Multi-plane confocal microscopy with multiplexed volume holographic gratings [Invited]

Area of Science:

• Optics and Photonics
• Microscopy Techniques
• Metrology

Background:

• Traditional confocal microscopy requires axial scanning, limiting imaging speed.
• Volume holographic (VHG) gratings offer unique light manipulation capabilities.
• Previous VHG-based confocal imaging methods have shown promise but require further development.

Purpose of the Study:

• To propose and evaluate a novel multi-plane differential confocal microscopy (DCM) system.
• To achieve axial scan-free imaging with enhanced axial resolution and optical sectioning.
• To demonstrate the system's applicability for surface metrology and fluorescence imaging.

Main Methods:

• Development of a VHG grating-based multi-plane DCM system.
• Simultaneous acquisition of two depth-resolved optically sectioned images.
• Evaluation using a silicon micro-hole array with ~10 µm depth separation.

Main Results:

• Achieved axial scan-free imaging capability.
• Demonstrated simultaneous acquisition of two optically sectioned images.
• Measured an axial sensitivity of approximately 25 nm.
• Exhibited high axial sensitivity and optical sectioning ability.

Conclusions:

• The proposed multi-plane DCM system enables efficient, high-resolution 3D imaging without axial scanning.
• The system offers significant advantages for reflective surface profiling and multi-plane fluorescence imaging.
• Potential applications include label-free biological sample metrology and industrial inspection.