Ma Haotong, Liu Zejin, Jiang Pengzhi, Xu Xiaojun, Du Shaojun
College of Opto-Electronic Science and Engineering, National university of Defense Technology, Changsha, Hunan, China.
Opt Express. 2011 Jul 4;19(14):13105-17. doi: 10.1364/OE.19.013105.
We propose and demonstrate the improvement of conventional Galilean refractive beam shaping system for accurately generating near-diffraction-limited flattop beam with arbitrary beam size. Based on the detailed study of the refractive beam shaping system, we found that the conventional Galilean beam shaper can only work well for the magnifying beam shaping. Taking the transformation of input beam with Gaussian irradiance distribution into target beam with high order Fermi-Dirac flattop profile as an example, the shaper can only work well at the condition that the size of input and target beam meets R(0) ≥ 1.3 w(0). For the improvement, the shaper is regarded as the combination of magnifying and demagnifying beam shaping system. The surface and phase distributions of the improved Galilean beam shaping system are derived based on Geometric and Fourier Optics. By using the improved Galilean beam shaper, the accurate transformation of input beam with Gaussian irradiance distribution into target beam with flattop irradiance distribution is realized. The irradiance distribution of the output beam is coincident with that of the target beam and the corresponding phase distribution is maintained. The propagation performance of the output beam is greatly improved. Studies of the influences of beam size and beam order on the improved Galilean beam shaping system show that restriction of beam size has been greatly reduced. This improvement can also be used to redistribute the input beam with complicated irradiance distribution into output beam with complicated irradiance distribution.
我们提出并演示了对传统伽利略折射光束整形系统的改进，以精确生成具有任意光束尺寸的近衍射极限平顶光束。基于对折射光束整形系统的详细研究，我们发现传统伽利略光束整形器仅在放大光束整形方面表现良好。以将具有高斯辐照度分布的输入光束转换为具有高阶费米 - 狄拉克平顶轮廓的目标光束为例，该整形器仅在输入光束和目标光束尺寸满足(R(0)≥1.3w(0))的条件下才能良好工作。为了改进，将该整形器视为放大和缩小光束整形系统的组合。基于几何光学和傅里叶光学推导了改进的伽利略光束整形系统的表面和相位分布。通过使用改进的伽利略光束整形器，实现了将具有高斯辐照度分布的输入光束精确转换为具有平顶辐照度分布的目标光束。输出光束的辐照度分布与目标光束的辐照度分布一致，并且相应的相位分布得以保持。输出光束的传播性能得到了极大改善。对光束尺寸和光束阶数对改进的伽利略光束整形系统的影响的研究表明，光束尺寸的限制已大大降低。这种改进还可用于将具有复杂辐照度分布的输入光束重新分配为具有复杂辐照度分布的输出光束。
