3D-scanning and miniature MPM objective with improved resolution at depth scanning.

Area of Science:

• Biomedical Optics
• Microscopy Engineering

Background:

• Compact 3D imaging systems like microendoscopic multiphoton microscopy (MPM) require miniaturized objectives and scanners.
• Maintaining focus and minimizing focal spot degradation during depth scanning are significant challenges in miniature MPM systems.

Purpose of the Study:

• To design and evaluate a miniature objective capable of depth scanning with stable focusing performance.
• To address focal spot degradation and enhance penetration depth for compact MPM applications.

Main Methods:

• A miniature objective was designed using an aspheric lens and a plano-convex lens (PCX).
• Depth scanning was achieved by actuating the aspheric lens with a shape memory alloy actuator.
• Spherical aberration was compensated using the PCX curvature to counteract refractive index mismatch during scanning.

Main Results:

• The custom objective demonstrated improved performance in focal spot degradation and penetration depth compared to existing designs.
• Resolution and signal intensity remained consistent over a ~400 µm depth scanning range.
• The objective maintained good focusing performance across the scanning range.

Conclusions:

• The developed miniature objective offers depth scanning and deep penetration capabilities within a compact profile.
• This design holds significant potential for advancing clinical applications of multiphoton microscopy.