Defocused imaging exploits supercritical-angle fluorescence emission for precise axial single molecule localization...

Area of Science:

• Optical Microscopy
• Nanotechnology
• Biophysics

Background:

• Single Molecule Localization Microscopy (SMLM) overcomes classical optical resolution limits.
• Axial (depth) position localization in SMLM is challenging due to the large depth of focus.
• Super-critical Angle Fluorescence (SAF) can improve axial localization precision when molecules are near the coverslip.

Purpose of the Study:

• To introduce a novel SMLM strategy using defocused imaging to leverage SAF for enhanced axial localization.
• To demonstrate the superiority of this defocused imaging approach compared to existing SAF-based methods.
• To present a simple, broadly applicable SMLM technique for research-grade microscopes.

Main Methods:

• Implementation of a defocused imaging strategy within the SMLM workflow.
• Acquisition of multiple sparse fluorescence recordings from a sample.
• Analysis of super-critical angle fluorescence (SAF) patterns generated by controlled defocusing.

Main Results:

• The proposed defocused imaging method significantly improves axial localization precision in SMLM.
• This approach outperforms established SAF-based techniques for axial position estimation.
• The method is compatible with standard research microscopes capable of controlled defocus.

Conclusions:

• Defocused imaging is an effective SMLM strategy for exploiting SAF to achieve high-precision axial localization.
• This technique offers a practical and superior alternative for depth imaging in SMLM.
• The simplicity and accessibility of this method will benefit various research fields requiring nanoscale imaging.