Thermal optical effect in axisymmetric structural laser resonator

In order to study the thermal optical effect (TOE) resulting from the axisymmetrical sources of thermal energy at the output mirror of CO₂ laser, the Heat Conduction Poisson Equation (HCPE) has been solved in the output mirror. Then the temperature distribution is given. The temperature variations will cause the surface distortion and the phase shift at the output mirror. Therefore, the output laser beam will be subject to thermal optical distortion and phase change. The numerical examples are to confirm our calculated results.     

温度对星载成像光谱仪谱线漂移的影响

为了研究温度对成像光谱仪谱线漂移的影响,分析了谱线漂移与光谱成像系统各镜面刚体位移之间的关系,建立了温度对成像光谱仪谱线漂移影响的理论模型,通过软件仿真和热光学试验对理论模型进行了验证和修正。基于线性光学理论建立了镜面刚体位移对谱线漂移影响的数学模型,使用蒙特卡罗法对理论模型进行了数值仿真验证;采用有限元法求解了温度载荷下各镜面的刚体位移,在Matlab软件环境下利用Code V的API函数对变形后的光学系统进行了光线追迹,求解了镜面刚体位移导致的谱线位置变化,研究了成像光谱仪的谱线漂移特性,得到了温度载荷作用下的谱线漂移模型;通过热光学试验对理论模型进行了验证和修正。结果表明,在8℃～28℃范围内,谱线在光谱方向仅发生整体平移,没拉伸或压缩效应;基于线弹性理论和线性光学模型建立的理论模型与试验结果吻合较好,最大偏差不超过12%,修正后的谱线漂移模型相对误差小于5%,绝对精度优于0.2pixel。     

基于长周期光纤光栅的可变体机翼翼表温度测试系统研究

为实现可变体机翼翼表温度的高精度的实时检测,设计了一种基于长周期光纤光栅(LPG)的温度测试系统.该系统采用长周期光纤光栅作为温度传感元件,高双折射光纤环镜作为边缘滤波器件.在边缘滤波理论研究的基础上,提出了一种降噪增敏的算法.实验中将LPG粘贴在可变体机翼翼表材料的表面,当外界温度发生变化时,LPG的谐振波长发生偏移...     

监测点波长对高双折射光纤环镜轴向应变灵敏度的影响

研究了高双折射光纤环镜监测点波长对轴向应变灵敏度的影响. 经理论推导得出高双折射光纤环镜轴向应变灵敏度公式. 结果表明: 当高双折射光纤材料选定后, 灵敏度随着监测点波长的增大而增大; 当监测点选定后, 监测点的灵敏度为常数, 波长变化与应变成线性关系. 实验选取不同波长的波峰进行应变灵敏度监测, 对各监测点进行数据拟合, 实验结果与理论分析一致. 研究结果对提高高双折射光纤环镜应变、温度等灵敏度具有指导意义. 关键词： 波长 灵敏度 监测点 高双折射光纤环镜     

Nonlinear mirror based on raman interactions

We analyze a nonlinear mirror based on Raman interactions. The mirror is a combination of a Raman-active medium and a tetrachroic mirror. The reflections of the nonlinear mirror at two input frequencies differing by the Raman shift are calculated and its properties and possible applications are discussed.     

旋转镜鼓式热像仪的光雷达回波特性

 旋转镜鼓式热像仪对光场的扫描主要由镜鼓来完成，在激光束的照射下，镜鼓棱及其邻域的后向散射不可避免地给散射光引进了一个附加的多普勒频移。对平行光束经热像仪后的动态回波特性进行分析研究，提出了一种测量光束多普勒频移的方法，并建立了相应的实验系统。实验结果与理论分析是一致的，为判别热像仪的工作方式提供了一种可能的方法。     

Electron-Cyclotron Resonance Heating in Tandem Mirrors

Using numerical ray-tracing techniques, we study the propagation and absorption profiles of electromagnetic waves launched in the end cells of three different tandem mirrots: Phaedrus, an overdense low-temperature tandem mirror with plugs; TASKA, a conceptual tandem mirror with plugs and thermal barrier; and TMX-U, a tandem mirror with a significant hot-electron population. In particular, the effects of weakly relativistic thermal anisotropy on the absorption profile are examined. In general, at sufficiently low densities and temperatures, the X mode can access the plasma and achieve significant heating of the electrons. As the electron temperature increases, the X mode gets quickly absorbed at the edge and only the O mode achieves significant penetration and heating. For sufflciently large launching angles, the presence of thermal anisotropy can actually shift the region of maximum absorption towards the electron-cyclotron resonance layer. Regions of whistler instability appear along rays launched nearly along the machine axis, when the thermal-anisotropy ratio, temperature, and density reach sufficiently high values.     

