定量分析光纤阵列位移及指向扰动偏差对合束激光光束质量因子M²的影响规律是实现合束激光光束质量有效控制的前提。根据衍射积分推导了紧凑型光谱组束系统中光纤阵列存在不同位移、指向扰动时合束激光的远场光强分布，利用Heisenberg不确定性原理推导出了合束激光光束质量因子M²的表达式。在恒定的子束数目下，分析了单路/多路光束分别存在位移、指向扰动偏差时合束激光光束质量因子M²的变化情况，并在一定的随机位移、指向扰动偏差下对不同子束数量的合束激光的光束质量因子M²进行了误差分析。结果显示：合束激光光束质量因子M²对沿光纤端面水平（x轴）方向的扰动量最为敏感，需要控制在微米量级；确定了光纤阵列的不同扰动量与合束激光光束质量因子M²之间的定量关系，给出了光纤阵列位移、指向精度控制要求；当参与合束的子束数量超过23束时，在特定的随机扰动量下，合束激光的光束质量因子M²的统计均值分别趋向各自的稳定值1.37、1.34、1.25，而标准差分别趋于0.05、0.06、0.04。

采用化学还原法制备了花状纳米银凝胶溶胶,沉积在硅片、二氧化钛薄膜、玻璃上,制备得到了AgNP@Si,AgNP@TiO2,AgNP@G 3种表面增强拉曼基底。以罗丹明6G(R6G)为探针分子,考察了3种基底的表面增强拉曼效果,重复性及均匀性。AgNP@TiO2和AgNP@Si的检出限为10-8mol·L-1,而AgNP@G的检出限为10-7mol·L-1,AgNP@Si的重复性和均匀性最优。结果表明,AgNP@Si的SERS增强效果最佳,并具有制备简单,重复性和均匀性好等优点。

There is a need to develop a non-destructive and fast detection method for bruising of fruits because the injuries lower quality of fruits, which lead to economic loss. In this paper, we propose a method to detect the bruise on apple surface with hyperspectral imaging technique. A hyperspectral image system consisting of a CCD digital camera, a line scanning spectrometer and a movable platform is designed to acquire the hyperspectral images of injured apples. Two models are established to distinguish the injured area on the surface from the normal area based on image processing technique with spatial clustering and Spectral Angle Mapper Classification (SAM), respectively. The discrimination accuracy of the SAM model is up to 100%, which is much higher than the spatial clustering model.

A portable near-infrared (NIR) spectroscopy analyzer is developed for rice wine analysis. The analyzer is composed of a lamphouse, a temperature-controlled sample chamber, a mini-spectrometer, and a control unit. The mini-spectrometer is based on the crossed Czerny-Turner structure grating platform and a linear InGaAs array detector with spectrum range of 1100?2500 nm and spectral resolution of 1.5-12 nm full-width at half-maximum (FWHM). The control software written in VC++ consists of three parts: the spectra acquisition, the model establishment, and the sample analysis. The calibration models of determination of alcohol and nonsugar solids in rice wine are established with 54 samples. After calibration, the portable analyzer is used for real-time analysis of the rice wine sample.

A novel optical fiber evanescent-wave (EW) sensing platform combining a taper and a refractive index (RI) gel residue is proposed. The platform includes two identical large core multimode fibers perpendicularly positioned to each other: one for excitation light delivery (i-fiber) and one for EW fluorescent signal collection (r-fiber). One end of the r-fiber is decladded to expose a segment of a cylindrical fiber core terminated with a taper. A small drop of rhodamine 6G (R6G) solution sample is distributed in such a way that it surrounds the side wall of the cylindrical portion of the core and covers the i-fiber end face. The fluorescent signal is recorded under the following conditions: 1) the entire taper is exposed to air; 2) the entire taper is immersed into a large gel block; 3) the taper is covered with a gel residue. A dramatic rise of the fluorescence signal is observed in the third case, which is over 20 times more than the level achieved from the first two cases. We reveal that the intensive mode coupling in the sandwiched air-gel-taper architecture accounts for this phenomenon, which is discussed in detail.

The critical findings associated with end-face total internal reflection (TIR) phenomemon we proved before are reported. In particular, these findings reveal that the end-face-TIR capable rays experience enormous mode mixing when encountering a roughened end face. As a result, 94% of the overall detectable power is contributed by this effect. With a smooth fiber end face, this figure is mere 52%. We interpret the mechanism behind these unusual phenomena and its significance for the performance enhancement of fiber optic evanescent wave sensor.