Thickness dependence of the optical constants of oxidized copper thin films based on ellipsometry and transmittance

Thin oxidized copper films in various thickness values are deposited onto quartz glass substrates by electron beam evaporation. The ellipsometry parameters and transmittance in a wavelength range of 300 nm-1000 nm are collected by a spectroscopic ellipsometer and a spectrophotometer respectively. The effective thickness and optical constants, i.e., refractive index n and extinction coefficient k, are accurately determined by using newly developed ellipsometry combined with transmittance iteration method. It is found that the effective thickness determined by this method is close to the physical thickness and has obvious difference from the mass thickness for very thin film due to variable density of film. Furthermore, the thickness dependence of optical constants of thin oxidized Cu films is analyzed.

Investigation of the Effect of Film Thickness and Heat Treatment on the Optical Properties of TeSeSn Thin Films

Glassy substrates TeSeSn thin films were thermally evaporated onto chemically cleaned glass. The as-deposited (as-prepared) and annealed thin films were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and optical transmission. The optical absorption of the as-prepared and annealed TeSeSn thin films is studied in the wavelength range of 300 nm - 900 nm. The direct optical energy gap (Eg) increases from 1.989 to 2.143 eV with increasing the thickness of the as-prepared films from 100 to 200 nm. The annealed TeSeSn films showed a decrease in the optical energy gap with increasing the annealing temperature. The effect of heat treatment on the lattice dielectric constant (εL) and carrier concentration (N) are also studied.

Development of Dual-light Path Monitoring System of Optical Thin-film Thickness

The accurate monitoring of optical thin-film thickness is a key technique for depositing optical thin-film. For existing coating equipments, which are low precision and automation level on monitoring thin-film thickness, a new photoelectric control and analysis system has been developed. In the new system, main techniques include a photoelectric system with dual-light path, a dual-lock-phase circuit system and a comprehensive digital processing-control-analysis system.The test results of new system show that the static and dynamic stabilities and the control precision of thin-film thickness are extremely increased. The standard deviation of thin-film thickness, which indicates the duplication of thin-film thickness monitoring, is equal to or less than 0.72%. The display resolution limit on reflectivity is 0.02 %. In the system, the linearity of drift is very high, and the static drift ratio approaches zero.

Effect of Film Thickness on Properties of a-Si∶H Films

The a-Si∶H films with different thickness smaller than 1 μm were deposited by plasma enhanced chemical vapor deposition (PECVD) under the optimum deposition conditions. The effect of different thickness on film properties is analyzed.The results show that,with the increase of the film thickness,the dark conductivity, photoconductivity and threshold voltage increase, the optical gap and peak ratio of TA to TO in the Raman spectra decrease, the refractive index keeps almost constant, and the optical absorption coefficient and current ratio of on/off state first maximize and then reduce.

Optical analysis of ball-on-ring mode test rig for oil film thickness measurement

There are few experimental results available on film thickness at speeds above 5 m/s and they are almost all based on the optical ball-on-disc test rig.In contrast to the contacts in a rolling bearing,in which the lubricant in the oil reservoir distributes symmetrically,ball-on-disc contact shows asymmetry of lubricant distribution due to centrifugal effects.In order to closely imitate the contact occurring between the ball and the outer ring of a ball bearing,this study proposes an experimental model based on ball-on-glass ring contact.An optical matrix method is used to analyze the optical system,which is composed of a steel ball-lubricant-chromium-coated glass ring.Based on the optical analysis,the measurement system is improved in order to obtain a high quality interference image,which makes it possible to measure the film thickness at high-speeds conditions.

New Numerical Method to Calculate the True Optical Absorption of Hydrogenated Nanocrystalline Silicon Thin Films

The enhanced optical absorption measured by Constant Photocurrent Method (CPM) of hydrogenated nanocrystalline silicon thin films is due mainly to bulk and/or surface light scattering effects. A new numerical method is presented to calculate both true optical absorption and scattering coefficient from CPM absorption spectra of nanotextured nano-crystalline silicon films. Bulk and surface light scattering contributions can be unified through the correlation obtained between the scattering coefficient and surface roughness obtained using our method.

