摘要
同步辐射波荡器光源相干性能逐步提高,使得同步辐射相干光学实验对理论模拟的要求越来越高。对同步辐射光束线空间相干性进行有效的评估,可以指导相干光束线的设计及其相干光学实验的开展。本文利用部分相干光传播计算模型,数值模拟了上海光源软X射线干涉光刻光束线部分相干光的传播,理论和实验结果进行了比较,得到不同参数下的空间相干性,分析了误差产生原因。相干性的定量分析结果可以为实现空间相干性的定量控制提供依据。
Background： Synchrotron radiation （SR） has some unique features such as higher brightness and continuously adjustable wavelength. Sometimes SR source will be a unique choice in some experiments. And with the development of the SR facility, especially the appearance of various low emittance undulators, the experiments such as coherent diffraction imaging （CDI） that needs high brightness coherence source can be conducted. The traditional ray trace software, such as Shadow, using the geometrical optics methods, could not be applied for the coherent beamlines. Purpose： We want to provide a basis for the beamline design and the X-ray coherent experiments, the effective evaluation of the spatial coherence in beamlines is needed. Undulator source, which can be calculated precisely, will become a plane source with some features. As the source of the beamline, undulator was calculated. And the spatial coherence of the exit slit can be calculated too. So we can analyze the coherence of the beamline. Methods： Firstly, we used BPM to measure the intensity of the diffraction of the slit, and simulated the intensity distribution of the slit diffraction using the MCI （a software written by ourselves） to confirm the coherent length of the secondary source at slit. Secondly, we calculated the undulator supposed as a plane source, and used the MCI to numerically calculate the propagation of partially coherent X-ray in the soft X-ray interference lithography beamline from the undulator to the exit slit. Finally, we compared the difference of the coherent length at the slit by the above two methods. Results： We calculated the coherent length at the different place in the beamline, such as mirrors and slits. The most important thing was that we could not only know the coherent length with different size of the slits, but also control the spatial coherence quantitatively. When the slit size was 40 μm×40 μm, the spatial coherence was almost fully coherent. And we used the method to do some simulation about the coherent experiments and the coherent beamline design. Conclusions： The new method was available for the coherence analysis of the beamline. The calculation of the undulator was proper. And the quantitative analysis and control of spatial coherence could provide a basis for the X-ray coherent experiments and the coherent beamline design.
出处
《核技术》
CAS
CSCD
北大核心
2013年第9期1-8,共8页
Nuclear Techniques
基金
国家自然科学基金项目(11005146和11275255)资助
