1 华中科技大学武汉光电国家研究中心,湖北 武汉 430074
2 九江中科激光技术研究院,江西 九江 332005
以Q235低碳钢为材料,研究了光束扫描对激光热丝焊的焊缝成形特性、微观组织和力学性能的影响。结果表明:在扫描激光的作用下,焊缝的成形变得更加均匀,飞溅减少,焊缝熔深减小,熔宽增大,截面熔合区底部变得更加平滑;扫描激光的加入降低了熔池的温度梯度,抑制了粗大柱状晶的生长,改变了铁素体晶粒形态,细化了熔合区组织,提高了焊缝韧性及延伸率;扫描激光促进了焊缝成分的均匀化分布,抑制了偏析,降低了熔合区显微硬度。由于激光作用面积增大等因素,光束扫描增强了激光热丝焊接对间隙的桥接能力。
激光技术 激光热丝焊接 光束扫描 微观组织 力学性能 中国激光
2024, 51(12): 1202106
光子学报
2023, 52(12): 1223001
上海交通大学 区域光纤通信网与新型光通信系统国家重点实验室,上海 200240
针对传统固态激光雷达中光束快速扫描控制响应速度和电压控制精度较低的问题,提出了一种基于透镜辅助光束扫描(LABS)技术和现场可编程逻辑门阵列(FPGA)的固态激光雷达测距系统。该系统采用收发一体的结构,系统中的LABS器件由1×16光开关芯片、4×4光纤阵列和透镜组成。根据LABS方案每一级只有一个光开关处于工作状态的特点,通过选择不同的发射器,将光束照亮到透镜的不同位置来实现光束的转向。光束扫描采用FPGA结合外部选通电路进行控制的方式,通过输出电压控制4级马赫-曾德尔干涉仪(MZI)型光开关工作,实现光束的快速切换。实验结果表明,该系统光束转向角度步长为0.35°,最大测距范围可达200 m,9.2 m内的测距误差约为1 cm。
光束扫描 现场可编程逻辑门阵列 激光雷达 光开关 beam steering, field programmable gate array, lida
北京理工大学光电学院复杂环境智能感测技术工信部重点实验室,北京 100081
光束扫描系统在光学显微成像中扮演着重要的角色,针对现有光束扫描中继系统尺寸、像差较大以及装调精度要求高的问题,提出一种双二维微机电系统(MEMS)振镜光束扫描方法。该方法采用两片二维MEMS振镜进行光束远心扫描,其中,一片MEMS振镜替代传统中继系统中的scan lens和tube lens,避免像差的引入,缩减系统尺寸,最终完成了小型化、结构简单和无像差的光束扫描系统设计。基于该方法构建了小型化共焦扫描显微镜,并对台阶样品进行扫描成像,验证了该方法的可行性。该方法为光学显微成像提供了一种新型的光束扫描手段,可为光学显微成像技术在深空探测、现场检测和生物医学等领域的进一步应用提供一种新的技术途径。
双二维微机电系统振镜 光束扫描 无像差 小型化 扫描成像 共焦 光学学报
2023, 43(21): 2111001
长春理工大学光电工程学院,吉林 长春 130022
针对通过微透镜阵列通光孔径的光束在不同条件下的填充问题,利用填充因子来表征微透镜阵列系统光瞳位置处光束的填充率,并分析其对系统探测距离、点扩散函数和光学传递函数的影响。基于近轴光学模型,构建了快速计算微透镜阵列扫描光学系统填充因子的数学模型,并提出一种系统设计方法。利用该方法设计了微透镜阵列扫描光学系统,所设计系统的实验结果与理论计算结果吻合,表明该系统的性能良好。
成像系统 光束扫描 微透镜阵列 填充因子 探测距离 点扩散函数 光学传递函数
1 之江实验室智能芯片与器件研究中心,浙江 杭州 311121
2 浙江大学光电科学与工程学院极端光学技术与仪器全国重点实验室,浙江 杭州 310027
3 上海电力大学电子与信息工程学院,上海 200090
4 浙江大学杭州国际科创中心, 浙江 杭州 311200
Overview: Two-photon lithography (TPL) has been a research hotspot in 3D micro/nano writing technology due to its characteristics of high resolution, low thermal influence, a wide range of processed materials, low environmental requirements, and 3D processing capability. It has shown unique advantages in the fields of life science, material engineering, micro/nano optics, microfluidic, micro machinery, and so on. This paper summarizes the research works done by researchers on different writing methods to improve TPL processing efficiency. Single-beam writing is the main method for TPL, which mainly depends on the speed of the scanning device. Single-beam writing has the advantages of simple system and high-quality beam, and it is easy to combine various effects to improve writing results. It mainly includes scanning modes based on the translation stage, galvo, polygon laser scanner, and acousto-optic deflector (AOD) (Fig. 2). All these modes have advantages and disadvantages. As for the scanning speed comparison, polygon laser scanner and AOD have relatively faster writing rates (faster than m/s). Multi-foci parallel