基于LCoS的头配显示器光学系统研究

Optical Research of Head Mounted Display with LCoS

头盔式显示器的迅猛发展对系统重量和成像质量方面提出了更高的要求。文章采用LCoS作为头配显示器的显示器件,同时利用衍射光学元件独特的负色散特性和以其任意的相位分布实现对光波面的任意相位调制的特点,在改进的Erfle目镜的基础上引入二元衍射面,台阶深度为0.142μm,总的环带数为253,最小特征尺寸为3.31μm。优化设计了具有30°视场,30mm有效焦距,8mm瞳径,25mm出瞳距离的目镜系统,其MTF值在全视场内整体上大于0.25,并且重量缩小为原Erfle目镜的1/8,大大减轻HMD光学系统重量,并提高了成像质量。

As the head mounted display has been progressing at a rapid rate in recent years, the demand for system of high performance and light weight is stronger and stronger. In this paper, LCoS is used as the display element in HMD for its great developing potential for its low cost and high performances in optical efficiency. The diffractive optical element, with the negative dispersive characteristic and the random phase distributing to realize random phase modulation for wave-front, is also used in our design and its depth of the step, the number of total periods and the minimum character size are 0. 142 μm, 253 μm and 3.31 μm, respectively. An eyepiece of 40° field-of-view （FOV）, 30 mm effective focal length, 8 mm exit pupil size and 25 mm exit pupil is designed, with MTF value 〉 0.25 in the full field of view and the weight is reduced to 1/8 in comparison with the Erfle eyepiece, which conduces to a head mounted display of light weight and high performance.