波片和偏振片对外差干涉仪非线性的影响

为了减小外差干涉仪的非线性误差,必须明确波片和偏振片对非线性误差的影响机理。通过理论分析和试验发现,波片和偏振片位于偏振分光镜之前和之后对非线性的影响是不同的。如果把有误差的波片和偏振片放置在偏振分光镜前面,其误差将100%地引入非线性。如果将相同的这些光学元件安装在干涉仪里面,有可能影响非线性,但通常在高阶误差范围内。     

A model of the construction of multielement reflectors for ultrasonic apparatus

A theoretical model of the construction of multielement reflectors in the range in which the amplitudes of the echo signals from +6 dB to −20 dB are formed in steps of 0.5, 1.0, 1.5, and 2.0 dB is presented. The use of multielement reflectors provides uniformity of tuning and systematic operative control of the nonlinearity of the inclined converter – electroacoustic channel system of ultrasonic apparatus, which enables the reliability and efficiency of ultrasonic control to be increased considerably.     

A Precision Dc Potentiometer Microwave Insertion Loss Test Set

A simple, accurate microwave test set has been devised for measuring coaxial or waveguide insertion loss. The instrument is designed primarily for highest precision with low attenuations. It is composed almost entirely of commercially available equipment and components, is portable, and can be operated in the laboratory or in the field from ac mains or batteries. The precision of the measurements depends on the connector type and value of the component measured. The precision is better than 0.0001 dB when measuring low insertion losses, discounting the error due to the connectors. Equipment nonlinearity reduces the precision in proportion to the measured attenuation in dB. The frequency range covered is 10 MHz to 40 GHz, which can be extended to 90 GHz with slight perfornance degradation.     

应变梯度对传感器弹性体非线性的影响及应用

以２０吨电阻应变柱式传感器为例，应用有限元理论和计算机仿真技术研究弹性体工作区应变情况，指出了应变梯度的存在，分析了应变梯度及其它因素对传感器非线性的影响，推导出传感器非线性误差计算公式。提出了传感器弹性体优化设计的新方法，并应用于５０吨电阻应变柱式传感器弹性体的设计，实现了应用计算机仿真技术对传感器非线性误差进行计算．预测及设计指导。     

A／D量化,非线性,微分非线性误差对非同步,准同步采样算法误差影响 …

本文提出了具有量化误差、非线性误差和微分非线性误差的Ａ／Ｄ转换器的数据学模型,在该数学模型的基础上,仿真分析了非同步采样法、准同步采样递推算法各种情况下的误差,包括功率测量中电压线性、电流线性、相位变化误差及电压测量的误差。由于分析中的条件更近接应用中的实际情况,因此,仿真分析的结论为测量仪器设计中的误差估计提供了重要依据。     

A Theoretical-Experimental Method of Estimating the Nonlinearity of Precision Digital-Analog Converters

The proposed method of estimating the nonlinearity of highly accurate digital-analog converters is based on subdivision of the conversion range of the converter into several parts. It is proposed to calculate the nonlinearity at the beginning and end of each part from the measured increments of the output signal of the converter. An analysis of the error in estimating the nonlinearity of the converter is given.     

Phase-measuring interferometry: new methods and error analysis

New methods that can be used to determine phase in phase-stepping interferometry are presented. It is shown that a combination of some of these methods can be used to reduce the error introduced by phase-stepper miscalibration and nonlinearity. Moreover these new algorithms can also be used to detect the presence of miscalibration or phase-shifter nonlinearity. A simplified approach to understanding the error introduced by miscalibration and nonlinearity of the phase stepper and its reduction in phase-shifting interferometry is also presented.     

