Studies on the characteristics of laser beams' coherent summation by grating

Experimental studies on laser beams' coherent summation by grating are described in this article, including the combination efficiency, the quality of the combined beam and the robustness of the beam combination system. The measured three He-Ne beams' combination efficiency is greater than 60% with the far field M2 about 1.3. The experimental studies show that if using an uniform splitter as a combiner in the equal strength laser beams' combination, when some of the laser units spoiled, the change of the combination efficiency simply equals the ratio of the number of the damage laser units to the total number of the laser units to be combined, and the wave-front of the combined beam still keeps good shape. The investigations introduced in this paper show that laser beams' coherent summation by grating can fulfill its task well with high combination efficiency, excellent combined beam quality and good robustness.