共查询到20条相似文献,搜索用时 171 毫秒
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介绍了采用液晶空间光调制器产生部分相干光的基本理论和方法;用分离变量的方式对算法进行了并行优化,对部分相干光生成线程进行了并行序列优化并测试了生成速度;设计了双孔干涉实验检测本方法所产生的部分相干光相干长度的准确性.实验结果表明:针对256×256像素的液晶空间光调制器,生成相干长度为0.15mm、0.9mm以及1.5mm的相位屏,图形处理器所用时间分别为0.9ms、1.75ms以及2.4ms,相比于采用中央处理器所用的计算时间16.5ms、37.8ms以及52.4ms,效率提升明显;考虑中央处理器读取、发送数据及液晶响应的时间,采用图形处理器并行加速的部分相干光实时生成方法的频率可达312Hz.实验生成相干长度为0.15mm和1.5mm的部分相干光束,光束相干度均方根误差分别为0.022 011和0.020 883,峰谷值分别为0.0743 25和0.072 998. 相似文献
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从理论和实验两方面对非均匀关联径向偏振部分相干光的产生进行了研究.理论上,基于相位关联与相干度的联系,推导出了非均匀关联径向偏振部分相干光的2×2阶交叉谱密度矩阵及相干度分布.实验上,利用一个相位型液晶空间光调制器的不同区域,对入射的完全相干的径向偏振光的两个正交偏振分量分别加载随机相位调制,并实验测量了这种光束的相干度分布及其对光强分布的影响.实验结果验证了光束相干度的非均匀关联结构,并且通过改变随机相位的高斯调制半宽可以改变光束的相干性分布.研究表明,随着随机相位的高斯调制半宽的增加,光束中两点间的相干度逐渐减小,其光强分布由圆环状逐渐变化为类平顶的光强分布.这种非均匀关联的径向偏振部分相干光在激光微操纵和材料加工等领域具有一定的潜在应用价值. 相似文献
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《物理学报》2017,(5)
从理论和实验两方面对非均匀关联随机电磁光束的产生进行了研究.在理论出棊于相位关联与柑干度的联系推导出非均匀关联随机电磁光束的2×2交叉谱密度矩阵及相干性分布.理论分析表明,这种非均匀关联随机电磁光束中两点间的相干度不仅和两点间距有关,而且和两点的位置有关.在实验上,利用两个相位型液晶空间光调制器对入射的完全相干光的两个偏振分量分别加载随机相位调制,并测量了随机电磁光束的相干度分布.实验结果表明,光束中间距相等的两点之间的柑干度随着两点与光斑中心的距离的增加而减小.实验结果与理论结果一致.这种非均匀关联的随机电磁光束在自由空间光通信和激光微操控等领域具有广阔的应用前景. 相似文献
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为获得较大的光束电控偏转范围,使用空间分辨力高达8 m的反射式液晶空间光调制器实现了对入射632 nm激光的电控偏转。利用双光束共焦干涉方法测量了液晶空间光调制器的电控相位延迟特性,最大相移量可达3。根据二元光学理论和器件的电控相位延迟特性,设计了周期台阶相位模式和相应的加载灰度图,以最大衍射效率实现对入射光束的闪耀电控偏转。结果表明:相位模式台阶数为8时,可以实现10 mrad的光束偏转,闪耀级次衍射效率可达46%。利用二元光学的衍射模型对影响衍射效率的关键因素进行了分析,认为器件较低的填充因子和周期台阶模式相位重置点诱导的指向矢回程区是限制光束衍射效率的主要因素。 相似文献
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针对光束轨道角动量的研究主要集中在相干光束的研究,而对于部分空间相干光束的轨道角动量研究较少,依据部分相干光的Wigner分布函数推导出部分相干光的轨道角动量表达式,分析了部分相干光的轨道角动量谱特性。采用Mercer展开法得到了轨道角动量谱,计算了给定部分相干光束的轨道角动量谱,讨论了部分相干性对轨道角动量谱的影响。研究结果表明:部分相干光和相干光具有相同的轨道角动量表达式,部分相干光的轨道角动量谱随着相干性的变差而愈发弥散,携带轨道角动量的部分相干光束的轨道角动量谱比不携带轨道角动量的部分相干光束的轨道角动量谱更容易受相干度的影响。 相似文献
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Suye Lü 《Optics Communications》2008,281(13):3514-3521
Taking the partially coherent cosh-Gaussian beam (ChG) as an illustrative example, the far-field divergence angle and directionality of partially coherent beams are studied. There are three competing physical mechanisms, i.e., the spatial coherence, diffraction and decentration, which affect the far-field divergence angle of partially coherent ChG beams. Two partially coherent ChG beams may generate the same far-field divergence angle, and partially coherent ChG beams may also have the same far-field divergence angle as a fully coherent ChG beam or as a fully coherent Gaussian laser beam if the three physical mechanisms are appropriately balanced. The consistency of the directionality of partially coherent beams expressed in terms of the far-field divergence angle and in terms of the far-field radiant intensity distribution is examined. Generally, two partially coherent beams with the same far-field divergence angle have not certainly the same far-field radiant intensity distribution. However, under certain conditions, it is possible to achieve the consistency of the directionality expressed in terms of the far-field divergence angle and of the normalized far-field radiant intensity distribution. 相似文献
