Effects of parameters in femtosecond laser micromachining on ablation of silicon

A series of ablation experiments on silicon surface by femtosecond laser system of 775 nm and 150 fs duration pulses were carried out.The morphological characteristics and the associated effect in the ablation were tested by atomic force microscope (AFM),scanning electron microscope (SEM),focused ion beam (FIB),and the optic microscope.The single pulse threshold can be obtained directly.For the multiple pulses,the ablation threshold varies with the number of pulses applied to the surface due to the incubation effect.By analyzing the experimental data,the thresholds of laser fluences under various laser pulse numbers were obtained,and the relationships between ablation area and laser energy and laser pulse number were concluded.Meanwhile,the periodic ripple structure on silicon surface was found.Under the condition of certain laser power,the number of laser pulse can influence the formation of ripples.     

一种C波段宽带二维扫描固态有源相控阵天线设计与实现

基于机载合成孔径雷达系统的具体应用,给出一种C波段宽带二维扫描固态有源相控阵天线的设计与实现方案. 该天线辐射阵面采用双层矩形微带贴片,由宽带偶极子激励. 通过增加金属隔墙和金属接地螺钉的加载来降低天线单元间互耦,实现了宽带二维相控扫描. 测试结果表明,辐射单元阵中驻波带宽(VSWR<1.6) 达到800 MHz(相对带宽约15%).     

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.     

New method of improving parts accuracy by adding heat balance support in selective laser sintering

In order to improve parts accuracy, a method of adding heat balance support （HBS） was proposed, and the detailed algorithm for generating HBS was developed. A number of experiments and a comparison between similar softwares, showed that the algorithm is efficient and feasible. Moreover, different features of riBS were studied for different kinds of materials, such as PS and nylon. The research findings indicate that automatically adding HBS can significantly improve the accuracy of the parts, and that the algorithm for generating HBS is efficient and precise.     

基于CCD的回波信号图预处理软件设计与实现

随着光散射法测量PM2.5颗粒物浓度技术的发展,该技术成为测量大气PM2.5浓度的主要手段之一。散射激光雷达接收到的信号为回波信号图,通过建立回波信号图灰度值与PM2.5浓度的关系模型,实现对颗粒物浓度的测量。该技术需要对回波信号图进行预处理并提取散射信号,为了实现一种高性能、可实时测量的回波信号图预处理系统,设计一款基于Delphi7语言的实时图像处理软件。该软件通过对内存分配双缓冲区域、设置采集频率以及图像裁剪等方法,提高图片的采集与处理速率。实验结果表明,该软件操作简单、运行稳定且可扩展性较强。     

激光脉冲测量技术解析

介绍了超短激光脉冲技术的基本原理和产生过程,分析了超短脉冲的压缩技术以及近年来比较常用的几种测量技术直接测量法和间接测量法,重点研究了基于二次谐波的频率分辨光开关法（FROG）的脉冲测量法,以及这种测量方法的优缺点,并与自参考光谱相位相干电场重建法（缩写为SPIDER）进行了比较,分析了两种测量法各自的优缺点.     

增益开关激光脉冲时基抖动的测量方法

分析了增益开关激光脉冲抖动产生的原因及其分类.系统介绍了取样示波器法、相位噪声法、谐波分析法和互相关法等测量脉冲抖动的方法,并总结了它们的优缺点及适用范围.     

激光微细加工在电子工业中的应用

从电子工业的角度出发,介绍激光微细加工的应用,包括:激光打标、细导线剥离、微透镜列阵、激光光刻、激光表面改性等,并综述了它们的研究现状和未来发展趋势。     

量热和热分析在生物大分子体系研究中的应用

讨论了差示扫描量热法(DSC)和等温滴定量热法(ITC)用于生物大分子体系研究所得到的一些实验结果。内容包括了沙冬青抗冻蛋白热滞活性的测定、胶束解体浓度的确定二个方面内容。所有研究结果都给出了有关生物大分子变化的明确信息和确切结论。     

Parallel Spectral-Domain Optical Coherence Tomography for Non-Scattering Object Imaging

The parallel spectral-domain optical coherence tomography(PSDOCT) is described for high-speed optical coherence tomography(OCT) without lateral scanning. In this setup, the self-elimination of auto-correlation(AC) interference algorithm was used for eradicating the AC interference and ghost images. However, when performed in free space OCT, this algorithm still generated a weak DC component. The algorithm was improved by adding the background intensity part to compensate for the mutual interference between object and reference arms. The results demonstrate that the DC component can be eradicated. Compared with conventional OCT and complex Fourier-domain optical coherence tomography, the advantages of PSDOCT with the improved algorithm in free space are that it has no moving parts to generate consecutive phase shift, the structure of the object can be reconstructed immediately and automatically, and the speed is approximately 16 times faster than those of the other two in the same case.