Optical and electrical properties of InGaZnON thin films

The substrate temperature(Ts)and N2 partial pressure(PN2)dependent optical and electrical properties of sputtered InGaZnON thin films are studied.With the increased Ts and PN2,the thin film becomes more crystallized and nitrified.The Hall mobility,free carrier concentration(Ne),and electrical conductivity increase with the lowered interfacial potential barrier during crystal growing.The photoluminescence(PL)intensity decreases with the increased Ne.The band gap(Eg)narrows and the linear refractive index(n1)increases with the increasing concentration of N in the thin films.The Stokes shift between the PL peak and absorption edge decreases with Eg.The n1,dispersion energy,average oscillator wavelength,and oscillator length strength all increase with n1.The single oscillator energy decreases with n1.The nonlinear refractive index and third order optical susceptibility increase with n1.The Seebeck coefficient,electron effective mass,mean free path,scattering time,and plasma energy are all Ne dependent.

Analysis of reflection coefficient for coated optical waveguide devices

From an ordinary condition,using a full three-dimensional model theory and an infinite perturbation expansion method,an exact solution of the reflection coefficient for the coated narrow stripe-geometry optical waveguide devices has been derived.All six components and the vector property of the electromagnetic field have been considered.The results are suitable for the symmetric and asymmetric waveguides.

Effect of Heat Treatment on the Nanoscale Structure and Optical Properties of Cd₂SnO₄Thin Films Deposited by RF Magnetron Sputtering

Cadmium tin oxide Cd2SnO4 thin films with a thickness of 228.5 nm were prepared by RF magnetron sputtering technique on glass substrates at room temperature. AFM has been utilized to study the morphology of these films as a function of annealing temperature at the nanoscale. The optical properties of these films, such as the transmittance, T(λ), and reflectance, R(λ), have been studied as a function of annealing temperature. The optical constants, such as optical energy gap, width of the band tails of the localized states, refractive index, oscillatory energy, dispersion energy, real and imaginary parts of both dielectric constant and optical conductivity have been found to be affected by changing the annealing temperature of the films.

Assessments of tear meniscus height, tear film thickness, and corneal epithelial thickness after deep anterior lamellar keratoplasty

Objective： To assess the lower tear meniscus height（LTMH）, central tear film thickness（CTFT）, and central corneal epithelial thickness（CCET） after deep anterior lamellar keratoplasty（DALK）. Methods： This was a retrospective cross-sectional study of 20 patients who had DALK in one eye over a three-month period. LTMH, CTFT, and CCET of the operated eyes and the unoperated fellow eyes were measured using high-definition optical coherence tomography（HD-OCT）. Correlations between three OCT assessments and age, time following surgery, graft size, bed size, and the number of residual sutures were analyzed. Results： Compared to patients with keratoconus, patients with other corneal conditions had significantly higher CCET in the fellow eye（P=0.024）. For all patients, CCET in the operated eye was significantly negatively correlated with the number of residual sutures（R=-0.579, P=0.008）, and was significantly positively correlated with time following surgery（R=0.636, P=0.003）. In the fellow eye, a significant positive correlation was found between age and CCET（R=0.551, P=0.012）, and a significant negative correlation between age and CTFT（R=-0.491, P=0.028）. LTMH was found to be significantly correlated between operated and fellow eyes（R=0.554, P=0.011）. There was no significant correlation between LTMH and age, bed/graft size, time following surgery, or residual sutures（all possible correlations, P0.05）. Conclusions： Patients with keratoconus tend to have a thinner central corneal epithelium. Corneal epithelium keeps regenerating over time after DALK. DALK did not induce a significant change in tear volume compared with the fellow eye. Postoperative tear function might depend on an individual＇s general condition, rather than on age, gender, bed/graft size, time following surgery, or residual sutures.

