High power all-solid-state quasi-continuous-wave tunable Ti:sapphire laser system

This paper reports a high power, all-solid-state, quasi-continuous-wave tunable Ti:sapphire laser system pumped by laser diode (LD) pumped frequency-doubled Nd:YAG laser. The maximum tuned output power of 4.2 W (797 nm) and tuned average power of 3.7 W were achieved when fixing the Ti:sapphire broadband output power at 5.0 W and applying 750-850 nm broadband coated mirror.     

All-solid-state quasi-continuous-wave high power dispersion cavity tunable Ti:sapphire laser

An all-solid-state quasi-continuous-wave dispersion cavity tunable Ti:sapphire laser pumped by a laser diode pumped frequency-doubled Nd:YAG laser is reported. Using a dense flint glass prism as the dispersion element, a tuning range from 730 to 880 nm with the linewidth of 3 nm and the pulse width of 17.2 ns was obtained. The maximum output, power of this laser system was 5.6 W at 786.3 nm corresponding to an optical-to-optical conversion efficiency of 25.5% under the pump power of 22 W.     

基于轮廓特征的水下混凝土结构表面裂缝检测算法

针对水下混凝土结构表面裂缝难以准确检测的问题,提出了一种基于轮廓特征的水下混凝土结构表面裂缝检测算法;在对采集到的水下混凝土结构表面图像进行预处理和边缘检测后,首先通过计算图像中边缘的长度和曲率来进行初步判别,区分杂点和部分非裂缝;然后根据裂缝轮廓相互匹配的特征,利用模板搜索来检测出真实裂缝;最后连接裂缝边缘断开部分,优化裂缝检测结果;实验结果表明,与其它算法相比,该算法检测出裂缝的准确率与完整率至少提高了3.54%。     

An all-solid-state high power quasi-continuous-wave tunable dual-wavelength Ti：sapphire laser system using birefringence filter

This paper describes a tunable dual-wavelength Ti:sapphire laser system with quasi-continuous-wave and high-power outputs. In the design of the laser, it adopts a frequency-doubled Nd:YAG laser as the pumping source, and the birefringence filter as the tuning element. Tunable dual-wavelength outputs with one wavelength range from 700~nm to 756.5~nm, another from 830~nm to 900mn have been demonstrated. With a pump power of 23~W at 532~nm, a repetition rate of 7~kHz and a pulse width of 47.6~ns, an output power of 5.1~W at 744.8~nm and 860.9~nm with a pulse width of 13.2~ns and a line width of 3~nm has been obtained, it indicates an optical-to-optical conversion efficiency of 22.2{\%}.     

水面原位多角度偏振反射率光谱特性分析与离水辐射提取

偏振被定义为光的振动方向对于传播方向的不对称性。偏振信息是遥感数据空间、辐射、光谱信息之外的又一重要信息。对于光学遥感数据来说,偏振信息是对光谱信息的又一种补充。偏振遥感在水体应用中具有巨大潜力,其中一个非常重要的应用就是校正天空光水面镜面反射,从而得到包含水中物质信息的离水辐射信号。太阳入射光会在水面发生反射或者与水体中颗粒物发生散射作用,使得离开水面被遥感器接收的信号具有很强的偏振特性。目前开展的水体偏振遥感实验要么面向室外自然光条件下的清洁海洋水体,要么面向室内人造光源条件下的模拟水体,鲜有面向自然光条件下的浑浊内陆水体。本文通过组合地物光谱仪和汤姆森偏振棱镜,实现了自然光条件下内陆水体水面原位偏振反射率光谱测量。利用获取的典型内陆水体水面多角度偏振反射率光谱,定量分析了多角度观测条件下水体偏振光谱特性,以及从水面偏振信号中消除天空光水面镜面反射从而得到离水辐射信号的效果。当观测方位角为135°、观测天顶角为53°时,采用偏振测量剥离水表天空反射光的剥离效率较好,推荐采用该观测几何进行水面偏振光谱观测。相比于传统的非偏振水面光谱测量方法,水面偏振光谱测量方法受气象条件变化影响小,能够更精确的提取离水辐射。