Fast two-snapshot structured illumination for temporal focusing microscopy with enhanced axial resolution

Area of Science:

• Microscopy and Imaging Technologies
• Optical Engineering
• Computational Imaging

Background:

• Structured light illumination (SLI) is crucial for 3D imaging.
• Conventional SLI methods often require numerous image acquisitions, limiting imaging speed.
• Enhancing axial resolution and acquisition speed in SLI remains a key challenge.

Purpose of the Study:

• To develop and validate a novel two-snapshot SLI reconstruction algorithm.
• To improve the axial resolution and acquisition speed of 3D fluorescence microscopy.
• To implement the algorithm on a custom-built temporal focusing fluorescence microscope (TFFM).

Main Methods:

• A two-snapshot SLI algorithm using two phase-shifted raw structured images.
• Implementation on a custom TFFM with a digital micromirror device (DMD) for fringe pattern generation.
• Automatic fringe orientation detection, image rotation and subtraction, and parallel amplitude demodulation via Hilbert transform.

Main Results:

• Achieved an axial resolution enhancement factor of 1.25, closely matching theoretical estimation (1.27).
• Demonstrated comparable contrast reconstruction and optical cross-sectioning to conventional RMS methods.
• Showcased improved imaging speed by 2.5 times for two-photon systems due to reduced frame requirements.

Conclusions:

• The two-snapshot SLI algorithm offers a significant advancement for high-speed 3D imaging.
• The method provides comparable performance to existing techniques with enhanced speed.
• This approach is readily applicable to various sinusoidally modulated illumination systems for faster 3D reconstruction.