深圳大学物理与光电工程学院，广东 深圳 518060
在现有单次测量极高速成像方法中，直接成像方法的分辨率高但探测系统复杂，而计算成像方法探测系统简单但易损失空间分辨率。因此，提出一种基于偏振编码的极高速成像技术。所提成像系统利用半波片阵列和偏振片阵列对入射飞秒脉冲、出射飞秒脉冲和动态事件进行偏振编码，并通过线性方程组解码极高速动态的时序图像。通过构建光学模型并仿真，精确还原了多幅图像，验证了所提方案的可行性，理论摄影频率在1013 frame/s以上，本征空间分辨率可达114 lp/mm。所提成像系统结合了直接成像和计算成像系统的优势：线性方程组精确求解，不会导致光学系统分辨率损失；时序图像叠加使探测结构只需分光不需要对不同时刻的图像进行空间上的分离，简化了探测器的结构。该极高速成像系统的时间分辨率仅受脉冲宽度限制，可以实现飞秒级动态事件的探测，并且随着脉冲宽度的缩短，其时间分辨率可以得到进一步提升。
成像系统 偏振编码 极高速成像 线性方程组 时序图像 飞秒脉冲 光学学报
2022, 42(20): 2011002
Author Affiliations
Abstract
1 Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, Shenzhen Key Laboratory of Micro-Nano Photonic Information Technology, College of Physics and Optoelectronic Engineering, , Shenzhen 518060, China
2 College of Electronics and Information Engineering, , Shenzhen 518060, China
Applying an ultrafast vortex laser as the pump, optical parametric amplification can be used for spiral phase-contrast imaging with high gain, wide spatial bandwidth, and high imaging contrast. Our experiments show that this design has realized the 1064 nm spiral phase-contrast idler imaging of biological tissues (frog egg cells and onion epidermis) with a spatial resolution at several microns level and a superior imaging contrast to both the traditional bright- or dark-field imaging under a weak illumination of . This work provides a powerful way for biological tissue imaging in the second near-infrared region.
optical parametric amplification ultrafast vortex laser pulse spatial resolution phase-contrast imaging Chinese Optics Letters
2022, 20(10): 100003
深圳大学电子科学与技术学院深圳市微纳光子信息技术重点实验室, 广东 深圳 518060
提出了一种基于波长编码的超短太赫兹(THz)脉冲单次探测方法。该方法将新型正交平衡电光取样技术和波长编码技术结合起来, 同时拥有这两种方法的优点：能对超快太赫兹脉冲实现高调制度和高信噪比的单次实时测量。为了实现单次测量, 采用线性啁啾激光脉冲作为探测光, 将太赫兹电场对探测脉冲的时域调制映射到频域, 并用光谱仪对频域信息进行单次采集。在电光取样技术方面, 采用正交平衡探测取代传统波长编码单次测量, 通过设置两臂静态偏置相位, 使它们大小相等、符号相反, 实现对称推挽式调制, 从而有效提高近0°偏置点附近的探测线性度和调制深度, 并有效抑制动态噪声。
测量 超快光学 太赫兹 电光测量 动态噪声 啁啾脉冲
Author Affiliations
Abstract
State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800
Micro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the size of the focal spot was improved from 2.7 times diffraction limitation (DL) to 1.6 DL. The spot size focused by an f/4 off-axis parabola (OAP) in the target chamber was measured to be 5.8 micron (full-width at half-maximum (FWHM)), and a peak intensity of 2.6*10^(20) W/cm2 was obtained at the output power of 120 TW. Peak intensity exceeding 10^(21) W/cm2 or even 10^(22) W/cm2 can be expected with smaller f-number focusing configuration and wavefront correction.
钛宝石激光器 超快激光 光束整形 微光学 140.3590 Lasers, titanium 140.7090 Ultrafast lasers 140.3300 Laser beam shaping 350.3950 Micro-optics Chinese Optics Letters
2006, 4(10): 583
中山大学超快速激光光谱学国家重点实验室和中山大学物理系,广州,510275
提出一种求解正常声光相互作用拉曼-内斯(Raman-Nath)方程的矩阵级数解法,该解法直观方便且具有普遍性.计算结果表明,对Q=4.1π,Bragg衍射的效率只有97.5%;对非对称入射,以往的Raman-Nath近似解误差较大;指出提高Bragg衍射效率的有效途径在于提高声光频率比并给出计算声光器件最优长度的计算公式.
声光效应 衍射效率 拉曼-内斯方程 矩阵级数解法
