LD注入调频扫描系统研究

为了减小扫描系统测量误差,可以利用半导体激光器注入式调频装置和光栅来建立扫描系统。通过改变注入电流来改变半导体激光器的输出光频,使输出光入射在光栅上,随着频率的改变,衍射光的衍射角会发生改变,进而衍射光点的位置发生改变,从而实现无机械光点扫描,能够消除扫描测量过程中机械抖动和振动带来的误差。     

基于二维光栅和检偏器阵列的实时空间偏振解码技术

提出了一种基于二维光栅和检偏器阵列的空间偏振解码技术。编码光场中一部分光束经过孔径光阑、1/4波片后由二维光栅衍射分束,不同级次的衍射光被聚焦在空间滤波器上获得(±1,±1)级四个衍射光束,它们经检偏器阵列后被探测器阵列所接收,利用探测到的四路光强信号可以实时解码得到空间位置信息。该技术可将空间偏振编码的相位延迟量范围扩大到-180°～180°,在相位延迟量-90°、90°附近仍可以精确解码。实验采用的空间编码光场的测量范围为-9.32～9.68 mm,三次实验结果的最大测量误差为0.15 mm,很好地验证了该技术的有效性。     

双波长集成光栅干涉微位移测量方法

介绍了一种基于双波长激光的集成光栅干涉位移检测方法,利用该方法对硅-玻璃键合工艺制作的集成光栅位移敏感芯片进行了测试实验。实验系统主要由敏感芯片、波长为640nm和660nm的双波长半导体激光器、双光电二极管及检测电路组成,敏感芯片则由带反射面的可动部件和透明基底上的金属光栅组成。入射激光照射到光栅上产生衍射光斑,衍射光的光强随可动部件与光栅之间的距离变化,通过分别测量两个波长的衍射光强信号并交替切换选取灵敏度较高的输出信号,实现了一定范围内的扩量程位移测量,并得到绝对位置。实验结果表明,利用双波长集成光栅干涉位移检测方法测得敏感芯片可动部件与基底光栅的初始间隙为7.522μm,并实现了间隙从7.522μm到6.904μm区间的高灵敏度位移测量,其噪声等效位移为0.2nm。     

非激光在怀特池中的传播特性

为了探索怀特池在不同特性光源条件下的性能,在使用虚拟仪器技术对怀特池反射光程进行仿真的基础上,研究了提高反射次数的一般规律和方法,同时特别研究了具有一定发散角的光束在怀特池中反射的模型,提出了光束直径及发散角与反射次数之间的关系,该关系可用于指导非激光光源的怀特池应用。仿真结果证明,光束直径和发散角越小,可达到的最高反射次数越多,实验也证明了这一点。     

Multibeam laser writing of diffractive optical elements

A new version of the method of direct multibeam laser writing of diffractive optical elements (DOE) is proposed and investigated. A writing area in the form of an array of focused light spots is formed by splitting the writing laser beam into multiple beams by using a Dammann grating and focusing of these beams in the plane of a moving carrier with a photosensitive material. Adjustment of the radial pitch of writing and correction of the uniformity of the beam intensity is carried out by tilting the Dammann grating and displacing it in the dispersion direction. In writing DOEs, the radial pitch of discrete displacement of the writing area with respect to the plane of the DOE is set equal to or multiple of the average radial distance between the radial projections of the centers of the focused light spots. This version provides improved performance and accuracy due to high-quality paralleling of the writing beam and the averaging effect in superimposed writing.     

线性位移台直线度高精密外差干涉测量装置

直线度测量中往往存在有限的测量范围、精度低和阿贝误差等问题。本文提出了一种高精密直线度外差干涉测量装置,该装置由Koester棱镜、角锥棱镜、1/4波片、楔面棱镜和楔面反射镜构成。楔面棱镜为直线度传感元件,角隅棱镜和楔面反射镜是测量信号的回光元件。双频激光信号进入直线度干涉仪后组成几何空间对称四光路测量信号。四路测量光走过几乎完全相同的路径有效地提高了干涉仪的稳定性,并且使空程误差最小化。使用楔角为1°的楔角棱镜和2π/512细分的相位计,直线度测量分辨力为17.71nm。该方法不需要与行程同长的大反射参考镜,但同样能实现高分辨率,理论和实验证明空间对称测量结构避免了由俯仰,偏转和滚转角引起的阿贝误差的串扰,而且光学元件少,结构简单,方便易用,结果可以直接溯源到米的定义。     