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针对激光汇聚铬原子束沉积,提出了一种定性评价原子束横向准直度的多狭缝技术。与其他检测技术相比,它设计简单,使用方便,能够非常直观快捷地定量评价原子束横向准直度。理论模拟的结果显示,在我们实验条件下这种技术给出的铬原子束准直前横向宽度为13.8mm,半高宽为12mm,发散角为4.1mrad,准直后横向宽度为12.2mm,半高宽为4.8mm,发散角为1.6mrad。 相似文献
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提出了利用Fabry-Perot干涉仪的反射场实现高光谱分辨率激光雷达精细探测大气光学参量的新方法和思路.设计了高光谱分辨率的分光系统,并分析了干涉仪反射场的光谱透过特征曲线.结合高光谱激光雷达探测信号特征,讨论分析了谱分离比和瑞利信号透过率随反射率和腔长的变化曲线,同时结合误差传递公式,建立了仿真分析模型,讨论了回波光束发散角和入射角变化对激光雷达探测结果的影响.结果表明,所提出的Fabry-Perot干涉仪反射场可以实现高光谱分辨率激光雷达探测系统的精细分光,同时探测结果误差随回波光束发散角变化不敏感,控制发散角在10 mrad以内,入射角在1.5 mrad以内时,可以实现气溶胶光学参数廓线的高精度探测. 相似文献
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采用激光跟踪仪及配套带软件Insight对兰州重离子加速器冷却储存环主环磁铁进行了安装和准直。首先建立全局坐标系,用来确定从源体到实验环各子系统的理论原点的位置;而各个子系统又分别以各自的理论原点为基础建立局部坐标系,用来安装定位本系统内的各个元件;对各个子系统中的每一个元件还采用了元件坐标系。准直测量时,先在每块磁铁上焊接8个测量基准;然后对磁铁上的基准进行测量,以确定其在元件坐标系中的位置;再架设激光跟踪仪,测量主环控制网点,恢复主环局部坐标系,根据元件在主环局部坐标系中的位置及理论坐标,计算出相关的变换参数;转入元件坐标系,采用激光跟踪仪及Insight 软件显示实时测量坐标及其与理论值之差,其精度达到0.15 mm。 相似文献
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Pu Zhou 《Optics Communications》2010,283(6):1071-1074
The mechanism for beam quality degradation in recently developed phase locking of high power solid state lasers, which is caused mainly by partially coherent property of element beam and partially phase locking of the laser array, is analyzed in detail. Analytical expression for propagation of partially coherent partially phase-locked laser array in turbulent atmosphere is obtained based on extended Huygens-Fresnel principle. The effect of coherence width, phase error and intensity of turbulence on the beam quality in the target-plane is studied in detail. The tolerance on phase error for laser array with different coherence property is analyzed. It is concluded that the laser array with better coherence is more sensitive to turbulence, and phase control can improve beam quality in the receiving plane only in the case when the element beam has good beam quality and propagates in weak turbulence. 相似文献
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We report a dramatic improvement of the spatial coherence and beam divergence (0.66 mrad) of a 13.2 nm wavelength Ni-like Cd tabletop laser by injection seeding the soft x-ray laser amplifier with high-harmonics pulses generated in a Ne gas jet. This phase coherent laser is an attractive light source for at-wavelength interferometry of extreme ultraviolet lithography optics and other applications. 相似文献
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Bijendra Singh S.R. Daultabad V.V. Subramaniam Ashim Chakraborty 《Optics Communications》2008,281(24):6080-6090
Performance of a kinetically enhanced copper vapor laser (KE-CVL) with various stable/unstable “alignment free” CAT-EYE resonator configurations are presented here in this paper. The laser used in the experiment was a 45 mm bore (∼2 l discharge volume) kinetically enhanced copper vapor laser developed in our laboratory and capable of generating maximum power of ∼80 W (at ∼9.8 kHz). The efficiency of the laser was ∼1.4% and beam divergence of ∼3.5 mrad in a plane-plane standard multimode cavity. For the first time performance of unstable CAT-EYE resonator is demonstrated