The Impact of Mirror Arrangement on Beam Pointing Stability

The output power stability of a regenerative amplifier is directly affected by the beam pointing stability. Misalignment of the resonant cavity can cause a deviation in the direction of the beam, thereby increasing diffraction loss, reducing the net gain inside the cavity, and ultimately causing fluctuations in output power. Therefore, to ensure the stability of output power, it is first necessary to ensure the stability of beam pointing. This article investigates the influence of mirror arrangement on the stability of beam pointing. A mirror transmission model was established based on modal analysis and misalignment optics, and the influence of mirror arrangement on beam pointing stability was discussed using the arrangement of large mirrors (Model A) and mirror groups (Model B) as research objects. Simulations and experiments were conducted using a regenerative amplifier in a high-power laser device as a case study. The Monte Carlo simulation results show that the stability of model B is significantly better than that of model A. Comparing the continuous energy output of a regenerative amplifier for over 22 hours, the stability of beam pointing is characterized by the stability of output energy when only the arrangement of the mirrors is changed. When using Model A, the stability PV value of the average power output of the regenerative amplifier is 60.704%, and the RMS value is 14.729%; When using Model B, the stability PV value of the average power output is 2.325%, and the RMS value is 0.429%. The arrangement of Model B is significantly better than that of Model A. The experimental results show that the arrangement of mirrors can significantly affect the beam pointing stability of the regenerative amplifier, thereby affecting the stability of its output power.