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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:10,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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针对光纤激光器自混合干涉传感应用,研究了光纤激光器自混合干涉特性,运用四镜法布里-珀罗腔模型对掺铒线形腔光纤激光器自混合干涉效应进行了理论分析,对不同反馈水平下的自混合干涉信号进行了数值模拟,获得了光反馈条件下光纤激光器输出特性.外腔长度的改变会调制激光器的输出强度,外腔长度变化半个波长,对应一个干涉条纹,弱反馈条件下,由反馈引起的激光器的频率变化可以忽略.设计了基于光纤激光器的自混合干涉实验,实验结果和理论分析相符合.此研究结果为进一步开展光纤激光器的自混合干涉传感应用研究奠定了理论与实验基础. 相似文献
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从菲涅耳-基尔霍夫衍射公式出发推导出了粗糙面近场衍射方程。通过对观察面散斑光强统计特性的分析,提出了采用镜射光强分量法测量表面粗糙度的思想。为验证该方法的有效性,首先用计算机模拟产生具有不同统计特性的随机表面,然后对由随机表面产生的散斑场及其光强分布进行计算。计算结果表明,与传统的散斑对比度法相比,散斑镜射光强分量法测量弱粗糙表面粗糙度具有更大的适用范围和更高的测量精度,克服了散斑对比度法易受表面横向相关长度影响的缺点。通过实验对计算机模拟结果进行了验证。 相似文献
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通过对由纳米磁流体运动引起的双扫描激光散斑干涉光场及其变化做拉盖尔-高斯滤波下的傅里叶变换,获得动态散斑干涉图对应的光学涡旋分布及变化特征。分析认为,光学涡旋分布及变化对应着由纳米磁微粒及其团族的运动所引起的动态散斑变化。当纳米磁微粒聚集到分散的过程中,动态激光散斑光场的奇异场分布发生相应变化,说明了磁流体运动过程对应涡旋密度有先大后小,再由小变大的两个变化;并且光学涡旋密度高,对应较小颗粒的散斑场,磁流体处于稳态的状况;光学涡旋密度低,对应较大颗粒的散斑场,对应着磁流体激烈的运动。研究结果体现了奇异场分布变化和纳米磁流体动后趋稳的过程存在对应关系。 相似文献
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为了精确描述超声散斑场的特性,提出了采用计算机模拟产生超声散斑场的方法.利用模拟产生的高斯相关随机表面,获得了这类表面远场超声散斑场,同时得到了声强分布和相位分布.与实验产生的散斑场进行对比,建立了超声散斑场接收的实验系统,取与计算模拟相同的参数,获得了实验散斑场.通过对比发现:计算机模拟产生的超声散斑场相位存在奇异点,奇异点周围相位分布类似漩涡,计算机模拟产生的散斑场与实验得到的散斑场强度分布相似,强度值比实验产生的散斑场强度大,携带有用信息的高亮散斑较多,暗点较少,更利于研究和分析. 相似文献
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时间序列散斑干涉场中相位函数的计算 总被引:3,自引:2,他引:1
散斑干涉或电子散斑干涉计量应用于连续运动或变形物体时,就会产生一个时变的散斑干涉场,通过摄像系统连续地采集这一时变散斑场,可获得一系列时间序列散斑干涉图,通过对序列散斑图上各点在时间轴上光强值的变化进行分析,提出了一种基于时间序列的分析方法,用以提取干涉场的相位值,进而获得物体全场变形信息。 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
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Effect of angle of incidence on self-mixing laser Doppler velocimeter and optimization of the system 总被引:1,自引:0,他引:1
Wei Huang Huaqiao Gui Liang Lu Jianping Xie Hai Ming Deyong He Huanqin Wang Tianpeng Zhao 《Optics Communications》2008,281(6):1662-1667
Based on the theory of speckle and self-mixing interference in laser-diode, three-facet cavity model is introduced to analyze laser Doppler effect based on self-mixing interference in the case of a rough surface, and numerical solution of the signal is obtained. Simulation results of speckle-modulated Doppler signal based on self-mixing effect and tracking accuracy at different incident angles are given using parameters employed in the experiment. Simulation results indicate incident angle of around 30° is most suitable when both tracking accuracy and signal amplitude are considered. Experimental waveforms agree well with simulation results, and similar conclusions as simulation predictions about changing trend of tracking accuracies of the system at different incident angles can be made. Combining with difference frequency analog phase-lock loop (PLL) technique and appropriate sampling time, a laser Doppler velocimeter with tracking accuracy better than 1.3% in the range of 10-470 mm/s is realized. 相似文献
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The self-mixing interference in distributed feedback laser diode (DFB-LD) with multiple external cavities is analyzed. Each external cavity is considered to be an optical thin film, and the equivalent reflectivity can be got from the theory of the thin film optics, the general expressions of gain and frequency in compound laser cavity are theoretically deduced. This principle is helpful to build the fiber-coupled self-mixing interference system. Considering that different parameters have influence on self-mixing interference, we make some simulation analysis at different conditions. The output of self-mixing interference is analyzed in numerical analysis, and the amplitude variations of the output gain is discussed along with different parameters, e.g., the coupling coefficient, the linewidth enhancement factor, and the reflection coefficient of external reflector. 相似文献
