基于二次反馈激光自混合新型测距方法

在基于激光自混合干涉的理论上,提出了一种利用二次反馈激光自混合干涉的新型测距方法。利用三角波电流对半导体激光器进行调制,得到一次反馈自混合干涉信号。通过对信号分析可知,当半导体激光器被调制后,会产生一系列的模跳,模跳的数量与绝对距离成正比。通过计算在一个三角波电流调制周期内模跳的数量,就可以求出绝对距离。利用多重激光自混合的概念,提出该种新型测距方法。建立了距离测量系统,进行了实验验证。实验结果表明:由于步长分辨率精度的提高,测距精度明显提高。     

基于DSP的激光自混合干涉测振仪信号采集与处理系统

结合三角波电流调制型激光自混合干涉技术,设计了基于DSP的数据采集与处理系统,完成了对来自光电探测器的干涉信号的采集与处理。该系统接口电路简单灵活,具有采样频率可由程序设置、采集速度和精度较高,并且可以实现6通道同步采样转换的特点。实验结果表明,该数据采集与处理系统完全能够满足高速交变激光自混合干涉信号的采集与处理在实时性和高精度方面的要求。     

自混合干涉信号的位相调制

自混合干涉因其结构简单、紧凑、稳定且易准直等特点而被广泛应用于测量领域。从自混合干涉和电光晶体调制位相的基本原理出发,通过将电光晶体引入自混合干涉外腔调制,研究了自混合干涉测量中电光晶体的位相调制性能。实验证明,利用晶体的调制性能对自混合干涉信号进行位相调制,在很宽的频率范围内都能保证很高的调制精度,测量误差小,具有很好的应用前景。     

半导体激光微小振动实时干涉测量仪

设计了一种半导体激光干涉测量仪,可以实时测量物体的微小振动。通过信号处理电路对干涉信号进行分析,得到实际振动的振幅和频率。给出了具体的理论分析,实验结果验证了该干涉仪的实用性。     

激光干涉测振仪

结合我们工作的实际需要,本组于1972年研制了一套激光干涉测振仪,主要用于校准振动传感器.振幅的测量可以准确到0.2μm,实验表明,与使用读数显微镜比较,精度提高了,而且操作方便,大大缩短了校准实验的时间. 一、基本原理 由于氦氖气体激光器输出的激光单色性非常好,波长很稳定,因此用激光的波长来度量振动位移幅度的大小,具有较高的精确度.激光干涉测振仪基本原理如图1所示. 激光干涉测振仪是根据光学干涉原理制成的.光学系统基本与迈克耳孙干涉仪相同.氦氖气体激光器输出的激光(λ=0.6328μm),经过半透半反镜,将激光分为两束.透过的部分(M…     

用激光二极管自混合干涉测量距离

通过改变激光二极管工作电流,利用自混合干涉信号的相位变化来测量外腔长度.激光二极管工作电流变化导致激光频率变化.工作电流变化引起的干涉信号的相位变化与外腔长度成正比.干涉信号的相位变化2π,对应光频变化的等效长度的1/2.由于改变工作电流激光二极管激光光频可调节范围远小于激光频率,光频变化的等效长度远大于激光波长,激光二极管自混合干涉测量距离的精度远小于测量位移的精度.     

激光自混合干涉在微位移测速上的应用

对传统光电码盘测速的原理进行了介绍,分析其精度较低的原因,提出了基于激光自混合干涉技术的一种激光高精度码盘传感器,并设计了数据采集系统。对自混合干涉的基本理论进行了阐述,分析了基于条纹计数法激光测速的原理,并搭建了基于条纹计数法的激光测速模型用于代替传统的光电码盘测速。实验研究了激光自混合输出与被测物体位移之间的关系,实验结果表明基于激光自混合干涉技术的激光码盘在测量精度上比传统光电码盘有很大提高,并且结构简单,适用范围广。     

