共查询到20条相似文献,搜索用时 15 毫秒
1.
高速激光通信中接收机与光斑中心很难处于精对准状态,导致水下光通信链路难以稳定建立.首先采用蒙特卡洛仿真统计法分析激光光子在海水中传输的接收光强分布规律,再通过实验对接收端的光斑图像进行采样分析,利用曲线拟合得到接收器位置与接收光强的关系.仿真与实验结果表明:光束经过25 m的水下传输,接收光强分布仍近似为高斯分布.采用非线性估计算法(扩展卡尔曼滤波)与基本状态控制反馈理论,根据接收光强度估计接收器当前位置与最大光强处的距离,通过反馈算法实现接收端与光斑中心的主动跟踪对准.算法仿真结果显示,接收端对准误差在2 mm以下,稳定后接收效率超过98%. 相似文献
2.
This paper presents a set of formulae for estimating the light spot position projected on a quadrant detector (QD). A novel method of annular segmentation calculus (ASC) is designed to analyze the detecting light spot of QD. The influences of the spot movement mode, spot energy distribution, and dead area to the dynamic range and the detection sensitivity are analyzed. It is shown in simulations that our new formulae have achieved a much better results to increase measurement accuracy. It is also shown that on the condition of the same spot size, the detection sensitivity of Gaussian distribution is prior to uniform distribution. The detection sensitivity of diagonal mode is better than cross mode. The detection sensitivity increases with increase in the size ratio of dead area to spot. The simulating and experimental results show that the measuring range of QD is 400 μm, and the resolution is 50 μm. The study presented here will be beneficial in developing the nanomechanical displacement detection techniques. 相似文献
3.
4.
The directional accuracy of threaten laser is highly dependent on the laser spot center location accuracy for the laser warning system. On the basis of analyzing the spot features on wide field of view (FOV) fish-eye imaging laser warning system, a refinement of existing methodology based on fitting a 2D Gaussian distribution for estimating the center of the spot is developed. The proposed procedure is using a linear least squares based algorithm to determine the best-fitting parameters of the Gaussian. However, in contrast to the standard Gaussian Fitting procedure, this new scheme gives rise to equations that are rigorously linear in the transformed unknown parameters which can be solved easily by linear least squares estimators. To validate the accuracy of the proposed algorithms, experimental approaches with a type of laser warning detector and simulated threaten laser in laboratory are used to quantify its performance. The experimental results show that this method outperforms significantly the commonly used location technique. It is less susceptible to the non-100% fill ratio of CMOS and large unsymmetrical optical aberration of fish-eye lens. The positioning precision in paraxial region and 80° incident angle region are 1/60 pixels, 1/30 pixels respectively. The biggest error is less than 1/20 pixels. The proposed method is suitable for wide FOV laser warning system for high accuracy and low computational complexity. 相似文献
5.
衍射光学元件由于可以实现对高斯光束的整形而被重视,其通常的设计方法为G-S算法,由于使用傅里叶变换运算量大、费时长,将快速汉克尔变换应用到这些算法中可以极大地提高运算速度,节省运算时间,为设计复杂的光束整形元件提供了高效、可行的方法。本文利用该种方法设计针对中心波长为775 nm、光束束腰口径为6 cm的激光器,成功设计了一个具有二阶相位的折衍混合光学元件。仅单独这一片元件,既可在距离其35 m处得到一半径为200μm的圆形平顶光斑,均方根误差D0.021。当抽样值取2~15时,在普通PC机上运行时间仅为20.05 s,大大节省了优化设计时间(整个优化设计过程往往需要几十次甚是上百次这种运算)。同时利用离子刻蚀技术加工了该折衍混合元件,并进行了实际测试,结果与设计值基本相符,整形效果较好。这种单片的整形元件不仅整形效果好,还有利于与激光器的集成,简化系统的调节。 相似文献
6.
7.
提出利用部分相干光通过透镜列阵系统实现靶而的均匀辐照, 透镜列阵能获得边缘陡峭且顶部较平坦的准近场焦斑, 透镜列阵的适当同心度偏差又使各子束的斑纹相互稍微错开, 使干涉斑纹变密, 而入射的激光是空间相干性减少了的部分相干光, 可进一步抑制了透镜列阵系统焦斑的小尺度不均匀性. 使用广义衍射积分理论, 对高斯-谢尔光束通过透镜列阵光学系统的焦斑光强分布进行了详细的二维模拟研究, 比较了完全相干光与部分相干光经过透镜列阵的匀滑效果. 数值模拟表明, 应用同心度偏差和适当离焦时, 可实现焦斑均匀性和能量利用率同时达到最佳的效果. 相似文献
8.
9.
OFLID: Simple method of overlap factor calculation with laser intensity distribution for biaxial lidar 总被引:1,自引:0,他引:1
We proposed a simple overlap factor calculation method based on laser intensity distribution (OFLID), which is simple, practical and can be applied to any specific laser intensity distribution. In order to obtain the laser intensity distribution and parameters of our laser system, we designed a simple experiment to measure them, and then simulated an ideal Gaussian and uniform laser intensity distribution with the measured parameters. The OFLID calculation results indicated that the overlap factor of the measured distribution has approximately half the relative error of that of the ideal Gaussian distribution in the increasing range field for our lidar. Specifically, the laser intensity distribution should be regarded in the overlap correction of the lidar signal. Theoretically, the OFLID method can reduce the error caused by the hypothesis of ideal uniform or Gaussian intensity distributions in the analytical method. In addition, the method is easy to implement for overlap correction, signal simulation and system configuration optimization for biaxial lidar. 相似文献
10.
