Sidelobe-free deterministic 3D nanoscopy with λ/33 axial resolution

Area of Science:

• Optics and Photonics
• Biophysics
• Nanotechnology

Background:

• Deterministic 3D super-resolution microscopy often struggles with axial resolution, typically showing elongated focal spots.
• Existing methods like isoSTED offer improved axial resolution but introduce optical complexity and sidelobes.
• High-order nonlinear optical effects can enhance resolution and suppress sidelobes.

Purpose of the Study:

• To develop an easy-to-use, sidelobe-free deterministic 3D nanoscopy technique with high axial resolution.
• To achieve precise light-matter interaction in a confined volume for advanced applications.

Main Methods:

• Developed the UNEx-4Pi strategy, combining ultrahighly nonlinear excitation (UNEx) using photon-avalanche nanoparticles with mirror-based bifocal vector field modulation (4Pi).
• Utilized a mirror-assisted single-objective bifocal self-interference strategy for system simplicity and robustness.
• Investigated the effect of optical nonlinearity on focal spot characteristics and sidelobe suppression through theoretical studies.

Main Results:

• Theoretical studies confirmed sharper focal spots and suppressed sidelobes with increased optical nonlinearity.
• Experimentally achieved a sidelobe-free focal spot with an axial resolution of up to λ/33 (26 nm) using a single low-power continuous-wave beam.
• Demonstrated bioimaging of BSC-1 cell nuclear envelopes with an axial resolution of 32 nm.

Conclusions:

• The UNEx-4Pi method provides a simple, robust, and effective deterministic strategy for 3D super-resolution imaging with exceptional axial resolution.
• This technique overcomes limitations of existing methods by achieving sidelobe-free imaging and high axial confinement.
• UNEx-4Pi holds significant potential for advancing technologies in super-resolution sensing, imaging, lithography, and data storage.