利用总积分散射仪对光学薄膜表面散射特性的研究

利用总积分散射仪对不同条件下制备的金属银膜、Y₂O₃稳定ZrO₂（YSZ）薄膜、TiO₂薄膜和1064 nm与532 nm双波长增透膜的表面均方根（RMS）粗糙度和散射特性的变化规律进行了系统研究,并与样品的制备条件、生长过程、材料组成及光学特性等各方面相结合,对测量结果做出了合理解释,从而使总积分散射测量在其他领域的研究得以扩展和应用. 关键词： 光学薄膜 表面散射 总积分散射仪     

Analysis of skin surface roughness by visual assessment and surface measurement

In this study, we analyze the surface roughness of human skin using human visual assessment and statistical features of three-dimensional shape data and goniometric reflectance data. We use eight skin replicas taken from the cheeks of women. First, we perform human visual assessment to obtain the roughness rankings. Second, we measure three roughness parameters by currently used methods. These parameters show no significant correlation with the roughness rankings. Third, we measure the skin surface shape to calculate surface normal vectors. We show that the surface normal distribution of the skin is isotropic and Gaussian, and the standard deviation has a good correlation with the roughness rankings. Finally, we analyze the goniometric reflectance data to approximate the surface reflection using the Oren-Nayar model. We find that the standard deviation estimated using this model corresponds to the roughness rankings. Thus, this parameter can be effectively used for describing skin roughness.     

Modifying of etching anisotropy of silicon substrates by surface active agents

The influence of alcohol additives on etch rate anisotropy of Si(hkl) planes has been studied. The etching processes were carried out in 3 and 5 M KOH aqueous solutions saturated and non-saturated with alcohols. Isopropanol, 1-propanol and tert-butanol were examined. It has been showed that the etching process cannot be controlled only by the surface tension of the solution. Saturation of the etching solution with alcohols modifies etch rate anisotropy, lowering the ratio of the etch rate of (110) and vicinal planes to the etch rate of (100) plane. The morphology of Si(hkl) planes etched in 3 M KOH solution saturated with tert-butyl alcohol has been studied in detail. Smooth (331) and (221) planes have been achieved in this solution. The (100) plane turned out to be densely covered by hillocks, opposite to the (100) plane etched in weak-alkaline solution saturated with isopropanol. To explain this phenomenon, the mechanism of hillocks formation on Si(100) surface has been proposed.     

Simultaneous surface area measurement for multiple objects by geodesic active contour

A novel scheme to the area measurement of multiple objects is proposed. This scheme is suitable for the simultaneous and exact measurement of multiple objects’ surface areas with different shapes. A geodesic active contour is applied and this scheme consists of three steps. Firstly, the active contour converges to the object's contour edge from an initial position via the iteration of level set functional ?. Secondly, for the convergent active contour, the sub-pixel area measurement and centroid measurement are applied to compute every object's area and centroid simultaneously. Finally, a centroid-self-calibration technology is applied, which measures the pixel's size equivalence with the computed centroid and a dual-frequency laser to measure every object's true surface area. Experiments indicate that this scheme's measurement repetition error can decrease to ±0.4% and that its single measurement error can decrease to ±0.2%. Compared to conventional area measurement schemes, this scheme is highly efficient (i.e., simultaneous measurement of multiple objects’ areas) and highly accurate.     

Quantitative surface normal measurement by a wavefront camera

A compact wavefront camera that allows users to quantitatively measure the intensity and wavefront at a remote object plane is reported. The camera is built from a chip-scale wavefront sensor that we previously developed. By measuring the wavefront of the image and calibrating the wavefront relationship between the image and object planes, the wavefront at the object plane can be computed and the surface normal of the object can be derived. We built a prototype camera and calibrated the wavefront relationship. In a proof-of-concept experiment, a set of concave mirrors with different focal lengths (50-200 mm), were imaged. The results agree well with their expected values. To demonstrate the application of the camera, we applied this method to measure the deformation of a microfluidic channel under pressure.     

Prediction of clad angle in laser cladding by powder using response surface methodology and scatter search

Currently, laser cladding is an important process that allows the deposition of thick protective coatings on substrates. The article presents an experimental investigation of the influence of processing parameters on clad angle in laser cladding by powder (LCP). The clad angle is determined from the mathematical expression relating to the clad height and clad width. The cladding angle model was developed in terms of laser power, scanning speed, and powder mass flow rate by means of response surface methodology. A first-order equation covering a narrow range of the variables and a second-order equation covering a wide range of the variables are presented. An optimization technique, Scatter Search, is used to determine optimal processing parameters. The adequacy of the predictive model was tested by analysis of variance and found to be adequate.     

