Compact dark-field confocal microscopy based on an annular beam with orbital angular momentum

Area of Science:

• Optics and Photonics
• Microscopy Technology

Background:

• Diffraction distortion limits resolution in traditional microscopy.
• Miniaturization of advanced optical systems remains a challenge.

Purpose of the Study:

• To develop a compact dark-field confocal microscopy (DFCM) system.
• To generate orbital angular momentum annular beams using a two-mode fiber for enhanced imaging.

Main Methods:

• Utilized fiber-mode excitation-assisted orbital angular momentum annular beam generation.
• Employed a two-mode fiber to avoid diffraction distortion.
• Implemented a system to fully block reflected light for high contrast.

Main Results:

• Achieved high imaging contrast with a steady central dark-spot.
• Demonstrated system feasibility by imaging 2D and 3D samples.
• Successfully compressed the DFCM volume for system miniaturization.

Conclusions:

• The proposed fiber-based DFCM system offers a miniaturized solution with high contrast.
• The technology shows potential for detecting subsurface defects and high-contrast biological imaging.