衰荡腔测量中的腔参数选择

 基于谐振腔失调灵敏度参量随腔长的变化关系，提出了一种衰荡腔，它是由共焦腔将腔长缩短为原来的0.73得到的稳定腔。根据光束传输规律和失调腔矩阵方法，以及光腔衰荡法测量原理和曲线拟合方法，建立了腔长、腔镜角度失调下光腔衰荡法的反射率测量模型。通过数值模拟，研究了这种稳定衰荡腔中，腔微小失调对反射率测量结果的影响，并与相同失调情况下共焦衰荡腔的测量结果进行了对比分析。结果表明，这种稳定腔用作衰荡腔，测量结果受腔镜角度失调影响较大，而受腔长失调影响小；其长度较短，便于工程应用；衍射损耗较小，测量精度高。     

光学元件失调对光腔衰荡高反射率测量影响的理论分析

在利用光反馈光腔衰荡技术测量大口径光学元件反射率及其均匀性分布时,需要对光学元件进行二维扫描测量,而在扫描过程中光学元件的倾斜失调将对测量结果造成影响.本文根据失调谐振腔光束传输增广矩阵,通过数值运算模拟了在对称共焦腔和一般稳定腔情况下,光反馈衰荡腔结构中由样品倾斜失调引起的输出腔镜上光斑中心位置变化以及对反射率测量的影响.仿真结果表明:对称共焦腔情况下,输出腔镜上奇数次光斑无漂移,偶数次光斑漂移量为固定值|在一般稳定腔情况下,输出腔镜上奇偶数次光斑均往复振荡漂移.分析表明,该系统对样品失调角度的敏感程度与样品在腔内的位置以及腔长有关,通过改变样品在腔内位置,选择适当腔长以及包络拟合法可以减小样品失调对测量结果的影响.     

腔镜失调与面型误差对光束质量影响研究

 在准确测量腔镜面形加工精度的基础上，通过光学模拟软件ZEMAX实现了氧碘化学激光器折叠虚共焦非稳腔的光学建模，利用光腔模型进行了腔镜面形误差对光束质量影响的研究以及腔镜失调对光束波前影响的分析，在空腔的情况下利用调腔He-Ne激光进行了光束质量测量实验。实测结果与建模数据基本符合，验证了该方法的可行性。     

腔镜失调对激光陀螺信号输出的影响

研究了不同腔镜结构不同失调情况对空间谐振式激光陀螺中光束空间位置的影响.利用Collins积分与Collins程函理论以及MATLAB软件工具,对腔镜失调前后激光陀螺中光束传输进行了仿真计算.结果表明,相同失调量的不同反射镜所产生的拍频频差是不同的,且分别从M1和M4镜探测到的拍信号频不相同|对于小增益激光器,使用球面镜的腔镜结构较平面镜的腔镜结构更易形成稳定光束空间位置分布|由所计算的空间坐标xn可以看出,双向行波光束的光斑中心发生了偏移,在一定的失调量下将会影响到激光陀螺的拍频输出.研究结果对激光陀螺的工程检测和腔镜调整有指导作用,有助于激光陀螺测量准确度的提高.     

角隅全反镜谐振腔激光器的输出特性

 在高功率脉冲气体激光器中，用角隅反射镜作为全反镜，平行平面镜作为输出镜构成角隅全反镜谐振腔。对角隅腔激光器的输出特性和抗失调稳定性进行了研究，并与平凹腔和平平腔激光器进行了比较。实验结果表明：在角隅全反镜失调角为16 mrad时，角隅腔激光器的单脉冲输出能量下降9.2%，且近场输出光斑没有明显变化；而凹面全反镜失调角仅为0.4 mrad时，平凹腔激光器输出能量下降了9%，近场输出光斑严重变形。在输出镜正前方3.12 m处测量，当角隅镜偏转16.3 mrad时，激光器输出光斑与标准状态时的输出光斑重合；凹面全反镜失调角为0.4 mrad时，激光器输出光斑位移14 mm。经模式仪分析表明，角隅腔激光器近场光强分布均匀。     

光学元件失调对光腔衰荡高反射率测量影响的理论分析

在利用光反馈光腔衰荡技术测量大口径光学元件反射率及其均匀性分布时,需要对光学元件进行二维扫描测量,而在扫描过程中光学元件的倾斜失调将对测量结果造成影响.本文根据失调谐振腔光束传输增广矩阵,通过数值运算模拟了在对称共焦腔和一般稳定腔情况下,光反馈衰荡腔结构中由样品倾斜失调引起的输出腔镜上光斑中心位置变化以及对反射率测量的...     