Influence of the architecture on ADC error modeling

The influence of the architecture on analog-to-digital converter modeling is investigated for the three most widespread architectures: integrating, successive approximations, and flash. The effects of main error sources are analyzed in terms of integral and differential nonlinearity with the aim of setting up a unified error model. Such a model is useful both to economically generate a look-up table for error correction and to quickly produce diagnosis models for fault detection and isolation. Numerical simulations aimed to show the model effectiveness and experimental tests carried out to validate the model are discussed     

大范围二维纳米位移台的控制及非线性校准的实验研究

搭建了基于激光干涉仪测量原理的三轴微位移测量系统,对大范围二维纳米位移台的控制及非线性校准进行实验研究。介绍了双频激光干涉仪测量系统的构成;编写了纳米位移台的控制程序和激光干涉仪数据采集程序;阐述了位移台的非线性校准方法,并通过实验对比了多项式三阶拟合和三阶分段拟合的差别,验证了校准方法的准确性。实验表明:使用三阶分段拟合的校准方法效果更好,校准前,x轴的最大非线性误差为4.052μm,y轴的最大非线性误差为2.927μm;校准后,x轴的最大非线性误差为15nm,y轴的最大非线性误差为17nm,仅为原始非线性误差的1%。     

Numerical study of methods of linearization of the output characteristics of radio-frequency sensors of the level of dielectric media

Different constructions of the sensing elements of radio-frequency level sensors based on sections of long lines are numerically investigated by means of the Matlab program for the purpose of minimizing the measurement error caused by the nonlinearity of the output characteristic. It is shown that the nonlinearity is lowest for U-shaped designs. The nonlinearity factor KN may be regulated by varying the capacitance of a correcting capacitor connected to the input of the sensing element and (or) the length of one of the sections of the long line. In selecting an optimal capacitance of the correcting capacitor KN ≤ 0.15% for control media with dielectric permittivity in the range 2.2–30.     

偏振分光镜传输系数不等对非线性误差的影响

为了减小激光外差干涉非线性误差,必须考虑偏振分光镜透过率和反射率不等对非线性误差的影响。通过分析两臂透过率与反射率不等对测量信号的影响,推导出两臂反射率与透过率不等对激光外差干涉非线性误差一次谐波和二次谐波影响的理论模型。仿真结果表明,透过率与反射率不等将严重的影响非线性误差一次谐波的大小,当反射率为1而透射率由1变为0．85时,其非线性误差由0、56nm增加到2．03nm,同时非线性误差只是一次谐波和二次谐波的简单叠加。仿真结果表明调整偏振分光镜的旋转角度误差能够有效的消除两臂透过率与反射率不等对非线性误差的影响。为进一步指导调整减小或消除非线性误差提供了理论依据。     

Correction of detector nonlinearity for the balloonborne Michelson Interferometer for Passive Atmospheric Sounding

The detectors used in the cryogenic limb-emission sounder MIPAS-B2 (Michelson Interferometer for Passive Atmospheric Sounding) show a nonlinear response, which leads to radiometric errors in the calibrated spectra if the nonlinearity is not taken into account. In the case of emission measurements, the dominant error that arises from the nonlinearity is the changing detector responsivity as the incident photon load changes. The effect of the distortion of a single interferogram can be neglected. A method to characterize the variable responsivity and to correct for this effect is proposed. Furthermore, a detailed error estimation is presented.     

Intensity-ratio error compensation for triangular-pattern phase-shifting profilometry

We present an intensity-ratio error-compensation method to decrease the measurement error caused by projector gamma nonlinearity and image defocus in triangular-pattern phase-shifting profilometry. The intensity-ratio measurement error is first determined by simulating the measurement with the triangular-pattern phase-shifting method with ideal and real captured triangular-pattern images based on the ideal and real gamma nonlinearity functions. A lookup table that stores the intensity-ratio measurement error corresponding to the measured intensity ratio is constructed and used for intensity-ratio error compensation. Experiments demonstrated that the intensity-ratio error compensation method significantly reduced the measurement error in the triangular-pattern phase-shifting method by 28.5%.     

Dynamic Error of Rotating Flow-Rate Transducer

The dynamic error of a transducer due to the dynamic nonlinearity of the inertial rotor is considered. An estimate of the error is given and a simple method of substantially decreasing the error is proposed.     

