Preparation method of silicon-based aspheric cylindrical microlens array

An spherical cylindrical lens is an important micro-optical element that has the functions of laser collimation, focusing, homogenization, etc., and has a wide range of applications in laser communication, optical fibre sensing, lidar ranging, laser pumping and other systems. To reduce the volume of the optoelectronic system and improve the performance of the optical fiber, increasing the numerical aperture of the lens is a common solution. Proposes the use of silicon with a higher refractive index as an alternative material for the low refractive index quartz substrate, which greatly increases the numerical aperture of the lens under the same volume and at the same time reduces the amount of processing and improves the manufacturing efficiency. Aiming at the problem that traditional quartz microlens preparation methods are no longer suitable for silicon-based lenses, a mask-based moving exposure method is proposed to prepare photoresist aspheric patterns using multiple spin coating and cycle exposure methods to solve problems such as poor thick photoresist surface uniformity and obvious traces of the exposure mask. Plasma etching technology is finally used to transfer the pattern to realize the preparation of the microlens. Taking a silicon-based aspherical cylindrical microlens array with a numerical aperture of 2.9 as an example, the actual preparation process experiment was carried out.The surface precision PV of the prepare microlens array is 0.766 μm, the surface roughness Ra is 3.4 nm, and the surface finish was in line with the design value. The feasibility of the preparation method was verified. This method is expected to promote the large-scale application of aspheric cylindrical microlens array in compact infrared optoelectronic systems. © 2022 Chinese Society of Astronautics. All rights reserved.