Revolution of a trapped particle in counter-propagating dual-beam optical tweezers under low pressure.

Abstract

We presented faster and more accurate simulations and experiments describing the revolution of a suspended particle in optical tweezers under a low pressure. Instead of the state-of-the-art offline method of pinhole alignment, we proposed an in situ method of revolution suppression by adjusting the laser beam while observing the power spectral density and time-domain plot of the particle centroid displacement. The experimental results under different air pressures show that our method is more effective at low pressures. We observed that "revolution occurs when radial alignment error is below the threshold" and uncovered the mechanism behind this phenomenon. The rapidly growing Q value of the revolution indicates a high-precision resonance measurement method under lower air pressure compared with random translation measurements.