Design And Research Of The Long Wave Infrared Zoom System

With the development of the society, optical design industry is becoming more and more concerned by people, and gradually to be an important field of current researches in different countries. Infrared can be used for night detection, because of the capacity of passing throughthe dust and smoke. Hence the infrared zoom detector also penetrates into some special industries with its unique superiority. According to the requirement of3304factory of Chinese people’s liberation army general armaments department, this paper designs a long wave infrared zoom lens. Due to the aspheric surface design, the lens has simple structure to be installed easily, and good image quality.This paper firstly introduces the general situation of the development of infrared zoom lens, then describes three compensation methods, especially introduces the mechanical compensation method, and based on the analysis of the compensating curve, negative group compensation is selected as the structure design method.Based on the initial structure of a reference patent US4148548A and the use of CODE-V as optical design software, optimization design can be achieved. The detector is expected to be simple and convenient to carry. To simplify the system structure and eliminate aberration, this paper adds aspheric surface design, then evaluates the system image quality by field curvature, distortion and modulation transfer function. Though the image quality evaluation, it is founded that the distortion in various focal length is almost equal to zero, field curvature is also in the permitted range, and MTF value in the limit frequency is reached more than0.5.Combining with application and actual production, this paper gives the tolerance analysis of MTF value in the system, shows that the probability of MTF value above0.2is100%.Finally this paper cited a new method to design the cam curve. Namely inputting the shift position points of variable magnification unit in the PROE software, then setting the appropriate horizontal ordinate to get smooth cam curve, this method is easier than the general programming method.