Hatanaka Shuhei, Yamasaki Jun
Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan.
Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
Microscopy (Oxf). 2025 Jan 30;74(1):20-27. doi: 10.1093/jmicro/dfae040.
The spatial coherence and the axial brightness of a cold field emission gun, a Schottky field emission gun and a lanthanum hexaboride thermionic gun are precisely measured. By analyzing the Airy pattern from a selected area aperture, various parameters including the spatial coherence length are determined. Using the determined coherence length, the axial brightness of the field emission guns is estimated using the equation which we previously derived based on the discussion of the Wigner function of an electron beam. We also make some extensions in the method to be applicable to the measurements of the thermionic gun, which has anisotropic intensity distribution in most cases unlike the field emission guns. Not only conventional average brightness but also the axial brightness measured for the three kinds of emitters are compared accurately and precisely without being influenced by the measurement conditions.
精确测量了冷场发射枪、肖特基场发射枪和六硼化镧热离子枪的空间相干性和轴向亮度。通过分析来自选定区域孔径的艾里斑，确定了包括空间相干长度在内的各种参数。利用确定的相干长度，根据我们之前基于电子束维格纳函数的讨论推导的方程来估算场发射枪的轴向亮度。我们还对该方法进行了一些扩展，使其适用于热离子枪的测量，热离子枪在大多数情况下与场发射枪不同，具有各向异性的强度分布。不仅准确精确地比较了三种发射器的传统平均亮度，还比较了在不受测量条件影响的情况下测量的轴向亮度。