基于激光自混合干涉技术和小波变换的齿轮箱故障诊断

激光自混和干涉(SMI)技术是一种利用光反馈原理进行的振动检测技术,它具有结构简单,非接触式测量振动信号的特点。为了解决齿轮箱故障诊断的问题,提出了用激光自混合干涉技术提取信号,并通过小波变换对信号分析进行处理的方法。通过分析小波变换的各个分量以及最终经过小波变换去噪后的信号,能够准确地识别出齿轮箱在运转时所存在的周期性振动故障信号,实验得到的结果与理论值结果完全吻合。     

半导体激光自混频干涉速度仪的F-P模型分析

设计了一个半导体激光自混频干涉式测量物体振动速度的实验,利用双镜F_P(法布里_珀罗)等效模型,对半导体激光自混频干涉速度仪中的干涉效应进行了理论分析,推导了干涉信号理论模型的数学表达式,讨论了影响测量信号的因素。结果表明,在半导体激光自混频干涉速度仪的无源腔中空气密度的变化、无源腔长度的变化、激光波长的变化都将会导致信号漂移,从而引起测量误差。而被测物体表面的反射率越高,越有利于测量。     

振幅为百万分之一埃的极微振动测量技术

引 言 目前,由于激光技术的发展,使得各种精密测量技术也得到了很大的提高.本文介绍一种激光在测量极微振动方面的应用. 普通的激光测振仪是采用记录干涉条纹移过数目的方法.它只需要干涉条纹具有一定的反差度,而并不需要干涉条纹的强度分布具有很理想的余弦平方的规律性.也就是说,它对激光器、干涉仪并不要求很高.由于它的记数单元是一个条纹,相应的物体振动振幅为半个波长,因此它能够测量的最小振动振幅仅为半波长数量级.如果同时再采用分频技术,也只能测到1/4波长,1/8波长,1/16波长等精度.想要用这种方法把精度大幅度提高是不可能的. 最…     

The study of laser self-mixing vibrometer employing different feedback regime using a VCSELS

Laser interferometry based on self-mixing effect widely used to measure displacement, velocity, vibration and distance due to compactness, non-contact, as well as low cost. An important use of the self-mixing effect inside a laser diode is in optical self-mixing vibrometer. We have experimentally investigated self-mixing interference produced by the feedback of light from a vibrated target into a vertical-cavity surface-emitting laser for sensing applications. In this paper, the self-mixing vibrometer employing different feedback regime is discussed and a theoretical analysis is also proposed. Numerical analysis focused on the distortion self-mixing waveform. Numerical analysis and experimental results show that mode-hop occurs when the laser self-mixing vibrometer employing at high feedback level.     

Numerical simulation of phase modulation method used as high sensitive self-mixing vibrometry in vertical-cavity surface-emitting laser

The self-mixing interference technique is a compact sensing technique that has widely used for measuring vibrations. For purpose of increasing the accuracy of the vibration measurement system, a new phase modulation technique based on the self-mixing interferometer is presented. The phase modulation is obtained by varying the length of external cavity periodically. The vibration information of the external target is determined by the Fourier analysis method. Theoretical analysis and numerical simulations of phase modulation method used as high sensitive self-mixing vibrometry based on vertical-cavity surface-emitting laser are given in this paper.     

Laser Doppler vibrometry based on self-mixing effect

In this paper, a simple, compact and low cost laser Doppler vibrometer is presented. It is simply composed of a laser diode (9 mm in diameter, 2 g of weight, emitting at 825 nm) and by a two-lens optical system designed to focus the laser radiation on the vibrating target. This sensor can measure target velocity. The working principle is based on the self-mixing effect that occurs in a semiconductor laser diode when the emitted radiation is back reflected toward the cavity and then re-introduced inside. The target velocity is calculated measuring the frequency of the peak of the spectrum of the signal generated by a photodiode mounted on the back facet of the laser diode. In this article, the design and the realisation of the vibrometer is reported. The self-mixing vibrometer has been calibrated in the range 0–300 mm/s, using a rotating disk covered with white paper. The effect of the angle of measurement and target distance are reported. Finally, the sensor has been compared with a commercial laser Doppler vibrometer using a vibrating surface as a target.     

