全息光刻可通过空间光调制器数字微镜器件(DMD)加载计算全息图构建数字掩膜来实现，罗曼编码是常用的编制计算全息图的方法，它采用透明矩形孔的高度和位置分别编码全息图抽样单元的幅值和相位。通常，DMD再现此类二元全息图需合并多个微镜来表示单个矩形孔，这会大大降低其像素利用率和分辨率。针对这个问题，提出一种改进的罗曼编码，该编码充分利用DMD的二进制脉宽调制特性，采用灰度值编码全息图抽样单元的幅值,将全息图的透过率由二元型转换成灰阶型，从而有效减少单个抽样单元所占用的微镜数。采用MATLAB编程对改进的罗曼编码和博奇编码计算全息图进行模拟再现分析，得到改进的罗曼编码衍射效率约是博奇编码的3倍。以DMD为核心搭建了全息再现实验，得到改进的罗曼编码衍射效率约是博奇编码的2倍。可得出采用改进的罗曼编码可以显著提高衍射效率。

Holographic lithography can be realized by loading computer-generated hologram(CGH) on digital micro-mirror device ( DMD) to form the digital mask. Roman encoding is a commonly used method to generate CGH, which uses the height and position of transparent rectangular hole to encode the amplitude and phase of sample unit of hologram respectively. Usually, as reconstructing the binary hologram,the multiple micro-mirrors of DMD are combined to represent a single rectangular hole, and the utilization and resolution of its pixels can reduce. To solve the problem, an improved Roman encoding is introduced, which can make full use of the binary pulse width modulation of DMD and use the grayscale value to encode the amplitude of the sample unit, convert the transmittance of hologram from binary to grayscale and reduce the number of micro mirrors occupied by a single sample unit effectively. MATLAB is used to build the simulation model to reconstruct and analyze the CGHs produced by improved Roman encoding and Burch encoding. The results indicate that the diffraction efficiency of the improved Roman encoding is 3 times as much as that of the Burch encoding. The reconstruction experiment based on DMD is conducted, which demonstrates that the diffraction efficiency of the improved Roman encoding is 2 times as much as that of the Burch encoding. Therefore, using the improved Roman encoding can achieve higher diffraction efficiency.