用于去除非共振背景的圆偏振宽带CARS光谱研究

相干反斯托克斯拉曼散射(CARS)是一种受激拉曼现象,在显微成像时,存在非共振背景,会导致光谱产生峰位偏移和谱线变形。本文利用飞秒激光作为光源,通过光栅滤波系统产生窄带泵浦光,飞秒激光激发光子晶体光纤产生超连续谱作为斯托克斯光,两束光被调制为圆偏振光后同时激发样品产生CARS光谱。通过模拟计算说明圆偏振光可以有效去除各向异性材料CARS光谱中的非共振背景,从而使CARS光谱具有和自发拉曼相似的谱线形状。聚苯乙烯微球和液晶样品的CARS光谱实验结果与模拟计算基本相符,说明圆偏振是一种有效去除CARS光谱非共振背景的方法。     

Application of a diffraction grating and position sensitive detectors to the measurement of error motion and angular indexing of an indexing table

In this paper, two systems for the measurement of the error motion and angular indexing of a rotary indexing table have been developed. A laser diode, a laser holder and a position sensitive detector (PSD) are integrated as a simple measuring device for the measurement of the rotary error without using a precision reference artifact (a cylinder or a sphere), multiple probes or error separation methods. The laser diode is assembled in the laser holder and fixed on the rotary table. The PSD is set up above the laser holder to detect the position of an incident laser beam from the laser diode. When the rotary table rotates, the rotary error changes the direction of the incident beam and also the position of the spot on the PSD. For the measurement of the angular indexing, a reflective diffraction grating and two PSDs are integrated as a high-resolution angle measuring device without using an autocollimator or a laser interferometer system. The diffraction grating is set at the center of the rotary table and reflects an incident laser beam into several diffractive rays. Two PSDs were set up for detecting the positions of ±1st-order diffraction rays. A simple algebraic method is used to solve the angular indexing through an optical analysis. The experimental results showed the feasibility of the proposed test devices.     

长距离无衍射光莫尔条纹直线度测量系统的工作原理

在无衍射光测量直线度系统中 ,常常采用锥透镜作为产生无衍射光的元件。要实现长距离的直线度测量 ,则必须采用大口径锥透镜 ,制造成本较高 ,整个系统体积比较大。提出一种用偏转抛物镜系统来替代锥透镜产生无衍射光束 ,可以实现大口径无衍射光束。具有成本低 ,精度较高 ,实现方法简单等优点。     

分光镜对外差激光干涉仪非线性的影响

外差干涉仪的非线性误差不仅由激光源的椭圆偏振态或者非正交线偏振态引起,也由非理想的光学器件引起,其中分光镜是一个重要的误差源。除了通常熟知的偏振漏光,还分析偏振分光镜中可能存在的另一个误差,即偏振分光的正交性,介绍这种误差和其他各种原因(包括激光源的椭圆偏振态或者非正交线偏振态)对外差干涉仪非线性误差的影响,给出检测和区分两类不同频率混叠误差的方法。通过试验证实,偏振分光镜的漏光误差对外差干涉仪非线性的影响通常是可以被忽略不计的。试验研究还发现,与传统的理论假设相反,非偏振分光镜比偏振分光镜对外差干涉仪的非线性误差有着更严重的影响。     

Design and construction of a two-degree-of-freedom linear encoder for nanometric measurement of stage position and straightness

This paper presents a two-degree-of-freedom (two-DOF) linear encoder which can measure the position along the moving axis (X-axis) and the straightness along the axis vertical to the moving axis (Z-axis) of a precision linear stage simultaneously. The two-DOF linear encoder is composed of a reflective-type scale grating and an optical sensor head. A reference grating, which is identical to the scale grating except the scale length, is employed in the optical sensor head. Positive and negative first-order diffracted beams from the two gratings are superposed with each other in the optical sensor head to generate interference signals. The optical configuration is arranged in such a way that the direction of displacement in each axis can also be detected. A prototype two-DOF linear encoder is designed and constructed. The size of the optical sensor head is about 50 mm (X) × 50 mm (Y) × 30 mm (Z) and the pitch of the grating is 1.6 μm. It has been confirmed that the prototype two-DOF linear encoder has sub-nanometer resolutions in both the X- and Z-axes.     

