引力波及引力波的探测

引力波也叫引力辐射,是爱因斯坦广义相对论中的一项重要预言,是基础物理和天文学中一个重要的内容。人类为探索引力波付出了几十年的努力,从早期的棒状探测器到后来的激光干涉引力波探测器,各国学术机构和科学家们不断采用最先进的技术寻找引力波源,探测器的探测范围和灵敏度也不断提高。在探测引力波的过程中,形成了一门引力波天文学的新兴学科,使人们逐渐了解宇宙的奥秘,寻找宇宙中天体的运行规律,而引力波也成为了当今科学界学术重点和热门课题。     

开启引力波天文物理高级探测器新纪元

激光干涉引力波观察台(LIGO)是世界卓越的干涉型引力波探测设备。最初的LIGO探测器已经超出了设计的灵敏度,能够用来探测相距大约40 Mpc的双中子星的合并信号,探测信噪比等于8。当探测器还没被建造时,LIGO科研团队主要和Virgo团队合作,探究了大量天体物理学方面的上限。LIGO目前已经步入了先进探测的新领域,拥有升级版的先进LIGO干涉型探测器。LIGO实验室也和众多印度研究中心合作,在印度建立了一个先进的LIGO干涉仪。从而LIGO探测网络扩展了,拥有3个远距分散的干涉仪在单一网络中运行。     

适用于光黏工艺的干涉仪公差保证方法

空间干涉测量系统是空间引力波探测的重要组成部分。本文介绍了一种全玻璃材料的差频激光干涉仪的组成结构和工作原理,对差频干涉仪中双相干光束的匹配对准难题,介绍了一种适用于光黏装配工艺的角度公差和位置公差保证方法。这种方法采用了监测系统和微量调整机构相结合的方式,首先,监控系统可以实现光线相对位置的实时测量,给出被调整光线的调整方向和调整量;然后,微量调整机构可以在平面移动和轴向转动3个自由度上,对目标器件实现微米量级的微量调整;监控过程和调整过程反复迭代,可实现对光学元器件的高精度位置控制和角度控制。实验结果表明,在调整方向上角度公差优于80μrad,位置公差优于85μm。本方案基本满足差频激光干涉仪的装配精度需求,为后续更高精度的装配奠定基础。     

超精密测量技术冲破“封锁线”

正南极天文望远镜、空间引力波探测装置、极大规模集成电路制造装备要依靠超高精、光刻机度的测量…仪…这一系列关键装备的加工制造器对大量光学元件的各项参数进,都需行测量。以往,超精密测量技术受到国外封锁,成为制约高端装备制造发展的瓶颈问题近日工。,由上海理大学光电学院庄松林院士领衔的韩森教授团队与苏州慧利仪器有限责任公司共建联合实验室所研发的国产化高端产品--数字化激光干涉仪进展顺利。     

微幅超声窄脉冲的光学探测实验系统

本文自行研制了一微幅超声窄脉冲光学探测系统,讨论了Ｆａｂｒｙ－Ｐｅｒｏｔ干涉仪作为超声接收器的原理及特点,给出了系统各环节的测试结果以及探测到的窄脉冲激光超声信号、结果表明,利用该系统可成功地实现微幅超声窄脉冲的非接触式检测。     

飞秒激光光学频率梳装置

“飞秒激光光学频率梳装置”（简称“飞秒光梳装置”）可用于对时间、频率和长度的超高精度测量，在导航定位、引力波探测、光通信等领域有着重要的作用。由中国计量科学研究院承担的科技部科技基础性工作专项基金项目“飞秒激光光学频率梳的研究”，9月12日通过了由国家质检总局组织的成果鉴定。     

光量子噪声对激光干涉仪引力波探测器灵敏度的影响

激光干涉仪在引力波发现中起着关键作用,光量子噪声是干涉仪灵敏度进一步提高的主要障碍。详细分析了光量子噪声中霰弹噪声和辐射压力噪声产生的机制和主要特点,讨论了标准量子极限,扼要介绍了信号循环、压缩光场等标准量子极限突破技术。     

一种简单的大口径全息平面干涉仪

一、引言全息平面(或球面)干涉仪采用了全息干涉的一次曝光法或二次曝光法,相对于传统的平面(或球面)干涉仪,除少用光学元件外,更主要的是由于全息图具有位相误差补偿作用,大大降低了对仪器中主要光学元件的质量要求,从而使得研制大口径的平面(或球面)干涉仪成为现实。在国内也已有多人报道了这方面的研究成果。本文提出了一种结构十分简单的大口径平面干涉仪,除了激光光源部分外,仅用了一个用于大光束扩束的倒置望远系统和一个作为平面标准的平面反射镜。由于结构简单,所以调整方便,在一般的实验室或光学车间均能实现。     

压缩态光场在激光干涉仪引力波探测器中的应用

激光干涉仪在引力波发现中起着关键作用,标准量子极限是干涉仪灵敏度进一步提高的主要障碍,压缩态光场注入是超越标准量子极限的重要手段。分析了压缩态光场的主要特点,讨论了压缩态光场的产生机制,介绍了压缩态光场技术在超越标准量子极限中的应用。     

