Numerical analysis of the convergence speed of the SPGD algorithm with two different perturbation methods in coherent beam combination using active segmented mirror

An introduction was given to the active segmented mirror(ASM) used in coherent beam combination firstly. Based on the actuator distribution of ASM, the computational formula between the perturbation voltage of each actuator and the perturbation of piston or tip/tilt was acquired. Then the numerical analysis of correction process with two different perturbation ways in SPGD algorithm was carried on. By comparing the two correction processes, it was found that the convergence speed of the second method is 25 times as fast as the first one when there only existed piston error between the two beamlets, while the convergence speed was almost the same when there only existed tip/tilt error, and the convergence speed is 5 times when there existed both piston and tip/tilt error.