Apparatus for continuous, fast, and precise measurements of position and velocity of a small spherical particle

摘要

The position and velocity of optically levitated glass spheres (radii 10–20 μm) moving in a gas are measured accurately, rapidly, and continuously using a high‐speed rotating polygon mirror. The experimental technique developed here has repeatable position accuracies better than 20 μm. Each measurement takes less than 1 μs and can be repeated every 100 μs. The position of the levitated glass spheres can be manipulated accurately by modulating the laser power with an acoustic optic modulator. The technique provides a fast and accurate method to study general particle dynamics in a fluid.