative amplifier resonators are typically designed in the second stability region to achieve a sufficiently large beam diameter. However, resonators in this region are highly sensitive to misalignment, and longer resonator length exacerbates this sensitivity. Therefore, maintaining beam pointing stability in regenerative amplifiers is critical for ensuring stable output power. To achieve a long resonator length within a limited space, mirrors are commonly used to fold the resonator, and their arrangement influences beam pointing stability.

This study analyzed the impact of mirror arrangements on beam pointing stability within the resonator to ensure stable output power. Using modal analysis and microvibration theory, we examined the spatial distribution of disturbances on optical elements. Two mirror arrangement models were developed: a large-mirror configuration (model A) and a mirror-array configuration (model B). We used a regenerative amplifier in a high-power laser system as a case study, conducting Monte Carlo simulations and a over continuous 22-hour energy output experiment to compare the effects of these mirror arrangements on the output energy stability, thereby indirectly characterizing beam pointing stability.

Experimental and simulation results indicate that the mirror-array configuration (model B) significantly outperforms the large-mirror configuration (model A) in terms of beam pointing stability, even under the same vibration amplitude. During a over continuous 22-hour energy output test, model A exhibited a peak-to-valley (PV) value of 60.704% and an RMS (root-mean-square) value of 14.729% in average energy output stability. In contrast, model B achieved a much lower PV value of 2.325% and an RMS value of 0.429%. The mirror-array configuration effectively minimizes the impact of individual mirror disturbances by averaging errors across multiple elements, thereby enhancing the overall system stability. Conversely, the large-mirror configuration amplifies the influence of a single mirror’s stability owing to the multiple reflections required by each large mirror, which can degrade system performance. Although the large-mirror setup theoretically reduces the number of optical elements and potential error sources, it demands higher stability from each mirror. When mirror stability is consistent, the mirror-array configuration demonstrates stronger resistance to disturbances, leading to significantly improved beam pointing and energy output stability compared to the large-mirror configuration.

This study uses structural modal analysis and examines the influence of microvibrations on beam pointing to establish a kinematic model for the microvibration of individual optical elements. Additionally, it analyzes the spatial distribution of disturbances on these elements. By comparing the large-mirror configuration (model A) and mirror-array configuration (model B), the study explores how mirror arrangements affect beam pointing stability. Theoretical analysis shows that the mirror-array configuration (model B) outperforms the large-mirror configuration (model A), regardless of whether the mirrors are correlated or uncorrelated. In tests in which only the mirror arrangement was changed, a over continuous 22-hour energy output experiment showed that model A had an average energy output stability with a PV value of 60.704% and an RMS value of 14.729%. In contrast, model B achieved a PV value of 2.325% and an RMS value of 0.429%. These results highlight the clear advantages of the mirror-array configuration over the large-mirror setup. The experimental results indicate that the mirror arrangement significantly affects the output energy stability of regenerative amplifiers. In summary, the mirror arrangement affects beam pointing stability in laser systems, thereby influencing energy output stability. The study provides theoretical support and practical guidance for the design of precision laser systems.