with a CVL/KE-CVL. On using unstable CAT-EYE resonator the divergence of the laser beam reduced to ∼0.22 mrad (∼20-fold reduction as compared to conventional plane-plane cavity), ∼40 W output power and with excellent misalignment tolerance. The laser output power was found to be within ∼5% drift/decline with misalignment angle of about 4 mrad between the mirrors. This is a significant improvement in comparison to standard conventional unstable resonator (M ∼ 50) CVL where ∼0.5 mrad divergence is achieved with power drift/decline of about 45% at ∼4 mrad misalignment angle.Off-axis unstable CAT-EYE unstable resonator was also demonstrated for the first time with further reduction in beam divergence to ∼0.13 mrad and with output power of ∼28 W. The misalignment tolerance was found to be highest in case of off-axis unstable CAT-EYE resonator with decline/drift in laser power of only ∼10% for misalignment angle as high as ∼8 mrad. Performance with intra-cavity apertures in plane-plane type CAT-EYE resonator for transverse mode control is also presented for the first time in CVLs. It is observed that the laser beam divergence reduces significantly to 1.25 mrad (a factor of 2) on using an aperture of ∼3.5 mm at the CAT-EYE reflector as compared to its normal (R = F = d) configuration without aperture. In case of stable CAT-EYE resonator the average beam divergence reduces from 8 mrad to 4 mrad (factor of 2) on using intra-cavity aperture of about 3 mm. It was also observed that high misalignment tolerance was retained on using intra-cavity apertures in almost all the CAT-EYE resonators. Use of intra-cavity mesh was also demonstrated for the first time with stable CAT-EYE resonator for improving the beam focus-ability. Average beam divergence was reduced by a factor of 2.5 (from 8 mrad to 3 mrad) on using intra-cavity mesh. These new configurations in CAT-EYE resonators in KE-CVLs are found to be effective in improving and controlling the laser beam divergence significantly with additional characteristic of high misalignment tolerance. 相似文献
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克服大气湍流对近地大气光通信质量影响,可归结为在接收端的照明均匀化,而采用部分相干光照明则是提高照明均匀性的一种有效途径。提出利用多模光纤的模间色散产生一个具有部分相干光特性的合成光源的方法,分析了该光源的产生原理,表明光束发散角由光纤芯径和发射透镜的焦距决定,由模间色散产生的光程差越大,该合成光源的空间相干性越差。仿真结果表明形成1 mrad远场发散角的合成光源是可行的,因而适于在空间光通信中应用。 相似文献
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K. Nagashima M. Tanaka M. Nishikino M. Kishimoto M. Kado T. Kawachi N. Hasegawa Y. Ochi K. Sukegawa R. Tai Y. Kato 《Applied physics. B, Lasers and optics》2004,78(7-8):927-932
We have succeeded in developing a laser-pumped X-ray laser with full spatial coherence at 13.9 nm. The X-ray laser beam with a very small divergence of 0.2 mrad was generated from double target experiments, where a seeding light from the first laser medium was amplified in the second laser medium. The observed divergence was close to the diffraction limit value within a factor of two. The seeding light was amplified in the second medium without refraction influence and the gain coefficient was 7.9 cm-1. From the measurement of visibility, it was found that the spatial coherent length was longer than the beam diameter. PACS 41.50+h; 42.55.Vc 相似文献