用于六自由度纳米微动台的位移传感器研制

为测量六自由度纳米微动台的运动,研制了基于光纤微弯原理的位移传感器。设计了新颖的光纤微弯调制结构,利用补偿光纤消除了光源波动对测量精度的影响。实验证明位移传感器的测量精度为±0.048μm,位移分辨率为10 nm,显著优于同原理的其他位移传感器。     

Real-time white light reflection confocal microscopy using a fibre-optic bundle

We describe a real-time white light reflection con-focal microscope incorporating an optical fibre bundle and characterise the optical performance of the bundle. The use of an incoherent light source enables us, for the first time, to present speckle-free endoscopic reflected light confocal images. The system has potential application for in vivo studies.     

Non-contact optical probing sensor — applying optical feedback effects in laser diodes

The possibility of a non-contact optical distance/displacement sensor, making use of optical intensity variations caused by optical feedback effects in laser diodes, was investigated. A compact sensor system and a simple signal processing technique were proposed to realise the sensor system. The experimental results indicated that the resolutions were of sub-mm order in distance measurements and about 40 nm in displacement measurements. The allowable maximum speed of displacement can be improved up to several cm/s. The influence of temperature variation on the measurement accuracy was discussed and the advanced sensing technique utilising a synthetic wavelength of laser diodes was proposed. These methods are applicable even to an object with rough surfaces.     

水膜厚度光纤检测系统

针对海水泵滑靴副水膜厚度测量需求,利用反射强度调制型位移光纤传感器工作原理设计并实现了一种水膜厚度检测系统。设计了与海水泵结构相对应的光纤探头,其采用具有较好补偿功能的三圈同轴型光纤束结构消除了由光源强度、反射表面性质以及光纤光强损耗和弯曲损耗等因素带来的影响;开发了由光源模块、电源模块、光电转换模块、低通滤波模块、信号比值模块等组成的前置器用于信号调理。对开发的水膜厚度光纤检测系统进行了静态性能和动态性能测试实验,结果表明:该检测系统的测量精度可达微米级,测量系统的量程为1 000μm,灵敏度为3.45mV/μm,动态性能良好,满足了对海水泵水膜厚度的检测需求。     

光纤声发射传感器

一种用于状态监测和故障诊断的新型声发射传感器已经研制成功。它基于全光纤法布里—珀罗干涉仪原理。其分辨率高达埃级,频率范围为100kHz～1.4MHz。由于信号光束和参考光束在同一根光纤中通过,所以消除了温度变化、微弯效应以及电磁干扰等环境影响,并具有很高的测量稳定性。     

Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths. It is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realize imaging of optical contrast on the sub-wavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical contrast, is found to be ≈100 nm for light wavelengths in the visible region. We demonstrate imaging of near-field components of a dipole field and purely dielectric contrast (related to well-width fluctuations in a semiconductor quantum well) with a spatial resolution of ≈100 nm. The results obtained show that such a near-field technique can be used for polarization-sensitive imaging with reasonably high spatial resolution and suggest a number of applications for this technique.     

Polarization contrast in reflection near-field optical microscopy with uncoated fibre tips

Using cross-hatched, patterned semiconductor surfaces and round 20-nm-thick gold pads on semiconductor wafers, we investigate the imaging characteristics of a reflection near-field optical microscope with an uncoated fibre tip for different polarization configurations and light wavelengths. It is shown that cross-polarized detection allows one to effectively suppress far-field components in the detected signal and to realize imaging of optical contrast on the subwavelength scale. The sensitivity window of our microscope, i.e. the scale on which near-field optical images represent mainly optical contrast, is found to be approximately 100 nm for light wavelengths in the visible region. We demonstrate imaging of near-field components of a dipole field and purely dielectric contrast (related to well-width fluctuations in a semiconductor quantum well) with a spatial resolution of approximately 100 nm. The results obtained show that such a near-field technique can be used for polarization-sensitive imaging with reasonably high spatial resolution and suggest a number of applications for this technique.     

