光斑

Due to shrinkage of the beam waist of laser mode to match the pump beam, this laser can attain very high intensity in the pump region of gain medium and therefore most of its gain is depleted even by a standing wave.

由於雷射模会自动调整大小以符合泵浦光斑，雷射可以在被帮浦增益介质区域内达到很高的光强度，而使得大部分的增益被高强度的驻波消耗掉。

A heat mode of laser penetrating of thick steel plates has been investigated and the relations between laser power and beam size as well as welding speed have been obtained through energy balance.

通过能量平衡原理研究了厚钢板激光深熔焊接的热源模型，得出了激光功率与光斑大小、焊接速度等的关系，并讨论了激光光束质量。

At present, our white-light LED spot, brightness, color temperature and appearance basically meet the needs of different customer requirements, and consistency in color and has done very well controlled.

目前我们的LED白光的光斑、亮度、色温及外型上基本上满足不同客户的要求，并在颜色一致性控制方面做得非常好。

A differential demodulation system of Laser Doppler is designed. Phase grating is adopt to obtain same intensity measured beams with big separative angle in the system,and by focusing the waists of two Gauss beams on the measured object with extender and collimating lens group, the smallest speckle and the superposition of plane waves are obtained.

设计了一种差动检波系统，采用相位光栅获得同光强、大夹角的测量光束，用扩束准直透镜组使两束高斯光束的束腰聚焦在被测物体上，得到最小光斑和平面波的叠加。

Using uniaxial amplification system composed of a high-resolution CCD,a fast axis collimation lens and cylindrical lenses,via laser emitters imaging and facula intensity-based centroid algorithm,the "smile" of diode laser array is measured.

采用高分辨率CCD、快轴准直透镜及柱面透镜组成的单轴放大系统对激光线阵发光单元成像及基于光斑强度求质心的算法实现了二极管激光线阵&smile&的测量。

This problem is also important and valuable in Nonlinear Optics. It will be very helpful to understand how the aberrations affect the course of three- wave mixing, such as the change of conversion efficiency, the distribution of intensity and phase.Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental waves aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立国防科学技术人学研究生院学位论文三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼一夏克传感器分别对IO64nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

Small signal solution of aberrated second harmonic generation is deduced from three-dimension three wave coupling functions. The numerical work gives out lot of results of different aberrations. The effects of the fundamental wave's aberrations, which will change the conversion efficiency, distribution of intensity and phase in the frequency conversion, is analyzed. It shows that when walk-off and diffraction effects could be ignored approximately estimation of the phase distribution of second-harmonic wave could be done. The far field divergent angle and second moment radius of harmonic wave will vary with the aberration of fundamental wave, but the far field divergent angle will be obviously smaller than that of fundamental wave. The phase distribution of both fundamental and harmonic wave is measured using Hartmann-Shack wave front sensor in the experiment with 1064nm and 790nm lasers, respectively. Results are given.

首次从三维三波相互作用方程组推导得到了位相畸变光束倍频的小信号解；通过建立三维数值模型，编写相应仿真程序，首次得到了位相畸变光束倍频过程的大量计算结果，深入细致地研究了位相畸变光束经非线性光学频率变换后谐波的转换效率、光强分布、位相分布以及影响它们的各种因素；得出谐波的远场发散角和光斑二阶矩的变化规律会因为基波像差的不同而不同，但谐波的远场发散角明显地比相应基波的小的结论；得到了在走离效应和衍射效应等影响许多因素可以忽略的情况下，位相畸变传递到二次谐波的估算式；举例分析了KDP三倍频方案中，基波位相畸变对二次谐波和三次谐波的影响；实验工作中，用哈特曼-夏克传感器分别对1064nm倍频过程和790飞秒超短脉冲倍频过程中的基波和谐波的位相分布进行了测量，给出了相应结果。

The plasma ignition threshold of metal is got through experimental and numerical study. The vapour and plasma ignition times of the target are got based on the equation of heat conduction and cascade model. We suppose that the plasma is ignited when generations of new electrons are born in vapour generation time. The influence of temperature on the thermodynamics and optics parameters of material also have been considered in the model. The resulting theory has good agreement with the experiment and overseas report. A blade method to measure the laser spot is given in this paper with validation and error analysis. The plasma threshold of metals in atmosphere and water ambients both are diagnosed with the light deflection and piezoelectric transducer. A Q-switched pulsed Nd:YAG laser operating at infrared (1064nm), visible(532nm) and ultraviolet (355nm) wavelengths has been used. Al、Fe、Cu are used as targets and get a similar results with both method. Theoretical and experimental analyses are applied on the influence of wavelength on the threshold have been done, both of which have shown that the plasma threshold of metals decrease as the laser wavelength increases; The plasma threshold of metals are higher in water than in air and the pressure of the shock wave in water is five times higher than in air .

从热传导方程和雪崩电离机制出发，假设当电子增值210倍时，考虑了温度对材料热力学和光学参数的影响时，得到了气化和等离子体点燃的时间，利用该模型进行计算得到的结果与国内外报道及自行通过实验测得的阈值基本一致；提出了利用刀刃法测量激光光斑面积的方法，并通过实验进行了验证和误差分析；利用光偏转装置和压电换能器分别对空气和水中金属等离子体点燃阈值进行了实验诊断，激光器均为调Q－YAG激光器（波长1064nm，532nm，355nm，脉宽10ns），靶材分别为Al、Fe和Cu，两种测试方法得到的等离子体点燃阈值基本一致；本文从实验和理论计算两个方面讨论了波长对等离子体点燃阈值的影响，均得到了等离子体点燃阈值随著波长的增加而减小的结论；对空气中和水中不同环境下金属等离子体的点燃阈值进行了比较研究，得到了金属在水中的等离子体点燃阈值比空气中的大，且水中产生的冲击波的压强是空气中的5倍左右的结论。

LED module adopts ultra bright super flux LED of wide emitting angle as light source. It is flamboyant and coloury, well-proportional color without facula. Various kinds of colors are provided to customer's choice.

LED发光模组是采用大发光角度超高亮度LED食人鱼作发光光源，色彩艳丽，色泽纯正，混色均匀，没有光斑，有各种发光颜色客户可供选择。

We sit at my kitchen table as the sun designs a mosaic of light on the tile floor.

我们坐在餐桌旁边，阳光照在地板上，形成马赛克状的光斑。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。