Wen-Shing SunChuen-Lin Tien Te-Yuan ChungYan-Nan Lin Ju-Yi LeeDung-Yi Hsieh Tsai-Wei Lin 《Optics and Lasers in Engineering》2011,49(8):1076-1088
We present an optical system design for determining the tilt angle and displacement of the test plane. The proposed optical system consists of a Blu-ray pickup head and a pigtailed laser diode with a uniform Gaussian beam. The optical system is evaluated by two optical design software packages, Code V and LightTools. A quadrant detector is used to detect the relative relationship of the VA, VB, VC and VD output signals, which can be used to measure the tilt angle and displacement on the test plane. Both the tilt angle and displacement on the test plane can be determined from the change in the beam shape on the quadrant detector. The proposed system can generate a circular uniform beam shape to reduce the misjudgment and to enhance the measurement accuracy. Various simulation cases are presented in detail to show the feasibility of the proposed system. 相似文献
11.
激光多普勒测速仪中散射光特性的研究 总被引:2,自引:0,他引:2
后向散射光特性与多普勒信号的质量密切相关。为了设计高性能的激光多普勒测速仪,运用散斑理论详细分析了激光多普勒信号的强度与散射光斑大小的关系,结合泛函理论给出了计算多普勒电流的散斑表达式,并通过实验的方法研究了回波信号的偏振特性及其强度分布。理论分析与实验结果表明,激光多普勒信号的强度与接收器件光敏面的直径成正比,与光斑的直径成反比;选用光斑较小的圆偏振激光束,并用光敏面尺寸较小的探测器在镜面反射方向上接收信号光,可以大大提高多普勒信号的信噪比,增强系统的探测能力,为提高系统的测量精度创造有利的条件。 相似文献
12.
13.
TEA-CO2激光辐照HgCdTe图像传感器的实验研究 总被引:1,自引:0,他引:1
利用TEA-CO2激光对碲铬汞(HgCdTe)图像传感器的干扰和损伤现象进行了实验研究,分析了干扰和损伤机理。探测器上激光能量密度小于255 mJ/cm2时,饱和像素仅出现在光斑区域,激光能量密度为425.8 mJ/cm2时,像素被损伤,观察到了弥散斑和暗环等现象。建立了探测器的激光辐照模型,计算了探测器的温升,讨论了温升与载流子浓度、迁移率的关系。分析认为,弥散斑的出现是探测器升温产生的热激发载流子浓度扩散所致,暗环的出现是迁移率与载流子浓度扩散共同作用的结果,像素的损伤则是因为温升导致汞的析出。 相似文献
14.
为缩短衰减倍率调整的时间,提高激光参数测试的效率,提出激光光强快速衰减算法。衰减倍率精确调整量由当前衰减倍率和采集到的光斑光强真实的最大灰度值共同决定。当因光电接收器件(CCD)饱和造成采集光斑图像失真时,即衰减倍率过小时,由于激光光斑的光强通常满足高斯分布,通过对光斑图像进行处理,去除饱和部分光强信息,对剩余部分光强信息利用最小二乘法进行三维高斯拟合,还原出激光光斑光强的真实分布并获得最大灰度值;当衰减倍率过大时,根据采集光斑图像可以直接获得当前最大灰度值,最后通过计算获得最佳的衰减倍率调整值,实现了激光光强快速准确的调整。算法的有效性通过步进电机带动的双轮可变衰减器及CCD配合得到验证。 相似文献
15.
实验研究了平顶飞秒激光经圆锥透镜后在熔融石英中的成丝及超连续辐射.与高斯飞秒激光的成丝对比发现,平顶飞秒激光可以获得在圆锥透镜焦深区域内强度分布更为均匀的等离子体细丝,这一特征更有利于飞秒激光在固体介质中进行微纳加工等领域的应用.并且,在不损伤熔融石英的条件下,平顶飞秒激光成丝可以获得更高能量、更高转换效率的超连续辐射,这是因为若产生光强相近的细丝,平顶飞秒激光所需的初始激光能量更高,此激光能量下产生的细丝长度更长、均匀性更好. 相似文献
16.
17.
18.
由于激光烧蚀靶材产生的等离子体呈高斯分布,其中所包含粒子密度及性能的空间分布极不均匀,因此脉冲激光沉积法难以制备性能与膜厚均匀的大面积薄膜。提出并构建了衬底自转与一维变速平移机构,衬底匀速自转的同时,进行一维平移,越靠近等离子体中心平移速率越大、反之越小,达到均匀镀膜的目的;在此基础上建立了机构运动参数对膜厚影响的数学模型,通过仿真模拟分析关键参数对膜厚分布的影响;通过运动参数优化指导实验,最终获得了直径为200mm、不均匀性不超过±4%的大面积类金刚石膜,与仿真优化结果吻合。 相似文献
19.
20.
实验研究了平顶激光光束经微透镜阵列在熔融石英中成丝的演化以及超连续辐射的产生,并进一步与高斯光束的成丝和超连续辐射进行了对比研究.分别对这两种光束的多丝传输进行了横向和纵向成像.结果表明,使用平顶光束可以获得更为均匀的多丝分布,成丝的起点也更为一致;尤其重要的是,相对于高斯光束,平顶光束可以使用更高的入射激光脉冲能量而不会造成介质的损伤,从而可以获得更高脉冲能量和更高转换效率的超连续辐射. 相似文献