调频激光干涉绝对距离测量技术及其信号处理

最最的绝对距离测量方法是非相干飞行时间测量法。随后，在小数重合法的基础上，产生了多波长干波绝对距离测量技术。随着半导体激光器的发展，８０年代又出现了调频干涉绝对距离测量方法，并很快成为一种新的测长技术。本文在综述绝对距离技术及方法的基础上，着重介绍了调频激光干涉绝对距离测量技术的一些新发展及其几种不同的信号处理。     

用于绝对距离测量的0．6328μm氦－氖激光外差干涉仪

提出了一种用于绝对距离测量的新型外差干涉仪，它采用０．６３２８μｍ双模氦－氖激光器，光外差干涉和电信号混频、比相技术，直接测量合成波小数级次。此法避免了该领域常用的外差干涉仪的不足和拍波干涉仪结构复杂的问题，而且测量精度高、抗干扰能力强、测量时间短，使绝对距离测量技术更具有实用性。     

红外拍频锁定型绝对距离干涉仪的研究

利用3.39μm波段双线氦氖激光器作光源实现了作者提出的拍波锁定绝对距离干涉仪新方案。在阐述绝对距离干涉计量的逐级精化理论和上述氦氖激光两级合成波测长方案的基础上,着重分析了双波长拍波锁定干涉测长原理,给出了实验原理图和部分测量结果。分析表明,拍波锁定绝对距离干涉仪的干涉条纹尾数测量精度已达5×10~(-4)。     

线性调频激光双干涉仪绝对距离测量的研究

提出一种双干涉仪绝对距离方法，利用参考干涉仪的误差补偿作用，有效地抑制了激光器光学特性相关误差源对外腔半导体激光器线性调频绝对距离干涉测量系统的影响，提高了测距精度。文中介绍了测量原理和实验装置，作了误差补偿分析，并给出实验结果。     

一种针对频率扫描测量系统的信号处理方法

设计了一种针对频率扫描绝对距离测量系统的信号处理算法。该系统采用基于电流调制式的频率扫描方法,利用一个比对干涉光路与一个测量干涉光路进行同步测量。两路扫描干涉信号分别由两个光电探测器进行光电转换,作为绝对距离计算处理的输入信号。分析了测量系统的原理与扫描干涉信号的特点,应用两步差分卷积算法进行信号处理,提取的比对光路与测量光路的周期或频率信息进行绝对距离测量。分析了该算法的周期计算误差。实验验证这种方法具有较大的计算优势。     

基于飞秒激光器光学频率梳的绝对距离测量

提出使用飞秒激光器的光学频率梳测量绝对距离的方法.将一个飞秒激光器作为绝对距离测量的光源,搭建迈克尔逊干涉结构,利用色散干涉原理进行相应的光谱分析,得到干涉光路的光学路径差引起的相位差,最终计算出干涉光路的光学路径差.实验结果表明我们的长度测量方法精确度高,分辨力达到纳米量级.最小测量距离达到9 μm,非模糊范围达到5...     

可调谐激光二极管在绝对距离干涉测量中的应用

可调谐激光二极管在绝对距离干涉测量中的应用Ｊ．Ｔｈｉｅｌ等１．前它传统的步进干涉仪仅允许测量反射镜的移动位移凸Ｌ，该位移量由下式给出：ＡｂＬ＝Ａｇｂ·５５－－（１）其中激光波长Ｋ。７８０ｕｒｎ，而西中为探测到的干涉条纹数。静态距离Ｌ。。ｓ的测量方法是...     

一种新型光纤干涉测量系统

提出一种可以测量１米以上绝对距离的光纤干涉测距系统，采用两部分干涉结构，分别对靶标进行定位及光程调谐和对距离进行测量。通过引入已精确标定的光纤进行光程倍增以扩大系统的动态范围，对系统的信号处理方法进行了初步讨论，并给出系统仿真的结果。     

表面粗糙度干涉图像处理系统

介绍了表面粗糙度干涉图像处理和该系统以静态干涉图像处理技术对表面粗糙度检测的过程。该系统通过对一帧白光干涉图像的处理，可对Ｒａ值≤０．２μｍ的多刻线样板，试件表面粗糙度绝对、非接触、快速、自动地测量；该系统通过对白光和纳光二帧干涉图象的联合处理，以白光定位、纳光定度可对沟槽深度Ｈ≤５μｍ的标准单位刻线深度绝对，非接触，准确地测量。     

可调合成波长链绝对距离干涉测量

本文提出一种利用半导体激光器的波长调谐特性实现的可调合成波长链绝对距离干涉测量方法 ,针对不同的待测距离 ,可选择不同的合成波长链 ,完成对待测距离的由粗测到精测的整个过程。文中基于这种方法构建了干涉测量系统 ,该系统利用压电陶瓷调制的在一条直线上的两个双光束干涉仪 ,使待测距离被包含于一个交流信号的相位项中 ,从而使小数条纹的测量转化为相位测量 ,合成波干涉条纹的小数级次由单波长干涉信号的相位测量值计算得到。文中以外尺寸测量为例描述了实验装置 ,实验结果表明 ,在现有的测量系统和实验条件下 ,待测距离小于 5mm时的测量极限偏差优于 2 0μm。     

Self-mixing interferometry based on a double-modulation technique for absolute distance measurement

A new, to the best of our knowledge, method for the measurement of the absolute distance of a remote target based on the laser diode self-mixing interferometry is presented. A double-modulation technique is introduced to improve the measurement resolution. Wavelength modulation of the laser beam is obtained by modulating the injection current of the laser diode. Phase modulation of the laser beam is obtained by an electro-optic crystal in the external cavity. Absolute distance of the external target is determined by the Fourier analysis method. Theoretical analysis and numerical simulations are given. Experimental results show that a resolution of +/-0.3 mm can be achieved for absolute distance ranging from 277 to 477 mm.     

