Acousto-optic Q-switched laser performances of Er^3＋：Yb^3＋：LuAl3（BO3）4 crystal at 1.5-1.6 μm

The cavity tuning characteristics of orthogonally polarized dual-frequency He-Ne laser at 1.15 μm are presented. Vectorial-extension model based on semi-classical laser theory reveals that cavity tuning characteristics are related to beat frequency, relative excitation, and type of Ne isotope. Distortions of cavity tuning curves become moderate with the increase of beat frequency because of the weakening of the crosssaturation effect. Distortions are enhanced with the increase of relative excitation because of the combined action of the self-saturation and cross-saturation effects. By adopting dual-isotope Ne instead of monoiso- toplic Ne, distortions are reduced because of the misalignment between peaks of the self-saturation and net gain coefficients. The theoretical calculations are in good agreement with the corresponding experimental results.     

完全分配可交换子空间格代数上的中心化映射

基于Hilbert空间H上的一个完全分配可交换子空间格代数Alg L,考虑Alg L上的中心化映射.设为Alg L上的一个可加映射,用完全分配可交换子空间格代数的结构性质和代数分解,证明了:若存在正整数m,n≥1,使得A∈Alg L,(Am+n+1)-Am(A)An∈F I成立,则存在Alg L中心里的元素λ,满足A∈Alg L,有(A)=λA.     

一个无k次幂因子D.H.Lehmer数的渐近性质

设素数p>2,对任何满足条件1 a相似文献   

数字地震图的分析与探讨

从数字地震记录图分析入手,结合地震台站的基本环境,对数据进行处理。找出选址环境对记录的影响与排除方法,以期在今后地震监测工作中得到一些启发。     

空中目标红外辐射强度计算通用模型及其应用

提出了一种适用于空中扩展目标和小目标红外辐射强度计算的通用模型,该模型消除了对环境温度依赖较大的背景偏置的影响,可有效提升外场复杂多变环境条件下航空目标红外辐射特性测量结果的精度。结合某型航空目标动态红外特性测试数据,探讨了小目标红外辐射强度的计算问题,结果表明:对于中波红外小目标,大气表观辐射强度对总辐射强度的贡献可以忽略,可以采用简化模型计算总辐射强度,但对于长波小目标红外辐射,简化模型不再适用。对红外小目标和扩展目标的外场动态测试数据分别进行了处理,并与理论结果作比对验证,结果验证了模型的正确性。     

试论10kV配网线路故障及危害处理

随着社会经济的发展与工农业生产的不断进步,对电力资源的需求越来越大,电力系统的安全可靠运行直接影响着生产建设的稳定发展,因此受到了高度重视。10k V配网线路在电力系统输送电方面发挥着不可替代的作用,若其发生故障则会造成不可忽视的电力耗损以及生产损失。该文对10k V配电网线路故障的原因进行探究,并根据具体问题提出几点危害处理的防范措施。     

激光回馈引起的微片Nd:YAG激光器频差调制

微片激光器由于自身的内应力会输出频率分裂的正交偏振的两个模式.研究了回馈对微片激光器频差的影响.研究发现:在回馈的作用下微片激光器的频差大小呈现出以初始频差为中心的类正弦的频差调制,周期为λ/2;频差调制曲线的幅度与回馈水平成正比,但是当回馈水平过强时会出现偏振态跳变,从而使频差消失;在一定的回馈外腔范围内,频差调制曲线的幅度与初始频差亦成正比.并利用复合腔模型和激光器的自洽理论进行了理论分析和模拟,所得结果与实验结果相符.此调制现象在精密测量领域有潜在应用.     

Tuning Characteristics of Frequency Difference for Zeeman—Birefringence He—Ne Dual Frequency Laser

Characteristics of frequency difference tuning of Zeeman-birefringence He-Ne dual frequency lasers (ZBDFLs) are explored.We design an automatic system of tuning cavity and power detection,which can tune the laser cavity and record the tuning curves of light power and frequency difference simultaneously.A synthetic phenomenon by Zeenman effect,mode pulling effect and birefringence effect is verified to exist in ZBDFLs.By analysing the tuning behaviour,this synthetic phenomenon is discovered and qualitatively explained for the first time.     

Laser Feedback Technique for Precise Retardation Measurements

A simple and precise retardation measurement based on laser feedback is demonstrated. The measurement principle is based on polarization flipping induced by optical feedback from an external birefringence cavity. The measured wave plate is located in the external cavity. When the length of the external cavity is tuned, the polarization states of laser will flip between two eigenstates, and the position of polarization flipping in one period of intensity modulation will vary with retardation of the wave plate. The duty ratio of two eigenstates is used to determine the retardation. Main advantages of the technique are that it is compact, low cost, fast and flexible. Especially, it is insensitive to a fluctuation of laser intensity and is suitable for on-line measurement. The experimental results have shown that the measurement uncertainty is better than 0.03° in the range 30°-150°.     

Intensity Tuning in Single Mode Microchip Nd：YAG Laser with External Cavity

We investigate the characteristics of intensity tuning in a single mode microchip Nd：YAG laser with an external cavity. The undulation of laser intensity in a period of A/2 change of the internal cavity length is observed. Two different optical feedback cases are performed. One is an external cavity reflector perfectly aligned and the other is an external cavity reflector tilted. However, the fluctuation frequency of laser intensity in a period of A/2 change of the internal cavity length in these two cases is found to be determined by the ratio of external cavity length to internal cavity length. Meanwhile, for the tilted external cavity, the fluctuation frequency is also related to multiple feedbacks in the tilted external cavity.