Highly corrected close-packed microlens arrays and moth-eye structuring on curved surfaces

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Fabricating precise optical elements on curved surfaces presents significant challenges.
• Existing methods for creating microlens arrays often lack scalability or adaptability to non-planar substrates.
• Moth-eye structures are desirable for anti-reflective and light-trapping applications but require advanced fabrication.

Purpose of the Study:

• To develop a novel method for fabricating near-micrometer-sized, close-packed coherent microlens arrays on spherical and aspheric surfaces.
• To utilize a compact holographic projector system for precise grid patterning on curved substrates.
• To investigate the optical properties and potential applications of the fabricated microlens arrays, including their use as moth-eye relief structures.

Main Methods:

• A compact holographic projector system was employed to generate standing-wave interference patterns.
• A photolytic process using a photoimageable bisbenzocyclobutene (BBC) polymeric resin was used to form the microlens arrays.
• The system enabled multimicrometer down to submicrometer grid patterning on curved surfaces.

Main Results:

• Successfully fabricated near-micrometer-sized, close-packed coherent microlens arrays on both spherical and aspheric surfaces.
• The resulting microlenslets exhibit a near-paraboloid contour due to material absorption during the photolytic process.
• Demonstrated optimization of meridional ray trajectories for each microlenslet to achieve single-point or locus-of-points focusing.

Conclusions:

• The developed holographic projection system offers a viable and compact solution for fabricating advanced microlens arrays on complex surfaces.
• The fabricated microlens arrays, with their controllable focusing properties and moth-eye relief structure potential, are promising for optical applications.
• This technique advances the capability for creating micro-optical elements on non-planar substrates, opening new avenues in optical design and manufacturing.