The design of a zoom optical system in short-wave infrared

With the continuous development of detection technology in short-wave infrared (SWIR) and the increasing demand to maintain reconnaissance continuity on the target, the need for a zoom optical system in short-wave infrared is rising as well. Due to the short focal length of the current zoom optical system in short-wave infrared and the challenge of correcting chromatic aberration in glass materials in large aperture, the dispersion characteristics of visible light optical glasses of Chengdu Guangming Company in the short-wave infrared band of 0.9μm ~1.7μm are statistically analyzed and a glass catalog was established, based on which material screening and material matching are carried out. A zoom optical system in short-wave infrared with a 20x zoom ratio was designed in this paper. The three-piece combination structure was adopted in the variator and compensator of the system, and the combination of high- and low-dispersion glass materials was adopted to correct chromatic aberration. The optical system adopts the zoom mode of mechanical compensation, the zoom range is 50mm~1000mm, and the F number is 6. At room temperature, the MTF of each field is close to the diffraction limit. The temperature adaptation range of the optical system is -40℃~+60℃, and only the axial movement of the compensator is used to carry out active athermalization in a high and low temperature environment, and the imaging quality is excellent throughout the temperature range. The system adopts secondary imaging to constraint the aperture of the system and the aspherical design to ensure imaging quality. The designed optical system can match the InGaAs short-wave infrared detector with an array size of 640×512 pixels and a pixel pitch of 15μm. This paper provides a good solution for the design of a zoom optical system in short-wave infrared with long focal length and large aperture.