用于星载激光通信终端的绝对式光电角度编码器

针对星上激光通信终端二维转台的精确控制,设计了实时测量转台旋转角度的专用型光电角度编码器。根据星载激光通信终端所需测角系统的设计指标,分别对光电角度编码器的码盘、指示光栅及光电信号的提取方法进行了设计和选择。其中,格林二进制绝对式编码结合高质量的电子学细分,实现了编码器24位的绝对角度测量;四象限矩阵编码方式有效地减小了码盘的径向尺寸;分体读数头式指示光栅较整周玻璃盘大幅度压缩了体积和重量。在室温条件下对安装在星载激光通信终端上的光电角度编码器进行了测角精度检测。结果表明:该测角系统的角度测量精度约为0.7″(优于1.0″)。激光通信终端设备的在轨稳定运行及捕获、跟踪和通信功能的正常发挥,进一步验证了所设计的光电角度编码器测角精度高、抗辐射能力强、工作可靠性高,满足星载激光通信终端设备的应用要求。     

闪耀透射光栅衍射规律的分析和验证

基于标量理论研究了不同槽形角,不同刻线密度的透射式闪耀光栅对使用波段的影响,推导了闪耀透射光栅的衍射光能量分布规律。分析证明了透射闪耀光栅在衍射能量最强方向上衍射光的衍射角与入射光的入射角之间的关系满足Snell定律。给出了入射角、衍射角与槽形角之间的关系式,研究了不同刻线密度和槽形角条件下衍射光能量分布的规律。对闪耀透射光栅进行了测量和比较,结果表明:已有闪耀透射光栅测量的结果与理论计算数据相吻合。制备了聚二甲基硅氧烷(PDMS)可调谐闪耀透射光栅,应用研究的理论公式测量了该闪耀透射光栅在拉伸与自由状态下的闪耀波长和光栅刻线密度,结果显示其波长测量误差在5nm以内。拟合了光栅的等效槽形,验证了实时监测PDMS光栅槽形和刻线密度随拉力大小变化的规律。     

用于激光频率参数测量的飞秒光学频率梳

近年来随着光纤制造技术和飞秒激光技术的成熟,以掺铒(Er)光纤光学频率梳为代表的频率梳技术,逐步突破了光学 频率测量领域,在长度测量、精密光谱分析、超低相位噪声微波频率产生、精密时间频率传递、温度测量等领域发挥出越来越重 要的作用,已成为许多高端科研领域的基础性工具。 但飞秒光学频率梳所解决的重要问题是对激光频率进行测量。 本文主要 面向激光频率参数测量的需求,研制基于掺 Er 光纤飞秒激光器的光学频率梳,在实现光学频率梳稳定运转的前提下,通过非线 性光学频率变换技术,实现光谱范围从掺 Er 光纤光学频率梳的中心波长向各个待测激光波长的转换,并完成与多个不同波长 激光的拍频信号探测。 目前已验证的飞秒光梳可测频率范围为 500 ~ 2 000 nm;频率稳定度和准确度为 10 -16 量级;线宽为 Hz 量级。 该指标满足了激光频率特性参数测量的需求,为激光绝对频率、频率漂移、线宽等参数的测量提供了基础性的测量工具。     

一种天线反射面测量新方法

为了更加便利地实现对天线反射面的测量,在传统测量方法经纬仪钢带尺法的基础上,引入了角度前方交会的测量原理,即将两台经纬仪与天线反射面旋转轴同轴布置组成一个测量系统,利用激光经纬仪发射的同轴激光束在天线反射面上形成光斑,用另一台经纬仪观测光斑并读出俯仰角度。俯仰角度测量值换算后即可得出该点的法向偏差,从而实现对天线反射面的测量。新测量方法原理简单,适用性强,实现了对天线反射面的无接触测量。     

