基于液滴稳态面形计算的微小透镜制作技术

Fabrication Technology of the Microlens Based on the Numerical Calculation of the Droplet Stable Shape

微小透镜作为典型微小光学器件在应用光学领域有着重要作用。依据液滴稳态球冠面形具有最小自由能的成形原理,分析了液滴接触角和体积对其面形的影响;通过编程软件Surface Evolver对微小液滴的建模,对液滴的稳态面形进行了数值计算;利用按需滴定的体积调控和不同疏水性基底材料的接触角改变,得到了不同尺寸、不同面形的聚合物透镜。实验测量与面形仿真具有良好的一致性。结果表明,液滴接触角增大,则透镜底径减小,高度增大;液滴体积增大,则透镜底径与高度均增大;且液滴体积较小时,可以得到非球面系数较小的球面面形透镜。透镜的光学参数测量和成像实验表明,通过调节接触角和体积能够制作出不同光学参数且光学性能良好的微小透镜。

Microlenses as the typical micro-optical devices play an important role in the field of applied optics. According to the formation principle that the steady-state spherical cap shape of the droplet has the minimum free energy, the effects of the droplet contact angle and volume on its shape were analyzed. By modeling the micro droplet with the programming software Surface Evolver, the numerical calculation of the droplet steady-state shape was performed. By changing the droplet volumes as required and the contact angles on different hydrophobic substrates, a series of the polymer microlenses with different sizes and shapes were fabricated. The experimental measurements of microlenses are in good agreement with simulation results. The measurement results show that when the droplet contact angle increases, the bottom diameter of the microlens decreases while the height increases; when the droplet volume increases, the bottom diameter and height of the microlens increases. In addition, when the volume of the droplet is small, the spherical microlens with small aspherical coefficient can be obtained. The optical parameter measurement and imaging experiment show that the droplet microlenses with different optical parameters and good optical properties can be fabricated by adjusting the contact angle and volume.