Utilization of the high spatial-frequency component in adaptive beam shaping by using a virtual diagonal phase grating
Utilization of the high spatial-frequency component in adaptive beam shaping by using a virtual diagonal phase grating
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DOI：
10.1038/s41598-019-40829-7
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发表时间：
2019-03
影响因子：
4.6
通讯作者：
Y. Nakata;Kazuhito Osawa;N. Miyanaga
中科院分区：
文献类型：
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作者：
Y. Nakata;Kazuhito Osawa;N. Miyanaga
正方形平顶光束是一种基本形状，在超高功率激光、均匀表面处理和医学工程等各种应用中都有很高的需求。在本实验中，提出了一种新的、简单的自适应光束整形系统方案，利用空间光调制器和4f系统编码的虚拟对角位相光栅来产生具有高均匀性和边缘陡度的正方形平顶形状。光栅矢量kgg与待提取的物光束轮廓的法向矢量skx和ky不平行，因此，残余分量和提取的分量分别击中4f系统的傅里叶平面。因此，使用传递平行tokxandky分量的空间-频率滤波器，剩余分量被滤波器阻挡，而不损失提取分量的高空间频域。当滤光片宽度为1.0 mm时，整形光束的边缘高度在20μm内增加，不到传统垂直位相光栅的20%。
A square flattop beam is a fundamental shape that is in high demand in various applications, such as ultra-high-power lasers, uniform surface processing and medical engineering. In this experiment, a new and simple scheme of the adaptive beam shaping system to generate a square flattop shape with high uniformity and edge steepness using virtual diagonal phase grating encoded on a spatial-light modulator and a 4fsystem is proposed. The grating vectorkgis non-parallel to the normal vectorskxandkyof the objective beam profile to be extracted; thus, the residual and extracted components hit separately on the Fourier plane of the 4fsystem. Consequently, using a spatial-frequency filter passing components parallel tokxandky, the residual components are blocked by the filter without loss of the high spatial-frequency domain of the extracted component. When the width of the filter was 1.0 mm, the edge of the shaped beam increased in height within 20 μm, which is less than 20% of that obtained with conventional vertical phase grating.