Impairments Approximations in Assembled mmWave and Radio Over Fiber Network

The fiber nonlinearity and phase noise (PN) are the focused impairments in the optical communication system, induced by high-capacity transmission and high laser input power. The channels include high-capacity transmissions that cannot be achieved at the end side without aliasing because of fiber nonlinearity and PN impairments. Thus, addressing of these distortions is the basic objective for the 5G mobile network. In this paper, the fiber nonlinearity and PN are investigated using the assembled methodology of millimeter-wave and radio over fiber (mmWave-RoF). The analytical model is designed in terms of outage probability for the proposed mmWave-RoF system. The performance of mmWave-RoF against fiber nonlinearity and PN is studied for input power, output power and length using peak to average power ratio (PAPR) and bit error rate (BER) measuring parameters. The simulation outcomes present that the impacts of fiber nonlinearity and PN can be balanced for a huge capacity mmWave-RoF model applying input power carefully.     

Working attenuation standards in the decimeter and centimeter wave range based on fixed coaxial attenuators

The main measurement error components of fixed coaxial attenuators were investigated. Numerical values of the mismatch, random, and flange errors were obtained. The resultant error can be reduced to 0.01 dB/10 dB at frequencies below 12 GHz. Translated from Izmeritel'naya Tekhnika, No. 10, pp. 42–44, October, 1999.     

Calibration of the standard ratio devices of integrated standards at rf and microwave frequencies

The results are given of developments and investigations of an automated apparatus for calibrating attenuators in the frequency range 10 MHz to 18 GHz for use as working attenuation standards. It is shown that automated apparatus for calibrating microwave wattmeters is suitable for calibrating coaxial fixed and stepped attenuators with an error of lower than ±0.02 dB per 10 dB. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 45–48, May, 1997.     

Heterodyne interferometer with subatomic periodic nonlinearity

A new, to our knowledge, heterodyne interferometer for differential displacement measurements is presented. It is, in principle, free of periodic nonlinearity. A pair of spatially separated light beams with different frequencies is produced by two acousto-optic modulators, avoiding the main source of periodic nonlinearity in traditional heterodyne interferometers that are based on a Zeeman split laser. In addition, laser beams of the same frequency are used in the measurement and the reference arms, giving the interferometer theoretically perfect immunity from common-mode displacement. We experimentally demonstrated a residual level of periodic nonlinearity of less than 20 pm in amplitude. The remaining periodic error is attributed to unbalanced ghost reflections that drift slowly with time.     

应用Hilbert变换判断框架结构非线性的方法

研究了在地震作用下应用Hilbert变换判断框架结构非线性的方法。提出利用结构频率响应函数幅值曲线和其Hilbert变换后幅值曲线的均方误差值作为衡量结构相对非线性程度的指标，并研究了该指标与输入地震波峰值之间的关系。建立了基于Bouc-Wen模型的框架结构非线性反应计算模型，在考虑测量噪声影响的情况下利用此模型对不同峰值地震作用的框架结构进行了数值仿真分析。结果表明，运用Hilbert变换可以有效地判断结构的非线性状态，所提出的均方误差指标能较准确地确定结构的相对非线性程度，该方法在结构的振动控制和健康监测中具有一定的参考价值。     

光学倍频影响激光外差干涉测量精度的机理

为了同时提高激光外差干涉测量的分辨力和精度,必须深入分析光学倍频对激光外差干涉测量精度的影响机理。在此基础上,建立了光学倍频相位测量模型,从理论上证明,光学倍频能够实现对激光外差干涉信号的细分,提高测量分辨力。光学倍频改变非线性误差的相位而使非线性误差减小,但同时改变了激光干涉多普勒频移的v/c平方项,使得残余累计误差增大。仿真结果表明,光学N倍频使非线性误差减小到原来的1/N,但使残余累计误差增大N2倍。因此,光学倍频仅适用于低速测量的场合。