A Novel Fabricating Method of Micro Lens-on-Lens Arrays with Two Focal Lengths

Xin Liu; Min Li; Jiang Bian; Junfeng Du; Bincheng Li; Bin Fan

doi:10.3390/mi12111372

A Novel Fabricating Method of Micro Lens-on-Lens Arrays with Two Focal Lengths

Micromachines (Basel). 2021 Nov 8;12(11):1372. doi: 10.3390/mi12111372.

Authors

Xin Liu^{1

2

3}, Min Li¹, Jiang Bian¹, Junfeng Du¹, Bincheng Li², Bin Fan¹

Affiliations

¹ Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu 610209, China.
² School of Optoelectronic Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
³ University of Chinese Academy of Sciences, Beijing 100049, China.

Abstract

Micro lens-on-lens array (MLLA) is a novel 3D structure with unique optical properties that cannot be fabricated accurately and quickly by existing processing methods. In this paper, a new fabricating method of MLLAs with two focal lengths is proposed. By introducing the soft lithography technology, nano-imprint technology and mask alignment exposure technology, MLLAs with high precisions can be obtained. A MLLA is successfully fabricated with two focal lengths of 58 μm and 344 μm, and an experiment is carried out. The results show that the MLLA has excellent two-level focusing and imaging abilities. Furthermore, the fabricated profiles of the MLLA agree well with the designed profiles, and the morphology deviation of the MLLA is better than 2%, satisfying the application requirements. The results verify the feasibility and validity of the novel fabricating method. By adjusting mask patterns and processing parameters, MLLAs with both changeable sizes and focal lengths can be obtained.

Keywords: mask alignment exposure technology; micro lens-on-lens arrays; microlens arrays; nano-imprint technology; photoresist reflow method; soft lithography.