Design, fabrication and experiment of diffractive optical element to realize Nd:YAG laser beam smoothing

The hybrid algorithm, combing Hill-climbing and Simulated Annealing, and hollowed-out mask are adopted to design and fabricate the diffractive optical element (DOE) with diameter 80mm, to realize beam smoothing for the fundamental wave and the third harmonic wave of Nd:YAG laser. The edge of the DOE is measured by the profilometer, which shows a rather large etching depth error exists. The performance of the DOE is experimentally studied with a pulse-operating Nd:YAG laser. Focused spots have been obtained with the corresponding design size and sharp edge, while a large top modulation exists too. The feasibility of the DOE used in the solid laser beam smoothing is preliminary proved by these firstly obtained experimental results.