共查询到20条相似文献,搜索用时 62 毫秒
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散斑条纹图的自适应窗口滤波方法 总被引:2,自引:0,他引:2
针对散斑噪声很难用常用的滤波方法进行滤除,在已有等值线滤波方法的基础上,提出一种更优的自适应窗口滤波方法。由于等值线窗口是在条纹方向图的基础上得到的,深入研究条纹方向的求取方法,提出了一种更为可靠的条纹方向求取算法,在得到高精度条纹方向的同时,还能估计出条纹的密度。使用等值线窗口技术,保持了窗口形状的自适应能力,然后利用对条纹密度的估计,根据条纹的宽度来确定滤波窗口的大小,实现了滤波窗口大小的自适应。最后,根据条纹方向和滤波后的图像可以直接得到条纹密度变化较大的单幅散斑图的相位结果。 相似文献
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半导体激光器内自混合散斑干涉 总被引:1,自引:1,他引:0
在散斑和半导体激光器的自混合干涉理论的基础上,提出了基于法布里一珀罗腔的自混合散斑干涉模型,对粗糙表面产生的激光器内自混合散斑干涉效应(SMSI)进行了详细的理论研究和分析,得到了粗糙腔条件下的激光动力学的数值解。模拟产生了高斯相关随机表面及其在夫琅禾费面上产生的散斑场,以及该散斑场与相干光场叠加所形成的光场,分析了这些情况中光强的统计特征,与已知实验情况进行了对比,模拟结果与已知统计结果相同。给出了粗糙表面运动时激光器输出增益的变化及其概率密度分布。对由于照明宽度和外腔长度的变化而给粗糙表面运动时激光器输出增益变化带来的影响进行了分析。实验结果和模拟结果相符。 相似文献
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半导体激光器的自混合散斑干涉测量流体速度 总被引:6,自引:4,他引:6
提出了一种简便的激光自混合散斑干涉测量流体速度的方法。根据散斑和法布里-珀罗腔的理论,提出了半导体激光器的自混合散斑干涉模型。研究了流体运动时在半导体激光器内产生的自混合散斑干涉效应(SMPI),给出了激光器输出增益的变化及其概率密度分布。得到了激光自混合散斑干涉平均频率与流体速度之间的关系。模拟计算和实验结果验证了这个关系。利用散斑干涉的平均频率与流体速度的关系测量了高分子材料溶液的速度,并在溶液浓度和背景光变化时,对流体速度进行了测量、比较和分析。实验表明。在溶液浓度不太低时,测量误差小于8%。 相似文献
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激光显示中散斑噪声的抑制 总被引:1,自引:0,他引:1
为了消弱散斑噪声,提出了最优化的斑纹减弱方法。给出采用最少数量的位相分布模式产生最大的斑纹减弱效果的位相型光学元件应满足的条件,证明了此位相分布格式可以由阿达姆矩阵的行或者列得到,并以绿光为例验证了所设计位相型衍射元件的斑纹减弱效果显著,采用衍射元件调制前后散斑对比度由8.4%减弱到2.7%。 相似文献
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光纤全息散斑干涉计量 总被引:1,自引:1,他引:0
脉冲激光经光导纤维传输后,其偏振性变化为随机分布,相干性有所降低,但它用在全息干涉计量中却有突出的优点,对于涉条纹的形成和清晰度没有影响。经常使用的光纤散斑全息干涉系统有两种类型:一种是只用传光束形成物光,参考光,此种系统形成的全息象清晰度有所下降,但做全息干涉计量时对条纹的衬比度和清晰度没有任何影响.另一种类型是物光和参考光都是用光导纤维传输,然后用光纤传象束将物体的象进行传输,再用透镜将其成象在底片上,做双曝光全息干涉时则形成全息散斑干涉计量,用全息方法再现时干涉图类似“杨氏”条纹。本文对上述两种系统,结合实验结果、分三种情况进行了研究。文章共分为三个部分:(一)引言;(二)散斑全息干涉计量;(三)结论。 相似文献
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合成孔径激光成像雷达(SAIL)时空散斑效应严重影响了成像质量。在时空散斑效应基础上,分析了合成孔径激光成像雷达中的散斑天线接收特性,建立了光学接收天线散斑孔径积分场的物理模型,模拟了目标分辨单元光学接收天线散斑孔径积分场距离向时间变化、方位向空间变化的二维分布。分析了不同接收天线散斑尺度比、不同天线积分起始位置对接收天线散斑孔径积分场的影响,并根据其统计性质得到散斑效应影响较小的接收天线尺寸和接收天线积分范围,为合理设计散斑效应较小的接收天线尺寸提供了参考,对进一步分析时空散斑效应如何影响SAIL目标成像有直接意义。 相似文献
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B. Ruth 《Optics & Laser Technology》1987,19(2)
An optical device for in-plane velocity measurement is described. Laser light is focused by the use of an optical fibre onto the object, and the device utilizes the dynamic sparkle effect for velocity determination. The influence of different optical fibres on the speckle formation is investigated with special respect to fibre movement, and as the diameter of the aperture used for speckle detection also affects the measuring signal, an optimum value is found. A simple electronic circuit processes the measuring value proportional to the object velocity. 相似文献
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Autocorrelation analysis for a velocity measurement based self-mixing speckle in an erbium-doped fiber ring (EDFR) laser is
presented. The expression for the velocity measurement is deduced. Theoretical analysis reveals that the velocity of a random
