我国光学润滑脂的现状及发展前景

<正> 一、光学仪器对光学润滑脂的要求光学仪器的润滑机构比较复杂,有滚动轴承、球面、圆柱面、蜗轮蜗杆、齿轮、多头螺纹等,所以光学润滑脂应具有下列要求。1.从光学玻璃方面考虑,即从光学仪器的“防霉防雾”性能方面考虑,光学润滑脂应该具有: (1)小的蒸发量,以避免油蒸气在镜面上凝聚,形成所谓的“雾”,影响观察。(2)润滑脂本身不长霉,即不提供霉菌生     

分块镜扇形子镜驱动点位置优化计算

在光学综合孔径共相位检测微调系统中,分块镜子镜三自由度微动调节机构通常采用3个并联的微位移致动器来驱动各子镜,使单个分块镜具有独立的姿态调整能力,从而实现了光学共相位误差的纳米级精确校正。以理论力学原理作为切入点展开了分析,针对微动机构的稳定性、tilt-tip调节灵敏度等,根据所给定几何参数的子镜三驱动点位置对其进行了优化计算。经数学建模和仿真计算,得到了定参数子镜的三驱动点最佳位置坐标,进而归纳出了普遍适用的优化评价方法。     

光通信 其他

TN923.13 2006032597自由空间光通信ATP系统中精瞄偏转镜的设计=Designof fine pointing tip/tilt mirror of ATP system for freespace optical communication[刊,中]/邵兵(哈尔滨工业大学机器人研究所.黑龙江,哈尔滨(150001)) ,孙立宁…∥光学精密工程.—2006 ,14(1) .—43-47二维精瞄偏转镜是自由空间光通信中捕获、跟踪和瞄准(ATP)系统的关键组成部分,对偏转镜进行了机构设计和有限元模态分析,偏转镜采用压电陶瓷驱动器驱动,采用柔性铰链传动。研制了集驱动、检测、主控模块为一体的数字式精密定位控制器,在实验室构建了两套测试系…     

车载光学平台双层隔振系统设计与试验研究

 分析了冲击、振动对车载精密光学系统的影响,指出了光学平台的变形和振动是影响车载精密光学系统精度和稳定性的主要因素,提出了车载光学平台双层隔振系统的设计方案。采用ANSYS有限元方法分析了光学平台隔振系统的振动模态和减振比,完成了车载状况下的光学平台振动测试。分析与测试结果表明,车载光学平台的双层隔振结构具有良好的稳定性,且对环境强振动有很好的衰减作用。该双层隔振技术方案及其分析测试方法,对于各种车载精密光学系统和设备具有重要的工程应用价值。     

连续变焦镜头焦距输出结构的设计

根据光学设计中变倍组与补偿组的移动量与系统焦距的关系,设计了一种在变焦距镜头连续变焦时能准确输出焦距值的结构。该结构由蜗轮蜗杆驱动,以直线位移传感器为反馈元件,采用一个连接杆将直线位移传感器与变焦镜组进行固定连接来保证镜组的移动量直接反馈为位移传感器的电压值。与传统的通过齿轮传动将焦距变化反馈到旋转电位器的结构相比,该结构消除了由齿轮传动的空回、凸轮带动钉的间隙以及电位器的误差值等带来的影响。精度分析表明,采用这种高精度的直线位移传感器,加在其上的电压的变化可直接换算成焦距的变化,因此提高了焦距输出的精度。     

光刻物镜中光学元件精密轴向调整机构的设计与分析

柔性铰链与高准确度驱动器的结合是实现光学元件轴向精密调节的重要方法.本文介绍了一种采用柔性铰链的轴向精密调节机构,推导并得出了其实现精密调节的原理.通过对应用柔性调节机构的一种典型光机系统的刚度分析,得到在不超过柔性铰链材料屈服应力情况下,光学元件的最大轴向位移可以达到200μm以上;同时,对一种典型参量的柔性结构做了模态分析,得到其一阶固有频率为185.1Hz,证明了调节机构的固有频率满足工作要求.分析了驱动力在此种轴向调整机构中对镜片面形的影响,结果表明:调整机构在接近最大允许驱动力作用下对镜片面形影响为4.41nm,说明其对光学元件的面形影响较小.该研究结果为柔性光学元件轴向调节机构的应用提供了有力依据.     

