Light-field fluorescence microscopy (LFM) is a powerful elegant compact method for long-term high-speed imaging of complex biological systems, such as neuron activities and rapid movements of organelles. LFM experiments typically generate terabytes of image data and require a substantial amount of storage space. Some lossy compression algorithms have been proposed recently with good compression performance. However, since the specimen usually only tolerates low-power density illumination for long-term imaging with low phototoxicity, the image signal-to-noise ratio (SNR) is relatively low, which will cause the loss of some efficient position or intensity information using such lossy compression algorithms. Here, we propose a phase-space continuity-enhanced bzip2 (PC-bzip2) lossless compression method for LFM data as a high-efficiency and open-source tool that combines graphics processing unit-based fast entropy judgment and multicore-CPU-based high-speed lossless compression. Our proposed method achieves almost 10% compression ratio improvement while keeping the capability of high-speed compression, compared with the original bzip2. We evaluated our method on fluorescence beads data and fluorescence staining cells data with different SNRs. Moreover, by introducing temporal continuity, our method shows the superior compression ratio on time series data of zebrafish blood vessels.

We demonstrate the generation, spectral broadening and post-compression of second harmonic pulses using a thin beta barium borate (BBO) crystal on a fused-silica substrate as the nonlinear interaction medium. By combining second harmonic generation in the BBO crystal with self-phase modulation in the fused-silica substrate, we efficiently generate millijoule-level broadband violet pulses from a single optical component. The second harmonic spectrum covers a range from long wave ultraviolet (down to 310 nm) to visible (up to 550 nm) with a bandwidth of 65 nm. Subsequently, we compress the second harmonic beam to a duration of 4.8 fs with a pulse energy of 0.64 mJ (5 fs with a pulse energy of 1.05 mJ) using chirped mirrors. The all-solid free-space apparatus is compact, robust and pulse energy scalable, making it highly advantageous for generating intense second harmonic pulses from near-infrared femtosecond lasers in the sub-5 fs regime.

光学频率梳（简称光频梳）作为一种优秀的多波长光源在通信领域具有巨大的应用潜力。通过将光频梳光源与波分复用技术（WDM）、空分复用技术结合（SDM），通信系统可以具有百Tbit/s量级的传输速率，在5G/6G通信、物联网、自动驾驶等方面具有重要的应用价值。目前实现光频梳的方法主要有以下四种，分别为基于锁模激光器产生飞秒光频梳、基于光学微腔产生光频梳、基于电光调制器产生光频梳以及基于行波四波混频产生光频梳。它们各具特点，但均很难同时实现宽光谱、高信噪比、高平坦度、高的单梳齿功率以及梳齿频率间隔大范围可调，这在一定程度上影响了光频梳在光通信领域的应用。本文提出基于受激布里渊激光腔产生种子梳，采用腔外负色散光纤进行脉冲压缩，进一步利用色散调控的高非线性氟碲酸盐光纤进行扩谱，从而实现光频梳产生。数值计算结果表明，通过该系统，我们可以得到重复频率大范围可调、光谱覆盖整个O-U波段且在O-U波段梳齿强度标准差小于5 dB的平坦光频梳，证明了通过基于布里渊激光腔与色散调控高非线性氟碲酸盐光纤的光学系统产生可用于光通信的平坦光频梳的可行性。

不同于普通图像压缩，多光谱图像压缩除了需要去除空间冗余同时还需要去除光谱间冗余，近年来研究表明端到端的卷积神经网络模型在图像压缩方面具有很好的性能，但对于多光谱图像压缩其编解码器并不能有效解决同时高效提取到多光谱图像空间和光谱间特征的问题，同时也会忽略图像局部特征信息。针对以上问题，本文提出了一种融合多尺度特征卷积神经网络的多光谱图像压缩方法。所提出网络在压缩模型的编解码器中嵌入了可以提取出不同尺度下空间和光谱间特征信息的多尺度特征提取模块，以及可以用来捕捉局部空间信息和光谱信息的空间光谱间非对称卷积模块。实验表明，与传统算法如JPEG2000和3D-SPIHT以及深度学习方法相比，在Landsat-8的7波段和Sentinel-2的8波段数据集上所提出模型的峰值信噪比（PSNR）指标高于传统算法1-2dB。在平均光谱角度（MSA）指标的衡量下，所提出的模型在Landsat-8数据集上优于传统算法约8×10^-3 rad，在Sentinel-2数据集上优于传统算法约2×10^-3 rad。满足了多光谱图像压缩对空间和光谱间特征提取以及局部特征提取的要求。

初始磁场电源系统用于激励千特斯拉级内爆磁压缩装置的初级线圈产生初始磁场，是内爆磁压缩装置的关键设备。在分析千特斯拉级内爆磁压缩装置初始磁场电源需求和技术难点的基础上，系统设计了核心部件选择方案和主脉冲电路及控制系统结构，研制成功一套输出电压1～40 kV可调、主放电电流脉冲上升沿约60 μs、总峰值电流达3.2 MA的初始磁场电源系统，已应用于千特斯拉级内爆磁压缩装置动态试验。

The large-aperture pulse compression grating (PCG) is a critical component in generating an ultra-high-intensity, ultra-short-pulse laser; however, the size of the PCG manufactured by transmission holographic exposure is limited to large-scale high-quality materials. The reflective method is a potential way for solving the size limitation, but there is still no successful precedent due to the lack of scientific specifications and advanced processing technology of exposure mirrors. In this paper, an analytical model is developed to clarify the specifications of components, and advanced processing technology is adopted to control the spatial frequency errors. Hereafter, we have successfully fabricated a multilayer dielectric grating of 200 mm × 150 mm by using an off-axis reflective exposure system with Φ300 mm. This demonstration proves that PCGs can be manufactured by using the reflection holographic exposure method and shows the potential for manufacturing the meter-level gratings used in 100 petawatt class high-power lasers.