Fabrication of polymer microlens array with controllable focal length by modifying surface wettability

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Microlens arrays are crucial optical components in various imaging systems.
• Fabricating microlens arrays with precise control over optical properties like focal length remains a challenge.
• Existing methods can be costly and complex, limiting widespread adoption.

Purpose of the Study:

• To develop a straightforward and low-cost technique for fabricating microlens arrays.
• To achieve controllable focal lengths in the fabricated microlenses.
• To explore the potential of these microlens arrays in optical applications.

Main Methods:

• Utilizing interfacial energy between liquid-state acrylate resin and solidified polydimethylsiloxane (PDMS) within microholes.
• Manipulating surface modification processing time of PDMS microholes to control acrylate resin curvature.
• Investigating the influence of microhole diameter on microlens focal length and aperture.

Main Results:

• Successfully fabricated low-cost microlens arrays with tunable focal lengths ranging from -296.3 μm to -67.4 μm.
• Achieved a numerical aperture of 0.45 for the microlenses.
• Demonstrated that both focal length and aperture are influenced by microhole diameter.
• Showcased the ability to use concave microlens arrays as masters for duplicating convex microlens arrays.

Conclusions:

• The developed technique offers a simple and cost-effective approach to producing microlens arrays.
• The method allows for flexible control over focal length and aperture, making it suitable for diverse optical designs.
• The fabricated convex microlens arrays exhibit good image quality, indicating their practical utility in imaging devices.