Annual observation and analysis of aerosol optical properties in Tianjin coastland

Seasonal variation of the Tianjin coastal atmospheric aerosol opticalproperties are important for improving the atmosphere correction precision of marinesatellite and learning the environment of the boundary between the Bohai Sea and theland. In this paper, the aerosol optical data of Tianjin coastal area from April 2010 toMay 2011 were observed by using the CE317 Solar Photometer, and the aerosol opticalproperties were analyzed. The results show that: Aerosol Optical Thickness (AOT)spectra are basically in accord with Angstrom relationship; there are three basic typesof AOT daily variations, which are rising type, levelling type, and declining type; inTianjin Coastland, the mean value of AOT is highest in autumn, which is 0.686. Thevalue is lower in spring and summer, and hits the lowest point in winter. Angstromexponent α increases successively from spring, summer, autumn to winter. Due to thedusty, the angstrom exponent α in spring is lowest, the mean of which is 0.854.Compared with Qingdao Coastland, the atmospheric aerosol optical properties presentcharacteristics of regionality.

Real Time Derivation of Atmospheric Aerosol Optical Properties by Concurrent Measurements of Optical and Sampling Instruments

The understanding of aerosol properties in troposphere, especially their behavior near the ground level, is indispensable for precise evaluation of their impact on the Earth’s radiation studies. Although a sunphotometer or a skyradiometer can provide the aerosol optical thickness (AOT), their application is limited to daytime under near cloud free conditions. In order to attain the multi-wavelength observation for both day- and night-time including cloudy conditions, here we propose a novel monitoring technique by means of simultaneous measurement using a nephelometer (450, 550, and 700 nm), an aethalometer (370, 470, 520, 590, 660, 880, and 950 nm), and a visibility meter (550 nm). On the basis of the multi-wavelength data of scattering and absorption coefficients from the nephelometer and aethalometer, respectively, first we calculate the real-time values of aerosol extinction coefficient in addition to the Angstrom exponent (AE). Then, correction of these values is carried out by comparing the resulting extinction coefficient with the corresponding value obtained from the optical data of visibility-meter. The major reason for this correction is the loss of relatively coarse particles due to the aerodynamic effect as well as evaporation of water content from particles during the sampling procedure. Then, with the ancillary data of vertical aerosol profile obtained with a lidar (532 nm), the temporal change of AOT is estimated. In this way, information from the sampling can be converted to the ambient properties in the atmospheric boundary layer. Furthermore, daytime data from a sunphotometer (368, 500, 675, and 778 nm) and a skyradiometer (340, 380, 400, 500, 675, 870, and 1020 nm) are used to validate the resulting AOT values. From the overall procedure, we can estimate the AE and AOT values from the sampling data, with uncertainties of approximately 5% for AE and 10% for AOT. Such a capability will be useful for studying aerosol properties throughout 24 hours regardless of the solar radiation and cloud coverage.

Nonlinear optical properties of novel H-shaped chromophores

Novel and effective H-shaped chromophores were doped into polymethyl methacrylate （PMMA） to form guest-host polymer thin films. The measurement results of Maker fringe method show that the polymer thin films containing the H-shaped chromophores as a guest exhibit high second harmonic coefficients （d33） compared with other two-dimensional chromophores.

基于多项式求根的双厚度透射法确定液体光学常数

光谱反演法可实现液体光学常数(消光系数和折射率)的确定,其中双厚度透射法是有代表性的光谱反演法之一。由于液体自身无法形成确定的形状,需要盛放在透明容器(液体池)中,因而通过实验测量得到的光谱透射率包含了液体池光学常数的影响,这使得基于双厚度透射法所建立的光谱透射率方程极为复杂,难以求得解析解,通常采用反演法来计算液体的光学常数。现有的反演法存在如下问题:一是反演迭代耗费时间,二是反演迭代会引入误差,三是反演法得到的液体折射率存在二值问题。为解决上述问题,基于三层介质结构(液体池),考虑光在两种介质分界面上的多次反射,建立液体厚度满足整数比的光谱透射率方程组。通过代数运算获得与消光系数有关的多项式方程,求解并选择大于0小于1的实数根来计算消光系数;另求解关于液体池光学窗口反射率的一元二次方程,选择大于0小于1的根来计算液体和容器分界面的反射率,进而计算得到液体折射率的两个值。再用另一材料制作的液体池测量液体的光谱透射率,然后结合已经得到的消光系数作相关计算,会另外得到液体折射率的两个值,从四个值中选择相同者即为液体的折射率。作为应用示例,选用文献中水在0.5~1.0μm光谱范围的光学常数作为“理论值”、光学常数已知的石英玻璃和有机玻璃作为液体池材料。在不考虑仪器测量误差的情况下,将上述文献数据代入光谱透射率方程,计算得到的透射率作为“实验数据”。然后用多项式求根的方法确定水的光学常数,所得结果与“理论值”完全符合。模拟过程和计算结果表明:新方法是可用的,该方法解决了反演法的计算耗时、迭代误差以及折射率的二值问题,为液体光学常数的确定提供了一个新选择。

