1 中北大学信息与通信工程学院, 山西 太原 030051
2 中北大学仪器与电子学院, 山西 太原 030051
可见光高速摄影是研究弹丸侵彻过程的重要方式, 然而弹丸侵彻过程中发出的强烈闪光会导致高速摄影丢失诸如着靶、 侵入等时刻的关键画面。 因此, 分析侵彻光谱发生机理、 选取合适的侵彻过程光学观察窗口尤为重要。 针对400 mm直径高强度钢卵形弹以804 m·s-1侵彻20 cm厚度45#钢靶的实验, 设计了光谱瞄准采集设备。 利用多模光纤耦合物镜在距离靶板25 m处采集了侵彻全过程积分光谱, 采集区覆盖靶板直径431 mm。 对侵彻靶板破片中可能存留的弹头熔融物质以及弹托其他样品进行LIBS(laser induced breakdown spectroscopy)分析, 并与侵彻积分光谱成分对比分析。 研究表明, 侵彻光谱与高速碰撞闪光光谱发生机理相同, 均包含连续光谱与线光谱。 615～700 nm区间内的平稳积分连续光谱由两部分组成: (a)弹靶少量金属元素和O Ⅰ、 O Ⅱ发射光谱的展宽积分; (b)少量热辐射光谱积分。 侵彻热辐射主要源于剪切应变做功和摩擦做功, 然而侵彻光谱中的热辐射强度明显低于高速碰撞光谱, 这是弹丸在剪切冲塞、 侵彻后大部分动能得以保留造成的; 侵彻过程可见光光谱具有明显原子发射谱线, 主要来自于金属原子及其一级电离的发射光谱。 干扰最强的可见光成分来源于588.88～589.53和766.41～766.43 nm的FeⅠ等离子体线光谱, 且由于斯塔克展宽效应, 线光谱呈洛伦兹线型, 其FWHM(full width at half maximum)可达27 nm。 因此, 在野外环境侵彻实验中, 当Fe为弹靶主要成分时, 380～450 nm为可见光高速摄影的最佳观察窗口, 可以避免侵彻发光干扰, 实现对侵彻全过程拍摄。 考虑到大气对该波段的散射影响, 应保证高速摄影设备的光通量。
侵彻 发射光谱 光学观察窗口 Penetration Emission spectrum Optical observing window LIBS LIBS
Author Affiliations
Abstract
1 MOE Key Laboratory of Weak Light Nonlinear Photonics and School of Physics, Nankai University, Tianjin 300071, China
2 National Laboratory of Solid State Microstructures and School of Physics, Nanjing University, Nanjing 210093, China
3 Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
Transporting information is one of the important functions of photons and is also the essential duty of information science. Here, we realize multiple imaging by detecting photons with changeable wavelengths based on time-resolved correlation measurements. In our system, information from multiple objects can be transported. During this process, the wavelength of the photons illuminating the objects is different from the wavelength of the photons detected by the detectors. More importantly, the wavelength of the photons that are utilized to record images can also be changed to match the sensitive range of the used detectors. In our experiment, images of the objects are reconstructed clearly by detecting the photons at wavelengths of 650, 810, and 1064 nm, respectively. These properties should have potential applications in information science.
110.4190 Multiple imaging 110.6915 Time imaging Chinese Optics Letters
2017, 15(8): 081101