lithography can obviously promote efficiency, elevating the speed by dozens or even hundreds of thousands of times, mainly based on spatial light modulator (SLM), digital micromirror device (DMD), microlens array (MLA), diffractive optical elements (DOE), multi-beam interference, and so on (Figs. 3-15). Multi-foci parallel lithography based on SLM is most widely used owing to its high efficiency and ability to flexible and independent control of each single beam, but the refresh rate is still insufficient. DMD has a higher refreshing rate (32 kHz), but the state-of-the-art beam parallelism realized by DMD is severely limited. More parallel beams are further required for improving the processing efficiency. The 2D pattern exposure method based on SLM or DMD can further improve the TPL efficiency with the superiority of generating flexibly designed pattern (Figs. 16-18). However, the 2D projection exposure technology is still difficult to achieve high writing precision, especially the axial resolution. An available method to improve the axial precision is spatially and temporally focusing an ultrafast laser to implement a strong intensity gradient at the spatial focal plane that restricts polymerization within a thin layer. The 3D projection method will be the most efficient writing method in the future, especially in 3D device processing (Figs. 19-20). Researchers used this technique to make hollow tubular and conical helices structures, increasing the processing speed by 600 times. However, the research results show that the current 3D projection can only process simple 3D structures. Further researches on 3D exposure processing of complex structures are expected, which will effectively expand its application in various fields. Authors believe that with the effort of researchers on efficiency improvement gradually, TPL can further highlight its advantages to promote the development of life science, materials engineering, micro-nano optics, and many other fields.
飞秒激光直写 双光子光刻 单光束扫描 多焦点并行 面曝光 体曝光 femtosecond laser direct writing two-photon lithography single-beam scanning multi-focus parallelism pattern projection 3D projection exposure
强激光与粒子束
2022, 34(12): 121006
1 中国科学院光束控制重点实验室, 四川 成都 610209
2 中国科学院光电技术研究所, 四川 成都 610209
3 中国科学院大学, 北京 100049
Risley棱镜通过共轴独立旋转的方式对扫描视场范围内的光束实现任意指向, 因结构紧凑、指向精度高、功耗低、响应迅速等特点而广泛应用于激光雷达、红外对抗、光学侦察等领域。螺线扫描方式可以满足视场可控、覆盖率可控、周期可控、速度稳定等指标要求。但由于扫描轨迹设置以及受电机最大速度、加速度等因素的限制, 在最大张角和最小张角附近, 棱镜的速度依然存在一定的突变, 造成过大的伺服控制误差。针对此问题, 采用滤波与插值结合的方法优化扫描轨迹。实验表明:优化后棱镜的旋转速度趋于平滑, 最大伺服控制误差从约1 200″, 减小至约300″, 减小至原来的1/4。该方法降低了因棱镜速度突变而造成的随动伺服控制误差, 优化了棱镜的旋转过程, 降低了棱镜因速度突变而产生的抖动, 有利于提升系统的扫描精度。
Risley棱镜 光束扫描 等速螺旋线 速度突变 轨迹优化 risley prisms beam scanning archimedes spiral speed-mutation trajectory optimization