共查询到18条相似文献,搜索用时 93 毫秒
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基于希尔伯特变化的微小振动激光多普勒信号处理 总被引:1,自引:0,他引:1
为了实现对固体目标微小振动参数的测量,建立了微小振动的激光多普勒信号模型。采用希尔伯特数字运算,将激光多普勒振动信号的即时信号采样转化为信号的谱采样。通过频谱计算得到每个振动周期中瞬时频率的平均数,应用差值采样序列积分计算得到振动频率,最后根据振动信号频率变化与振幅的关系得到振幅。采用希尔伯特方法对实验测试结果进行处理验证,并分析了误差来源。实验结果表明:实验测量目标的振动振幅约为1.85×10-4m,转动的圆频率约为170 Hz。因此,应用希尔伯特变换方法处理测量的目标微小振动信号,获取目标运动的参数是可行的。 相似文献
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采用外差探测方式, 建立了全光纤结构的激光多普勒测振仪,用来测量经空气传播耦合引起的散射体振动,以期感知振源振动信息。实验探索了散射体材料、固定方式和相对振源位置等对空气耦合振动的影响,得到了200~2700 Hz频率范围内6种散射体振动响应特性曲线。结果表明:通过空气耦合引起的散射体振动,在相同振源振幅下,散射体振动的振幅一般随频率升高而升高; 在材料、固定方式和相对振源位置等因素中,散射体材料对振动响应特性的影响是主要的,后两者只影响局部细节。 相似文献
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一种新型的激光自混频测振的方法 总被引:3,自引:3,他引:0
1引言在激光器的许多应用中,我们都尽可能的避开出射光的自反馈现象.尽管如此,还是被来自各种各样的光学元器件所组成的共振腔产生的反射光所困扰.自反馈不仅增加了噪音强度,而且同时大大改变了激光器输出的特性曲线,这种作用的性质已被Lenstra等人‘’‘描述过.然而我们正是利用了这种“不利”的特性构成了自混频激光测振系统.2基本原理激光自混频干涉的简单装置如图1所示.首先由激光垂直照射在待测物体上,利用从待测物体上反馈的光对激光器输出功率调制,然后从尾光接收调制信号,这种可被提取的携带外界馈信息的光反馈调制后… 相似文献
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直升机旋翼挥舞、摆振的激光动态测试系统 总被引:10,自引:1,他引:9
提出一种直升机旋翼挥舞、摆振角的动态测试系统。在直升机桨毂安装与旋翼同步旋转的三叉件 ,每个三叉件悬臂上装有光学三角位移传感器和线阵 CCD位移传感器 ,实现了动态测量直升机旋翼桨叶的挥舞和摆振角。为保证系统在恶劣条件下正常工作 ,系统采用了加装干涉滤光片、L D调制技术和自动增益控制电路等一系列技术措施。最后给出了实验结果。由位移 -角度转换和传感器自身的非线性引起的误差用若干静态标定点为节点插值的方法修正。得到较高精度的测试曲线 相似文献
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光声/光热光谱技术已经广泛应用于痕量危险化学品和爆炸物的探测,并显示出高效的探测能力。然而,该技术通常需要在光声池中进行分析,并使用高灵敏度麦克风或压电传感器记录振动信号,因此不适用于在安全距离外的开放环境中探测泄漏的危险物质或爆炸物。为此,利用强度调制的量子级联激光器(QCL)激发微量固体(聚四氟乙烯)和气体(丙酮)的光声效应,借助自主研发的远距离激光多普勒测振仪(LDV)对QCL产生的光振动信号进行检测。通过扫描QCL的波长,测量振动信号的幅值并获取光声光谱,其结果与傅里叶变换红外光谱的结果高度一致。实验结果表明,自制的远距离LDV可以在距离达200 m的开放环境下有效地检测痕量固态和气态化学品的光声信号。 相似文献
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通过统计理论和维纳-辛钦定理推导出激光外差探测系统光电流的功率谱函数,分析了光电流谱线分布与激光光源线宽、中频信号频率以及信号光相对本振光传输延迟时间的关系,修正了相关文献中光电流功率谱的理论公式.根据信号与噪声理论建立了激光线宽引起的相位噪声的一维概率分布模型,并据此得到了基于激光波长、探测距离以及激光线宽的极限位移分辨率的数学模型.对光电流的功率谱和外差光学极限位移分辨率进行了相关的数值仿真,结果表明延迟时间与相干时间的关系决定光电流谱线分布的情况.当激光波长为532 nm,激光线宽在1 kHz,探测距离为100 m时,光学极限位移分辨率为0.266 nm,相关文献中的实验数据与理论推导结果相符合. 相似文献
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在线偏振飞秒激光激发下, 菌紫质通过双光子光化学反应可以生成具有永久光致各向异性的蓝移产物F540态. 基于F540态的永久光致各向异性, 通过调控飞秒激光空间光场分布, 可以在菌紫质薄膜中实现永久光信息存储. 本文使用纯相位型空间光调制器调制飞秒激光光场, 在物镜焦平面上生成光学点阵图案, 可以将信息快速记录在菌紫质薄膜中. 同时, 通过改变入射激光偏振方向, 可以实现偏振复用光存储, 这在高密度光存储和数据加密领域具有潜在应用. 相似文献
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Joris Vanherzeele Steve Vanlanduit Patrick Guillaume 《Optics and Lasers in Engineering》2007,45(6):742-749
This paper shows how a scanning laser Doppler vibrometer (LDV), an instrument designed to measure vibrations of structures or objects, can be used in a non-traditional fashion to identify acoustical sources. This is achieved by measuring the changes in the optical path induced by local fluctuation of the air refraction index to which the LDV is sensitive. The acoustical signal used is sinusoidal and may be recovered by scanning at a uniform rate over a subject area (continuous scan) parallel to the source axis and demodulating this signal. Due to the fact that the measured scan area is in fact a line integral over a measurement volume between the laser head and a rigid object needed to reflect the laser beam, multiple view planes around the axis of the acoustic source are usually measured. These are then passed through a tomographic algorithm, thereby reconstructing the full sound field. In this article however, only one view plane is measured, but the acoustic source is placed on a rotating surface with fixed rotational frequency, thereby imposing a modulation on the measured spectrum. Demodulation will allow reconstruction of the three-dimensional sound field. 相似文献
