Escape forces and trajectories in optical tweezers and their effect on calibration.

摘要: Whether or not an external force can make a trapped particle escape from optical tweezers be used to measure forces. Combined with the linear dependence of forces on trapping power, quantitative measurement obtained. For this measurement, is at edge trap, away region near equilbrium position where trap described as spring. This method provides ability higher for same beam compared using lower risk damage specimens. Calibration typically performed by increasing fluid flow exert until it escapes. In calibration technique, usually assumed along straight line in direction fluid-flow. Here, we show that instead follows curved trajectory, which depends rate application (i.e., acceleration flow). limit very low acceleration, surface zero axial during escape. The required produce and hence acceleration. result variations factor two. have major impact determine efficiency. Even when measurements are all regime, efficiency 20% more still occur. We present computational simulations generalized Lorenz-Mie theory experimental how increase discuss calibration.