Sun Tianxiao, Zhang Xiangzhi, Xu Zijian, Wang Yong, Guo Zhi, Wang Jian, Tai Renzhong
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.
Canadian Light Source Inc., University of Saskatchewan, 44 Innovation Boulevard, Saskatoon, Saskatchewan S7N 2V3, Canada.
J Synchrotron Radiat. 2021 Mar 1;28(Pt 2):512-517. doi: 10.1107/S1600577520016112. Epub 2021 Jan 21.
Scanning mode is a key factor for the comprehensive performance, including imaging efficiency, of scanning transmission X-ray microscopy (STXM). Herein is presented a bidirectional scanning method designed for STXM with an S-shaped moving track. In this method, artificially designed ramp waves are generated by a piezo-stage controller to control the two-dimensional scanning of the sample. The sample position information is measured using laser interferometric sensors and sent to a field-programmable gate array (FPGA) board which also acquires the X-ray signals simultaneously from the detector. Since the data recorded by the FPGA contain the real position of each scanned point, the influence of the backlash caused by the back-turning movement on the STXM image can be eliminated. By employing an adapted post-processing program, a re-meshed high-resolution STXM image can be obtained. This S-track bidirectional scanning method in fly-scan mode has been implemented on the STXM endstation at the Shanghai Synchrotron Radiation Facility (SSRF), and successfully resolved the ∼30 nm interval between the innermost strips of a Siemens star. This work removes the limitation on bidirectional scanning caused by motor backlash and vibration, and significantly improves the efficiency of STXM experiments.
扫描模式是影响扫描透射X射线显微镜（STXM）综合性能（包括成像效率）的关键因素。本文介绍了一种专为STXM设计的具有S形移动轨迹的双向扫描方法。在该方法中，由压电平台控制器生成人工设计的斜坡波，以控制样品的二维扫描。使用激光干涉传感器测量样品位置信息，并将其发送到现场可编程门阵列（FPGA）板，该板同时从探测器获取X射线信号。由于FPGA记录的数据包含每个扫描点的真实位置，因此可以消除反向运动引起的间隙对STXM图像的影响。通过采用适配的后处理程序，可以获得重新网格化的高分辨率STXM图像。这种飞扫模式下的S形轨迹双向扫描方法已在上海同步辐射装置（SSRF）的STXM终端站上实现，并成功分辨出西门子星最内条纹之间约30 nm的间距。这项工作消除了电机间隙和振动对双向扫描的限制，并显著提高了STXM实验的效率。