基于反射光谱的薄膜光学常数和厚度测试

薄膜的光学常数(折射率、消光系数)和厚度决定了镀膜零件的光学性能,因此根据实际条件掌握薄膜的光学常数和厚度是膜系结构设计和性能优化的重要环节。本文采用傅里叶红外光谱仪测试薄膜样品的反射光谱曲线,通过单纯形优化算法拟合反射光谱曲线,借助不同色散模型,构建目标优化函数,获得薄膜光学常数和厚度,拟合结果与采用椭偏仪测试的结果具有较好的一致性。将拟合得到的薄膜光学参数及厚度代入反射率理论计算模型,通过理论计算模型得到的反射率曲线和实验测试曲线吻合良好,折射率测试结果与计算结果的最大相对误差小于1.8%,厚度测试结果的相对误差不大于0.4%,考虑消光系数的反射光谱拟合曲线与测试曲线相对误差的最大值小于2%。该方法只需测量薄膜的反射光谱曲线,通过计算就能得到薄膜的光学常数及厚度。该方法测试计算简单、精度高、适用范围广,对光学薄膜结构设计、优化和加工具有一定的实际应用价值。

Two-Stream Approximation to the Radiative Transfer Equation:A New Improvement and Comparative Accuracy with Existing Methods

Mathematical modeling of the interaction between solar radiation and the Earth's atmosphere is formalized by the radiative transfer equation(RTE), whose resolution calls for two-stream approximations among other methods. This paper proposes a new two-stream approximation of the RTE with the development of the phase function and the intensity into a third-order series of Legendre polynomials. This new approach, which adds one more term in the expression of the intensity and the phase function, allows in the conditions of a plane parallel atmosphere a new mathematical formulation of γparameters. It is then compared to the Eddington, Hemispheric Constant, Quadrature, Combined Delta Function and Modified Eddington, and second-order approximation methods with reference to the Discrete Ordinate(Disort) method(δ –128 streams), considered as the most precise. This work also determines the conversion function of the proposed New Method using the fundamental definition of two-stream approximation(F-TSA) developed in a previous work. Notably,New Method has generally better precision compared to the second-order approximation and Hemispheric Constant methods. Compared to the Quadrature and Eddington methods, New Method shows very good precision for wide domains of the zenith angle μ 0, but tends to deviate from the Disort method with the zenith angle, especially for high values of optical thickness. In spite of this divergence in reflectance for high values of optical thickness, very strong correlation with the Disort method(R ≈ 1) was obtained for most cases of optical thickness in this study. An analysis of the Legendre polynomial series for simple functions shows that the high precision is due to the fact that the approximated functions ameliorate the accuracy when the order of approximation increases, although it has been proven that there is a limit order depending on the function from which the precision is lost. This observation indicates that increasing the order of approximation of the phase function of the RTE leads to a better precision in flux calculations. However, this approach may be limited to a certain order that has not been studied in this paper.

