合肥光源逐束团横向反馈系统

 介绍了在合肥光源研制的一套横向(x, y方向)高频、宽带逐束团测量和反馈系统,以及抑制耦合束团不稳定性的初步实验。其中重点介绍了在该系统研制过程中所涉及的部分关键技术：矢量运算模块的开发使得反馈系统的调试简易方便;Notch滤波器用于滤除反馈信号中的直流分量以及回旋频率分量,节省反馈功率;激励条带的研制。初步的反馈实验结果表明：反馈系统开启后不稳定性振荡得到抑制。     

合肥光源横向反馈系统的改进与试验结果

介绍了在合肥光源横向模拟反馈样机系统进行的改造和升级。主要包括前端束流位置信号处理模块的重建和与直流成分剔除单元模块。同时还进行了信号矢量合成模块的优化与改造、增加独立可调增益模块以及优化信号传输线路在内的重要改进。对改进后的反馈系统进行了抑制耦合束团不稳定性试验,相关试验数据分析结果表明,反馈系统提供的注入阻尼率提高了一个数量级。     

托卡马克装置反馈稳定区(Ⅱ) 实验部份

本文给出在CT-6B托卡马克装置上同时用两套快速反馈系统,加热场反馈系统和垂直场反馈系统,所得的各种反馈稳定区实验结果,并与理论计算结果进行了比较,实验的稳定区稍小于理论值。     

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介绍了HL-2A等离子体密度反馈控制系统的设计和实现。从密度反馈控制系统的设计原理、硬件设计和软件设计几方面,论述了等离子体密度反馈系统在HL-2A装置上的实现。实验证明,该系统实现了维持稳定可靠的密度波形的要求。     

反馈抑制HLS注入过程中β振荡的尝试

为了提高注入束流的积累,抑制由于注入系统误差所引起较大的β残余振荡是非常有必要的.本文较系统地介绍了合肥光源(HLS)抑制注入β振荡反馈系统的设计思想、原理和线路,并提供了它的初步实验结果.作为原理论证和预研,我们使用了一个相对简单的模拟滤波器和移相器对Kicker过程激发的β振荡进行反馈,看到了明显的抑制作用.为以后研制低频和高频反馈系统,研究抑制束流的横向和纵向不稳定性打下基础.     

光学信息处理讲座第十一讲 相干光学反馈技术

电子学中的反馈技术在光学领域中的引入,给光学信息处理带来了灵活性.本文着重讨论相干光学反馈系统. 相干光学反馈的基本原理:在系统输出端取出部分二维输出信号,将其与输入信号叠加后,重新输入系统,并对其二维空间频谱进行调制,得到一个非线性的、可变的系统传递函数. 实现相干光学反馈技术的光学系统有多种形式,其中主要包括二反射镜型反馈系统[1]、四反射镜型环形反馈系统[2]、平行平板型法布里-拍罗干涉仪反馈系统[3]和共焦球面型反馈系统等[4]. 一、二反射镜型反馈系统[4] 二反射镜型反馈系统是在常规的相干光处理系统(4f系统)的基础…     

托卡马克装置反馈稳定区(Ⅱ)——实验部份

本文给出在CT-6B托卡马克装置上同时用两套快速反馈系统,加热场反馈系统和垂直场反馈系统,所得的各种反馈稳定区实验结果,并与理论计算结果进行了比较,实验的稳定区稍小于理论值。 关键词：     

BEPCII横向束流反馈系统前端电子学

选择了一台商业化的前端电子学RFTF（radio frequency front-end for transverse feedback system）用于BEPCII横向束流反馈系统, 这是跟进世界先进加速器技术的具体实施。在BEPC同步运行模式下对RFTF的性能进行了测试实验，结果表明使用RFTF可以得到理想的波形，能够满足BEPCII横向反馈系统的需要，但是，当储存环出现不稳性时，系统无法正常工作，这就要求BEPCII纵向不稳定很小或者用纵向反馈系统来抑制存在的纵向不稳定。     

双中频超外差式信号补偿闭环反馈系统的设计

为补偿搜索雷达发射机探测信号或系统的不稳定性,提出了一种雷达发射机的双通道信号补偿闭环反馈系统;该反馈系统采用双中频超外差式结构,将发射机的高频发射信号两次下变频,得到的中频信号反馈到雷达发射机前端,与发射机一起构成闭环控制系统;中频信号对发射机输入端的中频信号实时检测,以补偿发射信号的幅度和相位不稳定性,从而提高了搜索雷达对探测目标的高精度测量;系统应用结果证明,该系统方案稳定可靠,具有一定的实用价值和参考意义。     

合肥光源数字横向逐束团反馈系统

为了克服横向耦合束团不稳定性对合肥光源的不利影响,在合肥光源(HLS)研制了一套数字横向逐束团反馈系统。该系统使用直接采样前端,同时针对合肥光源水平方向工作点和垂直方向工作点太过接近的情况,修改了数字处理器的FPGA程序,使得单个处理器能够实现独立的双通道反馈。束流试验验证了反馈系统能有效抑制横向不稳定性,并可以提高注入流强。     

Phase measurement accuracy of feedback interferometers

Feedback interferometers are described with specific reference to potential applications in micro-machines. A theoretical analysis is developed to determine the linearity, stability, and noise performance of this type of interferometer. The theoretical analysis was tested using a prototype high-precision feedback interferometer which showed that, at a feedback loop gain which enabled the system to track 6 fringes, the linearity of the interferometer was better than λ/100 and single phase measurements could be made with an accuracy of λ/80.     

