基于超快光克尔门的高时间分辨三维显微成像技术

Developing high time resolved microscopic imaging technique has very important significance for observation of the ultrafast processes occurred on the micro scale such as the ultrafast process of the interaction between light and matter. Most traditional high time resolved microscopic imaging techniques are mainly suitable for two-dimensional imaging, while the femtosecond digital holography with the ability of three-dimensional (3D) imaging has a narrow longitudinal imaging dynamic range due to its short coherent length. Therefore, in this project we propose a high time resolved microscopic imaging technique based on the optical Kerr gated supercontinuum white light. This technique can provide the high temporal-and-spatial resolution and the large longitudinal imaging dynamic range for the 3D imaging. The study includes:.(1) Investigating the competition mechanism between the optical Kerr effect and the coherent effect, eliminating the influence of coherence effect on optical Kerr gate, and realizing the high-contrast optical Kerr gate to improve the temporal resolution and signal-to-noise ratio of the imaging system..(2) Investigating the generation of the stable and uniform supercontinuum white light, and studying the control technique of the chirp character of the supercontinuum white light in the transmission process to improve the spatial resolution of the imaging system..(3) Investigating the control technique of the pulse duration of the supercontinuum white light to realize the continuously tunable longitudinal imaging dynamic range.. The final goal is to exhibit a high time resolved 3D microscopic imaging system using optical Kerr gate characterized by the temporal resolution of TR<0.5 ps, the longitudinal and transverse spatial resolutions of LSR<20 μm and TSR<5 μm, respectively.

发展高时间分辨的显微成像技术，对观测微区内光与物质相互作用等超快过程具有重要的意义。目前通用的高时间分辨显微成像技术主要适于二维成像，而可用于三维成像的飞秒数字全息等技术由于飞秒脉冲激光的相干长度短，致使这种技术的纵向成像动态范围较小。为此，本项目提出基于超快光克尔门选通超连续白光的三维显微成像技术，该技术具有时间和空间分辨率高，以及纵向成像动态范围大等优点。主要研究内容包括：通过研究超快光克尔门中相干效应与光克尔效应的竞争机制及相干效应的抑制技术，实现高对比度的光克尔门，从而提高成像的时间分辨率和信噪比；通过研究稳定均匀的超连续白光产生及其传输过程中的啁啾特性的调控技术，提高成像的纵向空间分辨率；通过调控超连续白光的持续时间，实现成像纵向动态范围连续可调；展示基于超快光克尔门的高时间分辨三维显微成像系统，时间分辨率优于500fs，纵向和横向分辨率分别优于20μm和5μm。

本项目重点解决高时间分辨光克尔门选通显微成像技术中关键技术问题。项目组研究了基于碲酸盐等非线性光学玻璃的超快光克尔门特性及其在成像领域的应用；首次发现并解释了泵浦光空间强度分布不均匀性造成探测光强度分布出现不同花样分布的现象；提出了使用光谱仪与彩色CCD联合检测光克尔门谱中的物体三维形貌信息新方法，实现了100飞秒，20微米的高时空分辨率的光克尔门选通超连续谱的物体三维形貌瞬态成像；提出了一种飞秒外差光克尔门选通成像新方法，有效地增加光克尔门选通成像的图像边界清晰度，并显著提升了成像系统的空间分辨率，实现了小于5微米的空间分辨率；首次提出使用非线性光学玻璃的光克尔门获得信号强度大，对比度高的弹道光子选通图像的技术途径，研究了散射体不同特性对该技术成像结果的影响；采用蒙特卡洛算法进行数值仿真研究了散射介质参数对超短脉冲在散射介质传播过程中时间和空间分布、以及各散射阶次光子强度比例分布的影响。. 本项目共发表的标注本项目资助的SCI收录论文16篇，EI收录论文1篇，获得授权发明专利1项（已收到授权批复通知），参加国内、国际会议4次，其中做特邀报告1次，口头报告2次。项目负责人以第四完成人身份获2014年度陕西高等学校科学技术奖一等奖1项、2015年度陕西省自然科学一等奖1项（已公示，待批）。本项目具有重要的理论研究意义和广泛的应用前景。