A Laser Interference System for Detecting Gravitational Waves

New principles of a gravitational wave detection system based on the use of pendulum-type laser strainmeters (LSMs) spaced by a large distance are discussed. By arranging three pendulum-type LSMs with 1000-m arm lengths on 316-km sides of equilateral triangle, it is possible to provide for the threshold sensitivity of this system within up to the 23rd decimal point in a frequency interval from 3 to 950 Hz for detecting extraterrestrial signals propagating at the speed of light.     

Modeling the Dynamics of a Gravitational Interferometer in the Field of the Earth

The results are given of a numerical modeling of the behavior of a Fabry–Perot–Michelson optical interferometer utilizing suspended mirrors in the variable gravitational field of the Earth. The possibility is demonstrated of separating and reconstructing the signals in the interferometer arms and of filtering the coherent noise. A prediction is made of the maximum attainable sensitivity of the apparatus to variations of the gravitational gradient.     

The Development of Phasemeter for Taiji Space Gravitational Wave Detection

Taiji space gravitational wave detection utilizes the laser interferometer to convert the tiny distance change into the phase fluctuation of the beat note. As to realize the sensitivity of 1 pm/√ Hz, the phasemeter needs to calculate the phase with the precision of 2πμ rad/√ Hz in the frequency range of 0.1 mHz and 1 Hz. In this paper, we report recent progress of the phasemeter for Taiji. Noises which possibly affect the measurement sensitivity are tested and discussed, especially the sampling noise and the frequency jitter. Finally, the accuracy of the phasemeter is calibrated. The result shows that the sensitivity has reached the requirement of Taiji in the frequencies between 0.01 Hz and 1 Hz, 0.1 mHz–1 mHz. Noises in the range of 1 mHz and 0.01 Hz, which have not yet depressed well, are dominated by the clocking jitter and the thermal fluctuation.     

Interferometer Utilizing Free Masses as a Device for Measuring Gravitational Gradients

A Fabry–Perot–Michelson optical interferometer utilizing suspended mirrors is considered as a device for measuring low-frequency variations of the Earth's gravitational field. The operating principles of the instrument, the system for maintaining the angular alignment of the mirrors at the operating point, and a simplified model of the gravitational field are all described. The variations of the field at the location of the interferometer are modeled numerically and estimates are given of the magnitudes of the measurable effects. The results are used as a basis for modeling the operation of the instrument as a whole.     

Length Sensing and Control in the Virgo Gravitational Wave Interferometer

The gravitational wave detector Virgo is presently being commissioned. A significant part of the last three years was spent in setting up the cavity length control system. This paper was carried out with steps of increasing complexity: locking a simple Fabry-Perot cavity and then a Michelson interferometer (ITF) with Fabry-Perot cavities in both arms, and finally recycling the light beam into the ITF. The applied strategy and the main results obtained are described     

A Compact Atom Interferometer for Future Space Missions

Atom interferometry represents a quantum leap in the technology for the ultra-precise monitoring of accelerations and rotations and, therefore, for the science that relies on these quantities. These sensors evolved from a new kind of optics based on matter-waves rather than light-waves and might result in an advancement of the fundamental detection limits by several orders of magnitude. This paper describes the current status of the Space Atom Interferometer project (SAI), funded by the European Space Agency. In a multi-pronged approach, SAI aims to investigate both experimentally and theoretically the various aspects of placing atom interferometers in space: the equipment needs, the realistically expected performance limits and potential scientific applications in a micro-gravity environment considering all aspects of quantum, relativistic and metrological sciences. A drop-tower compatible atom interferometry acceleration sensor prototype has been designed, and the manufacturing of its subsystems has been started. A compact modular laser system for cooling and trapping rubidium atoms has been assembled. A compact Raman laser module, featuring outstandingly low phase noise, has been realized. Possible schemes to implement coherent atomic sources in the atom interferometer have been experimentally demonstrated.     

激光干涉仪非线性的测量

激光干涉仪和高精度位移传感器的非线性一般为1～5nm,为了对这样的非线性进行测量,必须使用高精度测量方法,并建立高精度测量装置。文中描述了高精度拍频法布里 珀罗激光干涉仪,和利用它对工业激光干涉仪的非线性进行的测量实验。测量范围大于1.3μm,测量不确定度约为2nm。     

Constraints on Non-Newtonian Gravity From the Experiment on Neutron Quantum States in the Earth’s Gravitational Field

An upper limit to non-Newtonian attractive forces is obtained from the measurement of quantum states of neutrons in the Earth’s gravitational field. This limit improves the existing constraints in the nanometer range.     

Fast Computation Algorithm for Discrete Resonances among Gravity Waves

Traditionally resonant interactions among short waves with large real wave-numbers were described statistically, and only a small domain in the spectral space with integer wave-numbers, i.e. discrete resonances, had to be studied separately in resonators. Numerical simulations of the last few years have shown unambiguously the existence of some discrete effects in the short-wave part of the wave spectrum. Newly presented model of laminated turbulence explains theoretically the appearance of these effects, thus putting forth a novel problem – construction of fast algorithms for computation of solutions of resonance conditions with integer wave-numbers of orders 10³ and more. Example of such an algorithm for 4-wave interactions of gravity waves is given. Its generalization for different types of waves is briefly discussed.     

