Design of catadioptric middle infrared continuous zoom lens for uncooled infrared detector

For uncooled 320×240 infrared detector, a catadioptric middle infrared continuous zoom lens is presented. The optical system is divided into three segments. First of all, a reflective system is designed as the front system. Then the continuous zoom lens which matches with the reflective system as the back system is designed. The conversed back system is assembled at the first imaging of the optical system with the reflective system. A continuous variable magnification catadiootric telescope is obtained. Projection objective is designed based on the telescope lastly. To ensure the imaging quality of the system, the whole system is optimized with the CODE V software. The system can realize 200mm~800mm continuous zoom. The designed result shows the system has the advantages of simple structure, short zoom path and smooth zoom locus, high image quality and approached or reached to the diffraction limit.