适用于圆筒形增益区的同轴四镜腔的失调分析

采用矩阵光学方法，对适用于可见光的圆筒形增益区同轴四镜腔中的腔镜因倾斜而产生的失调特性进行了分析，给出了相关计算公式。该四镜腔由同轴的一个复曲面全反镜和两个光学玻璃加工的透镜和一个平面输出镜组成。以He-Ne激光器为例，给出了数值计算结果，关键元件复曲面镜的失调对输出的影响较大。这为腔元件的加工以及腔镜的安装调试提供了参考。     

可调谐PPLN中红外光参量振荡器失调特性

 通过对晶体进行周期调谐,实现了中红外参量光输出,在此基础上研究了晶体移动、腔镜偏转等对失调特性的影响。结果表明：由于PPLN通道的小尺寸波导特性和参量振荡特性,其失调特性不同于常规激光器。PPLN晶体沿不同轴移动的功率变化曲线有不同的特点,沿x轴移动的失调容限大于沿y轴移动的失调容限;腔镜的失调容限与腔镜偏转方向有关,腔镜横向偏转的失调容限大于纵向偏转的失调容限;PPLN晶体温度和通道对失调容限几乎没有影响。     

大口径薄片激光器失调输出特性

对大口径的薄片激光器的失调输出特性进行了理论和实验研究,V-型腔由平面输出耦合镜和凹面反射镜及孔径光阑组成。基于矩阵光学和失调衍射积分方程得到了激光器的功率失调曲线。实验测量了在200 Hz泵浦频率下加入不同孔径光阑后谐振腔失调对输出功率的影响和谐振腔失调对光束质量的影响,以及在300 Hz泵浦频率下输出功率分别与平面输出耦合镜和凹面反射镜失调的关系。实验结果表明:失调输出功率和失调角度成二次函数关系,失调容限和腔镜口径成正比,光束质量因子随失调角度的增大而变小。     

正支共焦非稳腔的离焦像差特性

 正支共焦非稳腔在出光过程中易受环境扰动而造成腔长失调，易受热积累影响而使腔镜变形，从而使输出光束产生离焦像差和部分其它像差。为了实现对离焦像差的校正，针对不同的产生原因，提出了2种离焦像差特性分析方法：一为腔镜相对位置失调引起的离焦像差特性理论分析方法，它是另一种分析方法的基础；二为腔镜变形引起的等效腔长变化导致的离焦像差特性分析方法，它是实际激光器中的主要分析方法。得到了离焦像差与腔长的特性关系和离焦像差与腔镜变形量之间的特性关系。研究表明：腔长改变和腔镜变形对离焦像差的影响本质是一样的，都是改变了谐振腔的共焦点位置；腔长改变或腔镜矢高变化与离焦像差都成近似的线性关系。实验验证了离焦像差特性分析方法的有效性，最后指出离焦像差特性可作为激光器中离焦像差动态补偿的有效依据。     

Output beam analysis of high power COIL

As the output power of a chemical oxygen iodine laser (COIL) increases, the output laser beam instability appears as the far-field beam spot drift and deformation for the large Presnel number unstable resonator. In order to interpret this phenomenon, an output beam mode simulation code was developed with the fast Fourier transform method. The calculation results show that the presence of the nonuniform gain in COIL produces a skewed output intensity distribution, which causes the mirror tilt and bulge due to the thermal expansion. With the output power of COIL increases, the mirror surfaces, especially the back surface of the scraper mirror, absorb more and more heat, which causes the drift and deformation of far field beam spot seriously. The initial misalignment direction is an important factor for the far field beam spot drifting and deformation.     