激光干涉仪的细分技术

激光干涉仪通常采取Machelson(迈克尔逊)干涉仪形式,由于反射器的作用,直接接收的脉冲当量为A／2(约0．3μm),对于精密测量来说,显然是不够的。如何提高激光干涉仪系统的分辨率是激光干涉仪中的重要技术,有多种激光干涉仪的细分方法,概括起来为光学细分和电子细分两大类,本文介绍了几种典型方法,并分析了各种方法的特点。     

Air-coupled acoustic method for testing and evaluation of microscale structures

A noncontact testing and characterization approach for microscale structures based on air-coupled acoustic excitation and optical sensing is proposed and demonstrated. Using an air-coupled transducer to externally excite and a laser Doppler vibrometer/interferometer to capture transient displacement wave forms, the experimental approach results in a technique to determine mechanical properties of microscale structural elements. The effectiveness of this method has been demonstrated on commercially available microcantilever beams and microscale rotational oscillators fabricated for this study. The resonance frequencies and mechanical properties (Young's modulus and stiffness) extracted from the transient displacement wave forms have been compared, with good agreement, to computational and simplified analytical models for each case. It is also shown that the technique could serve to diagnose stiction problems of microscale structures. Some potential advantages of the approach described include the simplicity of the test setup, functionality at room conditions, noncontact and nondestructive operations, and repeatability and rapid turn-around time for the evaluation of modal parameters and mechanical properties of microscale structures.     

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.     

激光干涉仪在非球面光学元件制造中的应用

为了提高检测精度,研究了用激光干涉仪检测非球面光学元件的方法,阐述了激光干涉仪的工作原理.并通过实验证明了这种方法既简单方便,又适用于非球面度不高的光学元件.缩短了加工时间,减少了对专业人员的投资支出,因此大大提高了生产效率.     

Problems regarding linearity of data of a laser interferometer with a single-frequency laser

In this paper, the main causes of scale nonlinearity of a laser interferometer with a single-frequency laser and a quadrature fringe detection system are described. The primary causes of scale nonlinearity are quadrature phase shift error and imperfect optical elements in the interferometer and detection unit. A method for measuring this nonlinearity with an optical compensator is described. Nonlinearities arising from quadrature phase shift error, unequal amplitudes, and electronic offsets in the detection unit can be compensated by means of a PC program as described herein. By using a differential interferometer with a resolution of 0.3 nm, the nonlinearity compensation was experimentally verified, and by averaging the measured values for 20 s, a linearity better than ±0.5 nm was achieved.     

激光双谱线功率的不一致性与拍波干涉仪对准精度的关系

双谱线功率一致性是拍波干涉测长方案对激光光源提出的特殊要求。本文从拍波干涉仪对准方法的实际出发,在分析双谱线拍波干涉仪输出信号的基础上,研究了双谱线功率不一致与拍波干涉仪对准精度的关系,提出了基本对准盲区和盲区扩大量的新概念,建立了描述盲区扩大量与双谱线相对功率差之间关系的解析表达式。为设计拍波干涉仪的激光稳定环路和提高拍波干涉仪的对准精度提供了理论分析工具。     

用于测量大型离轴反射式光学系统的波像差的便携式干涉仪的研制

为便于检测离轴三反形式的光学系统,自行研制的便携式的干涉仪用于检测光学系统的波像差。该设备利用平面镜作为标准镜,通过平面波与球面波的转换与被测光学系统进行干涉,屏弃了一个标准球面镜对应一个被测光学系统,减少了标准镜的数量的同时,降低了成本。检测速度快捷,结果准确。该设备总重量不超过5公斤,体积小、便携、价格低廉,具有很大的发展前景。     

A new multichannel interferometer system on HL-2A

A new multichannel HCN interferometer has been developed on HL-2A tokamak, which is characterized by two techniques: (1) the wave-guide HCN laser with cavity length of 6 m to increase the optical resource power and (2) high response room temperature waveguide Schottky diode detectors to obtain good beat signal. The space resolution is 7 cm by the use of focusing metal mirrors mounted on the vacuum chamber and a compensated optical system. In the 2006 experiment campaign, this new interferometer has been applied for plasma density profile and density sawtooth measurement.     

Absolute interferometric test for high numerical-aperture spherical concave surfaces: Gravitational effect

Spherical concave surfaces with high numerical apertures are required in industry for lithography optics at ultraviolet and X-ray wavelengths. Among the systematic errors in these spherical-surface test, the gravitational deformation has not been separated from the other optical aberrations. We utilized a two-surface comparison method to quantify the gravitational deformation in a vertical Fizeau interferometer. Certain aberrations vary with rotation around the optical axis. We averaged the ordinary aberrations and isolated the aberration caused by gravitational deformation. Experimental results show that a 4-in concave surface with an F-number 0.75 reveals to have a gravitational deformation of 7 nm peak-to-valley.