High-accuracy absolute distance measurement using frequency comb referenced multiwavelength source

We propose a new approach to multiple-wavelength interferometry, targeted to high bandwidth absolute distance measurement, with nanometer accuracy over long distances. Two cw lasers are stabilized over a wide range of frequency intervals defined by an optical frequency comb, thus offering an unprecedented large choice of synthetic wavelengths. By applying a superheterodyne detection technique, we demonstrated experimentally an accuracy of 8 nm over 800 mm for target velocities up to 50 mm/s.     

Radio frequency controlled synthetic wavelength sweep for absolute distance measurement by optical interferometry

We present a new technique applied to the variable optical synthetic wavelength generation in optical interferometry. It consists of a chain of optical injection locking among three lasers: first a distributed-feedback laser is used as a master to injection lock an intensity-modulated laser that is directly modulated around 15 GHz by a radio frequency generator on a sideband. A second distributed-feedback laser is injection locked on another sideband of the intensity-modulated laser. The variable synthetic wavelength for absolute distance measurement is simply generated by sweeping the radio frequency over a range of several hundred megahertz, which corresponds to the locking range of the two slave lasers. In this condition, the uncertainty of the variable synthetic wavelength is equivalent to the radio frequency uncertainty. This latter has a relative accuracy of 10(-7) or better, resulting in a resolution of +/-25 microm for distances exceeding tens of meters. The radio frequency generator produces a linear frequency sweep of 1 ms duration (i.e., exactly equal to one absolute distance measurement acquisition time), with frequency steps of about 1 MHz. Finally, results of absolute distance measurements for ranges up to 10 m are presented.     

White-light interferometer with dispersion: an accurate fiber-optic sensor for the measurement of distance

We present a fiber-optical sensor for distance measurement of smooth and rough surfaces that is based on white-light interferometry; the sensor measures the distance from the sample surface to the sensor head. Because white light is used, the measurement is absolute. The measurement uncertainty depends not on the aperture of the optical system but only on the properties of the rough surface and is commonly approximately 1 microm. The measurement range is approximately 1 mm. The sensor includes no mechanical moving parts; mechanical movement is replaced by the spectral decomposition of light at the interferometer output. The absence of mechanical moving parts enables a high measuring rate to be reached.     

High-precision absolute distance and vibration measurement with frequency scanned interferometry

We report high-precision absolute distance and vibration measurements performed with frequency scanned interferometry using a pair of single-mode optical fibers. Absolute distance was determined by counting the interference fringes produced while scanning the laser frequency. A high-finesse Fabry-Perot interferometer was used to determine frequency changes during scanning. Two multiple-distance-measurement analysis techniques were developed to improve distance precision and to extract the amplitude and frequency of vibrations. Under laboratory conditions, measurement precision of approximately 50 nm was achieved for absolute distances ranging from 0.1 to 0.7 m by use of the first multiple-distance-measurement technique. The second analysis technique has the capability to measure vibration frequencies ranging from 0.1 to 100 Hz with an amplitude as small as a few nanometers without a priori knowledge.     

激光回馈精密测量技术及应用

介绍了激光回馈干涉的理论模型,阐述了激光回馈测量灵敏度高、装置结构简单、可自准直、能够对非合作目标进行精密测量的技术特点。探讨了激光回馈测量技术在工业和科研领域中的应用方向,包括位移、角度、振动、绝对距离测量等,指出利用倍频复用、频率复用、偏振复用、全程准共路等技术可提高回馈测量的应用性能。分析了激光回馈测量相较传统干涉测量的优势,展望了激光回馈测量技术在科学研究、工业生产、精密制造等领域的应用前景,提出通过提高光源稳频精度、研究不同光回馈水平下的实验现象和理论模型、探索新型激光器的回馈效应等方式,进一步提升激光回馈干涉仪的灵敏度和测量性能。     

Accuracy of a multiple height-transfer interferometric technique for absolute distance metrology

A multiple height-transfer interferometric technique was developed to increase the absolute distance measurement capability of a metrology system that uses a tunable laser. Using multiple accurately calibrated reference heights, this technique relaxes the requirement of knowing accurate wavelength information for multiple wavelength interferometry while maintaining its advantages. We present an uncertainty analysis, analyze the primary sources of uncertainties limiting the performance of this technique, and discuss how errors can be minimized. Measurement results of 3D images obtained from a variety of objects are presented. The measurement uncertainty is experimentally demonstrated to be 0.3?μm over 50?mm for two discontinuous surfaces with a confidence level of 95% in a lab environment.     

Absolute interferometry with a 670-nm external cavity diode laser

In the past few years there has been much interest in use of tunable diode lasers for absolute interferometry. Here we report on use of an external cavity diode laser operating in the visible (lambda ~ 670 nm) for absolute distance measurements. Under laboratory conditions we achieve better than 1-mum standard uncertainty in distance measurements over a range of 5 m, but significantly larger uncertainties will probably be more typical of shop-floor measurements where conditions are far from ideal. We analyze the primary sources of uncertainty limiting the performance of wavelength-sweeping methods for absolute interferometry, and we discuss how errors can be minimized. Many errors are greatly magnified when the wavelength sweeping technique is used; sources of error that are normally relevant only at the nanometer level when standard interferometric techniques are used may be significant here for measurements at the micrometer level.