Zoom optics is important in many applications and especially IR zoom optics in military applications for reconnaissance, detection and recognition of important targets. As IR array detectors of small pitch and large format become commonly available, performance requirement of IR zoom optics has been upgraded for better spatial resolution, lighter weight, and smaller size which is particularly relevant to airborne IR zoom optics.

This thesis addresses two main issues usually raised in the development of an airborne IR zoom optics: the design of a compact system and a smart management of tolerance for better performance. The design of a compact system proceeds in three phases. In the first phase, the basic concept and layout of the optical system is determined. In the next phase, a method is devised to equalize the pixel response of the IR detector in the system. In the third stage, the system is athermalized.

In the first phase, the reimaging structure is applied to the optics to obtain a 100% of cold stop efficiency and to minimize the size of optical aperture. In addition, the overall package size can be reduced and the optics has the flexibility in the layout by the installation of folding mirrors.

In the second phase, the new approach which provides the blurred image to the detector by the use of a variator of the zoom optics is proposed. Through, the IR detector is able to have a uniform image to effectively correct the non-uniformity of it without any opto-mechanical support and extra space.

In the third phase, an efficient method for the athermalization which uses the zoom loci of the zooming lenses depending on the temperature variations is applied to the zoom optics and its performance is verified through the thermal analysis. In fact, this approach does not require any additional moving mechanism and space. Thus it can make the system compact and simple.

As for the tolerance management, both tolerances of fabrication and assembling are combined to correctly predict the real performance of the completed system. The wavefront error of the system is analyzed by utilizing Zernike polynomials and the sensitivity of the various parameters to the tolerances is obtained. Based on this sensitivity analysis, the optimal tolerance of fabrication parameters are determined and the best compensators for assembly process are selected. By using this method one can accurately predict the best possible performance of a completed optical system in practice with good confidence.