Effect of alignment accuracy on focal spot during beam superposition process

Multi-beam combination is an effective way to improve the laser output power. In this paper beam alignment influences on the character of focal spot in energy synthetic cases are discussed. By using two beams with rectangular aperture, we analyze the focal spot characteristics of the two beams in different alignment cases. When the two beams are completely aligned, their focal spots overlap completely, and the focal spot energy is the sum of the two beams. We also discuss three common alignment errors, and compare their influences on the character of focal spot in the actual beam alignment system. ZEMAX software is used to simulate the design system and the results are proved by experiments. The results show that the component position error will reduce the energy and increase the root-mean-square radius of focal spot.