Subnanometer localization accuracy in widefield optical microscopy

TL;DR

This paper introduces a comprehensive calibration method using aperture arrays to achieve subnanometer localization accuracy in widefield optical microscopy, addressing systematic errors and enabling precise nanoscale measurements.

Contribution

It develops novel aperture array reference materials and calibration techniques that significantly improve localization accuracy and reliability in widefield optical microscopy.

Findings

Achieved localization errors approaching atomic scale

Developed calibration methods correcting aberrations

Validated applicability across multiple light sources

Abstract

The common assumption that precision is the limit of accuracy in localization microscopy and the typical absence of comprehensive calibration of optical microscopes lead to a widespread issue - overconfidence in measurement results with nanoscale statistical uncertainties that can be invalid due to microscale systematic errors. In this article, we report a comprehensive solution to this underappreciated problem. We develop arrays of subresolution apertures into the first reference materials that enable localization errors approaching the atomic scale across a submillimeter field. We present novel methods for calibrating our microscope system using aperture arrays and develop aberration corrections that reach the precision limit of our reference materials. We correct and register localization data from multiple colors and test different sources of light emission with equal accuracy, indicating the general applicability of our reference materials and calibration methods. In a first application of our new measurement capability, we introduce the concept of critical dimension localization microscopy, facilitating tests of nanofabrication processes and quality control of aperture arrays. In a second application, we apply these stable reference materials to answer open questions about the apparent instability of fluorescent nanoparticles that commonly serve as fiducial markers. Our study establishes a foundation for subnanometer localization accuracy in widefield optical microscopy.