采用衍射掩模产生白光横向平顶光束  

Horizontal white light flat-topped beams produced by the diffraction mask

作　　者：陈芳萍 张晓婷 刘楚嘉 漆宇 庄其仁 Chen Fang-Ping;Zhang Xiao-Ting;Liu Chu-Jia;Qi Yu;Zhuang Qi-Ren(Fujian Key Laboratory of Light Propagation and Transformation,College of Information Science and Engineering,Huaqiao University,Xiamen 361021,China)

机构地区：[1]华侨大学信息科学与工程学院福建省光传输与变换重点实验室,厦门361021

出　　处：《物理学报》2018年第14期146-157,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61178015;61605049);福建省科技重大项目(批准号:2016H6016)资助的课题~~

摘　　要：白光横向平顶光束在定向背光式自由立体显示器中有重要应用.本文提出一种采用带蝶形小孔阵列的衍射掩模片获得白光横向平顶光束的方法.根据广义惠更斯-菲涅耳衍射积分和多波长叠加原理,推导出光强分布计算式.设计一套实验装置,数值模拟并实验验证出射光束在不同距离的横向光强分布以及小孔蝶形凹度(蝶形中心高度与边长的比值)对横向光强分布的影响.结果表明:当选择小孔蝶形凹度为0.50—0.66时,可以得到平顶因子F 0.89的白光横向平顶光束,横向平顶光束的宽度随着传输距离的增大而增大,而平顶因子基本不变.实验还发现柱面透镜的折射色散和衍射色散可以互相抵消,使白光横向平顶光束基本无色散.The flat-topped beam is a special beam with wide applications in the directional backlight autostereoscopic display,and it is used as a directional backlight in the horizontal direction. However, it is still challenge to white light flat-topped beams with the traditional flat-topped beam shaper. In this paper, it is proposed that diffraction mask with butterflyshaped hole arrays and cylindrical lens be used to produce the horizontal flat-topped white beams. The surface of the LCD backlight mask is covered by a layer of diffraction mask, where the butterfly-shaped holes are arranged in line along the vertical direction. Simultaneously, the height and width, hole center height are kept identical, and the ratio between the center depth and the perimeter of butterfly-shape hole is defined as the concavity. A flat convex cylindrical lens is placed in front of diffraction mask gaplessly. The uniform light field from LCD backlight is transformed into the white light flat-topped beams and projected on the receiving screen by the diffraction mask and cylindrical lens. Based on the Huygens-Fresnel diffraction integral, the intensity distribution formula of diffraction of the single wavelength light source on the receiving screen is derived. Furthermore, the intensity distribution formula on the screen is derived by super positioning the multiple wavelengths. The proposed method is verified by both numerical simulation and experimental validation. Numerical simulations elucidate the effects of the different transmission distance and butterfly hole concavity on the white light flat-topped beam flat-topped factor. The stimulated results show that the propagation distance does not influence the white light beam transverse intensity distribution characteristics of flat top. With the beam propagation distance increasing, the horizontal width of flat-topped beam becomes larger. When the concavity of the butterfly hole decreases, light intensity distribution shifts from Gaussian to flat type. However, the flat-topped factor decrea

关 键 词：白光横向平顶光束 衍射掩模 惠更斯-菲涅耳衍射积分 柱面透镜 

分 类 号：O436.1[机械工程—光学工程]