Absolute Position Total Internal Reflection Microscopy with an Optical Tweezer

Abstract

A non-invasive, in-situ calibration method for Total Internal Reflection Microscopy (TIRM) based on optical tweezing is presented which greatly expands the capabilities of this technique. We show that by making only simple modifications to the basic TIRM sensing setup and procedure, a probe particle's absolute position relative to a dielectric interface may be known with better than 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 in measurement range over conventional TIRM methods. The technique's advantage is in the direct measurement of the probe particle's scattering intensity vs. height profile in-situ, rather than relying on calculations or inexact system analogs for calibration. To demonstrate the improved versatility of the TIRM method in terms of tunability, precision, and range, we show our results for the hindered near-wall diffusion coefficient for a spherical dielectric particle.

10 pages. Submitted for peer review 8/20/2014

Cited by in corpus (5)

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• Height Distribution and Orientation of Colloidal Dumbbells Near a Wall
• Detecting and analysing wavelength-scale optical gradients at an interface by their effects on the internal reflectance near the critical angle