Two-Photon Excitation STED Microscopy with Time-Gated Detection

Area of Science:

• Microscopy
• Super-resolution imaging
• Biophotonics

Background:

• Two-photon excitation stimulated emission depletion (2PE-STED) microscopy offers super-resolution capabilities.
• Implementing 2PE-STED with continuous-wave (CW) lasers simplifies architecture but faces signal-to-noise challenges.

Purpose of the Study:

• To introduce a novel 2PE-STED microscope utilizing time-gated detection.
• To address signal degradation caused by time-gated detection in CW 2PE-STED systems.
• To demonstrate enhanced imaging of sub-cellular structures.

Main Methods:

• Development of a 2PE-STED microscope incorporating time-gated detection.
• Application of a multi-image deconvolution algorithm to recover signal-to-noise ratio (SNR) and signal-to-background ratio (SBR).
• Algorithm simultaneously reassigns early photons and removes background noise.

Main Results:

• Effective silencing of fluorophores achieved with moderate stimulated emission beam intensity.
• Demonstrated recovery of SNR and SBR, overcoming limitations of time-gated detection.
• Successful imaging of sub-cellular structures with the developed system.

Conclusions:

• The novel 2PE-STED system with time-gated detection and a CW laser is feasible and efficient.
• The developed deconvolution algorithm effectively restores image quality degraded by time-gated detection.
• The algorithm shows potential for future all-pulsed 2PE-STED implementations.