光学平台微角振动激光探测方法研究

 设计了精密动态测角实验系统，该系统利用扩束镜正向和逆向不同的光学变换性质，将共孔径双向传输的倍增式角敏光学系统与光电精密位置传感器（PSD）相结合，并从理论上分析了高灵敏光学测角的基本原理，给出了被测角与传感器信号的关系。为消除光电噪声对探测分辨率的影响，信号处理引入了相关检测模式。通过压缩系统噪声信号的等效带宽，从频域中滤除干扰信号的频率成分，实现了从噪声中提取高分辨角度信息。     

一种便携式干涉仪动镜系统的设计

动镜扫描系统是傅里叶变换红外光谱仪中唯一不断运动的部件,其扫描的精度与行程直接影响仪器的信噪比、重复性与分辨率等指标。在利用立体角镜的光学特性和柔性簧片枢轴的机械特性的基础之上,设计了一种结构紧凑,体积小巧的干涉仪动镜扫描系统,设计了基于模糊控制算法的控制器,对动镜的扫描速度进行精密的控制。实验表明,动镜机构的扫描稳定性优于99.8%,所测得的红外光谱具有较高的信噪比能够满足高精度定量分析的要求。     

基于柔性铰链支撑的动镜扫描系统

为了改进傅里叶变换红外光谱仪的动镜驱动装置,设计了一种基于柔性铰链支撑的动镜扫描系统。采用柔性铰链的支撑方式和音圈电机的驱动方式,利用具有高精度高稳定性的直角型柔性铰链支撑机构支撑动镜,利用音圈电机驱动动镜前后往复运动,采用DSP控制系统对动镜的匀速进行控制。实验结果表明所设计的动镜扫描系统具有方向稳定性、速度稳定性、抗震性能优越等优点。     

信息光学 其他

TP3912006054294基于图像处理的微装配自动调焦系统=Micro-assemblyauto-focusing system based on i mage processing[刊,中]/段瑞玲(清华大学精密仪器及机械学系.北京(100084)),段惠波…//光学精密工程.—2006,14(3).—468-472介绍了一个基于图像处理的自动调焦系统,该系统由光学显微镜、CCD、力矩电机和齿轮传动机构等组成。调焦系统中采用粗/精结合的调焦方法,即首先采用基于Krisch边缘检测算子的清晰度评价函数对被测物体进行粗调焦,并在计算机上采集了包含目标的大致轮廓和边缘的显微图像;然后针对全景图像上的某个目标区域采用基…     

软质齿轮影像法测量及系统误差和随机误差分析

通过实验了解影像法测量时的误差特性,分别对塑料、木质等软质齿轮公法线及模数在数显投影仪进行测量,并对实验数据进行分析处理,得到测量的系统误差主要来自测量时零线的对齐误差,通过对比检定法计算得出。随机误差主要来自于测量人员对齿廓的瞄准误差,通过A类不确定度进行计算得出。另外测量仪器的不确定度,按B类不确定度计算,由于其远小于A类不确定度,故忽略不计。对比塑料齿轮和木质齿轮测量的结果,得出软质齿轮测量的随机误差与材料、加工特性及表面质量相关的特点。木质齿轮的加工变形小于塑料齿轮,而且加工后齿廓表面质量较好,使得木质齿轮测量的随机误差小于塑料齿轮的随机误差。     

A time domain approach to diagnose gearbox fault based on measured vibration signals

