Tracking of colloids close to contact

TL;DR

This paper introduces a template-based algorithm for tracking micron-sized colloids near contact, significantly reducing systematic errors caused by overlapping diffraction patterns, thereby improving measurement accuracy in particle interaction studies.

Contribution

The authors present a novel template matching method that tracks only unaffected parts of particle images, applicable to various particle shapes, enhancing precision in colloid tracking near contact.

Findings

Reduces systematic errors compared to standard methods

Effective under realistic experimental conditions

Applicable to arbitrarily shaped particles

Abstract

The precise tracking of micron sized colloidal particles - held in the vicinity of each other using optical tweezers - is an elegant way to gain information about the particle-particle pair interaction potential. The accuracy of the method, however, relies strongly on the tracking precision. Particularly the elimination of systematic errors in the position detection due to overlapping particle diffraction patterns remains a great challenge. Here we propose a template based particle finding algorithm that circumvents these problems by tracking only a fraction of the particle image that is insignificantly affected by nearby colloids. Under realistic experimental conditions we show that our algorithm significantly reduces systematic errors compared to standard tracking methods. Moreover our approach should in principle be applicable to almost arbitrary shaped particles as the template can be adapted to any geometry.