Fast fabrication of curved microlens array using DMD-based lithography

Zhimin Zhang,Yiqing Gao,Ningning Luo,Kejun Zhong

doi:10.1063/1.4941356

Abstract

Curved microlens array is the core element of the biologically inspired artificial compound eye. Many existing fabrication processes remain expensive and complicated, which limits a broad range of application of the artificial compound eye. In this paper, we report a fast fabrication method for curved microlens array by using DMD-based maskless lithography. When a three-dimensional (3D) target curved profile is projected into a two-dimensional (2D) mask, arbitrary curved microlens array can be flexibly and efficiently obtained by utilizing DMD-based lithography. In order to verify the feasibility of this method, a curved PDMS microlens array with 90 micro lenslets has been fabricated. The physical and optical characteristics of the fabricated microlens array suggest that this method is potentially suitable for applications in artificial compound eye.

Highlights

Inspired artificial compound eye, similar to natural compound eye, has attracted a great deal of research interest because of the unique and outstanding capabilities for wide field of view (FOV) imaging and high-sensitivity motion detection.[1,2] A typical artificial compound eye imaging system is mainly composed of the microlens array and the photo-detector.[3]
We report a fast fabrication method for curved microlens array by using digital micromirror device (DMD)-based maskless lithography
When a three-dimensional (3D) target curved profile is projected into a two-dimensional (2D) mask, arbitrary curved microlens array can be flexibly and efficiently obtained by utilizing DMD-based lithography

Summary

INTRODUCTION

Inspired artificial compound eye, similar to natural compound eye, has attracted a great deal of research interest because of the unique and outstanding capabilities for wide field of view (FOV) imaging and high-sensitivity motion detection.[1,2] A typical artificial compound eye imaging system is mainly composed of the microlens array and the photo-detector.[3]. The fabrication deforming a planar microlens array is flexible, the complex process and harsh control condition may restrict its development. The spatial light modulation (SLM) based lithography,[13,14,15] such as using digital micromirror device (DMD), can provide a fast and convenient strategy for forming microelements. DMD-based lithography system is a planar exposure system, so the digital mask of planar microelement can be designed. It is difficult to design the digital mask of curved microelements for the planar exposure system. After lithography and polydimethylsiloxane (PDMS) replication, curved microlens arrays are formed. The fabrication quality, geometric size and surface roughness of the finished curved microlens array have been measured and verified by an optical profiler. The optical focal length of micro lenslet and the point spread function (PSF) are investigated using an optical measurement system

FABRICATION PROCESS AND MASK DESIGN

RESULTS AND DISCUSSIONS

CONCLUSIONS