光学畸变是影响光学设备测角精度的一项重要因素，针对靶场红外&可见光炸点经纬仪存在光学畸变较大影响测试精度的问题，分别采用了基于多项式拟合法、多面函数拟合法、Kriging插值法这3种光学畸变校正方法验证校正效果。经验证：红外采用各阶多项式拟合法的畸变校正效果差异不明显，修正后均能优于8"，而可见光成像设备三种模型差异较大，需五阶才可将误差降到10"以下；采用多面函数拟合法时，平滑因子对结果精度影响较大，核函数影响不明显，应将重点放在平滑因子的选取上；优化参数向量对Kriging预测模型的影响较大，尤其当变异函数为高斯函数时更为敏感，畸变向量的异向性特征不突出的情况下，Kriging插值的优势不显著。

Random lasers are a type of lasers that lack typical resonator structures, offering benefits such as easy integration, low cost, and low spatial coherence. These features make them popular for speckle-free imaging and random number generation. However, due to their high threshold and phase instability, the production of picosecond random lasers has still been a challenge. In this work, we have developed three dyes incorporating polymer optical fibers doped with various scattering nanoparticles to produce short-pulsed random fiber lasers. Notably, stable picosecond random laser emission lasting 600 ps is observed at a low pump energy of 50 µJ, indicating the gain-switching mechanism. Population inversion and gain undergo an abrupt surge as the intensity of the continuously pumped light nears the threshold level. When the intensity of the continuously pumped light reaches a specific value, the number of inversion populations in the “scattering cavity” surpasses the threshold rapidly. Simulation results based on a model that considers power-dependent gain saturation confirmed the above phenomenon. This research helps expand the understanding of the dynamics behind random medium-stimulated emission in random lasers and opens up possibilities for mode locking in these systems.

Fluorescence detection is widely used in biology and medicine, while the realization of on-chip fluorescence detection is vital for the portable and point-of-care test (POCT) application. In this Letter, we propose an efficient fluorescence excitation and collection system using an integrated GaN chip consisting of a slot waveguide and a one-dimensional photonic crystal (1D PC) waveguide. The slot waveguide is used to confine the excitation light for intense light–sample interaction, and the one-trip collection efficiency at the end of slot waveguide is up to 14.65%. More interestingly, due to the introduction of the 1D PC waveguide, the fluorescence signal is directly filtered out, and the excitation light is reflected to the slot waveguide for multiple excitations. Its transmittances for the designed exciting wavelength of 520 nm and the fluorescent wavelength of 612 nm are 0.2% and 85.4%, respectively. Finally, based on numerical analysis, the total fluorescence collection efficiency in our system amounts to 15.93%. It is the first time, to our knowledge, that the concept of an all-in-one-chip fluorescence detection system has been proposed, which paves the way for on-chip fluorescence excitation and collection, and may find potential applications of miniaturized and portable devices for biomedical fluorescence detection.