基于光纤3×3耦合器干涉仪及相位跟踪的振动测量系统

研究了基于光纤3×3耦合器迈克尔逊干涉仪及反馈跟踪相位变化的振动测量系统。该测量系统包含两个反馈控制环节:一个反馈控制环节用于补偿由于环境干扰引起的相位随机漂移;另一个反馈控制环节用于跟踪由于振动引起的相位变化,从而实现对振动幅值及振动方向的测量。该系统可对频率为1.5~200Hz的振动进行测量,测量分辨率可达到10nm。     

Adaptive wave-front correction by means of all-optical feedback interferometry

A novel adaptive wave-front correction system based on an all-optical feedback interferometer is described. In this system the two-dimensional output fringe intensity from a Mach-Zehnder interferometer with large radial shear is optically fed back to an optically addressed phase-only liquid-crystal spatial light modulator. Consequently, without a separate aberration-free reference wave, the modulator phase approximates the conjugate of the interferometer phase that is directly related to the phase of the input aberrated wave front, so this system is applicable in adaptive optics. We successfully achieved real-time correction of aberrated wave fronts: A diffraction pattern that was seriously distorted because of aberrations was transformed into a diffraction-limited spot immediately after the feedback loop was closed.     

Active phase stabilization in a two-fiber interferometer

We report on the frequency spectrum of phase fluctuations of a two fiber interferometer in a normal laboratory environment. A feedback system in connection with a piezo regulator is used for compensation of the fluctuations. The resulting stability of the compensator has been measured.     

Laser diode interferometer used for measuring displacements in large range with a nanometer accuracy

In this paper, the displacement of an object is measured with a photothermal phase-modulating laser diode interferometer. A feedback control system is designed to reduce the measurement errors caused by the fluctuations in the optical wavelength of the laser diode and the vibrations of the optical components in the interferometer. A new method is proposed to enlarge the measuring range of displacement. Using this method, the measuring range is enlarged from half wavelength to nearly 125 μm and the measurement accuracy is about 1 nm. The simulation and experimental results have shown the usefulness of the method and the feedback control system.     

Surface-profile measurement by means of a polarization Sagnac interferometer with parallel optical feedback

We describe a novel feedback interferometer for real-time, unambiguous measurement of surface profiles that consists of a polarization Sagnac interferometer and an optically addressed phase-only spatial light modulator. In this system the output intensity from the Sagnac interferometer is optically fed back to the phase modulator placed in one arm of the interferometer, which produces a sawtooth fringe intensity profile (instead of the conventional cosinusoidal one) that is directly and unambiguously related to the surface profile. Preliminary experimental results demonstrate the feasibility of applying this system to surface-profile measurement.     

Vibration-displacement measurements with a highly stabilised optical fiber Michelson interferometer system

A highly stabilised vibration-displacement measurement system, which employs fiber Bragg gratings (FBGs) to interleave two fiber Michelson interferometers that share the common-interferometric-optical path, is presented. The phase change in the interferometric signals of the two fiber Michelson interferometers have been tracked, respectively, with two electronic feedback loops. One of the fiber interferometers is used to stabilise the system by the use of an electronic feedback loop to compensate the environmental disturbances. The second fiber interferometer is used to perform the measurement task and employs another electronic feedback loop to track the phase change in the interferometric signal. The measurement system is able to measure vibration-displacement and provide the sense of direction of the displacement. The frequency range of the measured vibration-displacement is from 0.1 to 200 Hz and the measurement resolution is 10 nm.     

Recent developments in laser-diode interferometry

Laser-diode (LD) interferometry based on heterodyne techniques is described. The developments covered include: sinusoidal phase- modulating, distance-measuring feedback and phase-shifting interferometry. The wavelength is controlled by the laser injection current and is continuously or stepwise changed to introduce a time-varying phase difference between the two beams of an interferometer with unbalanced optical path lengths. A feedback interferometer is described with electronics to stabilize the phase shift and to lock the interferometer on a preset phase condition by controlling the injection current of the LD. An automated phase-measuring interferometric system is developed in which the laser current is changed to synchronize intensity data acquisition with the clocks of a charge-coupled device. A typical experimental result shows measurements of the profile of a diamond- turned Al surface.     

光热正弦相位调制干涉仪中相位的抗干扰测量

在正弦相位调制半导体激光干涉仪中,半导体激光波长随注入电流和温度漂移而产生相位测量误差,同时干涉仪的机械振动和干涉仪两臂中的空气扰动也会引入相位误差,在已有光热正弦相位调制干涉仪中引入反馈机制,有效地降低了上述误差,增强了干涉仪的抗干扰能力,使用此干涉仪测量了物体的位移,测量结果表明这种方法可以有效地提高相位的测量精度。     

A microchip laser feedback interferometer with nanometer resolution and increased measurement speed based on phase meter

We introduce a new signal processing method based on phase meter into heterodyne microchip Nd:YAG laser feedback interferometer. The nanometer resolution and a higher measurement speed are realized. The factors determining the accuracy are analyzed. The displacements of the Physik Instrumente nanopositioning system and two piezoelectric transducers were measured. Experimental results indicate laser feedback interferometer’s ability of measuring nanoscale displacement and present promising application prospects in noncooperative targets measurement.