Absolute Position Total Internal Reflection Microscopy with an Optical Tweezer

摘要

A non-invasive, in-situ calibration method for Total Internal ReflectionMicroscopy (TIRM) based on optical tweezing is presented which greatly expandsthe capabilities of this technique. We show that by making only simplemodifications to the basic TIRM sensing setup and procedure, a probe particle'sabsolute position relative to a dielectric interface may be known with betterthan 10 nm precision out to a distance greater than 1 $\mu$m from the surface.This represents an approximate 10x improvement in error and 3x improvement inmeasurement range over conventional TIRM methods. The technique's advantage isin the direct measurement of the probe particle's scattering intensity vs.height profile in-situ, rather than relying on calculations or inexact systemanalogs for calibration. To demonstrate the improved versatility of the TIRMmethod in terms of tunability, precision, and range, we show our results forthe hindered near-wall diffusion coefficient for a spherical dielectricparticle.