半导体远红外反射镜中反射率和相位研究

以GaAs材料为例，研究了半导体远红外反射镜中的反射率和相位.通过拟合不同掺杂浓度下样品的远红外反射谱，得到了自由载流子的弛豫时间随掺杂浓度变化的经验公式，并把该规律应用到数值计算中.详细讨论了反射镜的结构和材料参数对反射率R和相位φ的影响.根据腔体内吸收率最高的判据得到了最优的反射镜的参数，并计算了这种优化后的反射镜的波长选择特性.最后，通过远红外反射光谱的测量，从实验上验证了这种反射镜的实际效果. 所得结论为半导体远红外器件中的反射镜设计提供了参考. 关键词： 远红外反射镜 反射率 相位     

干涉检测中环境温度引起的镜面变形分析

在达到1 nm量级的光学元件表面面形干涉检验时,被检元件由温度变化引起的面形偏差是不能忽略的.分析了干涉检验时存在的各种环境温度情况,对不同情况下被检元件内外温度分布进行了仿真,并将温度场作为静力学分析的载荷条件,进行了镜面温度变形分析.计算出了带支撑的直径为300 mm凸球面透镜在不同温度分布下的镜面变形量,并通过球...     

空间望远镜主镜的热光学特性分析

主镜是空间望远镜光学系统的重要组成元件,其热光学特性将为光学系统的热控设计提供依据。利用建立在集成分析基础上的热光学分析方法,分析了某空间望远镜主镜在三种不同的温度分布形式,即在径向温度、轴向温度、周向温度梯度的作用下对光学系统成像质量的影响,结合设计的要求,根据计算结果给出了许用温度梯度的范围。     

温度和支撑方式对1.2 m SiC主镜面形的影响分析

为了研究温度和支撑方式对大口径SiC主镜用于地基望远镜的影响,基于1.2 m SiC主镜建立了有限元模型,分析了主镜在被动支撑和自由膨胀时,恒定温度场,轴向温度梯度,径向温度梯度和内外温差等对主镜面形的影响.结果表明,存在温度梯度时,支撑方式影响不明显,无论是被动支撑还是自由膨胀,镜面面形均很大.在达到热平衡后,即稳态温度场下,支撑方式的影响明显,只有在主镜自由膨胀时,温度对主镜面形的影响比较小,镜面的RMS<0.02 nm/℃.因此如果主镜采用柔性支撑或浮动支撑方式,大口径SiC主镜可以应用在地基望远镜中.     

大口径轻量化主镜的温度场等效模型理论计算

针对大口径望远镜主镜在环境温度变化和太阳辐照变化引起的温度场变化进行了理论分析,根据圆柱坐标下设立的非稳态热传导方程和边界条件,利用分离变量法和格林函数法求解了主镜的温度场分布。为了验证求解的有效性,利用求得的温度场解析式和有限元软件分别分析了2.8 m口径望远镜实心主镜,反射面径向温度分布具有良好的一致性。表明该理论解析式能够较好地反映主镜反射面的温度场分布。将轻量化主镜进行无筋板的薄型镜热模型等效,并分别对两种镜子的温度场进行仿真计算,以此验证等效模型的正确性。轻量化主镜温度场的等效理论计算结果在主镜的早期设计研究阶段具有良好的参考价值。     

飞秒钛宝石激光器腔内双色镜反射相移的突变现象

研究了钛宝石激光器增益介质两端的两块双色镜的相移色散，发现反射相移在中心波长附近发生了突变，由此而造成反射相移色散在此点是不连续的，并对影响反射相移突变点的因素进行了详细的研究。     

