Lithographic fabrication of diffractive optical elements in hybrid sol-gel glass on 3-D curved surfaces

Taisheng Wang,Hongxin Zhang,Qiang Sun,Wenbin Xu,Zhijun Xu,Weixing Yu,Dengying Zhang,Hua Liu,Zhenwu Lu,Chunrong Li

doi:10.1364/oe.18.025102

Abstract

We demonstrate the lithographic fabrication of diffractive optical elements (DOEs) in hybrid SiO2/TiO2 sol-gel glass on 3-D curved surfaces. The concentric circular gratings with periods of 20 μm, 10 μm and 5 μm have been fabricated in sol-gel glass on concave lens by laser direct writing successfully. Continuous 3-Dimensional surface relief with a height of 435 nm, 110 nm and 50 nm has been obtained for the period of 20 μm, 10 μm and 5 μm respectively. The optical test results of the fabricated DOE shows only a little bit deviation from the theoretical calculated results which can be explained by 3-D curved surface effect. We believe this technology can be an effective method to fabricate DOEs with even more complex surface profile on 3-D curved surfaces in terms of its simplicity and cost-effectiveness.

Highlights

Diffractive optical elements are widely used in many areas such as hybrid refractivediffractive imaging systems, measurement of convex secondary mirrors, ultraviolet spectroscopic instruments, and test large-aperture convex aspheric surface [1,2,3]
We demonstrate the lithographic fabrication of diffractive optical elements (DOEs) in hybrid SiO2/TiO2 sol-gel glass on 3-D curved surfaces
The optical test results of the fabricated DOE shows only a little bit deviation from the theoretical calculated results which can be explained by 3-D curved surface effect

Summary

Introduction

Diffractive optical elements are widely used in many areas such as hybrid refractivediffractive imaging systems, measurement of convex secondary mirrors, ultraviolet spectroscopic instruments, and test large-aperture convex aspheric surface [1,2,3]. Laser direct writing, which enables a complex continuous-relief microstructure to be fabricated in a single exposure scan, can precisely control the process parameters. It has a great advantage over the other technologies for the fabrication of DOEs on a curved surface with precise alignment. The fabrication of DOEs in hybrid SiO2/TiO2 sol-gel glass on 3-D curved surfaces by laser direct writing is reported. The fabricated DOEs are optically characterized and compared with simulation results To our knowledge, this is the first time that the DOEs are fabricated in sol-gel material on 3-D curved surfaces by laser direct writing method

Fabrication and characterization

Optical test results and discussions

Conclusions