研制了一款模块化便携式的激光诱导荧光的检测仪。本检测仪以光纤耦合的稳谱405 nm LD激光器作为激发光源, 以改进的共聚焦光学结构的荧光探头作为荧光的收集模块, 微型光栅光谱仪作为荧光光谱分析模块。该检测仪采用模块化结构, 具有体积小、成本低、灵敏度高 、易操作等特点。 以荧光素钠为测试样品, 对仪器进行了评估。水的拉曼S/N值为935.67, 检测仪的最低检出限为1.9×10-11 g/L; 溶液浓度在10-10到10-12 g/L的范围内, 荧光强度的线性相关系数达到0.999 8, 线性范围超过3个数量级; 重复性测试中, 荧光峰值强度的相对标准偏差为RSD=3.36%, 荧光波长相对标准偏差RSD=0.14%。结果表明该检测仪具有灵敏度高、重复性好、线性范围宽等特点, 满足现场物品的实时快速检测需求。

针对不同环境光亮度下手机拍摄印品后提取秘密信息困难的问题, 提出一种基于奇异值信息熵不变特性的抗打印拍摄信息隐藏方法。将彩色载体图像转换到YCbCr颜色空间,选择Contourlet域低频系数进行奇异值分解, 利用奇异值信息熵的不变特性, 将全息加密的彩色QR码嵌入到彩色载体图像的奇异值中。实验结果表明算法不可见性好, 不仅对打印拍摄具有很好的鲁棒性, 而且对压缩滤波攻击及几何攻击后再次打印拍摄二次攻击仍然具有很好的抵抗性。以彩色QR码作为防伪信息, 可以携带丰富的版权信息, 使用手机即可识别, 方便快捷, 在商品包装防伪方面有着很好的实际应用价值。

采用连续高功率半导体激光器在45#钢表面熔覆制备了Ni-B型石英纤维复合涂层, 通过光学显微镜(OM)、扫描电镜(SEM)及能谱仪(EDS)对涂层显微组织、成分进行了研究。结果表明, 涂层与基体结合良好, 呈冶金结合; 涂层内中间偏上位置有少量黑色泡状物, 直径为10～20 mm, V槽底部存在由B型石英纤维溶解而形成的凹槽, 且与周围Ni基及基体产生原子分子间扩散; 硬度测试表明, 涂层硬度呈阶梯状分布, 最高达445 HV0.3, 为基体的3.25倍。

采用高功率半导体激光器在45#钢圆棒表面制备了Ni25、Co2和316L多层熔覆层, 用扫描电镜(SEM)、X射线衍射仪(XRD)对熔覆层的微观组织及物相进行表征, 并测试涂层试样的硬度与耐磨性能。结果表明, 熔覆层组织均匀、致密, 晶粒细小, 与基体成冶金结合; 激光多层熔覆时, 熔覆层经多层重叠扫描, 重复融化凝固造成层与层结合区存在一明显白亮带, 层内组织在该处存在明显分层现象; Ni25合金熔覆层主要物相有γ-Ni固溶体、BNi3、B2Fe3Ni3、C-Fe-Si等; Co2熔覆层主要由γ-Co、γ-Ni固溶体等组成; 多层熔覆层硬度和耐磨性相较于基体, 有较大提高, Co2合金熔覆层平均硬度值最高, 达到了584.7 HV0.3, 多层熔覆层经过多次重叠扫描, 重复融化凝固熔覆层硬度更加均匀。

The effect of shape, height, and interparticle spacing of Au nanoparticles (NPs) on the sensing performance of Au NP array is systematically investigated. Lengthening the major axis of elliptical NPs with the minor axis kept constant will cause the redshift of the local surface plasmon (LSP) resonance mode, enhance the sensitivity, and widen the resonance peaks. Larger height corresponds to smaller LSP resonance wavelength and narrower resonance peak. With each NP size unchanged, larger interparticle spacing corresponds to larger resonance wavelength and smaller full-width at half-maximum (FWHM). Moreover, duty cycle is important for sensitivity, which is largest when the duty cycle is 0.4.

Ultraviolet photo-lithography is employed to introduce two-dimensional (2D) photonic crystal (PC) structure on the top surface of GaN-based light emitting diode (LED). PC patterns are transferred to 460-nm-thick transparent indium tin oxide (ITO) electrode by inductively coupled plasma (ICP) etching. Light intensity of PC-LED can be enhanced by 38% comparing with the one without PC structure. Rigorous coupled wave analysis method is performed to calculate the light transmission spectrum of PC slab. Simulation results indicate that total internal reflect angle which modulated by PC structure has been increased by 7°, which means that the light extraction efficiency is enhanced outstandingly.

SiO2-TiO2 sol-gel films are deposited on SiO2/Si by dip-coating technique. The SiO2-TiO2 strips are fabricated by laser direct writing using an ytterbium fiber laser and followed by chemical etching. Surface structures, morphologies and roughness of the films and strips are characterized. The experimental results demonstrate that the SiO2-TiO2 sol-gel film is loose in structure and a shrinkage concave groove forms if the film is irradiated by laser beam. The surface roughness of both non-irradiated and laser irradiated areas increases with the chemical etching time. But the roughness of laser irradiated area increases more than that of non-irradiated area under the same etching time. After being etched for 28 s, the surface roughness value of the laser irradiated area increases from 0.3 nm to 3.1 nm.