Design of diffractive optical elements for controllable axial long depth of focus

Abstract

The controllable axial long depth of focus (DOF) is required in many optical applications, and the axial DOF of a light beam can be controlled by diffractive optical elements (DOEs). However, the trade-off between the sidelobe and controllable DOF often be ignored, which is difficult to implement their desired effect in many applications. In this paper, a modified Gerchberg—Saxton (GS) algorithm is presented for generating DOEs to realize suppressed sidelobe and controllable axial DOF in an acceptance variation of normalized intensity and sidelobe. In the simulation, we optimized the DOEs to control the length of DOF, suppress sidelobe and calculate spot size, and the corresponding length of DOF is within the range of 60λ to 600λ with a different portion (1-7) multi-pure phase DOEs at the numerical aperture is 0.035. Experimental results are also shown to demonstrate the effectiveness of the proposed algorithm. We anticipate that this optical system can be used in laser fabrications, including optical manufacture, highly dynamic cutting and high-quality cutting.