Micro-structure Measurement of Phase Grating Based on Digital Micro-holography
基于数字显微全息技术的相位光栅结构测量

The reconstruction research on 3D micro-structure of the phase grating via Digital Micro-Holography (DMH) was presented.In order to improve the lateral resolution based on the Mach-Zender interference system,two modes,with Micro-Objective (MO) magnification mode and with lens-less one,were proposed for magnifying the specimen.In DMH experiment with MO magnification mode,the 3D micro-structure distribution was obtained by combining Fresnel approximation approach and dual-wavelength technique to suppress the main phase aberration.For lensless magnification mode,the subtraction method was presented to eliminate the system total aberration to get the 3D phase information of the phase gating by using Fresnel approximation approach and the convolution approach,respectively.The experimental results were compared with the measurement results provided by Veeco interferometer,the parameters,such as the period and the height structure,of the phase gating were same and then the experiment in this paper was verified.The experimental conclusions were given.