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In this paper, a new fully automated scanning laser Doppler vibrometer (LDV) measurement technique is presented. In contrast to existing scanning LDV techniques which use a 2D camera for the manual selection of sample points, we use a 3D Time-of-Flight camera in combination with a CAD file of the test object to automatically obtain measurements at pre-defined locations. The proposed procedure allows users to test prototypes in a shorter time because physical measurement locations are determined without user interaction. Another benefit from this methodology is that it incorporates automatic mapping between a CAD model and the vibration measurements. This mapping can be used to visualize measurements directly on a 3D CAD model. The proposed method is illustrated with vibration measurements of an unmanned aerial vehicle 相似文献
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Joris Vanherzeele Steve Vanlanduit Patrick Guillaume 《Optics and Lasers in Engineering》2007,45(1):49-56
In the last decade the laser Doppler vibrometer (LDV) has become a widely spread instrument for measuring vibrations. It often offers accurate measurements with a high spatial resolution. However, the measurement time of the LDV and especially for the scanning LDV is long. Therefore, reducing the measurement time is an attractive objective. A way to achieve this is to use a single sine excitation (on a resonance frequency). However, this technique has two major drawbacks: the inability to provide information on the damping and a operational deflection shape that can differ from the true mode shape. In this article two methods will be introduced to reduce measurement time without these defaults. In the first method introduced in this article a narrow band multisine is used as excitation signal and the measured vibration signal in the time domain is represented by a model using sines and cosines with these fixed narrow band frequencies. The coefficients of those sines and cosines are then estimated on a global scale by means of a least-squares estimator. An important advantage of this particular technique is that one does not have to measure a full period of the signal, reducing time. The second method accelerates the measurement time for scanning LDV measurements. Using the time domain sequence from each previous scan point and a limited number of time samples from the current scan point, the full time domain sequence of the current scan point can be estimated. Both these methods are a key benefit for in-line quality control, which can have upwards of 1000 spatial measurement locations. The proposed techniques will be validated on both simulations and experiments of varying complexity. 相似文献
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设计了一种Offner光学系统,用于基于相位差异技术的图像恢复和光学系统波像差的辅助检测。该Offner光学系统采用同轴抛物面反射镜作为Offner反射镜,以高速CCD相机和Shack—Hartmann波前探测器作为接收元件,能完好地消除复色光源在图像恢复过程中带来的色差;设计的RMS波像差小于a/50(A=632.8nm),结构简单,容易实现。利用该系统分别以分辨率板和光纤光源为目标进行了图像恢复实验,经过恢复后的图像分辨率提高了19%。此外,利用该系统,采用相位差异算法解算了系统波像差,并与Shack—Hartmann波前探测器的测量结果进行了比较。比较显示两者的RMS波像差测量值相差5%,证明该系统同样能够进行光学波前检测。 相似文献
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通过对一般激光器的发光特点及柱面镜的光学特性进行分析,提出一种新型激光周视引信光学系统——柱面镜系统,即采用2个弧矢面正交的柱面镜组来改善激光束散角,以4个扇区来完成空间的周视功能。由于在半径为0.5~10m的圆周上光能量均匀性非常好,且系统光路具有可逆性,因此可用于大视场发射和接收的导弹引信中。该系统结构紧凑,易于加工和安装。靶场试验证明了该光学系统的可行性和实用性。该光学系统可代替目前仍在使用的反射式光学系统。 相似文献
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将成像光学系统同时用作激光发射天线的共口径设计可有效减轻卫星载荷质量和应对各种突发状况。首先根据激光通信的能量计算链路,分析了激光发射天线的设计要求,明确了激光发射天线与成像光学系统的不同;然后根据特定的成像光学系统给出了3种具有普适性的共口径设计方法,并对这3种方法的性能进行了分析和比较,给出了它们的优缺点和适用范围;最后对所设计的共口径系统进行了发射光束仿真,经过对设计系统加工、装调后进行了室内的成像、通信实验,结果显示发射激光的最小束散角可达18.2 μrad,接近系统衍射极限,出射光斑质量良好,接收到的图像与成像系统所成图像肉眼观测无失配。初步证实该共口径设计可实现光学系统的成像和通信任务要求。 相似文献