Synthetic system design method for off-axis stabilized zoom systems with a high zoom ratio.

Abstract

Stabilized zoom systems possess the advantages such as the simplified system layout, improved system stability, enhanced imaging performance, and a high zoom speed. The complex system design to achieve high performances requires calculations or investigations of the initial system for optimization and improvements, and thus, specific design techniques are pursued. In this study, we propose an automatic optical design scheme of synthetic characteristics for the off-axis stabilized zoom systems, which using focal length variable (FLV) opto-electronic elements and with a high zoom ratio. The study aims at evaluating and synthetically achieving the zooming properties and the image quality balance of entire focus imaging. The multi-element stabilized zoom systems are characterized using the Gaussian brackets expressions and their optimal solution ranges for high zoom ratios are deduced to achieve non-defocusing imaging in specific stroke ranges of FLV elements. Then considering the analytical characterization of the off-axis-induced primary aberrations at multi-conjugate positions, we use a conic surface to deduce the basic expression of the nodal aberration. Thereby the nonlinear global merit function is established with a semi-empirical mathematical model based on nodal aberration theory and nonlinear zoom equation for maintaining the stability of focal length and image plane drift. And the theory of Pareto Optimality is employed in the process of verifying the superiority of the solutions. Finally, a series of solutions for a high zoom ratio and aberration compensation are implemented and the optimal configurations with conical surfaces for an off-axis stabilized zoom system are obtained.