Research on micro-vibration measurement by a laser diode self-mixing interferometer

The self-mixing vibration signals are observed in the laser diode when the optical beam is back-scattered into the laser cavity which causes laser output power modulated. Based on these properties, a laser diode self-mixing vibrometer with wide dynamic range is proposed. This current investigation further reports new work to improve the accuracy and range of the measured vibration signals. Numerical simulations and experimental results are given and discussed. The experimental results show that the frequency measurement range can be achieved up to 22 kHz with 0.241% maximum relative error while utilizing the reflecting film. For amplitude measurement utilizing the same reflecting film, the error of measurement result is 4.77 nm which has approached nanometer order of magnitude.     

激光自混合显微系统的设计及实验研究

论述了自混合干涉技术的发展历程,并引入了自混合干涉显微技术的实验原理和研究近展;建立了He—Ne激光自混合干涉实验装置系统,获得了稳定的激光功率输出。然后,对基于激光自混合干涉技术的显微镜进行了研究,并详细给出了该系统的设计原理、装调方法和实验结果,得到了玻璃小球的三维形体信息图像。系统达到的横向分辨力1μm,纵向分辨力为15nm。上述实验结果证明自混合显微镜在微小物体的高精度形貌成像方面有着很大的潜力。     

利用自混合干涉效应的条纹计数法对扬声器振动特性的实验研究(英文)

基于半导体激光器的自混合干涉效应，通过实验研究了扬声器的振动特性。实验中，用粘在扬声器振膜上的反射镜作为目标物体（该反射镜的反射率为95％，扬声器用50Hz的正弦波驱动）,然后通过条纹计数法获得扬声器的振幅。实验结果表明，在一定范围内，扬声器的振幅与驱动电压呈线性关系。该实验装置极其简单紧凑，自混合干涉信号也十分清晰，实验方法迅速，价格低廉，易实现，而且不需要专用电源，也不需要其他的光学仪器，这一系列优点充分表明自混合干涉技术在振动测量领域具有广阔的发展前景。     

Measurement of the velocity inside an all-fiber DBR laser by self-mixing technique

The self-mixing interference for optical velocity sensing is experimentally investigated in an all-fiber configuration distributed Bragg reflector laser. Simultaneously, theory model of self-mixing interference laser Doppler velocimeter based on quasi-analytical method. The experimental results show Doppler shift frequency is linearly proportional to the value of the velocity which agrees well with theory analysis. The results preserve an enough signal-to-noise ratio around 40 dB in the range from 39.3–317.0 mm/s (measurement range depending on bandwidth of circuit) for velocity measurement. Additionally, the cutoff circuit is used in our system to get a stable Doppler signal and reduces the error rate to 0.136 % in practical measurement.     

基于适度光反馈自混合干涉技术的振动测量

光反馈自混合干涉技术是一种新浮现的有别于传统双光束干涉的一类新的测试技术。为了在适度光反馈下进行振动的精密测量,提出了一种基于适度光反馈自混合干涉技术的振动测量方法。经对光反馈自混合干涉信号条纹分析,发现通过选定合适的光反馈水平及激光器线宽展宽因数,可以得到锯齿干涉条纹。这种干涉信号不仅包含振动幅度信息也包含振动方向信息。该振动测量方法利用锯齿干涉条纹的特点,首先通过条纹记数实现大范围振幅粗测,具有半波长位移分辨力;然后基于适度光反馈下小数条纹的特点,给出了小于半波长位移测量的线性表达式,从而实现位移的精测。仿真计算表明,该方法可以实现大量程高分辨力振动位移测量,在叠加20 dB的噪声下,振幅测量相对误差平均为0.5%。