傅里叶变换红外光谱仪动镜倾斜误差分析

通过建立傅里叶变换光谱仪中动镜、定镜和干涉面的坐标对应关系,对动镜存在多个方向倾斜时的干涉光路进行了详细的分析。建立了非准直状态下干涉面光强分布的二维数学模型,确立了干涉图函数的数学表达式,从调制度、相位误差和频率噪声的角度,对动镜倾斜造成的影响进行了系统分析。在动镜的运动中,左右方向的倾斜和俯仰方向的倾斜对系统的影响彼此具有独立性,又具有叠加性;干涉图中初相位因子随光程差改变缓慢变化或快速变化,对相位误差的影响也不全相同。在倾斜误差分析的基础上,对动镜的最大倾斜角度和减少误差的方法进行讨论,并提出了两种动态准直校正的思路。     

傅里叶变换红外光谱仪中立方反射镜特性分析

在傅里叶变换红外光谱仪中,用立方反射镜作为动镜的光路系统比平面镜时的情形复杂。通过建立系统的数学模型分析光路,确定了干涉信号的数学表达式;从干涉图调制度的角度对系统在非理想状态下的运动误差容限以及安装误差容限进行了分析。结果表明,与动镜和定镜都采用角反射体的系统相比较,该系统动镜运动中其偏摆和顶点横移不会对干涉图产生影响;与动镜为平面镜的系统相比较,该系统不需要对动镜的动态校正就能满足调制度判据要求。     

相位检测法定镜自适应校正技术

为保持傅里叶变换光谱仪在动镜运动和外界震动等恶劣条件下动镜和定镜间的准直性,采用了相位检测法检测准直性误差的定镜自适应校正技术。介绍了相位检测法的基本原理和实现自适应校正的途径以及自适应校正系统的基本结构。采用高速压电倾斜镜作为驱动补偿元件,分析了相位检测精度对校正精度的影响。实验结果表明,采用自适应校正后系统干涉效率明显提高。     

柔性铰链支撑式动镜的误差分析

柔性铰链支撑式动镜系统广泛应用于便携式、工程在线测量的傅里叶变换红外光谱仪中。而在运动过程中,柔性铰链与动镜的微弱形变会给动镜引入不同程度的误差。通过建立数学模型,并结合调制度与初相位来分析系统存在的误差。结果表明:动镜的动态垂直度误差会严重影响信号干涉的质量,动镜行程、速度是其影响因素。可通过设计上的优化来减小其影响,对动镜的制作有借鉴意义。     

基于拟合算法的傅里叶变换光谱仪光谱反演

在傅里叶变换光谱仪(FTS)中,精确获取每个干涉信号采样点处的光程差是获取光谱图的关键。动镜速度的波动会对等时间采样造成采样误差,而当目标光源波长较短时无法直接利用传统方法进行等光程差采样。分析了速度波动误差对光谱的影响,并提出了一种基于拟合算法计算干涉信号每个采样点处光程差的方法,在动镜速度波动较大的情况下对可见光波段的干涉信号进行采样反演。实验结果表明,此方法准确度高,适用于各种傅里叶变换光谱仪。     

激光跟踪仪转镜倾斜误差的标定及修正

为了提高激光跟踪仪的测量精度,分析了跟踪仪的几何结构误差,重点研究了其转镜倾斜误差的标定和修正方法。利用矢量分析和坐标转换相结合的方法建立了跟踪仪转镜倾斜误差模型,推导出了跟踪仪几何空间坐标修正公式,并基于自准直仪、多面棱体和可调反射镜建立了高精度误差标定装置。利用标定装置分析了误差标定方法,通过系统仿真研究了转镜倾斜误差对系统测角误差及最终坐标测量误差的影响。利用误差标定实验检测出的系统转镜倾斜误差约为4″,将其带入坐标修正公式,并与修正前的坐标进行了比对分析。对比结果显示,经误差修正后系统空间坐标测量误差可减小约2×10-6,验证了转镜倾斜误差标定和误差修正方法的有效性,表明利用该方法可在不改变系统硬件结构的基础上提高测量系统的测量精度。     

