长沙理工大学 物理与电子科学学院，长沙 410114
为了研究横向分布为平顶高斯模式的宽带激光通过硬边光阑系统的光强分布特性，采用衍射积分公式推导了平顶高斯模式宽带激光的每一频率分量在光阑系统中的传输公式，再通过傅里叶变换得到时间域的传输公式，详细分析了光阑和频带宽度对强度分布的影响。结果表明，近场光强在截断参量较大时，仍保持一定的平顶分布特性，但是随带宽的增加强度分布变窄；截断参量较小时强度呈高斯分布，并且带宽的变化对强度分布没有太大影响；然而在远场时截断参量较小情况下的光强分布也明显表现出随带宽增加而变窄的现象，但随着截断参量增大，这一变化趋势变缓。这些结果对平顶高斯模式宽带激光的应用具有重要参考价值。
激光光学 宽带激光 衍射积分 硬边光阑 窄化现象 laser optics broadband laser diffraction integral hard-edged aperture narrowing effect
1 宜宾学院 光电信息研究所，宜宾 644007
2 四川大学 激光物理与化学研究所，成都 610064
利用拉盖尔－高斯模和厄米－高斯模的变换公式，并使用将二维矩孔光阑窗口函数展开为有限个复高斯函数之和的方法，得到了复宗量拉盖尔－高斯(LG)光束通过含矩形硬边光阑近轴ABCD光学系统的变换的解析传输公式，并对复宗量LG光束通过矩形硬边光阑的衍射和聚焦特性进行了研究。该方法对研究有不同几何对称性光阑光学系统的光束变换是有用的。
激光光学 复宗量拉盖尔－高斯(LG)光束 矩形硬边光阑 复高斯函数 laser optics complex-argument Laguerre-Gaussian(LG)beam rectangular hard-edged aperture complex Gaussian function
Author Affiliations
Abstract
1 School of Computer and Communication, Hunan University, Changsha 410082, China
2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, P.O. Box 800-211, Shanghai 201800, China
3 Mechanical Engineering College, Jiangsu University, Zhenjiang 212013, China
Based on the Huygens–Fresnel diffraction integral and Fourier transform, propagation expression of a chirped Gaussian pulsepassing through a hard-edged aperture is derived. Intensity distributions of the pulse with different frequency chirp in the near-fieldand far-field are analyzed in detail by numerical calculations. In the near-field, amplitudes of the intensity peaks generated by themodulation of the hard-edged aperture decrease with increasing the frequency chirp, which results in the improving of the beam uniformity.A physical explanation for the smoothing effect brought by increasing the frequency chirp is given. The smoothing effect isachieved not only in the pulse with Gaussian transverse profile but also in the pulse with Hermite–Gaussian transverse profile whenthe frequency chirp increases.
Frequency chirp Broadband laser Beam smoothing Hard-edged aperture Collection Of theses on high power laser and plasma physics
2006, 4(1): 72
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Mechanical Engineering College, Jiangsu University, Zhenjiang 212013, China
By means of the Huygens-Fresnel diffraction integral, the propagation expression of a laser beam passing through a hard-edged aperture is derived. The effects of the bandwidth on the transverse intensity distributions of the beam in the near and far fields are analyzed. It is found that, in the near field, the beam uniformity is improved with increasing the bandwidth and the broader the spectrum, the smoother the transverse intensity distribution is. Intensity spikes produced by low-frequency diffraction are eliminated in the diffraction patterns and the transverse intensity distribution near axis tends to smooth when the bandwidth increases. The intensity spikes produced by high-frequency diffraction still exist with increasing the bandwidth, but the amplitudes and numbers of them decrease. In the far field, there are only a few differences among the transverse intensity distributions of the beams with different bandwidthes. However, The secondary maximum intensity still presents for the beam with small bandwidth, and it decreases with increasing the bandwidth and is eliminated with large bandwidth.
broadband laser bandwidth beam smoothing hard-edged aperture transverse intensity distribution Collection Of theses on high power laser and plasma physics
2005, 3(1): 123
1 四川大学,激光物理与化学研究所,四川,成都,610064
2 江西师范大学,物理与通信电子学院,江西,南昌,330027
激光光束质量是一个很有现实意义的论题.对实际激光,一方面或多或少存在硬边光阑光学元件影响.另一方面,人们常对远场激光束的可聚焦能力感兴趣.对有光阑情况时光束传输因子(M2因子)的推广作了讨论.对有代表性的3种方法,即广义截断二阶矩法、渐近分析法和自收敛束宽法及其应用作了分析.引入了桶中功率(PIB)和β参数用以描述远场光束质量.然后,研究了实际应用对激光光束质量的一些要求和相关的评价参数.最后,讨论了复杂的高功率激光系统的全程光束质量控制问题.
激光光束质量 参数描述 硬边光阑 光束传输因子 桶中功率 Laser beam quality Parametric characterization Hard-edged aperture Beam propagation factor Power in the bucket
1 四川大学,激光物理与化学研究所,四川,成都,610064
2 宜宾学院,光电信息研究所,四川,宜宾,644007
使用傅里叶级数与有限个复高斯函数之和的乘积作为硬边光阑的窗口函数的近似式,提出了含硬边光阑近轴ABCD光学系统对光束变换的改进算法.以高斯光束的变换为例,推导出了一个表示为初等函数之和的近似解析传输公式.给出了数值计算结果,并与直接积分Collins公式和使用Wen方法的结果作了比较.研究表明,改进算法能兼顾计算精度和机时,并能用于远场和近场.而使用Wen方法时,在近场(小于0.12倍菲涅尔距离)有明显误差.
硬边光阑 傅里叶级数 复高斯函数 改进算法 Hard-edged aperture Fourier series Complex Gaussian function Improved algorithm
给出部分相干光通过硬边光阑后的强度二阶矩的计算公式,由此可得到部分相干光通过硬边光阑后的推广光束传输M2因子.以部分相干高斯谢尔模型光束为例,推导出相应的M2因子,并作了数值计算和分析讨论.
部分相干光束 推广M2因子 硬边光阑 高斯谢尔模型(GSM)光束