基于图像处理的位移测量传感器设计

针对光栅尺、容栅尺等位移测量仪器不易于现场安装的缺点,提出一种基于图像处理的位移传感器装置,使其在满足分辨率与响应速度的条件下,最大限度降低安装要求。该传感器基于激光鼠标原理,通过改进光学组件,使得传感器与参照物可以保持比较长的非接触空间。同时根据不同场合的需求,换装不同放大率的光学组件,以得到不同工作距离、分辨率的传感器。实验表明,该传感器易于安装在多数平面运动的待测物上,具有成本低、精度高、线性度好的优点,可广泛用于普通机床的数显改造、机器人的精确定位等场合。     

光纤pH传感器的设计

设计开发了一个用于环境水质 p H值监测的光纤传感系统。采用5发光二极管作光源 ,硅光电二极管作检测器 ,大芯径、大数值孔径的 Y型分叉光纤束作传感介质 ;染料指示剂苯酚红以两种方法固定 ,设计了相应的两种探头结构。系统中提出了双 L ED双光束补偿的设计思想 ,对两种探头的传感机理做了归一性推导。该系统体积小 ,价格低廉 ,性能稳定 ,响应灵敏度可达 0 .0 1 p H。     

光纤傅里叶变换光谱术在光纤光栅传感解调中的应用

介绍了光纤Mach-Zehnder干涉仪的基本原理和光纤傅里叶变换光谱仪(FFTS)的结构;基于光纤Mach-Zehnder干涉仪,采用傅里叶变换光谱算法对光纤Bragg光栅传感器的波长进行了解调。宽带光源发出的光经过光纤耦合器进入光纤Bragg光栅,其反射光由耦合器返回进入到FFTS中进行测量,FFTS的最高光谱分辨率达到0.05 cm-1,即在近红外1 550 nm波长处分辨率为0.012 nm。分别对光纤Bragg光栅的应变特性和温度特性进行了测量。测量显示:光纤Bragg光栅的应变灵敏度为0.833 pm/με,温度灵敏度为19.78 pm/℃。得到的结果表明FFTS系统具有高分辨率、大测量范围的特点,可满足光纤Bragg光栅传感器波长解调的需求。     

光纤传感器在涡轮轴向位移检测中的应用研究

以光纤传感原理为基础，采用一种强度补偿型反射式光纤位移传感器，借助光纤本身的优势，实现涡轮机轴向位移的实时监测。系统包括光源及其驱动电路、光纤传输通道、信号处理电路和信号输出系统。通过双路接收的方法消除因光源发光功率波动、光纤损耗变化以及环境干扰光等因素对测量结果的影响。采用稳压源驱动和温度补偿保证光源发光的稳定性，进行转速监测以补偿速度变化引起的误差。采用单片机完成被测信号的识别和处理，提高了测量的精度。     

A Laser Ranging System Using Chaotic Light

A novel laser ranging system using chaotic laser as probe light source is designed and presented.The system is made up of five components:chaotic light source,transmitter,receiver,data acquisition unit and data processing unit.Chaotic light is generated by an 808 nm,500 mW,single-mode laser diode with optical feedback cavity.Single target detection and multi-target detection are experimentally realized by correlating the chaotic reference light and the reflected or backscattered probe light.The performances,including the resolution of 18 cm within at least 130 m range and the sensitivity of-20 dB,are achieved and analyzed.     

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。     

机械零件三维表面形貌测量与评定的研究

介绍了机械零件三维表面形貌的测量与评定,分析了激光干涉式位移传感器的光学原理和干涉条纹信号的细分方法.激光干涉式位移传感器的精度达到了5nm左右.另外,带计量系统的二维工作台也是整个测量系统的关键部分.因为采用了光栅尺作为二维工作台的计量系统,所以在表面形貌的测量过程中二维工作台在X和Y两个水平方向上都能获得精确的定位.     

基于平面线圈的高分辨力时栅角位移传感器

针对现有时栅角位移传感器采用漆包线绕制工艺加工线圈,导致线圈布线不均且容易随时间发生变化进而影响测量精度的问题,提出一种基于PCB技术的新型时栅角位移传感器。该传感器通过在PCB基板的不同层上布置特定形状的激励线圈和感应线圈,形成两个完全相同并沿圆周空间正交的传感单元;当在两传感单元的激励线圈中分别通入时间正交的两相激励电流后,通过导磁定子基体和具有特定齿、槽结构的导磁转子对传感单元内的磁场实施精确约束,使两传感单元的感应线圈串联输出初相角随转子转角变化的正弦感应信号;最后通过高频时钟脉冲插补初相角实现精密角位移测量。利用有限元分析软件对传感器进行了建模和仿真。根据仿真模型制作了传感器实物,开展了验证实验,并对实验中角位移测量误差的频次和来源进行了详细分析。经过标定和补偿,最终获得了整周范围内误差在-2.82″~2.02″的时栅角位移传感器。理论推导、仿真分析和实验验证均表明,该传感器不仅能实现精密角位移测量,还能在激励线圈和感应线圈空间极距和信号质量不变的情况下,将位移测量的分辨力从信号源头提高1倍,且结构简单稳定、极易实现,特别适用于环境恶劣的工业现场。     

