为了实现具有复杂位相结构的二元光束整形元件,提出了采用方光点的激光直写系统来逐点光刻浮雕位相结构的方法,通过双远心投影缩微光路获得5～20 μm方点,光点尺寸对应于最小位相单元,从而获得了位相结构的高质量直写. 分析了高斯光点和方光点位相单元结构对二元整形元件衍射效率的影响,方形两台阶二元整形元件的+1级衍射效率达到31%,给出了实验结果.

In order to realize the fabrication of binary beam shaping element with complex phase structures, a new method of making the relief phase structures under the dot-by-dot exposure mode is presented by using laser direct writing (LDW) system with the square-spot. The size of the square spot obtained with the projection optical configuration is set to match with the minimum phase unit which lead to exposure mode can be easily controlled. The diffraction properties of the phase unit structures etched with single Gaussian spot and square spot are discussed. The binary beam-shaping elements with two-steps by square-spot exposure have been achieved to 31% +1 order diffraction efficiency. The experimental results are given.