Microparticle velocity sensing using a conical lens fiber array

We report a microparticle velocity sensor with a conical lens fiber array. The conical lens fibers are linearly arrayed at the same interval to behave as a spatial filter. The characteristics of the sensor in terms of cone angle, divergence angle, aperture angle, blind area, and detection area are investigated. Compared with a sensor using a normal flat end fiber array, our sensor has a high signal-to-noise ratio with a smaller blind area and wider detection area to avoid the signal deterioration caused by movement deviation of particles from the fiber array. Taking advantage of not only a compact and tiny structure but also better ability of high electromagnetic noise tolerance, corrosion resistance, and temperature resistance, the sensor may have the potential for velocity sensing in harsh environments and microparticle sensing, such as sand movement monitoring in sandstorms, particle state monitoring in combustion, and more.