Fabrication of Random Microlens Array for Laser Beam Homogenization with High Efficiency

Area of Science:

• Optics and Photonics
• Laser Technology
• Materials Science

Background:

• Microlens arrays (MLAs) enable beam homogenization, compactness, and miniaturization in laser systems.
• However, MLA periodicity causes interference fringes, degrading the uniformity of homogenized laser beams.

Purpose of the Study:

• To propose and demonstrate a novel random microlens array (rMLA) structure for effective beam homogenization.
• To suppress coherence during homogenization by breaking MLA periodicity, enhancing light spot uniformity and energy utilization.

Main Methods:

• Developed a random microlens array (rMLA) by breaking the periodicity of traditional MLAs.
• Fabricated honeycomb and rectangular rMLAs using a combination of chemical etching and lithography.
• Evaluated the energy utilization and uniformity of homogenized light spots.

Main Results:

• Achieved high energy utilization rates of approximately 90% for both honeycomb and rectangular rMLAs.
• Demonstrated excellent uniformity for homogenized light spots: over 80% for honeycomb rMLA and over 85% for rectangular rMLA.
• Confirmed the feasibility of cost-effective fabrication for the proposed rMLAs.

Conclusions:

• The proposed rMLA effectively suppresses interference fringes, leading to superior beam homogenization.
• rMLAs offer a promising solution for achieving uniform, high-energy-utilization homogenized laser spots.
• The fabrication method is cost-effective, making rMLAs practical for various laser system applications.