在工艺上衍射光学元件是通过相位板来实现的,由于其多台阶化产生的不连续性,会对目标光场产生sinc调制,产生高级次衍射斑,损失了15%或者更多能量。通过对设计衍射光学器件的传统的IO迭代算法进行了研究,提出了一种与衍折射相结合的设计方法,在衍射光学器件的部分区域形成一块连续相位区域,减少了相位片台阶化区域的光强和衍射斑的强度。通过逐步变化连续相位对输出光强情况的影响的研究,可以优化相位参数,使入射到输出面的光束保证一定匀滑性的前提下,提高目标光场区域的衍射效率达到90%以上,能够满足均匀照明的要求。

The diffractive optical element is one of the main solutions to achieve uniform illumination,which is achieved through the pure phase element.There are sub-diffraction spots because of the discontinuity of pure phase element,which makes the beam lose 15% or more energy.Thus a diffractive-refractive method based on the traditional input-output algorithm is developed to design the diffractive optical element.This method makes part of a diffractive optical element continuous in phase,which reduces the light intensity in the discontinuous region of the element,therefore reduces the intensity of sub-diffraction spots.Through studying the influence of spherical phase factor on output light intensity,the phase parameter can be optimized to increase the diffraction efficiency of the incident beam onto the output to better than 90% with an acceptabe uniformity,which could meet the requirements of uniform illumination.