Session: 03-11-02: Laser-Based Advanced Manufacturing and Materials Processing II

Paper Number: 168220

Scalable Fabrication of Nickel-Based Microlens Array Molds via Hybrid Precision Molding and Micro-Electroforming 

Microlens arrays (MLAs), as core components of modern optical systems, demonstrate significant application value in optical communications, high-density optical storage, and super-resolution imaging. Their optical performance directly determines critical functionalities including beam homogenization control, multi-focal parallel imaging, and wave front phase modulation. However, the manufacturing technology for high-precision MLAs suitable for industrial-scale mass production still faces substantial challenges. Precision glass molding (PGM) has emerged as the predominant manufacturing process for MLAs fabrication, owing to its superior forming accuracy, batch consistency, and cost-effectiveness in large-scale production. Nevertheless, the mold materials employed in this technique generally exhibit characteristics of high hardness and brittleness, leading to technical problems during mold processing such as easy tool wear, constrained machining efficiency, and elevated comprehensive manufacturing costs. These limitations significantly impede the industrialization development of this promising technology. To address these issues, this study proposes a hybrid process combining precision compression molding with micro-electroforming to achieve the efficient fabrication of high-durability Nickel-based molds. First, a novel laser-assisted alignment precision molding method was developed to prepare micro-electroforming master templates. This method employs nanosecond laser direct writing technology to create positioning hole arrays on a SiC mold substrate. Precision ceramic balls were then assembled on this substrate to form a modular mold, which is subsequently used for compression molding to replicate concave MLA patterns on polymethyl-methacrylate (PMMA) surfaces. Second, the micro-features were transferred from the PMMA samples to a nickel block by the micro-electroforming process. To achieve sufficient structural integrity while maintaining cost-effective production schedules, multiple glass molding experiments were systematically conducted on electroplated molds with varying thickness gradients. The results demonstrated that nickel-based molds exceeding 2 mm in thickness exhibited superior mechanical strength, capable of withstanding repeated compression molding cycles under elevated temperature conditions (T>650°C). The nanosecond laser technology enables programmable fabrication of hole arrays with tunable spatial configurations (100-10000μm spacing) and customizable geometric patterns (circular/hexagonal), serving as a critical enabler for producing tailored nickel-based mold substrates. Subsequently, the micro-electroforming process demonstrates exceptional replication fidelity (>98% feature accuracy), faithfully transferring PMMA master template architectures into nickel molds. Geometrical profile and feature consistency of the fabricated nickel-based mold across processing step are characterized experimentally. Quantitative analysis of cross-sectional profiles verifies successful duplication of master template features. This hybrid manufacturing strategy achieves batch production of concave MLA molds with <1.5% form deviation and micron-level positional accuracy, while achieving 40% cost reduction through mold reusability exceeding 50 cycles. The developed methodology provides a scalable platform for fabricating multifunctional structured surfaces with applications ranging from beam shaping optics to laser parallel processing system.

Presenting Author: Yang Shu Shenzhen Technology University

Presenting Author Biography: Dr. Yang Shu
He received his B.S. and Ph.D in Mechanical Design and Theory from Hunan University in 2013 and 2021, respectively. From September 2018 to November 2020, he was working at The Ohio State University, USA as a visiting scholar with Professors Allen Y. Yi. He is currently working at Shenzhen Technology University, with research interests covering micro/nano manufacturing, optical compression molding.

Authors:

Yang Shu Shenzhen Technology University
Bosen Kuang Shenzhen Technology University
Peilin Zhang Shenzhen Technology University
Jiale Li Shenzhen Technology University
Can Yang Shenzhen Technology University