Output beam drift and deformation in high-power COIL

During the operation of a chemical oxygen iodine laser (COIL) with an unstable resonator of a large Fresnel number, as the output power increases, an instability of the output laser beam will appear, behaving mainly as far-field beam spot drift and deformation. In order to interpret this phenomenon, thermal expansion analysis on the scraper with finite element analysis method and a simulation of the output beam mode of this kind of laser by the method of Fast Fourier Transform were developed. From the experimental measurement and the calculation, we proposed that the presence of the nonuniform temperature distribution of scraper causes the front surface of the scraper to tilt and bulge due to thermal expansion. As the output power is increasing, all the mirror surfaces, especially the scraper's, will absorb more and more heat, causing thermal expansion of the mirror front surface to occur more seriously, thus resulting in the tilting and deformation of the far-field beam spot. The initial misalignment of the direction is also an important factor leading to the far-field beam spot drift and deformation.     

Roll angle measurement based on common path compensation principle

We propose a novel and compact roll angle displacement measurement method based on collimated laser position measurement and the common path compensation principle. The principles of the roll angle displacement measurement and the common path compensation are analyzed. The feasibility of the measurement method is verified, and the experimental results revealed a linear correlation coefficient of 0.99995 between the relative displacement of the measuring beam spot and the angular displacement. Furthermore, the theoretical measurement resolution is 0.013  arcsec. To test the performance of the compensation, a series of experiments, including one system stability experiment and two different environmental interference experiments, were performed. The experimental results indicated that the standard deviations of the measuring beam spot’s angular drift were improved by 82.6–87.2%. Thus, the stability of the system and the measurement resolution were improved.     

CW-COIL激光束漂移和光斑的诊断

 利用光斑动态分析仪测试技术，对连续波氧碘化学激光器输出的光束不稳定性进行定量诊断，其中包括光束的漂移、低频抖动、光强分布、光斑直径随时间的变化等内容，并初步分析了激光输出不稳定的原因。诊断的结果为激光器的稳定输出及激光—材料实验研究提供了依据。     

Parallel Plate Interferometer with a Reflecting Mirror for Measuring Angular Displacement

A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference (OPD) in the plane-parallel plate, which provides high sensitivity of the phase measurement. Detection of light transmitted through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer achieves a measurement repeatability of 10⁻⁸ rad.     

PID调节器在氧碘化学激光器谐振腔调腔中的应用

 通过对由比例（P）、积分（I）和微分（D）三个单元组成的PID调节器基本原理的介绍，指出合理设定PID调节器的参数是消除扰动的影响并实现腔镜快速、准确而稳定地移动的关键。实验结果表明，在调腔过程中应用PID技术，提高了静态时谐振腔各腔镜的同心度，而且在一定程度上保证了出光过程中谐振腔内各个腔镜的同心度，使得减小远场光斑的漂移和变形成为可能。     

光束指向稳定性高精度检测方法研究北大核心CSCD

光束指向稳定性是高能激光应用研究中的一项关键指标,光束指向稳定性的检测是高能激光系统性能实现的重要环节。以长焦距聚焦反射镜与高分辨率CCD(charge coupled device)为主要元件,构建高精度的光束指向检测装置。采用灰度重心法定位光斑中心,并以理想光斑与实测光斑为例进行验证,误差小于1个像元。利用CCD高频采样,统计单位时间内光斑中心位移,获得光束指向稳定性指标,检测实例精度可达1.25μrad。该方法简便易行,测量精度高,适用于各种波长的激光光束指向检测以及其他相关参数的测量。     

纳弧度分辨力角位移传感器及平均灵敏度标定

给出了基于六次临界反射棱镜的精密角位移传感器,采用的是差动式结构。实验结果表明,传感器灵敏度高,量程为500μrad,具有5nrad的分辨力。提出了适合于小量程角位移传感器的平均灵敏度的标定方法,可以快速标定平均灵敏度,降低标定过程中标定系统及传感器自身漂移对标定精度的影响。     

Optimal x-ray beam formation using a focusing mirror at the Langmuir synchrotron station

A beam focusing method is proposed for the Langmuir station of the Kurchatov synchrotron radiation source. This method can be implemented during experiments on recording the fluorescence yield intensity as a function of the angle between an incident beam and a sample surface. The x-ray beam is focused by a cylindrical mirror in such a way that the dimensions of the spot illuminated by the beam on a Langmuir film remain within the input angular aperture of an energy dispersive detector during scanning in the angle of incidence. The relationships for calculating the dimension of the illuminated spot in the scattering plane and the angular divergence of the focused x-ray beam are derived taking into account the dimension of the synchrotron radiation source and spherical aberration. Recommendations for optimizing station parameters and experimental conditions are presented.