Time-gating improves the spatial resolution of STED microscopy.

Area of Science:

• Optics and Photonics
• Biophysical Imaging

Background:

• Stimulated-emission depletion (STED) microscopy enhances resolution using a depletion beam.
• Spatial information is encoded in STED microscopy via a depletion channel with spatially-varying strength.

Purpose of the Study:

• To demonstrate that fluorophore lifetime encodes spatial information.
• To utilize fluorophore lifetime and time-gating for improved STED microscopy resolution.

Main Methods:

• Solving a kinetic model for fluorophore emission under time-varying STED pulses.
• Analyzing the impact of pulse duration and time-gating on resolution.
• Investigating time-gating with continuous-wave (CW) STED beams.

Main Results:

• Spatial information is encoded in fluorophore lifetime, usable for resolution enhancement.
• Optimal resolution is achieved with short STED pulses, but finite pulses can be compensated by time-gating.
• Time-gating with CW STED beams offers theoretically unbounded resolution.

Conclusions:

• Time-gated STED (T-STED) microscopy can significantly improve spatial resolution.
• Improved resolution comes at the cost of reduced image brightness.
• T-STED may offer performance benefits beyond resolution increases in specific applications.