surface is inversely proportional to the autocorrelation time of the self-mixing signal produced in the EDFR laser. In experiments,
a linear fit between the velocity and the reciprocal of autocorrelation time (autocorrelation frequency) is obtained for velocity
measurement. In a range of velocities from 100 mm/s to 350 mm/s, the measurement errors are evaluated to be less than 5%.
The signal length, the measurement distance, and the pump power are experimentally studied for gaining knowledge of the influence
on the velocity measurement. 相似文献
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用激光光束直接照射到测试表面,再用CCD采其变形前后表面散斑颗粒干涉形成的条纹,条纹图解析为测量点的位移量和变形量,进而得到其离面位移,在优化算法的时候采用π位相技术获取另一个π相移的变形条纹图像,将面内位移与离面位移分离,为了消除零级分量,让投影光栅移动1/2个周期.通过Matlab和四步位相算法给出了三维空间模型,得出变形后物体的离面位移数据.实验仿真数据表明其能够稳定地测量物体变形场三维分量,误差较低. 相似文献
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《中国光学快报(英文版)》2020,(5)
In order to achieve the accurate measurement of displacement, this Letter presents a self-mixing interference displacement measurement method suitable for the speckle effect. Because of the speckle effect, the amplitude of the self-mixing interference signal fluctuates greatly, which will affect the measurement accuracy of displacement. The ensemble empirical mode decomposition is used to process the interference signal, which can filter out high-frequency noise and low-frequency noise at the same time. The envelope of the self-mixing interference signal is extracted by Hilbert transform, and it is used to realize the normalization of the signal. Through a series of signal processing, the influence of speckle can be effectively reduced, and the self-mixing interference signal can be transformed into standard form. The displacement can be reconstructed by fringe counting and the interpolation method. The experimental results show that the method is successfully applied to the displacement measurement in the presence of speckle, which verifies the effectiveness and feasibility of the method. 相似文献
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为了实现实验室环境下测定光速,采用已知长度及折射率的单模零色散光纤作为传输介质,利用高精度时间间隔测量技术测量了光在该光纤中的传输延时。经过理论推导,求出光速c与作为传输介质的光纤长度L、折射率n及光纤延时τ之间的关系式,从而通过测量得到L,n及τ的值即可计算得到真空中的光速值。与传统的利用天文法及精密仪器测量光速的方法相比,采用比较先进的高精度时间间隔测量技术可使时间分辨率达到125ps,从而在实验室环境下,利用简单仪器得到了高精度的测量结果。最终测量所得光速为299928077m/s,误差为30860m/s。 相似文献
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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. 相似文献
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The statistical analysis of self-mixing speckles interference using Fabry-Perot cavity is described based on the theory of the speckle and the self-mixing interference in a laser diode. Speckle signal processing based on Fourier transform is presented in this paper. The linear dependence between the spectrum mean frequency and velocity of solution is given by simulation and proved by experiment. The experimental results show that this speckle signal processing can be used to measure velocity of target. 相似文献