| A vortex beam has a spiral phase factor that can cause a spiral wave front, and the number of different topological charge carrying different orbital angular momentum. Based on this characteristic, it has a wide range of applications in which information is encoded, optical manipulation, optical tweezers, Bio-medicine and so on. Specifically, this paper analyzed the vortex beam intensity, angular momentum, phase, polarization, and focusing characteristics, Poynting vector in theory, concluded that some of the basic characteristics of vortex beam. It focuses to introduce how to measure the number of vortex beam’s topological charge by interferometry. With mathematical tools, we can deduce theoretically the interference of plane waves and vortex beam, spherical wave and vortex beam, the interference between the vortex beams, the Young’s double-slit interference distribution between ring vortex beams’ interference and the interference patterns. By measuring changes of the interference patterns, we will know the topological charges of vortex beams. To produce such a vortex beam that has spiral phase, the paper also focuses on the three methods—computer-generated hologram, liquid crystal spatial light modulator (LC-SLM), spiral phase plate method, and also giving experimental schematic diagram. |
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