Design of Near Infrared Continuous Zoom Optical System

Abstract

In order to achieve continuous fine recognition of targets with limited distance, a large zoom ratio near infrared continuous zoom optical system has been designed. Based on the zoom system and its automatic design principle of aberrations, reasonable technical indicators were formulated, the initial structure of the system was determined, and the optical design software CodeV was used to optimize it to achieve a continuous zoom optical system with good imaging quality. The system uses a detector of 4.5-micron $\times$ 4.5-micron pixels, and the field of view is 2.7-degree $\times$ 2.7-degree $\sim$ 12.7-degree $\times$ 12.7-degree, F number is 4.8, using mechanical positive group compensation method, composed of front group, zoom group, compensation group and rear group, including 14 spherical lenses. The design results were evaluated for image quality and the cam curve was solved. The design and analysis results show that the system achieves a continuous zoom of 70-mm~350-mm in the 750-nano $\sim$ 900-nano band. The optical modulation transfer function of the system is better than 0.3 at Ill-lp/mm, the maximum distortion is less than 2%, the image quality is good, and the processing cost is low. The system has the characteristics of large zoom ratio, high resolution, compact structure and smooth zoom curve, and can be used for fine recognition of limited distance targets.