Abstract
Abstract Due to the increasing demand of the high-power laser applications, devices protecting detectors or human eyes, optical limiters, become an important research direction in the recent years. Nonlinear absorbing materials are attractive in designing this type passive optics limiters. The advantage of the optics limiter in the passive form is the speedy response to the incidence energy. Designs based on the nonlinear absorbing material can offer very strong excited-state absorption, and effectively restrain incidence energy. Besides the choice of nonlinear materials, there is another important issue in designing optics limiters, geometry. Different geometric arrangements, such as tandem structure and graded-density structure, have been proposed to achieve better limiting performance. The main purpose of those designs is creating a second protection for the chief absorption element. A dual-focus limiting design has demonstrated the best limiting performance with the price of increasing length. In this thesis we propose different designs to shorten the length as well as improving the imaging quality of this optical system. Spherical aberration and astigmatism are the primary aberrations in this situation. We simulate five different kinds of folded designs to shorten the total length of the original design. We are able to come up with a design that preserves the performance and make the whole system more compact. It can be useful in military applications.