Real-time surface shape measurement by an active interferometer

We have succeeded in video rate analysis of fringes stabilized by an active interferometer placed outside optical benches. The interferometer uses the closed loop control of injection current of a laser diode to compensate for fringe movement that is detected by a spatial filtering detector. A video image of the locked fringes with tilt is supplied to the real-time fringe analyzer that delivers unwrapped phase distribution from the three phase shifted fringes generated by the electronic moiré method. For a concave mirror of 130 mm diameter placed on a wooden desk we observed the repeatability of λ/60 for P-V surface error of λ/5.     

用表面等离子体共振传感器检测纳米间距

结合物理光学原理和表面等离子体共振（SPR）角度传感器,提出了可以突破衍射极限的纳米间距检测方法。在理论上建立起纳米间距和位相改变量之间的函数关系,借助于SPR角度传感器的高灵敏性,提出通过检测出射光束振动方向的p分量和s分量的位相差值来实现纳米间距的实时检测。模拟结果显示：纳米间距改变量从-0.5～0.5μm变化时,位相改变量可实现-150°～150°的变化,检测灵敏度〉1 nm。该检测方法能够实现10 nm以下间距的灵敏检测,且具有结构简单,易于操作,实时检测的特点。     

Two-colour phosphor thermometry for surface temperature measurement

Thermographic phosphor thermometry enables surface temperatures to be measured over a wide range extending from sub 0 °C to in excess of 1400 °C by utilising the temperature-dependent luminescent properties of lanthanide-doped ceramics. The technique is particularly advantageous where surface temperatures are high due to the difficulty in applying conventional techniques and is therefore particularly well suited to the study of surface temperatures and heat transfer in gas turbines. The paper describes a two-colour implementation of the technique based on the intensity ratio of emissions from two distinct lines in the spectrum. An imaging system based on a single CCD camera has been developed and is described as are the image processing routines. YAG:Dy and YSZ:Dy phosphors were calibrated over a temperature range from 300 to 900 K with a repeatability in the data of around ±0.6%. The response of the phosphors and the performance of the imaging system were demonstrated in a transient heating/cooling study of ceramic and metallic plates.     

棱镜耦合法测波导衬底折射率

本文对棱镜耦合法测波导衬底折射率进行了实验研究,在两种入射情况下,对石英玻璃、CaF_2、LiF衬底及C-813-8胶块进行了折射率测量,并得到有益的实验结果.     

An ultrasonic goniometer for surface stress measurement

An instrument has been constructed for the measurement of residual stress in steel. If necessary, large objects can be examined in situ. An account is given of the principles and construction. A special stressing frame provides for calibration. An application to residual stress in gear blanks has established a systematic variation of surface stress with nickel content and confirmed the overall effect of the surface hardening treatment.     

Platinum and palladium as substrates for surface enhanced Raman spectroscopy

Surface enhanced Raman scattering (SERS) has been observed from the electrogenerated I₂ and I^-₃ coadsorbed on Pt and Pd electrodes. Theoretical models on the SERS process that emphasize the important role of the optical properties of the metal substrate cannot be used to explain this observation. The electronic interaction between the adsorbate and the substrate is believed to be the most important mechanism for the observed SERS.     

硬度压痕表面积的共聚焦测量方法

提出了一种对角线长度小于20 μm的硬度压痕表面积共聚焦测量方法。激光扫描共聚焦显微镜以0.1 μm的间隔逐层对试样的压痕进行扫描测量,对全部数据集合的包络拟合获得压痕的三维数据。旋转平面法与法向量特征相结合精确提取压痕,通过三角网格构造算法得到压痕的表面积,进而计算出试样的硬度值。共聚焦测量方法与传统成像光学显微镜测量方法相比分辨率提升了30%,合成标准不确定度平均减小1 HV。实验结果表明:共聚焦测量方法实现了压痕表面积的高精度、高稳定性测量。     

Photoemission measurement of surface states for annealed silicon

Surface states on annealed silicon (111) and (100) surfaces were determined by comparing photoemission from clean and partially oxidized surfaces. Results are compared with previous photoemission measurements on cleaved surfaces.     

Modeling light propagation through taper-microfiber structures integrated on substrates

<正>We use the three-dimensional finite-difference time-domain(3D-FDTD) method to model silica taper-microfiber structures integrated on substrates.The dependence of the transmission on the length of the microfiber is investigated for two different structures.Optimization of the geometric parameters is provided and two substrate materials,namely MgF_2 and fluorosilicate glass,are considered.We also investigate the case where the structure is covered with a dielectric material.     

Thermally tempered glass surface stress measurement by critical ray

A critical ray was excited along the glass surface by laser beam incidence. Part of the critical ray was refracted during propagation. The angle of refraction depended on the refractive index of the glass sirface. When the glass surface was birefringent due to the photoelastic effect, the angles of refraction differed from each other between two linearly polarized beams. This difference allows surface stress determination.