自由曲面折/衍混合透镜的激光复合制备和光学性能研究

Free-form surface refractive/diffractive hybrid lens made of visible light material has stronger aberration and chromatic aberration correction ability. So it is favored by designers, with the development of photoelectric equipment in various fields to miniaturization and lightweight. Femtosecond laser has been proven the most feasible fabrication way for such optical element. But it is far from being able to meet the requirements of millimeter-scale application, due to inefficiently point-by-point scanning. In fact, its fabrication diameter is typically limited to 500μm. In terms of current situation, a laser composite fabrication mode (femtosecond laser dealing with the surface layer, Micro-stereoscopic printing the interior part), is innovatively proposed in this project。The fabrication time of laser composite fabrication mode is reduced eighty percent compared with femtosecond laser fabrication alone, for optical element of millimeter diameter. So a high-efficiency and high-precision fabrication scheme is provided for optical elements of millimeter diameter. The interaction mechanism between laser and mixed material of surface is expounded, and the fabrication model of combination of inner and surface layer is formed. The contradiction between layer thickness of femtosecond laser and surface accuracy and the alignment accuracy of lens is balanced by effective distribution mechanism of inner, surface layer and partial repetition layer. A flow-flying scanning micro-stereoscopic printing is proposed to solve the problem of discontinuity of internal structure, by combing z - axis scanning exposure and x - axis and y - axis wobulation technology. Thus, the free-form surface refractive/diffractive hybrid lens of surface roughness Ra≤20nm@RMS and visible materials is fabricated. It must push the applications of free-form surface refractive/diffractive hybrid lens in industry towards a new chapter.

随着光电设备向小型化、轻量化发展，具有更强的像差和色差校正能力、可见光材料的自由曲面折/衍混合透镜备受青睐。虽然飞秒激光被证实是此类元件最可行的加工途径，但由于逐点扫描、步距微小、效率很低，口径通常局限于500µm以内，远无法满足毫米量级应用需求。本项目创新性地提出激光复合制备模式（飞秒激光加工表层、微立体打印内部），相对飞秒激光，该模式可以将毫米量级自由曲面折/衍混合透镜的加工时间节省80%以上，是一种高效率、高精度的制备方案。阐述了激光与表层混合材料的作用原理，形成内部、表层和重复层有效分配机制，解决激光加工层厚与表面精度、透镜对准精度之间的矛盾问题。有机结合Z轴扫描曝光和X、Y轴wobulation技术，形成流动飞扫微立体打印，解决内部结构不连续问题。最终实现20mm口径、表面粗糙度Ra≤20nm@RMS、可见光材料的自由曲面折/衍混合光学透镜，推动其进入迈向工业应用的新篇章。

在项目持续的四年时间里，本项目团队不仅超额完成了全部研究计划，还进行了自由曲面微透镜阵列的研制，并将其应用于激光照明系统，该激光照明系统可以有效提升DMD光刻设备的光刻均匀性和集成度。研制的微透镜阵列在吉林省技术公关项目“紫外半导体激光高效、均匀光源模块研制”和长光中天光电科技有限公司横向项目“高均匀性光源模研发”中进行了实际应用和验证。探究了DMD单光子聚合与飞秒双光子聚合相结合的复合加工方法和加工工艺，包括横向对准、纵向对准和数据拆分。利用这种复合加工方法加工了多层衍射光学元件、折\衍混合透镜、双面自由曲面透镜以及微流控集成系统。讨论了光学元件独特性能和特定环境中的应用场景，为3D打印光学元件走向实用化奠定了坚实的理论基础和技术储备。研制了DMD光刻和打印工艺，提出了时空协调变换法、倾斜空间叠加法、微位移错位叠加法等一系列提高DMD刻写分辨率的方法，解决了图形的平滑性问题，配合热熔制作了微透镜阵列。通过静态拼接误差补偿以及旋转拼接转心补偿，在实验室平台和DMD驱动器低配置的情况下，获得了高精度拼接，实现了大面积加工结果。同时通过DMD与旋转偏振片相结合，成功地制作了液晶像素级微偏振阵列器件，为液晶偏振阵列器件的使用奠定了良好的加工基础。通过DMD与CCD原位测量分析相结合，实现了微流控通道内流动细胞的定位、筛选和标识。通过DMD与电化学沉积相结合，制作了各类高性能电极，以测试生物成分。

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