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采用双激光二极管阵列(LDA)侧面交错抽运Nd:YAG晶体,通过电光调Q的方式获得1064 nm动态脉冲激光输出.这种抽运结构可以使晶体内的增益场与谐振腔基模实现良好的匹配,易于得到良好的光束质量和大能量输出.抽运源采用峰值功率为100 W的准连续LDA,采用直接贴近抽运的方式,KD*P晶体作为电光Q开关.并应用高斯光束传输的ABCD定律,计算了谐振腔稳区范围,给出了较为合理的谐振腔参数.所设计的激光器在重复频率20 Hz,抽运能量1200 mJ时,获得了最大输出能量151 mJ,脉宽8.48 ns的1064 nm动态激光输出,光-光转换效率为12.6%. 相似文献
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The importance of technological processes like corrosion, ablation or deposition causes interest in the quantitative monitoring of changes at rough surfaces. Thus, there is a need for effective methods to measure the statistical parameters characterizing changes in the profile or the material composition of such objects. The speckle field scattered from the surface is used as information carrier and its change is measured by correlation. This is realized by sophisticated data acquisition and digital processing techniques. An important issue is the interpretation of the correlation output in terms of statistical parameters describing the surface change. For many random surfaces a geometrical relation between surface profile and optical phase proves satisfactory. This allows to determine the standard deviation of the profile change. For a verification, speckle decorrelation in model surfaces of known deviation is measured. The paper introduces the speckle correlation concept, outlines some history and current setups and describes methods for data evaluation. The reliability of the quantitative interpretation of the speckle decorrelation is demonstrated. The method is illustrated by studies of metal corrosion and material removal in the cleaning of historical objects by laser ablation. 相似文献
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Efficient and high-power laser-diode single-end-pumped Nd:YVO4 continuous wave laser at 1342nm 下载免费PDF全文
A compact, efficient and high-power laser diode (LD) single-end-pumped Nd:YVO4 laser with continuous-wave emission at 1342 nm is reported. With a single crystal single-end-pumped by fibre-coupled LD array, an output power of 7.36W is obtained from the laser cavity of concave-convex shape, corresponding to an optical-to-optical efficiency of 32.8%. The laser is operated in TEM00 mode with small rms amplitude noise of 0.3%. The influences of the Nd concentration, transmissivity of the output mirror and the cavity length on the output power have been studied experimentally. 相似文献
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Takuya Nayuki Takashi Fujii Koshichi Nemoto Mikio Kozuma Motonobu Kourogi Motoichi Ohtsu 《Optical Review》1998,5(5):267-270
We developed a simple method of continuous wavelength sweep using a commercial laser diode (LD) without antireflection (AR) coating. A 630 nm AlGalnP LD was installed in a Littrow-type external cavity. In this cavity, the LD has the same effect as an etalon, and its free spectral range can be controlled easily by the LD drive current. By scanning the grating angle of the external cavity and LD drive current simultaneously, we obtained single-mode oscillation and continuous wavelength sweep of over 22 GHz without mode hopping. This technique is simple and inexpensive because it does not need AR coating on its output facet, and does not use a servo system which requires apparatuses such as a lock-in amplifier and local oscillator. 相似文献
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单偏振控制器环形腔光纤激光器实验研究 总被引:1,自引:0,他引:1
理论分析了非线性偏振旋转环形腔作为类饱和可吸收体获得脉冲的物理机理。在光纤环形腔结构中,采用单个偏振控制器实现了非线性偏振旋转锁模,直接获得了脉冲宽度为131 fs的超短脉冲输出。实验中,采用性能稳定的976 nm半导体二极管激光器作为抽运源,使用高掺杂浓度的Er3 光纤为增益介质,通过调节偏振控制器,获得了光谱谱宽(3 dB带宽处)为23.5 nm的稳定锁模脉冲输出。脉冲中心波长为1535.9 nm,平均功率为5.91 mW,脉冲重复率为11.20 MHz。 相似文献