Infrared Zoom System

IR zoom system has been widely used in many fields,and now it is one of the new projects in IR technology research.The paper presents the methods for IR zoom system design based on the theory of visible light zoom system design. A new theory is given to accelerate the zooming procedure based on varifocal differential equation theory of zoom lens.Compared with visible light system, IR system has its characteristic. The environment effects the performance of IR optical system a lot. The shift of focus and atmospheric attenuation are two significant problems in the infrared region of the wavelength spectrum. The energy of IR light declines through the atmosphere. In this paper the operating distance and lens data are determinated based the analysis of IR feature of target and IR transmission and emission of the atmosphere. The shift of focus declines the performance of IR optical system, two methods for finding the solution of thermal effect are given, and the operating temperature sale is discussed.A long-wavelength IR zoom camera with a zoom rang of 4:1 and automatic athermalization has been developed with mechanical compensated method. The moving groups are two lens groups and the loci of zoom are simple, which allows easy access of optomechanical and electromechanical design.The focal length of the continuous zoom varies from 50mm to 200mm with good performance. In addition, a mid-wavelength IR zoom camera with a zoom rang of 4:1 has been developed with optical compensated method.