高精度激光平面干涉测量系统误差的研究分析方法

叙述了Fizeau激光平面干涉系统的测量原理.依据ISO发布的测量不确定度表示指南,对Fizeau型高精度移相激光平面干涉测量系统的误差进行了系统分析,给出了高精度激光平面干涉仪的各项误差及总误差,其合成标准不确定度为2.63nm.该研究分析方法可适用于同类仪器的测量不确定度评价.     

A Radial-shear Interferometer for Use with a Laser Source

An interferometer is described that combines the design simplicity of a laser interferometer and the insensitivity to vibration of a common-path instrument. It is used to test wave aberration in ‘single passage’.     

用于微位移测量的迈克尔逊激光干涉仪综述

迈克尔逊干涉术测量微位移可实现纳米甚至更高的分辨力,并且具备能直接溯源至激光波长等诸多优点,是目前微位移测量的重要技术手段.以限制迈克尔逊干涉仪品质提高的非线性误差为主要切入点,对目前各种基于迈克尔逊干涉原理的激光干涉技术进行了分类介绍,主要讨论了微位移测量中实现高精度和高分辨率的干涉测量技术,最后展望了激光干涉法测量...     

基于ACPT技术的纳米振动测量激光干涉仪

为实现高精度、高稳定的微小振动测量,设计了一种改进型迈克尔逊干涉仪,对其所采用的光学结构和解调算法进行了分析.信号解调方案基于载波调制和交流相位跟踪（ACPT）技术,相对应的光路采用双压电陶瓷（PZT）和准平面猫眼动镜以构成参考臂和测量臂,设计以改善信噪比、抑制低频干扰、增强系统稳定性、提高测量分辨力为目标.建立了纳米振动发生装置,搭建了振动信号测量系统,研究了激光干涉仪对振动信号的输出特性.实验结果表明,测量动态范围达到120 dB,信噪比高于40 dB,系统分辨力达到0.25 nm.该干涉仪可有效抑制诸如温度、湿度、压强、低频振动等带来的相位噪声的干扰,满足高精度、稳定、可靠的要求.     

A Remote,Non-destructive Laser Ultrasonic Material Evaluation System with Simplified Optical Fibre Interferometer Detection

An optical non-contact ultrasonic testing system is presented. It uses broadband surface acoustic wave impulses generated with a cylindrical lens focused laser line source. The detection of the ultrasound is achieved by a simple and yet effective design of optical fibre interferometer which provides good sensitivity and manoeuvrability. The effectiveness of the fibre interferometer is demonstrated by accurately measuring the broadband surface waves on various common metal structures. The measurement system’s ability for surface material evaluation is also demonstrated from fitting experimental surface wave dispersion curves with theoretical simulations. This measurement system can test small localised areas and miniature samples that were previously difficult to examine.     

新型长距离无导轨激光干涉仪

外腔半导体激光的线宽小于100 kHz,干涉相干距约为1000 m,波长可调节范围超过100 nm(1495～1645nm),应用上述二项特性,通过改变波长(频率)测得任意点到仪器的距离(不需要在测量计数时移动反光镜).其测量距离大于100 m,分辨率可以优于3 nm,不确定度可以达到2.5×10-6 L,达到工程测量对测长仪器的要求.为提高测量不确定度,还可以使用2个或2个以上特定波长,通过小数重合法,更精确测得与被测点的距离,不确定度可以达到5×10-7 L.其优点是:测量时无需导轨移动测量镜(对比双频激光干涉仪)、可以挡光进行间断测量(对比激光跟踪仪)、测量不确定度和分辨率精度指标高(对比激光测距仪).可以为尺寸大、形状复杂的几何物件和大型建筑物、基线场等精密测量提供十分有效的方法和工具.     

单频激光干涉仪条纹的偏振移相细分技术

提出了一种用于单频激光干涉仪条纹细分的偏振移相技术.通过偏振分光镜、波片等光学元器件产生四路依次相差90°相位的激光干涉信号,经过硬件电路的整形、放大和比较后,可以解决常见的光强"零漂"问题.共光路设计有效地消除了由于环境因素给测量带来的误差,提高了干涉系统的稳定性和重复性.移相技术不仅充分地利用光能量,而且四路信号更便于干涉条纹的计数和判向,同时为电子细分技术奠定了基础.     

扫描激光激发瑞利波探测材料表面微缺陷

提出了一种无损探测材料表面微小缺陷的新方法,利用移动扫描激光线源在材料表面激发的超声瑞利波,结合自行改进的差分式光偏转探测系统接收该超声波信号,并对该探测系统的测试原理进行了讨论;在利用系统进行实验研究时观察到:当激发激光源接近材料表面的人工缺陷时,探测信号的幅度会发生显著变化.通过对信号幅度变化规律的特征分析,可以对材料表面的微小缺陷进行诊断,亦证实了扫描激光线源技术在材料表面微小缺陷无损检测方面具有的应用价值.     

扫描激光激发瑞利波探测材料表面微缺陷

提出了一种无损探测材料表面微小缺陷的新方法,利用移动扫描激光线源在材料表面激发的超声瑞利波,结合自行改进的差分式光偏转探测系统接收该超声波信号,并对该探测系统的测试原理进行了讨论;在利用系统进行实验研究时观察到：当激发激光源接近材料表面的人工缺陷时,探测信号的幅度会发生显著变化．通过对信号幅度变化规律的特征分析,可以对材料表面的微小缺陷进行诊断,亦证实了扫描激光线源技术在材料表面微小缺陷无损检测方面具有的应用价值．