液晶自适应光学系统中倾斜镜的建模与控制

为了提高液晶自适应光学系统的波前探测精度,研究了该系统中倾斜镜的校正方法。分析了液晶自适应光学系统中各环节的物理特性,利用拉格朗日方程给出了倾斜镜系统模型的基本结构;采用子空间辨识方法确定了模型参数,同时利用非线性最小二乘算法对子空间模型的频域特性进行了修正。修正后模型幅频特性均方根误差为0.024 5dB,相频特性均方根误差为1.9008°。引入Smith控制策略来解决倾斜镜校正波前整体倾斜过程中的时滞问题;利用子空间辨识出的模型分别进行Smith和PID的仿真和实验验证,得到的结果与仿真计算相吻合,即在相同稳定裕度的情况下,采用Smith补偿PID算法的误差抑制带宽比传统PID算法提高了23.97%。最后,用提出的方法对一组湍流整体倾斜信号进行了校正。结果显示:采用Smith补偿PID算法的控制精度比传统PID算法提高了21.03%,证实提出的方法优化了倾斜镜的校正精度,保证了开环液晶自适应光学系统的波前探测精度。     

拼接镜主动光学共焦实验

为了实现对拼接镜的共焦调整,建立了拼接镜主动光学共焦实验系统。实验中,拼接镜由3块对边长300mm的正六边形子镜组成,子镜为球面,曲率半径为2000mm。采用Shack-Hartmann传感器进行共焦测量,用6个微位移平移台对两块子镜的离焦和倾斜进行调整。每个子镜对应Shack-Hartmann传感器的36个子孔径,用子孔径产生的像点位置偏移计算子镜之间的共焦误差。通过微位移平台调整,可控制子镜的轴向离焦误差优于1μmrms,倾斜误差在两维方向上均优于0.02″rms。实验表明,该方法适用于大型拼接镜面望远镜的共焦标定和实时调整。     

干涉仪成像畸变引起测量误差的校正方法

根据光学系统的波像差理论和干涉检测原理,分析了干涉仪系统的成像畸变对测量结果的影响,提出了对干涉仪系统的成像畸变进行标定和校正的方法.重点讨论了被测面的摆放存在倾斜和离焦两种情况下产生的测量误差,并提出了误差校正方法.实验中对同一个被测面进行多次测量,结果显示,干涉图样为3个条纹时的面形测量结果为30.96nm PV,...     

齿轮装夹倾斜误差对齿轮精度检测的影响研究

齿轮是机械传动中的重要零部件,制造精度要求高。对齿轮的使用要求也较高,常通过对齿轮精度测设备进行了分类介绍,针对齿轮装夹倾斜产生误差影响齿轮精度检测的问题,基于齿轮装夹定位原理,分析造成齿轮装夹倾斜误差的原因,构建含误差的齿面模型,分析装夹倾斜误差对齿轮偏差精度影响程度,齿轮装夹倾斜角度,通过齿轮检测中心对齿轮倾斜角度的偏差指标进行检测,可得出装夹倾斜误差对齿轮检测精度影响较大,还需进一步完善了齿轮装夹工艺理论。     

Zone-plate inteferometer to measure the positioning error of a cutting tool

A simple type of zone-plate interferometer has been developed to measure precisely the positioning error of a cutting tool. Interference fringes obtained by the interferometer are little affected by air turbulence in the optical paths and by machine vibrations. The shape of the mirrors surface being tested is spherical and is manufactured with an ultraprecision lathe. A zone plate is set at the midposition between the vertex of the spherical mirror being tested and the center of curvature of the mirror. The error in the shape of the mirror and the positioning error of the tool can be determined by analyzing the interference fringes. Two spherical concave mirrors were measured. One mirror was manufactured with a tool that had same positioning error. The positioning error was observed as distortion of the interference fringes. The images obtained by the zone-plane interferometer agree well with the images obtained by a Fizeau interferometer and a computer simulation based on the experimental results. The other mirror was manufactured with the tool after the positioning error had been eliminated, based upon the results of the above experiments. The interference fringes of the mirror show no distortion, and the error in the shape of the mirror is small.     

Critical alignments in plane mirror interferometry

Each axis of a plane mirror interferometer has three associated measurement vectors: the interferometer beam, mirror normal, and axis of measurement. The transducer axis of a plane mirror interferometer target is the mirror normal. This contrasts with a retroflector for which the transducer axis is the interferometer beam. The classical cosine error in x-y plane mirror interferometry is removed by the orienting the mirror normals in the travel plane. The axes do not have to be orthogonal to eliminate cosine error.     

