小口径双通道球幕投影镜头的设计

Design of small-caliber dual-channel dome screen projection lens

为提高球幕投影成像质量,提出了双通道球幕投影方案,并基于此方案,为3.05cm(1.2英寸)3DMD芯片技术投影机设计了双通道球幕投影镜头。根据投影方案确定了设计指标,对初始结构的选型做出了合理的分析,阐述了光学设计过程,给出了像差优化及设计结果的评价。为避免镜头口径过大引起的重心不稳,通过合理控制光线入射高度,将镜头首片透镜的口径进行了大幅度的压缩,最终口径仅为102mm。设计的成像质量高、像质均匀的球幕双拼投影镜头F#为2.5,反远比为6∶1,1.0视场在38lp/mm的Nyquist频率处MTF值为0.5,0.85以内视场的MTF值达到0.65以上,最大横向色差为4.7μm,小于0.5pixel。

To improve the image quality of dome screen projection, a scheme of dualchannel projection for dome screen was designed.And based on the scheme, a dualchannel dome projection lens for 3.05 cm （1.2 inch） projector with 3digital micromirror devices （DMD） chip technique was designed.According to the projection scheme, the design indices were determined, the initial structure selection was analyzed reasonably, the optical design process was expounded, and the optimization of the aberration and the evaluation of the design result were given.To avoid the barycentre instability problem caused by the lens aperture being too large, the aperture of the first lens of the lens was greatly compressed by reasonably controlling the incident height of the light, and the final aperture is only 102 mm. The image quality of the designed dome dualchannel projection lens is high and uniform, its F# is 2.5, the invertedtelephoto ratio is 6∶1, the modulation transfer function （ MTF） of 1.0 fieldof-view（FOV） is 0.5 at the Nyquist frequency of 38 lp/mm, the MTF within 0.85 FOV is above 0.65,and the maximal chromatic aberration is 4.7 μm, less than 0.5 pixel.