多焦平面三维投影光学系统设计

Optical Design of Three-Dimensional Projection on Multifocal Planes

为了解决传统立体显示器成像不满足人眼正常成像规律的问题,同时考虑到穿戴设备兼具质量小、体积小的特点,在计算分析光学系统参数的基础上,结合数字微镜元件(DMD)和压电可变形反射镜(PDM),利用Zemax软件设计出了具有多焦平面投影功能的光学系统。该光学系统由7片透镜组成,总长为200mm,视场角为40°,采用双远心光路结构。对光学系统的整体分析结果表明,改变PDM的曲率半径,可实现多焦平面的成像。人眼根据自身的调节作用,在特定位置处可观察到由各个焦面位置处(屈光度范围为0~3m^(-1))的二维图像重叠所带来的整体三维效果。最后对系统的成像质量进行分析,结果表明该系统在极限分辨率为37lp/mm时,各视场处的调制传递函数(MTF)均高于0.4,性能良好,满足设计要求。

It is a problem that the conventional stereoscopic display imaging does not satisfy with the regular imaging rules of human eyes.Besides,the miniaturization of wearable device needs to be considered.In order to solve these problems,Zemax is used to design a multifocal planes projection optical system combined with the digital micro-mirror device（DMD）and piezoelectric deformable mirrors（PDM）,based on calculating analysis of optical system parameters.This optical system uses double-telecentric optical path which is composed of seven lenses with a total length of 200 mm and a field of view of 40°.According to the overall analysis,changing the curvature radius of PDM can realize the multifocal planes imaging.At a particular position,human eyes can observe the overall three-dimensional effect which is overlapped by two dimensional images at the location of each focal plane（range from 0 to 3 m^（-1））.Finally,the imaging quality of the system is analyzed.The result shows that the modulation transfer function（MTF）value of the system is higher than 0.4 at the limit resolution of 37 lp/mm in all field of view.The performance is well and it meets the design requirement.