Study of extended optimization for U-type 2× zoom optics with free-form surface

In this paper a U-type 2× zoom miniature lens design with two prisms will have less overall length than a general optical design; however, with the zigzag path of light, aberrations like: spherical aberration, coma aberration, distortion, and Image Plan Offset will result. In such a design, a free-form surface prism with aspherical coefficients may significantly improve the system's performance if the coefficients of the free-form surface prisms are well optimized. A combination of the Taguchi Method and the robust multiple criterion optimization (RMCO) approach is employed in this study to achieve success in minimizing axial aberrations such as spherical and coma aberrations. In the RMCO approach, a Pareto-optimal robust design solution is set with the aid of experimental set-ups that use ANOVA results to quantify the relative dominance and significance of the design factors. It is concluded that the Taguchi Method and RMCO approach can successfully reduce the spherical aberration (43.93%) and coma (29.89%) of the U-type 2× zoom lens system.