Spectral analysis techniques to process vibration measurements have been widely studied to characterize the state of gearboxes. However, in practice, the modulated sidebands resulting from the local gear fault are often difficult to extract accurately from an ambiguous/blurred measured vibration spectrum due to the limited frequency resolution and small fluctuations in the operating speed of the machine that often occurs in an industrial environment. To address this issue, a new time-domain diagnostic algorithm is developed and presented herein for monitoring of gear faults, which shows an improved fault extraction capability from such measured vibration signals. This new time-domain fault detection method combines the fast dynamic time warping (Fast DTW) as well as the correlated kurtosis (CK) techniques to characterize the local gear fault, and identify the corresponding faulty gear and its position. Fast DTW is employed to extract the periodic impulse excitations caused from the faulty gear tooth using an estimated reference signal that has the same frequency as the nominal gear mesh harmonic and is built using vibration characteristics of the gearbox operation under presumed healthy conditions. This technique is beneficial in practical analysis to highlight sideband patterns in situations where data is often contaminated by process/measurement noises and small fluctuations in operating speeds that occur even at otherwise presumed steady-state conditions. The extracted signal is then resampled for subsequent diagnostic analysis using CK technique. CK takes advantages of the periodicity of the geared faults; it is used to identify the position of the local gear fault in the gearbox. Based on simulated gear vibration signals, the Fast DTW and CK based approach is shown to be useful for condition monitoring in both fixed axis as well as epicyclic gearboxes. Finally the effectiveness of the proposed method in fault detection of gears is validated using experimental signals from a planetary gearbox test rig. For fault detection in planetary gear-sets, a window function is introduced to account for the planet motion with respect to the fixed sensor, which is experimentally determined and is later employed for the estimation of reference signal used in Fast DTW algorithm.     

Dynamic analysis for a planetary gear with time-varying pressure angles and contact ratios

In this study, the dynamic responses of a planetary gear are analyzed when component gears have time-varying pressure angles and contact ratios caused by bearing deformations. For this purpose, this study proposes a new dynamic model of the planetary gear, in which the pressure angles and contact ratios change with time. The main difference from previous studies is that the present study regards the pressure angles and contact ratios as time-varying variables, while previous studies regarded them as constants. After nonlinear equations of motion for the planetary gear are derived, the dynamic responses are computed by applying the Newmark time integration method. The time responses for the present and previous studies are compared to show the effects of the time-varying pressure angles and contact ratios on the dynamic behaviors of a planetary gear. In addition, the effects of bearing stiffness on the pressure angles and contact ratios are also analyzed.     

Dynamic analysis for a pair of spur gears with translational motion due to bearing deformation

In this study, the dynamic response of a pair of spur gears is analyzed when the gear set has translational motion due to bearing deformation. A new dynamic model for the gear set, considering translational motion, is proposed, in which the distance between the centers of a pinion and a gear varies with time. Therefore, the proposed model regards the pressure angle and the contact ratio as time-varying variables, while the previous model regards them as constants. After deriving nonlinear equations of motion for the gear set, the dynamic responses are computed by applying the Newmark time integration method. This paper claims that the new model produces more accurate dynamic responses in comparison to those of the previous model. Some dynamic response differences between the new and previous models are demonstrated, and the effects of damping and stiffness upon the dynamic responses are also investigated.     

Prediction of airborne radiated noise from lightly loaded lubricated meshing gear teeth

This paper introduces a novel analytical method for determination of gear airborne noise under lightly loaded conditions, often promoting gear rattle of loose unengaged gear pairs. The system examined comprises a single gear pair, modelled through integrated contact tribology and inertial transient dynamics. Lubricant film thickness, structural vibration and airborne gear noise are predicted and correlated with experimental measurements undertaken in a semi-anechoic environment. Good agreement is noticed between the numerical predictions and the experimental measurements. The presented model is capable of estimating the airborne radiated gear noise levels and the dynamic behaviour of gear pairs under different operating conditions, with superimposed impulsive input speed harmonics.     