基于保偏镜组的外差干涉测量几何误差分析

角锥棱镜由于本身缺陷会导致失偏效应。在平面镜外差干涉仪中,使用一种保偏反射镜组替代角锥棱镜,以减小外差干涉仪的非线性误差。根据这个平面镜外差干涉仪的基本光路图,基于偏振分光棱镜和角锥棱镜的基本光学特性,分析了平面镜外差干涉仪中3个偏振分光棱镜偏摆角、仰俯角和滚动角,保偏反射镜组中2个偏振分光棱镜之间的间距和角度,以及角锥棱镜的偏摆角和仰俯角等误差对干涉仪的影响。推导出外差干涉仪中各个光学元件的最大安装误差,并规定好其加工精度,确保外差干涉仪性能。     

A high-precision five-degree-of-freedom measurement system based on laser collimator and interferometry techniques

A novel sensitivity improving method for simultaneously measuring five-degree-of-freedom errors of a moving linear stage is proposed based on collimator and interferometry techniques. The measuring principle and parameters of the system are analyzed theoretically. The experimental results proved that the resolution of the linear displacement of the proposed method has twice that of the current linear interferometer, and the resolutions of the two-dimensional straightness error measurement can be improved by a factor of 8 compared with the movement of the retroreflector itself by using multireflection and lens magnification. The resolutions of the pitch and yaw angular error measurement have been improved by a factor of 10 compared with the rotation of the plane mirror itself by using expander lenses. The whole measuring system is characterized of simple structure, small volume, and high precision. The moving component of the measurement system is wireless, which eliminates the errors and inconvenience introduced by the wire connection. Calibration and comparison tests of this system compared with Renishaw laser interferometer system have been carried out. Experimental results show good consistency for measuring a linear guide way.     

光栅干涉仪的运动误差原理

本文应用衍射光栅干涉仪的半波相位差面原理模型,说明光栅摆动误差引起的干涉条纹变化情况,进而分析得出光栅干涉仪运动误差公式。可作为设计和应用此种干涉仪的依据之一。     

Shape measurements of mirror surfaces with a lateral-shearing interferometer during machine running

A common path lateral-shearing interferometer with a minimum number of optical components has been developed. Because the interferometer is little affected by mechanical vibrations and air turbulence, it can be mounted on an ultraprecision lathe and can be used to measure the shapes of workpieces. A plane parallel glass plate is used to shear the wavefront under test in the interferometer. To analyze the interference fringes obtained by the interferometer precisely, a fringe-scanning method using a slight tilt of the glass plate is used. Zone plates that are computer-generated holograms are used to measure spherical and aspherical surfaces with the interferometer. A spherical and a parabolic concave mirror were measured with the interferometer. The spherical mirror was also measured by a Fizeau interferometer to compare the error with that measured by the lateral-shearing interferometer. The experimental results agreed well with those measured by the lateral-shearing interferometer.     

A Scanning System for the Michelson Interferometer with a Linear Motor Based on a Permanent Magnet

A scanning system for the moving mirror of the Michelson interferometer is described. The system is based on a linear motor with a ring-shaped permanent magnet. The operating velocity of the mirror is about 4 cm/s; the shift from the equilibrium position, ±2.5 mm. A mathematical model of the control system is discussed. The electrical schematic circuit of the control unit and tests results of the control system are described.     

Development in laser interferometry for position sensing

Interferometric developments which improve the performance of the laser interferometer as a position sensing device are described. The double pass attachment is an optical accessory which doubles the resolution of the Hewlett-Packard linear and plane mirror interferometers. Unlike previous attempts to extend resolution optically, this device does not fold just one of the two interfering beams and hence does not introduce error due to its own motion. Simple addition of a quarter wave plate to the attachment gives a differential version of the plane mirror interferometer. Various configurations of this differential interferometer, and their application to machine tools and to integrated circuit lithographic and inspection equipment, are discussed. A new ‘wavelength tracking’ device, based on differential interferometry, directly and precisely monitors changes in laser wavelength inside a highly stable mechanical cavity. Easily incorporated as an additional interferometer axis, the device improves compensation for changes in laser wavelength.