Spatial filter pinhole image acquisition based on beam self-fold back in a multi-pass amplifier laser system

Today the energy in a multi-pass amplifier laser system can reach 10,000 J high or more. The high-precision alignment of beams is one of the prerequisite conditions for the operation of multi-pass amplification laser systems. High-precision alignment reference acquisition is the base for a precise alignment emphasizing the precise far-field reference imaging of the final-pass pinhole. A new, to the best of our knowledge, method of imaging the reference pinhole based on the total reflection of a rectangular prism was proposed in this study. By plugging a rectangular prism into the laser beam line, the laser beam will be reflected and folded back directly to the final-pass line, while the middle stage amplification beam line is missed. The pilot beam will directly light up the reference pinhole, and a clear boundary pinhole image will be obtained. In a multi-pass laser amplification system, employing this method for laser collimation eliminates the necessity of introducing a new light source and mitigates the effects of multi-stage pinhole collimation, which significantly assists the rapid and precise collimation of multi-path optical systems within intense laser systems.