光学相干断层扫描在角膜塑形镜验配中的应用

目的:通过光学相干断层扫描(OCT)测量角膜塑形镜下泪液间隙厚度,探讨泪液间隙厚度与角膜塑形镜配适度之间的关系,为角膜塑形镜的验配提供一种更直观、量化的临床评估手段。方法:收集2023-01/12在我院验配角膜塑形镜的近视患者。在进行配镜之前,对所有患者都实施了全面的眼科诊断,涵盖了视力检测、裂隙灯检查、非接触眼压测量、眼底检查、双眼眼位检查、测量角膜直径、角膜地形图检查、泪膜破裂时间评估以及综合验光检查等项目。根据个人的检查结果选择试戴片的参数,待患者戴镜适应后进行荧光素染色配适度评估。将被检眼分为镜片过松组、镜片适配组、镜片过紧组。使用OCT测量三组被检眼泪液间隙厚度,评估三组数据之间差异性。结果:本研究共纳入近视患者49例77眼。验配前测得平均球镜度为-3.10±1.25 D,平均柱镜度为-0.43(-0.75,0)D,平均水平子午线角膜曲率(HK)为42.48±0.81 D,平均垂直子午线角膜曲率(VK)为42.98(42.25,43.50)D。镜片适配组21例34眼(13例双眼,8例单眼)、镜片过松组14例22眼(8例双眼,6例单眼)、镜片过紧组14例21眼(7例双眼,7例单眼)。三组受检者的主要基础资料比较无差异(均P>0.05)。使用OCT测量得出,镜片适配组、镜片过松组、镜片过紧组泪液间隙厚度分别为231.18(219.0,243.0)、220.41(214.0,224.3)、249.00(241.5,258.0)μm,三组厚度数值比较有差异(P<0.05)。结论:OCT技术提供了一种安全可靠的测量泪液间隙厚度的方法,它可以帮助评估角膜塑形镜的适配情况,为角膜塑形镜的验配评估提供了一种无创的、更直观和定量的评估手段。

40~90 nm波段极紫外多层膜研究进展

极紫外多层膜反射镜在许多科学与技术领域,如极紫外光刻、天体物理学、等离子体诊断、阿秒物理和自由电子激光等方面有重要应用。多层膜使极紫外波段反射镜在正入射条件下具有高反射率和窄带宽成为可能。多层膜反射镜是极紫外成像和光谱应用的重要器件,多层膜构成的极紫外成像系统已成功完成多个太阳单一谱线的成像观测。本文综述了40~90 nm波段最有前景的多层膜的研究进展。首先简要介绍了多层膜的基本原理,叙述了40~90 nm波段材料光学常数的测量,总结了Mg基、Sc基和镧系材料以及其他材料组成多层膜的进展,给出了目前达到的最佳反射率和带宽,阐明了多层膜的时间稳定性,从而为40~90 nm波段多层膜制备提供了技术指导。

氧化钒非制冷探测器吸收特性研究

随着氧化钒非制冷红外焦平面的像元尺寸的减小,导致探测器的吸收面积呈边长的二次方锐减,如何提高氧化钒非制冷红外焦平面阵列的吸收效率成为一个非常关键的研究课题。本文从材料和结构角度出发,分别在单层材料吸收特性、不同吸收结构、腔体高度、膜系厚度等几个方面对影响单层、双层氧化钒非制冷探测器光学吸收的各因素进行了全面系统的仿真。通过对各因素进行量化比较,同时结合仿真结果给出了提高氧化钒非制冷探测器吸收的系统方法,对于氧化钒非制冷探测器的设计与研究具有一定的参考意义。

点接触滑动-往复自旋运动润滑成膜规律研究

为模拟滚动轴承中常见的自旋工况,设计开发了1种可分别控制滑动速度和自旋速度的点接触光弹流滑动-往复自旋试验装置.采用新开发的装置对带有自旋的钢球-玻璃盘接触副形成的弹性流体动力润滑油膜形状、厚度等进行试验研究,考察了运动学参数与供油条件对点接触自旋运动膜厚分布的影响,针对非稳态工况中的滑动-往复自旋复合运动进行了试验研究,对接触区油池分布以及供油状况进行了fluent两相流仿真.结果表明:设计的试验装置可精确模拟接触副滑动-往复自旋复合运动,并实现了对该条件下的油膜分布可视化研究.随着钢球自旋角速度增大,经典的马蹄形相对卷吸中心线的对称性就会消失,自旋速度越大,非对称性越明显,载荷越大,最小油膜厚度越小.在非稳态运动过程中,最大自旋角速度时刻的油膜厚度低于稳态条件下相同角速度的油膜厚度;增大钢球往复自旋运动频率,对应时刻的油膜厚度变化减小.往复自旋运动大大缩小了乏油工况下接触区入口距离,与仿真结果一致.