Abstract
In this century, the optical plastic lenses have been widely used in smart phones with increasing production volume. Today, injection molding process has become the major production method due to the advantage of mass-production and lower costs. However, the polymeric materials would experience fast liquid-solid phase change due to rapid cooling during the process and exhibit consequential and dominant optical defects, i.e. post-shrinkage, birefringence and refractive index inhomogeneity. Now, all plastic lens manufacturers are facing the biggest challenges since quality improvements in circumventing all the defects in the lenses. In the process, the polymeric melt is injected via a runner system and gates into a mold, and then packed under high pressure until cooled to a solid part; hence, the melt has an thermo-mechanical history with visco-elastic effects. Consequently, the process introduces residual stresses and polymer orientation into the molded lenses which exhibit residual birefringence, lens warpage and shrinkage. The residual stresses would eventually affect the image quality of the injection molded lenses. In this thesis, a plano-convex lens molded with COP, ZEONEX 480R are used in the experiments. The wavefront measurement systems based on Shack-Hartmann sensor are adopted for verifications of factors influencing the image quality including surface deviations and birefringence. Then, CAE simulations based on commercial FEM predict stresses and warpage of the optical lens, and transforms the mechanical properties into the optical qualities so that wavefront aberrations could be calculated and verified. Finally, Optical performances such as PSF, MTF and Strehl Ratio are calculated based on the FFT of wavefront functions for serving the final optical quality.