Optical sectioning microscope with a binary hologram based beam scanning

We describe the development of a beam scanning microscope that can perform optical sectioning based on the principle of confocal microscopy. The scanning is performed by a laser beam diffracted from a dynamic binary hologram implemented using a liquid crystal spatial light modulator. Using the proposed scanning mechanism, unlike the conventional confocal microscopes, scanning over a two-dimensional area of the sample can be obtained without the use of a pair of galvo mirror scanners. The proposed microscope has a number of advantages, such as superior frame to frame repeatability, simpler optical arrangement, increased pixel dwell time relative to the time between two pixels, illumination of only the sample points without pulsing the laser, and absolute control over the amplitude and phase of the illumination beam on a pixel to pixel basis. The proposed microscope can be particularly useful for applications requiring very long exposure time or very large working distance objective lenses. In this paper we present experimental implementation of the setup using a nematic liquid crystal spatial light modulator and proof-of-concept experimental results.     

激光多普勒效应非接触井深测量研究

文中对激光多普勒效应应用于油气井井深测量进行了深入研究,提出了非接触式井深测量的思想.详细阐述了一款新型激光多普勒井深测量装置的设计方案及软、硬件设计过程.测量装置中的重要组成部分光学系统采用了双光束-双散射模式进行设计.两束入射光汇聚于运动测井电缆表面并被散射,光电检测器检测到任意两束散射光的"差拍"信号后,送入以TMS320VC5402为中央处理器的外接信号调理电路,再经FFT处理后传送给上位机进行分析处理并实现实时井深监测.该非接触式井深测量装置可有效克服接触式井深测量过程中存在的摩擦与滑动误差,从而达到提高井深测量精度的目的.     

Development of a simple system for the simultaneous measurement of pitch, yaw and roll angular errors of a linear stage

A simple measurement system has been developed and implemented for the simultaneous measurement of pitch, yaw and roll of the moving axes of a linear stage. This developed system is based on the principle of the diffractive theorem and optical triangulation. It is composed of a laser source, two quadrant detectors and a diffracting grating. The diffraction grating mounted on the moving axes of a stage reflects an incident laser beam into several diffractive rays and two quadrant detectors are set up for detecting the position of ±1st-order diffraction rays. When the diffraction grating moves, the locations where the diffractive beams are generated change and also the positions of the spots on two quadrant detectors. According to the relationship between the three angular motions of a moving stage and the output coordinates of two quadrant detectors, an inverse algorithm is used to solve these pitch, yaw and roll angular errors through a kinematic analysis .     

一种滚转角和直线度同步干涉测量方法的研究

提出一种用于精密线性位移台滚转角和运动直线度同步测量的激光外差干涉系统。该干涉系统由一个Koster棱镜、角隅棱镜、分光镜、1/2波片、直角棱镜、1/4波片以及楔面棱镜和楔面反射镜组成。楔面棱镜作为测量运动直线度和滚转角的传感器固定在线性导轨上,当双频激光器的光射入干涉系统中后,形成空间对称的六光束测量信号。空间结构对称、系统共光路的特点使光学分辨率比普通的迈克尔逊干涉仪高一倍,光程死区达到最小。系统稳定性好,抗环境干扰能力强。光路对称使得增加或减小的光程变化相同,其他自由度引起的光程变化相互抵消,仅有运动直线度和滚转角的变化可以进入光程差,有效地排除其他自由度及阿贝误差的串扰,实现高精密测量。试验证明相互平行且不同频率的两束光在同一反射系统中发生运动直线度偏移和滚转角变化时,通过两束光携带的不同相位信息能直接得到运动直线度和滚转角的变化值。它不需要一条与行程同样长度的大反射镜作参考便能够实现高分辨率测量,简单实用,可直接溯源米定义。     

基于激光准直瞄准的大直径测量系统的研究

如何提高大尺寸工件的在线测量精度，是大型机械加工的重要课题。针对大型立式车床的加工环境，本文提出了一种大端面工件在线测量方案。该方案采用激光准直瞄准定位，以测量瞄准误差为补偿，其合理的光路设计清除了阿贝误差，提高了瞄准精度。由于瞄准是以激光准直光束为基准，激光束的漂移造成基准的不稳定是整个测量系统最大的误差来源，而该方案采用“双光束反向漂移补偿法”抑制光束漂移，使角漂误差达到10^-6rad量级。实验结果表明，本方案的测量精度完全满足IT6的加工要求。