Simulation and optimization of microlens hot-melting fabricating process based on finite element method

As an important optical element, the microlens array has received more and more attention. Due to the advantages of a short production cycle, low cost, high efficiency, and easy to transfer, the photoresist hot-melting method has been widely used to fabricate microlens. Fabricating microlenses with large aperture and curvature radius are the basic requirements to ensure image quality. However, due to the limitations of photoresist material properties and the hot-melting process, the shape of the microlens is not easy to control. In this paper, the finite element fluid simulation software Fluent was used to simulate the microlens hot-melting fabricating process. Through the simulation, we could understand the formation process of the microlens. By multiple groups of simulation comparison, the key parameter in the formation of microlens was discussed. Besides, the simulation result shows that when a layer of residual photoresist is left around the original photoresist cylinder, microlens with larger diameter can be easily obtained. The experimental results are in good agreement with the simulation results. The comparison imaging experiment also illustrates that the microlens fabricated by the improved process has better imaging ability. Through simulation, this paper not only explains the mechanism of the hotmelting method, but also optimizes its process. The related research could expand the application range of the hot-melting method in the fabrication of microlens.