Dynamic simulation of planetary gear set with flexible spur ring gear

Ring gear is a key element for vibration transmission and noise radiation in the planetary gear system which has been widely employed in different areas, such as wind turbine transmissions. Its flexibility has a great influence on the mesh stiffness of internal gear pair and the dynamic response of the planetary gear system, especially for the thin ring cases. In this paper, the flexibility of the internal ring gear is considered based on the uniformly curved Timoshenko beam theory. The ring deformation is coupled into the mesh stiffness model, which enables the investigation on the effects of the ring flexibility on the mesh stiffness and the dynamic responses of the planetary gear. A method about how to synthesize the total mesh stiffness of the internal gear pairs in multi-tooth region together with the ring deformation and the tooth errors is proposed. Numerical results demonstrate that the ring thickness has a great impact on the shape and magnitude of the mesh stiffness of the internal gear pair. It is noted that the dynamic responses of the planetary gear set with equally spaced supports for the ring gear are modulated due to the cyclic variation of the mesh stiffness resulted from the presence of the supports, which adds more complexity in the frequency structure.     

Pseudo analytical solution to time periodic stiffness systems

An analytical form of state transition matrix for a system of equations with time periodic stiffness is derived in order to solve the free response and also allow for the determination of system stability and bifurcation. A pseudoclosed form complete solution for parametrically excited systems subjected to inhomogeneous generalized forcing is developed,based on the Fourier expansion of periodic matrices and the substitution of matrix exponential terms via Lagrange-Sylvester theorem. A Mathieu type of equation with large amplitude is presented to demonstrate the method of formulating state transition matrix and Floquet multipliers. A two-degree-of-freedom system with irregular time periodic stiffness characterized by spiral bevel gear mesh vibration is presented to find forced response in stability and instability. The obtained results are presented and discussed.     

ARJ21客机降落阶段起落架噪声试验研究

为了测量ARJ21客机的起落架噪声,在飞行现场分别采用改进的频域波束形成和解卷积算法对降落阶段的起落架噪声进行了测量。通过比较两种算法发现,解卷积算法比改进的频域波束形成算法具有更好的声源识别能力。为了提高传声器的利用率,设计了多臂螺旋阵,并且利用线性插值消除了多普勒效应。根据主起落架和前起落架的分布位置不同,将声源识别区域划分为两部分,在140—800Hz范围内对不同频段的1/3倍频程的起落架噪声进行了测量。结果发现:在250 Hz以上频段,主起落架为主要噪声源,且在中心频率500 Hz的1/3倍频程内为唯一强声源;前起落架在中心频率630 Hz的1/3倍频程内为主要噪声源。通过试验得到了主起落架和前起落架噪声在不同频段的分布特点,为起落架降噪设计提供了支持。      

A Simplified Formulation to Estimate Influence of Gearbox Parameters on the Rattle Noise

Occurrence of gear rattle in transmission systems can result in severe vibration and noise, which in applications such as automobiles is an important source of user discomfort. As a result , the reduction of the rattling noise has attracted lot of concerns. The rattling noise level is affected by several gearbox parameters, an understanding of which is essential to prevent the expensive design modifications at later stages of product development. To develop such understanding at the gearbox design stage, this paper analytically evaluates the gear parameters’ effect on the root mean square of the wheel gear acceleration under idling condition, which is known to be linearly correlated to the rattling noise level. Therefore, this evaluation allows for an investigation of the gear parameters’ influence on the rattling noise as well. This method is then verified by comparing the analytical results with the simulation results from a dynamic model built in SIMPACK as well as previously published experimental results. Thus, the proposed analytical evaluation method can optimize the gearbox specifications at the design stage to reduce the gear rattle noise level.     

Theory of electronic and optical properties for different shapes of InAs/In0.52Al0.48As quantum wires

In this work, we propose an efficient method to investigate optical properties as well as their dependence on geometrical parameters in InAs/InAlAs quantum wires. The used method is based on the coordinate transformation and the finite difference method. It provides sufficient accuracy, stability and flexibility with respect to the size and shape of the quantum wire. The electron and hole energy levels as well as their corresponding wave functions are investigated for different shape of quantum wires. The optical transition energies, the emission wavelengths and the oscillator strengths are also studied.