西南石油大学计算机科学学院,四川 成都 610500
为了解决传统的卷积神经网络着色方法带来语境混淆、边缘模糊和细节信息丢失度高等问题,设计了一个改进的基于密集神经网络的区域全卷积神经网络(R-FCN)和基于局部特征网络的双分支神经网络模型。通过DenseNet可准确提取信息,产生易于训练和高参数效率的密集模型,采用全连接的条件随机场优化分割结果来提高分割的准确率。验证阶段采用联合双边滤波对图像进行处理,弥补图像边缘模糊的缺点。实验结果表明:与现有着色方法相比,该方法有效地解决了细节丢失度高、颜色不饱和及边缘模糊的问题,能够产生更真实、更合理的彩色图像,取得了优异的效果。
激光与光电子学进展
2020, 57(12): 121006
Author Affiliations
Abstract
1 Key Laboratory of Chemical Lasers, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
Sodium-ethane excimer pairs are studied and proved to be a great choice of excimer pumped sodium laser (XPNaL) gain media. The lifetime of the sodium D2 line is studied in a sodium-ethane excimer system excited by a 553 nm laser, and the observed phenomenon of lifetime lengthening is discussed. Amplified spontaneous emission (ASE) of the sodium D2 line is successfully obtained, and its time-resolved and spectroscopic characteristics are studied experimentally. According to the intensity of the ASE signal under different sodium vapor atom densities, the sodium D2 line gain feature of sodium-ethane excimer pairs excited by the 553 nm laser is concluded.
140.1340 Atomic gas lasers 140.2180 Excimer lasers Chinese Optics Letters
2017, 15(11): 111401
1 中国科学院大连化学物理研究所化学激光重点实验室, 辽宁 大连 116023
2 中国科学院大学, 北京 100049
准分子宽带抽运钠金属激光器具有实现钠信标光源的潜质, 该激光器在运转过程中需要借助准分子将钠原子由基态转换为激发态, 因此有必要对由准分子解离产生的钠原子激发态荧光寿命开展实验研究。采用不同波长的蓝翼抽运光对不同温度的钠乙烷准分子体系进行激发, 分别测量钠D1线和钠D2线的荧光寿命。结果表明, 32P3/2与32P1/2能级的荧光寿命明显长于其自然寿命, 且激发波长越长, 荧光寿命延长得越明显。辐射捕获效应是导致荧光寿命延长的另一个因素。随着泵浦单光子能量下降, 钠乙烷准分子被激发到A2Π3/2态的概率变大, 能够长时间产生激发态钠原子, 这也会使荧光寿命延长。与钠D1线相比, 钠乙烷准分子体系钠D2线的放大自发辐射信号的可放大性更好。更好的可放大性以及较长的荧光寿命使得钠D2线激光更易于实现。
激光器 受激准分子激光器 碱金属蒸气 荧光寿命 辐射俘获 放大自发辐射
中国科学院 大连化学物理研究所, 化学激光重点实验室, 辽宁 大连 116023
首次实现了脉冲光解碘激光作为基频光的氢气振动受激拉曼变频,对碘激光的波长转换有着重要意义。在碘激光单脉冲能量100~130 mJ(脉宽100 ns)的条件下, 采用双次聚焦技术降低了高压氢气的振动受激拉曼变频的阈值,获得了波长为2900 nm中红外激光,光子转化效率最高达到8.7%。实验发现当拉曼介质氢气气压大于1 MPa后,一级斯托克斯光的拉曼转化效率不再随气压变化,并对这一现象进行了理论分析和归属。
振动受激拉曼变频 碘激光 量子转化效率 拉曼增益 vibrational stimulated Raman scattering iodine laser photon conversion efficiency Raman gain 强激光与粒子束
2017, 29(5): 051001
Author Affiliations
Abstract
1 School of Science, Changchun University of Science and Technology, Changchun 130022, China
2 Key Laboratory of Chemical Lasers, Dalian Institute of Chemical Physics, Chinese Academy of Science, Dalian 116023, China
Pulsed collimated blue light at 420.3 nm is generated in hot Rb vapor by upconverting the 778.10 nm pumping beam through four wave mixing process. The energy conversion efficiency exceeds 1% when a 45 cm-long, 170°C heated Rb cell is used. The influence of cell temperature, wavelength, and energy of a pumping laser are fully examined. The efficiency of the photon conversion is found to be more sensitive to the blue detuning of the pump light and less sensitive to the red detuning of the pump light. This phenomenon can be explained by stimulated hyper-Raman scattering involved in the four-wave mixing process.
190.4380 Nonlinear optics, four-wave mixing 190.4180 Multiphoton processes 190.7220 Upconversion 300.6210 Spectroscopy, atomic Chinese Optics Letters
2015, 13(12): 121903