A laser sensor with multiple detectors for freeform surface digitization

An integrated laser scanning sensor for freeform surface digitization is presented. The sensor consists of a diode laser light source and four position-sensitive device (PSD) detectors. The stand-off distance of the sensor is 180 mm and the measurable range is 90 mm. The Lambert model is applied to calculate the displacement between the sensor and the measured point on the object surface along the optical axis, under the assumption of a diffusive surface. The inclination angle of the measured point from the vertical plane of the laser beam is calculated by mathematical inference. Those data are used in error compensation to improve system precision. The new design of multiple detectors could increase the measurable angle and could solve the dead space problem in single point laser of triangulation measurement. The computer simulation and actual measurements show that the displacement resolution reaches 50 μm, and the system performs well in regards to stability and repeatability. The sensor system could be mounted on the NC machine orX-Y platform for freeform surface digitization.     

集成双光栅干涉微梁位移测量方法

介绍了一种基于集成双光栅干涉和CCD图像测量的微梁位移测量方法,并利用相位差约为π/2的一组光栅实现了扩量程位移检测。利用表面牺牲层工艺制作敏感芯片,在玻璃基底上刻蚀深度约为入射激光波长1/8的凹槽,凹槽上下的两组光栅与正上方对应的梁分别构成两组相位敏感集成光栅单元。利用1级衍射光将集成光栅单元成像在CCD靶面上,梁的位移变化通过CCD图像上对应光斑的灰度值变化来反映。实验结果表明,虽然玻璃凹槽腐蚀深度的误差导致光栅之间的相位差偏离π/2,但所制作的集成双光栅结构实现了多周期的扩量程位移检测,通过接近π/2相位差的两个光栅得到的光强信号的错峰使用,避免了干涉法正弦位移检测信号的峰谷不灵敏位置,实验测得微梁的位移变化为650nm。     

光纤F-P微位移测量实验研究

利用光纤自聚焦透镜作为F-P干涉仪的反射面,根据F-P干涉光谱相邻波峰之间的波长差与其干涉腔长之间的关系,实现微位移的测量。克服了光强型F-P传感器测量结果受光源波动影响、难以识别位移方向等缺点,可直接测量绝对位移,并可识别位移方向。经实验得到其位移测量误差小于2.5nm。     

融合五自由度位姿信息的单目内窥镜目标尺寸测量

针对低分辨率、弱纹理、缺少参照物的小场景下内窥镜图像目标测量困难问题,提出了融合5自由度电磁传感器的单目内窥镜下目标尺寸测量方法。首先,分析了基于5自由度传感器的内窥镜定位原理,得到内窥镜沿主光轴方向的位移。接着,以结石目标为例分析了图像目标关键信息的导航采集方法,即通过语义分割网络获得图像目标的轮廓信息,进而与内窥镜主光轴进行重合度判定,记录符合重合条件关键帧的图像目标长度信息与对应的位姿信息。最后,基于针孔相机成像模型,将目标成像比例关系与内窥镜沿主光轴的位移结合,建立了目标尺寸测量方法。实验结果表明：所提方法的测量误差控制在10%以内;对长度1～9 mm目标的平均测量误差为0.33 mm。能够满足单目内窥镜检查中对目标尺寸测量的稳定可靠、精度高、省时省力等需求。     

Subnanometric calibration of a differential interferometer

A novel self-calibration method is proposed for calibrating differential interferometers with subnanometer resolution, and the basic characteristics of the method are discussed. Analysis shows that without using any external reference, the calibration accuracy approaches the resolution limit of the interferometer, which is determined by the signal-to-noise ratio (SNR) and the stability of the measurement system. A compact differential interferometer that uses a laser diode as the light source has been developed in order to demonstrate the viability of the proposed calibration method. The conventional fringe-counting and phase modulation methods are combined in order to extend the measurement range and improve the resolution of the interferometer. The developed interferometer was calibrated using the new method, and the calibration results were compared to those obtained by a comparison calibration method that uses a capacitance displacement sensor as the reference.