In the visible spectrum vortex beams have found various applications, ranging from optical tweezers to super-resolution imaging. Recently, these beams have been demonstrated using X-rays and electron beams. However, so far, no in-depth discussion has been carried out on the vortex quality, which could become essential for a variety of vortex applications. Here, we investigate the mode conversion efficiency (MCE), vortex structure and stability (in terms of vortex splitting) of the vortex fields generated by spiral zone plates (SZP). We have designed and fabricated SZPs with varying topological charge of both binary and kinoform profile. Kinoforms are known for their 100 % diffraction efficiency in the ideal case. In this work, both types are contrasted with regard to the vortex quality. Utilizing ptychographic coherent diffraction imaging and by comparing to simulations the wavefront of the generated fields is characterized. It was found, that the MCE and vortex structure exhibit the same dependencies on material and ZP properties as the diffraction efficiency (DE) and that the kinoform profile in this sense also improves the vortex quality. With growing SZP charge the MCE decreases. The results link the parameters of optics to the properties of the vortices and help to maximize the performance of ZP based vortex generators for future applications.
Vortex beams with tunable "all-with-visible-light" dye-doped liquid crystal q-plates for broadband application
Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante（阿利坎特大学应用物理科学与技术大学研究所）；Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante（阿利坎特大学系统信号理论与物理工程系）；Departamento de óptica, Farmacología y Anatomía, Universidad de Alicante（阿利坎特大学光学、药理学和解剖学系）
Transverse quantum-state characterization of programmable electron optics
Friedrich-Alexander-Universität Erlangen-Nürnberg（弗里德里希·亚历山大埃尔朗根-纽伦堡大学）；CNR Istituto Nanoscienze（意大利国家研究委员会纳米科学研究所）；CNR Istituto per lo Studio dei Materiali Nanostrutturati（意大利国家研究委员会纳米结构材料研究所）；Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich（于利希研究中心恩斯特·鲁斯卡电子显微镜与光谱学中心）
