A Multicore Fiber-based Velocity Sensor

In some special working environments, such as high temperatures, strong electromagnetic fields, dark and narrow spaces, existing technologies such as laser doppler velocimetry (LDV) and high-speed photography velocimetry (HSP) cannot effectively measure the velocity of objects. Multi-core fiber (MCF) is a new type of microstructure optical fiber, which combines the characteristics of traditional optical fibers such as high temperature resistance and electromagnetic field resistance. At the same time, its structure is more compact and its volume is smaller, making it very suitable for working in harsh environments. In this article, we will use the special core layout structure of MCF, combined with their compact volume, to measure the velocity of object. The effects of distance between adjacent fiber cores and the number of cores on average coupling efficiency of spatial light are analyzed. Velocity error caused by the uniformity of fiber core layout is analyzed. An experimental comparison between MCF method and HSP method is conducted to verify the feasibility of the method.