PDMS基柔性近眼显示波导光学系统设计

Design of PDMS-based stretchable near-eye display waveguide optical system

针对近眼显示系统视场小、体积笨重、柔性差、量产性差等问题,文章采用在系统中加入自由曲面和聚二甲基硅氧烷(PDMS)基的设计方法。论述了柔性近眼显示光学系统的设计要求和工作原理,进行初始结构建立;分析了系统杂散光产生的原因,进行杂散光抑制设计;采用XY多项式自由曲面替换传统非球面,进行系统像差校正;采用柱面波导模拟波导弯曲,进行柔性波导弯曲优化分析,设计出一款兼备柔性弯曲能力、大视场和高成像质量的近眼显示光学系统。设计的近眼显示系统工作波段为400~700nm,出瞳直径为8mm,视场角为30°,厚度为1.5mm。在截止频率71lp/mm处,全视场的调制传递函数值均大于0.1,畸变小于5%,在波导变形弯曲半径大于500mm情况下,全视场的调制传递函数值在截止频率15lp/mm处均大于0.1,系统重量约为22.8g。设计结果表明实现了近眼显示光学系统小型化、轻量化和柔性化,可应用于新一代的头盔显示系统中。

Aiming at the problems of near-eye display system such as small field of view,bulky,poor flexibility,and poor mass production,the design method of adding free-form surfaces and polydimethylsiloxane(PDMS)groups to the system is adopted.First,the design requirements and working principles of the flexible near-eye display optical system are discussed,and the initial structure is established.Then analyze the reasons for the stray light of the system.Then use XY polynomial free-form surface to replace the traditional aspheric surface to correct system aberrations.Finally,a cylindrical waveguide was used to simulate the bending of the waveguide,and the optimization analysis of the bending of the flexible waveguide was carried out,and a near-eye display optical system with flexible bending ability,large field of view and high imaging quality was designed.The designed working wavelength of the near-eye display system is 400~700 nm and a pupil diameter of 8 mm,field of view is 30°,and a thickness of 1.5 mm.At a cut-off frequency of 71 lp/mm,the field of view Modulation Transfer Function(MTF)value is greater than 0.1 and system distortion is less than 5%,in cases where the waveguide deformation bending radius is greater than 500 mm,the modulation transfer function value of the full field of view is greater than 0.1 at the cut-off frequency of 15 lp/mm,and the system weight is about 22.8 g.The design results show that the design achieves the miniaturization,light weight and flexibility of the near-eye display optical system,and can be applied to a new generation of helmet display systems.