Using fluorescent beads to emulate single flurophores

TL;DR

This paper investigates how fluorescent beads can be used to emulate single fluorescent molecules for microscope calibration, analyzing differences in PSFs and proposing compensation methods to improve their similarity.

Contribution

It provides a theoretical analysis of the differences between beads and single molecules and introduces methods to model and compensate for size-related blurring effects.

Findings

Beads can emulate single molecules under specific conditions.

Size and emission pattern differences affect PSF similarity.

Compensation methods improve PSF matching.

Abstract

In this work, we study the conditions under which fluorescent beads can be used to emulate single fluorescent molecules in the calibration of optical microscopes. Although beads are widely used due to their brightness and easy manipulation, there can be notable differences between the point spread functions (PSFs) they produce and those for single-molecule fluorophores, caused by their different emission pattern and their size. We study theoretically these differences for various scenarios, e.g. with or without polarization channel splitting, to determine the conditions under which the use of beads as a model for single molecules is valid. We also propose methods to model the blurring due to the size difference and compensate for it to produce PSFs that are more similar to those for single molecules.