Refractive Index Distribution Of The Square-aperture Planar Microlens Array

With the development of science and technology, miniaturization lightweight, array, integration and intelligence have been the progressive direction of the optical components. Planar microlens array technology have increasingly been become mature, which makes the buried type planar microlens array uniform, perfect and array regular. This type microlens array show good optical properties in spotlight, imaging, collimation, shunt switch and refractive index distribution; at the same time, the small diameter and high density of microlens array are available for the high-capacity and multi-channel parallel processing of information.The square aperture planar microlens array, a new compact, regular and uniform radial refractive index microlens array, is fabricated by photolithographic and ion-exchanging technology. These technologies are used to achieve the size of optical element from millimeter to micron level, which marks the development from traditional optics to microoptics. Radial gradient-index microlens array have many advantages such as short focal length, large numerical aperture, small size, high resolution and easy to use, which can be widely applied in optical information transmission, processing, optical sensing and optical computing technology etc..In this paper, we focus on the ion exchanging theory and the refractive index distribution with the square-aperture planar microlens arrays. By lithographic ion-exchanging technology and a special technology to remove the1.0micron layer of titanium on the glass substrate, square-aperture planar microlens array is buried in the substrate and the fill factor of microlens array is nearly100%. We finished the detailed analysis of internal mechanism of ion diffusion and theoretical and experimental exploration, and obtained the refractive index distribution of square-aperture planar microlens arrays, which can be used as a favorable theory basis for the fabrication and application of this type square-aperture planar microlens array.First, we analyzed the ion thermal diffusion law based on the point source diffusion. With the relation of ion concentration distribution and the refractive index distribution of planar microlens array, the refractive index distribution was obtained. Then, the refractive index distribution was achieved from the diffusion equation. At last, we simulated this theoretical model under even square conditions with MATLAB, and found that the simulated results are agreement with the available experimental result perfectly, which provide a reliable theoretical basis analysis for the imaging of square planar microlens array.In conclusion, the result of refractive index distribution in this dissertation can provide a strong scientific basic for the improvement of fabrication process and optical performance and theory development of this type microlens array.