一种新的非球面零朗奇检测法

提出一种新的零朗奇检测法用于测量大口径非球面镜的面形。利用光线追迹和正弦条纹的相位信息设计补偿正弦光栅。使用透射液晶显示屏显示补偿正弦光栅并作为相移装置。一个离轴点光源发出的光被镜面反射后通过补偿正弦光栅,摄像机记录携带镜面偏差信息的相移条纹图。通过对相移条纹图的分析确定被测镜面的实际横向像差以及对应的理想横向像差,然后基于朗奇检测的几何原理得到被测镜面的偏差梯度,对其积分获得被测镜面的偏差,进而重建被测镜面的三维面形。与传统的零朗奇检测法相比,这种方法可以消除补偿光栅上每个条纹带边缘的锯齿形状,而且可以获得镜面上足够多的待测点信息。计算机模拟和初步实验验证了该方法的可行性。     

望远镜主镜温度场理论计算及主镜视宁度分析

提出了地基望远镜主镜在环境温度变化时的温度场理论模型,结合分离变量法和格林函数法求解出温度场的解析表达式。运用温度场理论解,分别以熔石英和BK7两种常用材料为例,在特定环境条件下,定量分析了传统主镜和薄主镜的主镜视宁度与主镜口径之间的关系;针对4m口径的传统主镜和薄主镜定量分析了其主镜视宁度与周围空气温度下降斜率的关系。地基望远镜主镜温度场理论计算的结果在主镜设计阶段对主镜视宁度的估量具有较大的参考价值。主镜温度场理论解还可以运用于各种口径及材料的主镜热变形及热应力计算等方面,具有普适的参考价值。     

Frequency locking of dye lasers by selective reflection on a glass/sodium vapor interface

The use of a pyrex/sodium vapor interface as a selective dye laser mirror is shown to produce frequency locking of the laser emission near the sodium D lines. The spectral shift of a few GHz from the line center and the magnitude of the energy spectral condensation measured are accounted for the calculations.     

可弯曲式微腔有机电致发光器件的光学特性

设计了结构为上反射镜/有机层/下反射镜/柔性基板的可弯曲式有机电致发光器件(FOLED)。利用几何光学模型计算了器件在不同弯曲情况下,其发光光谱随观测角和曲率的影响,并与平整器件的光谱作了比较。结果表明:1)基板向内弯曲时,随着观测角的增大,器件的发光光谱峰值出现蓝移,且蓝移的程度相对平整器件要大;随着曲率的增大,器件的发光光谱峰值出现蓝移。2)基板向外弯曲时,随着观测角的增大,器件的发光光谱峰值出现红移,但红移的程度不大;随着曲率的增大,器件的发光光谱峰值出现红移,且与基板向内弯曲时蓝移的程度相当。     

Method for suppressing the mirror image in Fourier-domain optical coherence tomography

A method, novel to our knowledge, for effective mirror image suppression in Fourier-domain optical coherence tomography based on a phase shift between neighboring A-mode scans is demonstrated. By realizing that the phase shifts of the real and mirror images are mutually reversed and assuming that the real image intensities of the two successive A-mode scans are the same, we can solve a set of two coupled equations to obtain the real image signals. The images based on the scanning of a high-resolution spectral-domain optical coherence tomography system are processed to show effective mirror image suppression results. Compared with a similar method of broad application, our approach has the advantages of shorter process time and higher flexibility in selecting the concerned image portions for processing.     

Thermo-optically driven adaptive mirror for laser applications

An adaptive mirror is investigated that is based on the deformation of the reflective surface due to thermal expansion of an underlying material that can be locally heated with an external light source. The mirror is made from a glass plate coated with a 1-mm-thick layer of a material with a large thermal expansion coefficient that was finally sputter coated with a thin gold film. The adaptive mirror is thermo-optically heated with an incandescent lamp. To generate the desired temperature pattern an aperture mask is used. The deformation of the adaptive mirror is measured with a Michelson interferometer. It is shown that the spatial resolution and amplitude of the deformation are sufficient for the application as an adaptive mirror. As a possible application the suitability of this mirror type as part of a laser resonator to generate a super-Gaussian mode is discussed. PACS 42.60.Jf; 42.60.By; 42.79.-e     

Optical compensation of geometrical distortion by a deformable mirror

An optical method for the real time correction of geometrical distortion is reported. It is based on the “fun-house-mirror effect”: An adjustable nonplanar mirror is introduced between object- and pupil-plane and generates a suitable (space-variant) shift of each pixel. The method is restricted to a certain class of distortions, which lead to continuous mirror surfaces (mirror must not break). We also investigate aberrations which are another restriction of the method. Our application was the improvement of TV-systems: before correction 20%, and after correction 50% of pixels had a distortion less or equal than one pixel distance.