4k数字放映机广角放映镜头的设计

为满足4k电影的短距离放映需求，设计一款广角放映镜头，可适配于采用三芯片DMD技术的放映机，最大投射比可达0.75∶1，相对孔径为1/2.2，反远比为4.6∶1，在66 lp/mm的Nyquist频率处，MTF值为0.42，边缘视场MTF值为0.25。最大横向色差为3.7 m0.5 pixel,最大畸变为2.5%。分析了反远距形式的特点，给出了合理选型、分配光焦度和计算关键技术参数的方法，以及像差校正过程中应注意的问题。最终设计出了符合设计指标的具有高分辨率的广角放映镜头，该镜头结构简单、成本低。

Design of wide-angle projection lens for 4k digital projector

To meet the need of 4k short distance movie projection, a wide-angle projection lens was designed, which is suitable for projectors with three digital micromirror-device (DMD) chips. The largest projection ratio could be 0.75∶1, the relative aperture is 1/2.2, the inverted telephoto ratio is 4.6∶1. At the Nyquist frequency of 66lp/mm, the resolution of center field is 0.42,and the resolution of marginal field is 0.25. The max lateral chromatic aberration is 3.7 μm, which is less than 0.5 pixel, and the max distortion is 2.5%. The feature of inverted telephoto was deeply analyzed, and the methods for choosing structure, distributing focal power and calculating key parameters were provided in the paper, additional, the issues needing pay attention during aberration correction were contained. Finally, a wide-angle projection lens with high resolution which could meet all the indices was designed, besides that, the lens has the feature of easy structure, low cost and high quality.